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In this paper we summarize our recently-published work on estimating horizontal response spectra and peak acceleration for shallow earthquakes in western North America. Although none of the sets of coefficients given here for the equations are new, for the convenience of the reader and in keeping with the style of this special issue, we provide tables for estimating random horizontal-component peak acceleration and 5 percent damped pseudo-acceleration response spectra in terms of the natural, rather than common, logarithm of the ground-motion parameter. The equations give ground motion in terms of moment magnitude, distance, and site conditions for strike-slip, reverse-slip, or unspecified faulting mechanisms. Site conditions are represented by the shear velocity averaged over the upper 30 m, and recommended values of average shear velocity are given for typical rock and soil sites and for site categories used in the National Earthquake Hazards Reduction Program's recommended seismic code provisions. In addition, we stipulate more restrictive ranges of magnitude and distance for the use of our equations than in our previous publications. Finally, we provide tables of input parameters that include a few corrections to site classifications and earthquake magnitude (the corrections made a small enough difference in the ground-motion predictions that we chose not to change the coefficients of the prediction equations).

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... In the case study (Section 11.12) the relationships developed by Kalkan and Gülkan (2004) and Boore, et al. (1997) are used both individually and in combination. They are selected due to the fact that the first one was derived based on local data and the second one was used in the development of the seismic zoning map of Turkey. ...

... The following attenuation relationship is proposed by Boore et al. (1997). The values of the coefficients involved in this attenuation relationship are tabulated in the form of "smoothed coefficients for pseudo-acceleration response spectra (g)" (Boore, et al., 1997). ...

... The following attenuation relationship is proposed by Boore et al. (1997). The values of the coefficients involved in this attenuation relationship are tabulated in the form of "smoothed coefficients for pseudo-acceleration response spectra (g)" (Boore, et al., 1997). ...

LECTURE NOTES for the graduate course CE 589 STRUCTURAL RELIABILITY taught at the Department of Civil Engineering, Middle East Technical University during the Spring 2021-2022 Semester.
Cite as:
“Yücemen, M. S, Lecture Notes, CE 589 Structural Reliability, Spring 2021-2022 Semester, Department of Civil Engineering, Middle East Technical University, Ankara, Tukey, June 2022”.
DOI: 10.13140/RG.2.2.19345.71529.
Note:
PDFs of the slides of the online lecture presentations related to the CE 589 Structural Reliability course are grouped into three parts and are also uploaded to ResearchGate under the following titles:
PART I REVIEW OF PROBABILITY AND STATISTICS PDFs of the slides of the lectures given;
PART II STRUCTURAL RELIABILITY PDFs of the slides of the lectures given;
PART III APPLICATIONS AND CASE STUDIES PDFs of the slides of the lectures given.
These presentations, which complement the Lecture Notes, can also be used for educational purposes without the written permission of the author by citing the source as:
“Yücemen, M. S, Presentations of the Lectures of CE 589 Structural Reliability course, Parts I/II/III, Spring 2021-2022 Semester, Department of Civil Engineering, Middle East Technical University, Ankara, Tukey, October 2022”.

... The Gökova fault zone and the Fethiye-Burdur fault zone stand out as the significant fault zones in the region. The attenuation relationships suggested by Boore et al. (1997), and Kalkan and Gülkan (2004) were used to determine the peak ground acceleration values on the bedrock for the 50-year economic life of the buildings for an exceedance probability of 10%. ...

... Finally, total ground motion magnitudes were calculated for the specified probability of exceedance by probabilistic evaluation. In the study, the seismic sources were defined as areal sources in the software Fig. 15 The PGA map generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) Fig. 16 The map of spectral acceleration with a period of T = 0.2 s generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) Fig. 17 The map of spectral acceleration with a period of T = 1.0 s generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) using their seismicity parameters. The seismic hazard analyses are conducted to predict the most hazardous earthquakes that may occur throughout the average economic life of the buildings. ...

... Finally, total ground motion magnitudes were calculated for the specified probability of exceedance by probabilistic evaluation. In the study, the seismic sources were defined as areal sources in the software Fig. 15 The PGA map generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) Fig. 16 The map of spectral acceleration with a period of T = 0.2 s generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) Fig. 17 The map of spectral acceleration with a period of T = 1.0 s generated based on the exceedance probability of 10% using the attenuation relationships of Boore et al. (1997), , Kalkan and Gülkan (2004) (map from Yılmazoğlu 2015) using their seismicity parameters. The seismic hazard analyses are conducted to predict the most hazardous earthquakes that may occur throughout the average economic life of the buildings. ...

Muğla Province, which has been selected as the study area, is located in the Aegean Extension Region (AER), where seismic motions are widely observed. Moreover, the AER is the most active part of the Eastern Mediterranean Region in terms of seismic activity, and this seismicity has been continuing increasingly. This study aims to determine the seismic hazard of Muğla Province and its surroundings by using the probabilistic seismic hazard method. The earthquake dataset including 19,824 seismic records that were used in the research was obtained from the national and international earthquake catalogs. The data about the active fault zones in the study area were acquired from the General Directorate of Mineral Research and Exploration. The seismic source zones were generated as homogeneous areas as possible taking into account the active fault zones. The earthquakes in seismic source zones were eliminated based on the time and distance frames. The annual recurrence relationships of the source zones were determined using the least-squares method taking into account the earthquakes with a magnitude of 5 or above. The peak acceleration values on the bedrock were calculated using the attenuation relationships of the selected local and global ground motion prediction models. The calculations were performed using the SEISRISK III software package utilizing the homogeneous Poisson Process Model according to the exceedance probability of 10% for 50 years (corresponding to the return period of 475 years). The peak acceleration values on bedrock were found to range between 0.11 and 0.42. The study revealed that the Gökova fault zone (Zone 4) was the most active source in terms of the seismic hazard in the region and that the seismic hazard of the southwestern part of the region was greater compared to other parts.

... They concluded that peak ground acceleration, maximum spectral acceleration and amplification ratio using SPT data is higher than the MASW data The correlation between standard penetration test N values and shear modulus of low strain was examined in the suggested work in [18]. ...

... They worked to develop the relationships between SPT N values & Low Strain Shear Modulus (Gmax).The methods[18] and[19] investigated for Indo-Gangetic basin in Lucknow in the identification of seismic site and correlation between velocity of shear wave and standard penetration test N value. The experiments are performed to measure the seismic site classification and subsurface lithology of ...

An endeavour has been made to assess the spatial fluctuation of the profundity of endured and designing bedrock in Gorakhpur Uttar Pradesh, North India utilizing Multichannel Analysis of Surface Wave (MASW) study. One-layered MASW study has been done at Madan Mohan Malaviya University of Technology, Gorakhpur campus and Shear-wave Velocity V S 30 are estimated. MASW overview at 3 location and a Standard Penetration Test SPT-N from the profound geotechnical boreholes data used for comparison of site classification. The deduction of this work might be utilized as contributions for seismic tremor risk the board by lessening the seriousness of earthquake shaking through plan of tremor Earthquake risk resilient structure strong designs. The data that collected from the MASW experimental setup is feed using the software ParkSEIS (v.3.0), we obtain Shear Wave Velocity (V S 30 ). The obtained V S 30 is used to plot Response Spectra for MMMUT Gorakhpur. The Time History data used in this thesis is Nepal Earthquake 2015 data which is collected from Indian Metrological Department (IMD) Delhi, India. SPT-N value data is collected from Awas Vikas Parishad for the New Administration Building build at MMMUT campus Gorakhpur. The Time History data of Nepal Earthquake 2015 is analysed using DEEPSOIL v7 Software and a systematic layer wise study of MMMUT Campus soil is carried out, results such as Ground Motion Parameters, Response Spectra, Spectral acceleration vs Frequency plot, Tripartite Spectrum and Response spectra corresponding to 5% damping are obtained.

... In some models or equations, site geological conditions were divided into only two categories: soil and rock conditions (Khademi 2002;Amiri et al. 2007). However, by considering other studies, three different site categories of soft and stiff soil and rock were used for the current study (Boore et al. 1997;Ambraseys et al. 2005a, b;Zare and Sabzali 2006). The reason for not choosing 4 site categories was the number of data points in each group; by choosing four site categories, the number of data points would be decreased, resulting in poor Fig. 1 Encircling of the Prey in 2D problem space (Mirjalili et al. 2014) modeling and an overfitting problem in GWO modeling. ...

... Because of the limited amount of information and knowledge in the recorded data of earthquakes, some parameters, such as alluvium depth and mechanism of rupture, were not considered in the present equation. This simplified the relationship application and allowed it to be compared to other GMPEs proposed by Boore et al. (1997), Khademi (2002), Zare and Sabzali (2006), and Amiri et al. (2007). ...

Ground motion prediction equations (GMPEs) are open challenge problems that have been developed since 1964. Parametric and nonparametric methods predict ground motion characteristics such as peak ground acceleration (PGA), velocity, displacements, and spectral accelerations. In the present study, the grey wolf optimization (GWO) algorithm was used to obtain a new and developed GMPE for predicting PGA. Data from recorded earthquakes from all over the world were collected, and after filtering of Mw and distance parameters, close to 2000 data were used for modelling. Three parameters of Mw (4–7.9), epicentral distance (0.25–115 km) and geological conditions (soft soil, stiff soil, rock) were used as input parameters for estimating PGA. Many previous studies classified geological conditions based on shear wave velocity at the top 30 m (Vs30), without taking into account the effect of Vs30 at each group. In this study, the effects of Vs30 were considered separately for each geological group too. Results showed that PGA decreased by increasing Vs30 and moving from soft soil toward rock. Finally, the relationship was compared with the other two relations suggested for the local region and global earthquakes, and despite the simplicity of the suggested relation gained by the GWO method, it estimated PGA in terms of accuracy to a good and acceptable level.

... CHEEP did not include Chiou and Youngs (2014) as one of its in-built GMPEs so stochastic models for this GMPE are also not available in the form required by this software. Because the software to repeat Scherbaum et al. (2006)'s inversion process is not available, the stochastic models provided in CHEEP for the WNA GMPEs of Abrahamson and Silva (1997) and Boore et al. (1997) were both used as proxies for the unavailable stochastic models for Chiou and Youngs (2014). By examining the match between the predictions from these stochastic models and the Chiou and Youngs (2014) GMPE over a wide range of magnitudes and distances it was confirmed that these stochastic models are suitable for the HEM. ...

... By examining the match between the predictions from these stochastic models and the Chiou and Youngs (2014) GMPE over a wide range of magnitudes and distances it was confirmed that these stochastic models are suitable for the HEM. In addition, similar backbone GMMs were obtained by using both the stochastic models for Abrahamson and Silva (1997) and that for Boore et al. (1997). As the backbone GMM was only being used for comparisons and not for the actual PSHA, and because small misfits between empirical and stochastic host models have previously been shown to be relatively unimportant (Campbell 2003;Douglas et al. 2006), it was decided that the use of these approximate stochastic models was sufficient for our purposes. ...

A key task when developing a ground-motion model (GMM) is to demonstrate that it captures an appropriate level of epistemic uncertainty. This is true whether multiple ground motion prediction equations (GMPEs) are used or a backbone approach is followed. The GMM developed for a seismic hazard assessment for the site of a UK new-build nuclear power plant is used as an example to discuss complementary approaches to assess epistemic uncertainty. Firstly, trellis plots showing the various percentiles of the GMM are examined for relevant magnitudes, distances and structural periods to search for evidence of “pinching”, where the percentiles narrow excessively. Secondly, Sammon’s maps, including GMPEs that were excluded from the logic tree, are examined to check the spread of the GMPEs for relevant magnitudes and distances in a single plot. Thirdly, contour plots of the standard deviation of the logarithms of predicted ground motions from each branch of the logic tree (σµ) are compared with plots drawn for other relevant hazard studies. Fourthly, uncertainties implied by a backbone GMM derived using Campbell (2003)’s hybrid stochastic empirical method are compared to those of the proposed multi-GMPE GMM. Finally, the spread of the percentile of hazard curves resulting from implementing the GMM are examined for different return periods to check whether any bands of lower uncertainty in ground-motion space result in bands of lower uncertainty in hazard space. These five approaches enabled a systematic assessment of the level of uncertainty captured by the proposed GMM.

... Thus, it requires an intensity measure that is able to well characterize a pair of horizontal ground motions. In the past decades, several types of intensity measures have been proposed, such as the geometric mean of as-recorded horizontal components [15], denoted by GM AR , orientation-independent geometric mean with period-independent rotation angles [16], denoted by GMRotIpp, and orientation-independent pp-percentile single-component spectrum [17,18], denoted by RotDpp. All these intensity measures, especially for the recently proposed intensity measure RotDpp, have been used to develop ground motion prediction equations (GMPEs) by many researchers [15,[19][20][21][22]. Since RotDpp overcomes some unrealistic characteristics of other proposed intensity measures, it is preferred to be used in developing GMPEs [21][22][23]. ...

... In the past decades, several types of intensity measures have been proposed, such as the geometric mean of as-recorded horizontal components [15], denoted by GM AR , orientation-independent geometric mean with period-independent rotation angles [16], denoted by GMRotIpp, and orientation-independent pp-percentile single-component spectrum [17,18], denoted by RotDpp. All these intensity measures, especially for the recently proposed intensity measure RotDpp, have been used to develop ground motion prediction equations (GMPEs) by many researchers [15,[19][20][21][22]. Since RotDpp overcomes some unrealistic characteristics of other proposed intensity measures, it is preferred to be used in developing GMPEs [21][22][23]. ...

Response history analyses are usually conducted to evaluate seismic performance of buildings. Since azimuth-dependent buildings are quite common in practice, bidirectional ground motions are considered to be important input motions for the analyses. Based on RotDpp target response spectrum that is widely used to characterize seismic loads of bidirectional ground motions, this study proposes a method to generate spectrum-matched bidirectional time histories using Hilbert-Huang Transform (HHT). To demonstrate applicability of the proposed method, 15 pairs of spectrum-matched bidirectional time histories are generated by the proposed method for a nuclear power plant site. The study further discusses compatibility between these generated bidirectional time histories and the RotDpp target response spectrum. After that, these spectrum-matched time histories are applied to calculate floor response spectra of a service building for a nuclear power plant. After analyzing relative errors of the calculated floor response spectra, advantages of the proposed method are demonstrated. The study finds that, bidirectional time histories generated by the proposed method well match the RotDpp target response spectrum, and they could also provide accurate seismic response analysis of three-dimensional buildings.

... Kowsari et al. [4,5] recalibrated the ground motion models (GMMs) to the dataset using Bayesian regression and Markov Chain Monte Carlo simulations which allow limited strong motion data to be combined with the prior information, and can well overcome sparse data in the research region. With the improvement of regression methods [6,7] and the accumulation of strong motion recordings, GMPEs gradually considered the influence of style-of-faulting, hanging-wall effect, or linear and nonlinear site response [8][9][10][11]. In 2008 and 2014, PEER NGA-West1 and NGA-West2 established a database containing strong motion data and related metadata in shallow crustal active tectonic regions worldwide. On this basis, five teams considered the earthquake source characteristic (magnitude, style-of-faulting, hanging-wall effect), path effect (distance), site effect (linear/nonlinear response of soil, basin response), and regional differentiation. ...

... Fig. 3 shows the epicenters, the focal sphere of the selected 48 earthquakes, and the fault distribution. A simple classification of style-of-faulting is made according to the rake angle [9]. The hypocentral depth is uniformly obtained from the China Seismic Network Center. ...

In this paper, we collect and process free-field strong motion recordings from 70 earthquakes for 4.2 ≤ MW ≤ 7.9 at 0 < Rrup < 300 km between 2008 and 2018 in the active tectonic regions of southwest China, and then establish a dataset containing 1324 average horizontal ground motion (ROTD50) and corresponding metadata such as parameters of the earthquake source, distance, and site. A new ground motion prediction equation (GMPE) for the average horizontal component of peak ground acceleration (PGA), peak ground velocity (PGV), and 5% damped acceleration response spectra at periods ranging from 0.033 to 8.0 s (SA (T = 0.033–8.0 s)) is introduced. This GMPE considers multiple influencing factors such as magnitude and distance saturation effect, geometric attenuation, style-of-faulting, hanging-wall effect, linear/nonlinear site response, and anelastic attenuation. The residual evaluation and median ground motion are presented. The predicted ground motions using the new GMPE are compared with predictions from the GMPE in western China and five NGA-West2 GMPEs, and the observed ground motions of strong earthquakes which occurred in southwest China. The results show that the proposed GMPE can better reflect the influence of the earthquake source characteristic, propagation media, site effect on the ground motion attenuation characteristic in southwest China, and works well versus independent strong motion data of earthquakes in southwest China, and well reflects the general feature of ground motions for the Wenchuan and Lushan earthquakes that is rich at short-period and weak at long-period. The new GMPE shows outstanding performance estimating the horizontal ground motion of the earthquakes in southwest China for MW 4.2–7.9 (related to style-of-faulting) and Rrup = 10–200 km, at sites with VS30 = 140–1130 m/s.

... The first probabilistic peak ground acceleration (PGA)-based seismic hazard map was formulated in 2003 (Kuka et al., 2003),18 which served as the base map for seismic risk assessment in Albania in 2003. The map currently in use by IGEWE is that of Kuka and Duni (2007), which is shown in Figure 9. Probabilistic seismic hazard map of Albania in terms of PGA for 475 years of return period (10% exceedance probability in 50 years) using the Boore et al. (1997) 19 ground motion prediction equation (GMPE) with rock site conditions (source: Boore et al., 1997;Kuka and Duni, 2007). 20 The 2015 hazard map of the Western Balkan countries in the framework of the North Atlantic Treaty Organization Science for Peace project (NATO Science for Peace Program, SPS Reference 984374) generally agreed with the 2007 version of the hazard map shown in Figure 9. ...

... The first probabilistic peak ground acceleration (PGA)-based seismic hazard map was formulated in 2003 (Kuka et al., 2003),18 which served as the base map for seismic risk assessment in Albania in 2003. The map currently in use by IGEWE is that of Kuka and Duni (2007), which is shown in Figure 9. Probabilistic seismic hazard map of Albania in terms of PGA for 475 years of return period (10% exceedance probability in 50 years) using the Boore et al. (1997) 19 ground motion prediction equation (GMPE) with rock site conditions (source: Boore et al., 1997;Kuka and Duni, 2007). 20 The 2015 hazard map of the Western Balkan countries in the framework of the North Atlantic Treaty Organization Science for Peace project (NATO Science for Peace Program, SPS Reference 984374) generally agreed with the 2007 version of the hazard map shown in Figure 9. ...

On the morning of Tuesday, November 26, 2019, at 3:54 local time, an MW 6.4 earthquake struck 16 km north of Durrës, a port city on the Adriatic coast and the second largest city in Albania. The epicenter was 33 km northwest of Tirana, the largest city and capital of Albania. Deaths and injuries were concentrated in Durrës and the village of Thumanë, though Tirana and several smaller municipalities in northwestern Albania were also affected. With 51 fatalities, the earthquake was the deadliest worldwide in 2019.
The EERI report of the earthquake is divided into four volumes:
(1) Volume 1 is the Executive Summary, which provides a brief overview of the key observations in all areas.
(2) Volume 2, “Seismology and Geotechnical Effects,” describes seismological aspects of the earthquake and a summary of geotechnical impacts.
(3) Volume 3, “Resilience and Recovery,” describes response and recovery as well as the performance of lifelines and transportation infrastructure.
(4) Volume 4, “Building Performance,” focuses on the performance of major construction types: residential masonry buildings, cast-in-place reinforced concrete buildings and prefabricated reinforced concrete buildings. Performance of special use buildings, including schools, hospitals, and heritage and religious structures, is also described. An overview of Albanian building codes and construction practices is also provided in this volume, along with damage assessment data collected by several of the reconnaissance teams.

... After the 2005 Kashmir earthquake, the BCP (2007) introduced PSHA based zoning map of Pakistan along with the seismic hazard provisions for the building code and placed the HKS and adjoining area under seismic zone 3 and 4, the area with a PGA ranges from 0.24 to > 0.32g. Following the hazard assessment work, Monalisa, Khwaja et al. (2007) utilized the Ambraseys et al. (1996) and Boore, Joyner et al. (1997) attenuation relations to produce the peak ground acceleration (PGA) curve for major cities in north Pakistan, including Kaghan, Muzaffarabad, andIslamabad. Later 2010, Hashash, Kim et al. (2012), Rafi, Lindholm et al. (2012), and Zaman, Ornthammarath et al. (2012) contributed to the hazard assessment of Pakistan. ...

... This equation is significantly modified from GMPEs developed by (Boore, Joyner et al. 1997). The generalized form of attenuation relationship (10) is mentioned below: ...

The Hazara Kashmir syntaxes (HKS) is located in the western Himalayas in Pakistan that marks the easternmost proximity of the western Himalayan mountain system and is regarded as one of the most tectonically active domains of the world. In this study, the seismic ground motion parameters have been calculated for Hazara Kashmir syntaxes and its surrounding. The seismic hazard parameters were computed using probabilistic seismic hazard analysis (PSHA) and the standard Cornell-McGuire method at each grid spacing of 0.1° × 0.1°. This study encompasses the seismic records of the historical and instrumental database to establish the recurrence relationship based on an appropriate ground motion prediction equation (GMPE). Recently developed, the Boore and Atkinson (2008) next-generation attenuation (NGA) and Akkar and Bommer (2007) attenuation relationships were adopted for hazard computation. The resultant peak ground acceleration (PGA) maps and spectral intensity curves at T = 0.05 to T = 3, for 100, 250, 475, 1000, and 2500 year return periods have been estimated at bedrock level. This study concludes that the seismic provision for the building code of Pakistan needs to be revised and updated.

... The 2001 NSHM considered several alternative GMMs all weighted equally. For earthquakes between M5 and 7, the 2001 model considered the following GMMs: for PGA, they applied the Boore et al. (1997), Sadigh et al. (1997), Campbell (1997), and Munson and Thurber (1997); for 0.2-s SA, they used the same suite but excluded the Campbell (1997) equation and applied a factor of 2.2 to the Munson and Thurber (1997) PGA GMM to estimate this high-frequency shaking; and for 1.0-s SA, they used the Boore et al. (1997) and Sadigh et al. (1997) equations. They considered similar models for earthquakes larger than M7: for PGA and 0.2-s SA, they applied the Sadigh et al. (1997) GMM and a modified version of Munson and Thurber (1997) GMM that considered alternative magnitude scaling parameters; for 1.0-s SA, they only used the Sadigh et al. (1997) GMM. ...

... The 2001 NSHM considered several alternative GMMs all weighted equally. For earthquakes between M5 and 7, the 2001 model considered the following GMMs: for PGA, they applied the Boore et al. (1997), Sadigh et al. (1997), Campbell (1997), and Munson and Thurber (1997); for 0.2-s SA, they used the same suite but excluded the Campbell (1997) equation and applied a factor of 2.2 to the Munson and Thurber (1997) PGA GMM to estimate this high-frequency shaking; and for 1.0-s SA, they used the Boore et al. (1997) and Sadigh et al. (1997) equations. They considered similar models for earthquakes larger than M7: for PGA and 0.2-s SA, they applied the Sadigh et al. (1997) GMM and a modified version of Munson and Thurber (1997) GMM that considered alternative magnitude scaling parameters; for 1.0-s SA, they only used the Sadigh et al. (1997) GMM. ...

The 2021 US National Seismic Hazard Model (NSHM) for the State of Hawaii updates the previous two-decade-old assessment by incorporating new data and modeling techniques to improve the underlying ground shaking forecasts of tectonic-fault, tectonic-flexure, volcanic, and caldera collapse earthquakes. Two earthquake ground shaking hazard forecasts (public policy and research) are produced that differ in how they account for declustered catalogs. The earthquake source model is based on (1) declustered earthquake catalogs smoothed with adaptive methods, (2) earthquake rate forecasts based on three temporally varying 60-year time periods, (3) maximum magnitude criteria that extend to larger earthquakes than previously considered, (4) a separate Kīlauea-specific seismogenic caldera collapse model that accounts for clustered event behavior observed during the 2018 eruption, and (5) fault ruptures that consider historical seismicity, GPS-based strain rates, and a new Quaternary fault database. Two new Hawaii-specific ground motion models (GMMs) and five additional global models consistent with Hawaii shaking data are used to forecast ground shaking at 23 spectral periods and peak parameters. Site effects are calculated using western US and Hawaii specific empirical equations and provide shaking forecasts for 8 site classes. For most sites the new analysis results in similar spectral accelerations as those in the 2001 NSHM, with a few exceptions caused mostly by GMM changes. Ground motions are the highest in the southern portion of the Island of Hawai’i due to high rates of forecasted earthquakes on décollement faults. Shaking decays to the northwest where lower earthquake rates result from flexure of the tectonic plate. Large epistemic uncertainties in source characterizations and GMMs lead to an overall high uncertainty (more than a factor of 3) in ground shaking at Honolulu and Hilo. The new shaking model indicates significant chances of slight or greater damaging ground motions across most of the island chain.

... The earthquakes that occurred within the last 100 years are used for estimating seismic parameters. Due to the unavailability of strong motion records, various attenuation relationships are adopted (Campbell, 1981;Joyner and Boore, 1981;Boore et al., 1993Boore et al., , 1997Campbell andBozorgnia, 1994 andAmbraseys, 1995) to calculate the peak ground acceleration (PGA) acting on dam sites. ...

... The probabilistic hazard calculation was performed to obtain 5 percent damped elastic hazard pseudoacceleration spectra and to generate the response spectrum compatible acceleration time histories for time domain analyses. Fig. 3 shows the elastic hazard acceleration spectra on the basis of Boore et al. (1997). ...

Turkey is an earthquake country and has so many dams, which are located in very active seismic regions. The construction of concrete-faced rockfill dam has been started in 1997 in Turkey. However, the concrete-faced rockfill dam has been used with increasing frequency in recent years in the country. Six concrete-faced rockfill dams ranging in height from 74 to 152 m have been designed and constructed since 1997. Further studies for twenty-five dams of this type are under design stage in Turkey. In this paper, concrete-faced rockfill dams (CFRDs) in Turkey are evaluated as
considering local seismic effects and their safety is also criticized when subjected to seismic excitation. Pamukluk dam, which has 95 m height from the foundation and is constructed as a concrete-faced rockfill dam at the southern portion of Turkey, was selected to carry out a research program to explain the unknown behavior of a CFRD under earthquake loadings. For that purpose, the finite element models (FEM) were used and the dam was analyzed under three separate seismic loadings. Especially the displacement of concrete faced lining was investigated by FEMs under dynamic loadings of the Operation-Based Earthquake (OBE), the Maximum Design Earthquake (MDE)) and the Safety Evaluation Earthquake (SEE) The dynamic analyses indicate that permanent displacements are considerably high for total stability of a CFRD structure under MDE loading condition, when compared with other loading condition. The differential displacement between the concrete panels in lining is also high under the strong ground shaking.

... The other result of statistical methods obtains earthquake input energy from attenuation models. Chou and Uang [18,19] conducted studies for predicting input energy for inelastic systems with a given site class, earthquake magnitude, source to site distance and structural ductility base on attenuation model proposed by Boore et al. [20,21]. Cheng [22] proposed an elastic input energy prediction equation developed using mixed-effects models by empirical regressions on a large number of strong-motions selected from the NGA database. ...

... Substituting the associated terms into Eq. (13), exact solution of earthquake input energy is derived, as shown in Eq. (21). ...

Statistic and theory based methods are mainly used for predicting earthquake input energy. Statistical energy spectrum methods need abundant time-history simulation and are lack of solid theoretical basis, while theoretical prediction methods are derived from structural dynamics with necessary assumptions, so that these methods have relatively low accuracy resulted from their assumptions. In this work the comparison of simulation and analysis showed that, due to the influence of structural transient response ignored by existing theoretical prediction methods, more than 40% errors exist in prediction of earthquake input energy for structures with low damping ratio and long period. Based on Fourier decomposition, a new theoretical method was proposed for earthquake input energy prediction considering the influence of transient response. The comparative analysis show that the proposed method significantly improves prediction accuracy of earthquake input energy.

... The characteristics of vertically propagated horizontal shear waves from bedrock are significantly influenced by the top 30 m strata (Anderson et al. 1996;Kuo et al. 2011). Therefore, the time-averaged shear wave velocity of the top 30 m (V S30 ) is widely utilized as a proxy to evaluate the variation of the ground motion as it travels through the soil medium to surface (Boore et al. 1997). V S30 is the primary parameter used in various site classification systems (BCP 2007;ICC I 2015). ...

The time-averaged shear wave velocity of top 30 m (V S30) is the most commonly used parameter to classify a site and evaluate its amplification characteristics for the seismic design. The in-situ seismic tests must be performed up to a depth of 30 m for obtaining the shear wave velocity (V S) profiles to estimate V S30. It is intimated that, in most of the cases, the measured V S profile does not extend up to 30 m due to numerous reasons including limitation of testing techniques and unfavorable field conditions. Since, the measurements of V S30 are unavailable for the majority of Pakistan and the world, the local geology and topographic slope or its combination are used to estimate V S30. However, there is no field-based validation of the estimated V S30 is performed in Islamabad-Rawalpindi region, the proxy-based estimation may lead to unrealistic results. To accommodate this, region specific extrapolation methods are developed. This study develops an empirical data-driven function of V S30 from shallow V S profiles by correlating V S30 with the time-averaged V S to depths less than 30 m. In this regard, 85 V S profiles are used from Rawalpindi-Islamabad region. A comparative analysis of the proposed procedure is carried out with the published methods. It is revealed that V S30 predicted by the proposed function results in close matches with the data measured in the western United States. In addition, the results indicate that the local geology and topographic slope proxies may not be acceptable for usage in the region due to their greater uncertainty. Finally, a procedure for extrapolating the V S profile from available shallow depth measurements up to 30 m is proposed.

... CHEEP did not include Chiou and Youngs (2014) as one of its in-built GMPEs so stochastic models for this GMPE are also not available in the form required by this software. Because the software to repeat Scherbaum et al. (2006)'s inversion process is not available, the stochastic models provided in CHEEP for the WNA GMPEs of Abrahamson and Silva (1997) and Boore et al. (1997) were both used as proxies for the unavailable stochastic models for Chiou and Youngs (2014) and similar backbone GMMs obtained. By examining the match between the predictions from these stochastic models and the Chiou and Youngs (2014) GMPE over a wide range of magnitudes and distances it was con rmed that these stochastic models are suitable for the HEM. ...

A key task when developing a ground-motion model (GMM) is to demonstrate that it captures an appropriate level of epistemic uncertainty. This is true whether multiple ground motion prediction equations (GMPEs) are used or a backbone approach is followed. The GMM developed for a seismic hazard assessment for the site of a UK new-build nuclear power plant is used as an example to discuss complementary approaches to assess epistemic uncertainty. Firstly, trellis plots showing the various percentiles of the GMM are examined for relevant magnitudes, distances and structural periods to search for evidence of “pinching”, where the percentiles narrow excessively. Secondly, Sammon’s maps, including GMPEs that were excluded from the logic tree, are examined to check the spread of the GMPEs for relevant magnitudes and distances in a single plot. Thirdly, contour plots of the standard deviation of the logarithms of predicted ground motions from each branch of the logic tree (σ µ ) are compared with plots drawn for other relevant hazard studies. Fourthly, uncertainties implied by a backbone GMM derived using the Campbell (2003)’s hybrid stochastic empirical method are compared to those of the proposed multi-GMPE GMM. Finally, the spread of the percentile of hazard curves resulting from implementing the GMM are examined for different return periods to check whether any bands of lower uncertainty in ground-motion space resulted in bands of lower uncertainty in hazard space. These five approaches enabled a systematic assessment of the level of uncertainty captured by the proposed GMM.

... In a possible earthquake, the density of sloping lands can increase the damage due to landslides (Cȩlebi, 1991;Sönmez, 2011). As a result of their simulation studies, Bouchon, Schultz, and Toksöz (1996), Boore, Joyner, and Fumal (1997) and Bouchon (1973) underline that the topography increases the recorded accelerations further. Pedersen, Le Brun, Hatzfeld, Campillo, and Bard (1994) point to the topography as a result of the huge acceleration increases in the peaks of the mountains. ...

Turkey is a country where various disasters occur frequently due to its geological structure and position, climatic characteristics, and morphology. Earthquake, flood, and landslide are the leading ones of these disasters. Hence, devastating earthquakes encountered and flood and landslide disasters caused by global climate change have led to significant loss of life and properties. Many settlement areas in our country contain various disaster risks. Determining the factors that cause these risks in advance and implementation of disaster risk reduction policies according to vulnerability levels in cities will help to minimize the losses resulting in pre-disaster, during and post-disaster periods. In this context, the settlement areas such as Central Yumurtalık, Haylazlı, Kalemli, Ayvalık, Yeniköy, Demirtaş, Sugözü, Narlıören located in Adana province were examined within the scope of disaster-sensitive planning. In the study, the analytical hierarchy process method was used, besides, an earthquake sensitivity analysis was established with the weight ratios determined as a result of the paired comparison matrix of the parameters, and the regions with risk of disaster in the city were identified.

... We used the acceleration time-histories to calculate the IMs in Table 9. They have been widely used in the development of ground-motion prediction equations and seismic hazard studies (Boore et al., 1997;Watson-Lamprey and Boore, 2007;Mezcua et al., 2008;Schmidt-Díaz, 2014;Douglas, 2017), as well as in the evaluation of expected damage (Park et al., 1987;Kostinakis et al., 2015;Muin and Mosalam, 2017;Pinzón et al., 2020a). Figure 22 shows the relation between PGA and hypocentral distance in the database. ...

Earthquakes are defined as a "violent shaking of the Earth’s crust and mantle, caused by forces acting inside the Earth". In most cases, these forces are caused by an energy release process generated from the contact of the Earth’s tectonic plates. Other less common causes are the human-induced earthquakes or those generated through volcanic activity. In either case, the energy is released in the form of multi-directional waves, which reach the surface, causing different effects. However, the intensity of an earthquake is not uniform in all its propagating directions. Many times, the motion is polarized due to the type of fault and/or the proximity to it, causing higher intensities in specific directions, depending on the dynamics and geometry of the rupture. This is what is known as the directivity effect. Furthermore, both the intensity and the shape of the wave vary depending on the propagation medium. Ground motion prediction models deal with the spread of the released energy from source to site. Local site effects, both soil effects and topographical effects, are also important. Rigid media, such as rocky and stiff soils, do not tend to amplify the seismic motion, while soft soils amplify specific frequencies depending on local sub-soil geology and on the motion characteristics. Directionality effects refer to the strong motion in a specific site. This thesis deals with two important issues related to directionality. The first one refers to the orientation of the sensors recording the seismic actions; the second one refers to the expected damage in buildings depending on the directions of their strong and weak main axes. It is worth to mention that nowadays, directionality effects are not considered in most structural regulations. In this thesis, special attention is paid to the directionality and soil effects. Since 2008, around 360,000 earthquake fatalities have been reported. This evidence demonstrates the need to develop more and better ways to assess and to prevent seismic risk. Therefore, the main objective of this thesis is to identify and evaluate the strong-motion directionality and the soils’ effects on the seismic hazard and risk, with applications to strong-motion data sets and soils’ in urban environments. This thesis is divided into three principal blocks: I) directionality effects, II) Soils effects, site classification and other seismic risk-related issues and, III) relevant case studies related to the previous two blocks. In the first block, directionality effects have been considered in the expected strong seismic actions, through the estimation of intensity measures using databases from Italy and Costa Rica. Also, in the assessment of the expected damage of buildings through non-linear dynamic analyses, a simplified approach has been proposed to consider directionality effects. In the second block, microzonation and soil-building resonance effects in the city of Barcelona are studied. In addition, a seismic site classification is defined for the Spanish strong-motion network. The dynamic soil-structure interaction, considering directionality effects and, the proposal of a new drift-correlated intensity measure, appeared as supplementary subjects in this block. Finally, in the third block, other relevant contributions were included to complement this dissertation. The results demonstrate 1) that directionality effects in expected seismic actions are significant and should be considered in Probabilistic Seismic Hazard Analysis (PSHA) and in seismic risk assessments; and 2) they confirm the relevance that site effects (soil effects), has both in seismic hazard studies and in the assessment of the expected damage. This PhD thesis wants to be an additional step towards the assessment, prevention, and reduction of the risk due to earthquakes.

... To calculate PGVs on the ground surface using the PGVs on stiff ground with a V S30 value of 600 m/s, as predicted by Si and Midorikawa (1999), information about the average shear-wave velocity in the upper 30 m of sediments (i.e., V S30 ) is required (Fukushima and Tanaka, 1990;Midorikawa, 1994;Boore, 1997;Power et al., 2008;Liu et al., 2013). Equation (7) can be used to calculate the site amplification factor (Amp) for the PGV using the value of V S30 at a site (Midorikawa, 1994), E Q -T A R G E T ; t e m p : i n t r a l i n k -; d f 7 ; 5 3 ; 4 5 8 ...

Rapid seismic intensity maps for damaging earthquakes enable the swift implementation of earthquake disaster mitigation action, issuance of accurate tsunami warnings, and prevention of associated secondary disasters. However, many countries lack dense local seismic observation networks, making it infeasible to obtain accurate seismic intensity maps of earthquakes within a few hours, particularly for earthquakes that have considerable source extents. In this study, we developed a new algorithm for rapidly obtaining seismic intensity maps of damaging earthquakes. With our model, source energy radiation is acquired using backprojection, and then the locations and relative amplitudes of the fault geometry and subevents are determined. Peak ground accelerations and peak ground velocities (PGVs) are subsequently calculated based on ground-motion prediction equations and the distribution of the estimated subevents. PGVs are then further site-corrected using the VS30 database (Wald and Allen, 2007; Heath et al., 2020). The algorithm was applied to the 2008 Mw 7.9 Wenchuan and 2010 Mw 6.9 Yushu earthquakes, and the resulting seismic intensity maps were highly similar to those generated by field surveys. The algorithm is simple and straightforward to use, and local real-time instrument observations are not required. Calculations can be performed automatically, and reliable seismic intensity maps can be issued within 30 min following damaging earthquakes. The model’s application may assist greatly with rescue and recovery efforts, and enable tsunami hazards to be evaluated immediately following earthquakes, particularly in regions lacking dense observation networks.

... The DSHA for Indian cities like Surat and Delhi, which are vulnerable to seismic hazard have been carried out by several researchers Satyam 2007, Thaker et al. 2011). DSHA for Gwader city of Pakistan was performed using a global GMPE (Ambraseys et al. 1996, Boore et al. 1997, Rahman et al. 2012. The GMPE for the Himalayan region was developed to carry out seismic microzonation studies for NCR Delhi (Rao and Rathod 2014). ...

This study attempts to evaluate the seismic hazard for the Jammu region based on a deterministic approach considering two earthquake scenarios using a logic tree framework. The Peak Ground Acceleration (PGA) values at bedrock level are estimated using already defined GMPEs for the Himalayan region by different researchers. The Main Central Thrust (MCT) and Reasi thrust are found to be the most critical capable of generating PGA > 0.8 g. The findings of the study indicate that the PGA at bedrock level for the region ranged from 0.14 g to 0.67 g. The DSHA in terms of bedrock level PGA for 50th and 84th percentile reveals that the maximum hazard level occurs in the western part of the Jammu region. The DSHA map of bedrock PGA for 50th percentile shows that central part is exposed to severe seismic hazard. The predicted PGA values can be used to assess the seismic stability of existing structures and for the design of earthquake-resistant structures in and around the Jammu region.

... The PGVs on the ground surface were estimated based on the PGVs on stiff ground with Vs30 = 600 m/s predicted by Si and Midorikawa (1999), and information about the average shear-wave velocity in the upper 30 m of sediments (Vs30) (Thompson et al., 2014;Liu et al., 2013;Boore, 2005;Midorikawa, 1994;Fukushima and Tanaka, 1990). ...

This study focuses on rapidly determining seismic intensity maps of earthquakes because it offers fundamental information for effective emergency rescue and subsequent scientific research, and remains challenging to accurately determine seismic intensity map in regions with sparse instrumental observations. Here we applied a novel method that consisted of array technology (back-projection), ground-motion prediction equations, and site corrections, to estimate the seismic intensity maps of the 2021 Mw 7.3 Madoi, Qinghai and the Mw 6.1 Yangbi, Yunnan, China earthquakes. We used seismic data recorded at European stations to back-project the source processes of the 2021 Mw 7.3 Madoi, Qinghai and the Mw 6.1 Yangbi, Yunnan, China earthquakes. The back-projected energy radiations were then used as subevents or used to define the fault geometry. Summing the contributions of each subevent or estimating the shortest distances from each site to the rupture fault, we obtained the ground motion (PGA and PGV) for each site under rock site conditions. The estimated ground motions were corrected at each site for local site amplification according to the Vs30 database. Our estimated seismic intensity maps and field reports showed high similarity, which further validated the effectiveness of the novel approach, and pushed the limit of earthquake size down to ~M 6. Such efforts would substantially help in the fast and accurate evaluation of earthquake damage, and precise rescue efforts.

... Typically, in this magnitude range, the site would behave linearly. In the linear range, Boore et al. (1997) and Walling et al. (2008) defined the site amplification as: ...

Abstract
This dissertation concerns developing a new ground motion model (GMM) for small to moderate potentially induced seismic events in Central and Eastern United States (CEUS) and ranking worldwide and local GMMs for Iran. The body of research work is carried out in two related studies.
The first study presents a new GMM. The proposed model is developed considering induced and potentially induced seismic events in CEUS. For this study, a comprehensive flatfile of potentially induced ground motions for moment magnitudes (Mw) between 3 and 6 and distances of less than 200 km is used. The Pezeshk et al. (2018) model, which is a hybrid empirical method, is selected as the base model for the development of the new GMM. The Pezeshk et al. (2018) model was developed and was calibrated for tectonic events in CEUS as part of the Pacific Engineering Earthquake Center (PEER) Next Generation of Attenuation (NGA) project referred to as the NGA-East project. This study follows the “mixed-effect” regression procedure to find the proposed model coefficients. The newly developed GMM is derived for peak ground acceleration and response-spectral ordinates at periods ranging from 0.01 to 10.0s, MW ranging from 3.0 to 5.8, and hypocentral distances of up to 200 km. As part of this study, the strength of the newly proposed model is discussed by performing a set of comprehensive residual analyses.
In the second study, recently developed worldwide and local GMMs are selected, and the capabilities of these models for seismic hazard analysis in Iran are evaluated. The data-driven selection methods scores determine the GMM weights for applying in seismic hazard forecasts. This study is based on an independent test database of recently recorded major earthquakes in Iran, such as the 12 November 2017 MW 7.3 Ezgeleh earthquake and the 25 November 2018 MW 6.3 Sarpol-e Zahab earthquake, along with the several earthquake events from 2000 to 2019. Three data-driven selection methods, including the Log-Likelihood (LLH) method, the Euclidean Distance-based Ranking (EDR) method, and the Deviance Information Criterion (DIC) method, were employed.
Keywords
Induced seismicity, Ground Motion Model, Ranking Ground Motion Models, Data-Driven Methods, Seismic Hazard Analysis,, Engineering seismology.
Please check the link for full text:
https://www.proquest.com/docview/2562848775?pq-origsite=gscholar&fromopenview=true

... The knowledge of S-wave velocities (V S ) and their average velocity in the first 30 m depth (V S30 ) has been used in seismic susceptibility analysis in urban areas. V S30 is also used in Eurocode 8 (EC8) (IPQ, 2010) for terrain classification, as well as in seismic engineering studies (Krammer 1996;Boore et al., 1997;Rosset et al., 2015). Several authors have mapped V S30 and earthquake damages distribution during different events (e.g., Kanli et al., 2006, Martínez-Pagán et al., 2014 and found that the areas with greater damages were located in areas with lower V S30 values. ...

Setúbal is a county located in the Lisbon metropolitan area (Portugal) which has been hit by historical earthquakes that were responsible for high social and economic losses. The 1858 earthquake, with an epicentre located offshore just south of the Setúbal region, is a good example of an earthquake that caused high damage (IX-VIII MM) in this county. The main city of the region is Setúbal itself, an important and populated urban agglomeration with several industrial facilities very close by. The old city centre is mostly settled upon shallow geological units and taking into consideration the historical seismicity, it is important to examine the possible site effects that could occur during future earthquakes affecting the Setúbal region.
The objectives of this study are therefore the characterisation of the seismic behaviour of Setubal's shallow geological formations and the evaluation of potential site effects. Shear wave velocity profiles were computed with the Refraction Microtremor (ReMi) method, spatial distribution of VS30 values was estimated and a map with the VS30 classification of soils according to the EC8 was produced. Spatial distributions of different data are presented and discussed: VS30 values, thickness of the shallow formations, top Pliocene surface, and results from Standard Penetration Tests (NSPT values). Numerical correlations between these parameters were established. Geotechnical characterisation was based on the analysis of 307 logs and 2950 Standard Penetration Tests. A total of 266 refraction microtremor measurements were performed obtaining VS profiles and VS30 values for 43 different sites. It was found that in Setúbal the majority of the Holocene units belong to EC8 class C (180-360 m/s) but, in the areas where the thickness of shallow formations (TSF) is lower, the Holocene units may belong to class B (> 360 m/s). The spatial distribution of VS30 highlighted that the Plio-Pleistocene, Miocene and Mesozoic areas show the best soil conditions corresponding to EC8 classes B and A. However, it was possible to identify a Plio-Pleistocene area with VS30 varying between 232 and 355 m/s, therefore belonging to class C. This fact highlights that site effects studies should not be performed solely based on geological criteria, but it is essential to estimate S wave velocities (VS) in situ.

... Prior to the NGA west-1 project (Power et al., 2008) the ground motion prediction equations were based on the geometric mean spectral values of the two as recorded ground motions across all oscillator periods. Five GMPEs by Abrahamson and Silva 1997, Boore et al. 1997, Campbell 1997, Campbell and Bozorgnia 2003, Sadigh et al. 1993, 1997and Idriss 1991 were widely in use prior to 2008. ...

The definition of hazard-consistent ground motions for seismic design has been an active area of research in the past few decades. With the advancements in computing power we have taken giant steps in performance based seismic design (PBSD). At the heart of PBSD is performing non-linear response history analysis to verify the performance of a structural design. Among the challenges faced by engineers conducting response history analysis is the selection/generation of a set of ground motions that are compatible with a target spectrum that is representative of the seismic demand of the structure of interest. There are several ways to obtain spectrum compatible records. One can do scaling of the ground motions to closely match the response spectrum of an individual record to the design target spectrum. Another method is based on time or frequency domain modifications of the recorded acceleration time series to make them spectrum compatible. The focus of this study is to use spectral matching techniques to represent
bi-directional demands accurately. The code spectrum represents bi-directional demand, which is quantified by either geo-mean spectrum (ASCE 7-05) or the maximum direction spectrum (ASCE 7-10). For 3-D analysis, the structure must be subjected to a pair of ground motions accounting for the bi-directional demand of the code spectrum. Although the present code provisions indicate that the RotD100 (Maximum direction) spectra of the individually matched motions be at least 110% of the design spectra, the values are well over 110% according to the analysis presented herein. The primary objective of this study is to propose a spectral matching method that captures the bi-directional demand of the structure and is compatible with design code requirements, named the “Match and Scale” approach. 398 pairs of ground motion records are considered to compute the mean and standard deviation of the scaling factors across oscillator periods. The proposed scaling factors represent the mean of the ratio of RotD100 spectral value of the individually matched motions to the spectral ordinates of the design target spectrum across all periods. Furthermore, another method to simultaneously match pairs of ground motions RSPmatchBi by Grant (2011), is explored for comparison purposes. The accuracy of the proposed method is assessed by performing non-linear time history analysis for bi-directional input and evaluating the variation in structural response as a result of considering different orientations of the input ground motion. The median structural response results from the proposed method is compared with the median response obtained with RSPmatchBi. The median responses fall in the same range, thus validating the proposed method.

... Fig. 9 illustrates the resulting seismic scenarios produced for the three analysed seismic sources by means of the application of the shakemap This methodology is based on (1) the production of hybrid EMS-ESI intensity maps; and (2) the selection of reliable seismic sources capable to reproduce the obtained intensity distributions in terms of ground horizontal acceleration maps. For this second step we use the ground motion prediction equation (GMP) of Boore et al. (1997) widely applied in the USGS ShakeMap Program (Wald et al., 2005). However, the USGS methodology was corrected by incorporating into the equations the topographical and geological correction factors proposed by Silva et al. (2017b). ...

This work presents a macroseismic analysis of the AD 1755 Lisbon Earthquake-Tsunami event by means of the combination of intensity data derived from the EMS-98 scale and the ESI-07 scale (Environmental damage). About 600 records of secondary earthquake environmental effects (EEEs) for the whole Spain have been used to define intensities, focused on the SW portion of the Iberian Peninsula. The Spanish data have been complemented with 308 EEEs records from Portugal. The analyses indicate maximum intensities of X EMS-ESI along the Atlantic margin of the Iberian Peninsula with 76 records of Tsunami environmental effects (TEEs). An important amplification (VIII – VII) occurred all along the Guadalquivir basin and the adjacent Betic front at epicentral distances of 300–700 km. In these zones 55 records of ground effects (ground cracks, Liquefactions and slope movements) are catalogued. In the rest of the territory of the Peninsula the most widespread effects were hydrogeological changes with 505 records in Spain and 196 in Portugal (total 701 records) covering all the intensity levels. Increase of flow discharges in springs and elevation of water level in wells was the common groundwater response to seismic shacking, especially in SW Iberia. In this zone water elevation in wells was between 5 and 3 m and persistent increases of discharges long-lasting (several days to two months). Persistent discharges on springs were linked in 143 cases to important SW-NE crustal faults (e.g., Alentejo-Plasencia Fault). From the Intensity distribution the historic seismic scenarios are explored by means of the development of empirical ShakeMaps. These consider the three classical seismic sources proposed for this earthquake: Gorringe Bank (G); Marques de Pombal Fault (M) and Atlantic delamination beneath the Gulf of Cadiz (C). However, individually these seismic sources are too small and unable to generate the resulting seismic scenario depicted by the intensity map developed in this work, with onshore seismic accelerations (PGA) up to 0.82 g. These acceleration values and the great amplification experienced throughout the Guadalquivir basin (0.34–0.52 g) are only possible considering a combination of the three seismic sources (GMC Source) probably related to shallow subduction or lithospheric delamination beneath SW Iberia and the Gulf of Cadiz. This will suggest an NNE-SSW offshore rupture length of 350–360 km with an overall rupture area of c. 84,500 km² resulting in an event magnitude 8.6 Mw calculated from empirical relationships. The results demonstrate the efficacy of these kind of approaches for better identifying and modelling seismic sources for historical events.

... i. regression-based predictive models based on a single or a combination of a few simple predictor variables (s), e.g., average shear-wave velocity in the topmost 30 m, VS30 (Borcherdt, 1994;Boore et al., 1997), site resonant frequency (e.g., Pitilakis et al., 2004;Pitilakis et al., 2013;Zhao et al., 2006;Hashash et al., 2019) or both (e.g., Luzi et al., 2011;Cadet et al., 2012;Régnier et al., 2014;Zhu et al., 2020a;Kwak and Seyhan, 2020); ...

In site response assessments, observation-based site-specific approaches requiring a target-reference recording pair or a recording network cannot be implemented at many sites of interest. Thus, various estimation techniques have to be utilized. How effective are these techniques in predicting site-specific site responses (average over many earthquakes)? To address this question, we conduct a systematic comparison using a large dataset which consists of detailed site metadata and Fourier outcrop linear site responses based on observations at 1725 K-NET and KiK-net sites. We first develop classic regression and machine learning (i.e., random forest) amplification models on a training dataset (1580 sites). Then we test and compare their predictive powers at 145 independent testing sites with those of the one-dimensional (1D) ground response analysis (GRA), and the empirical correction to the horizontal-to-vertical spectral ratio (eHVSR) of earthquakes (c-HVSR). The standard deviation of residuals between observations and predictions, i.e., between-site (site-to-site or inter-site) variability, is used as the benchmark. Results show that the machine learning amplification model using a few predictor variables, surface roughness, fP,HV, VS30 and Z2.5, achieves better performance than the 1D physics-based modelling (GRA) using detailed ground structures. This is because GRA is inflicted by a high level of parametric and modelling uncertainties. In addition, we propose a new machine learning amplification model using single-station eHVSR curve as a vector-valued predictor variable which is very effective in further lowering the between-site variability in the full frequency range 0.1-20 Hz. Meanwhile, GRA results can also be improved using eHVSR-consistent velocity profiles. These demonstrate the benefits of collecting on-site earthquake recordings and are particularly pertinent for cases where recording pair- or network-based empirical techniques remain a “luxury”. Future endeavors could further explore the modeling of more complex site effects using machine learning techniques, single-station recordings and geotechnical measurements, which could be an alternative to the physics-based simulation.

... In such early models, the description of site conditions was discrete and even binary (soil/rock), and the non-linear part was a correction depending on the predicted rock pga. After the introduction of V S30 as a continuous site-descriptor by Boore et al. (1997), the non-linear part of site terms became V S30 -dependent as proposed by Choi & Stewart (2005) and implemented later in the NGA suite of GMPEs (Power et al. 2008). It implies a significant increase in the number of GMPE site-term parameters to be regressed from the strong motion data sets, with actually limited constraints since only relatively only few recordings correspond to the very strong motion range where NL effects are pervasive. ...

Previous ESG blind tests and symposia, together with the advances in computation capabilities, allowed to significantly improve the reliability of numerical simulation for site response estimates. In parallel, the considerable progress in instrumentation has made available numerous high quality data sets, which allowed impressive developments in empirical ground motion prediction tools (GMPEs). Yet a number of important site amplification components are not, or incompletely, accounted for in such GMPEs, because of too poor site metadata or missing recordings, given the complexity of site amplification physics. One might dream that present-day numerical simulation tools, large data sets, and machine learning could be merged to establish more physics-based, statistically meaningful site terms providing a better (i.e., more accurate and less scattered) prediction of site amplification. This paper aims at discussing the maturity of such dreams for different components of site amplification, i.e., 1D linear site response, non-linear modifications, effects associated with surface topography, and aggravation factors in valleys and basins.
https://hal.archives-ouvertes.fr/hal-03329430/document

... Epistemic uncertainty, associated with the lack of knowledge and measurements as to the correct median ground motions and aleatory variability, expressing random variability in observed ground motions about the median prediction curve. Primarily, aleatory variability arises from different sources such as earthquake rupture, seismic wave propagation path, and local site effects and has generally been captured by the standard deviation of the GMM (Abrahamson and Youngs, 1992;Al Atik et al., 2010;Bommer and Crowley, 2006;Boore et al., 1997). It has been extensively investigated that the level of aleatory variability is a key parameter that influences seismic hazard calculations (Atkinson, 2006;Strasser et al., 2009;Zhao et al., 2006). ...

The earthquake ground motions of over 1700 earthquakes recorded on a small-aperture strong-motion array in south Iceland (ICEARRAY I) that is situated on a relatively uniform site condition characterized as rock, exhibit a statistically significant spatial variation of ground-motion amplitudes across the array. Both earthquake and microseismic horizontal-to-vertical spectral ratios (HVSR) have been shown to exhibit distinct and in some cases, bimodal peaks in amplification, indicating site resonance at periods of 0.1–0.3 s, a phenomenon that has been attributed to a surface layer of lava rock lying above a sedimentary layer, a structure that is then repeated with depth under the array. In this study, we implement a Bayesian hierarchical model (BHM) of the seismic ground motions that partitions the model residuals into earthquake event term, station term, and event–station term. We analyzed and compared peak ground acceleration (PGA) with the 5% damped pseudo-acceleration response spectrum (PSA) at oscillator periods of T = 0.05–1.0 s. The results show that the event terms, dominate the total variability of the ground-motion amplitudes over the array. However, the station terms are shown to increase in the period range of 0.1–0.3 s on most stations and to different extents, leading to an increase in the overall variability of ground motions at those periods, captured by a larger inter-station standard deviation. As the station terms are a measure of how much the ground motions at those stations deviate from the array average, they act as proxies for localized site effects and amplification factors. These results, improve our understanding of the key factors that affect the variation of seismic ground motions across the relatively small area of ICEARRAY I. This approach can help to improve the accuracy of earthquake hazard assessments on local scales, which in turn could contribute to more refined seismic risk assessments and engineering decision-making.

... Thus, several building codes around the world have adopted V S30 as the preferred site parameter for common engineering practices and ground motion prediction studies (Boore et al. 1994;Rastogi et al. 2011;Sairam et al. 2011;Stewart et al. 2015). Boore, Joyner and Fumal (1997) first incorporated V S30 as the site condition term in designing their attenuation relation. ...

... Looking back at our significant progress on site response estimation in the past 25 yr gives us a baseline for what can be achievable in the decades to come. For example, consider that V S30 was first introduced as a GMM explanatory variable just under 25 yr ago by Boore et al. (1997). Although far from perfect, the use of V S30 reflected a desire to more quantitatively incorporate site effects in seismic design, and V S30 now has a near-universal meaning in the community. ...

... Typically, in this magnitude range, the site would behave linearly. In the linear range, Boore et al. (1997) and Walling et al. (2008) defined the site amplification as: ...

This study presents a new ground motion model (GMM) for small-to-moderate potentially induced earthquakes for Central and Eastern United States (CEUS). We used a hybrid empirical model as the base model, which was developed and calibrated for tectonic events in Central and Eastern North America (CENA) as part of the Next-generation Attenuation-East (NGA-East) project. We calibrated the base model using a comprehensive database of potentially induced ground motions with smaller magnitudes and shallower depths than tectonic earthquakes, excluding all earthquake events and stations within the Gulf Coast region. We determined the model functional form coefficients using a mixed-effect regression procedure. The proposed GMM is derived for the peak ground acceleration and response-spectral ordinates at periods ranging from 0.01 to 10.0s, moment magnitudes ranging from 3.0 to 5.8, and hypocentral distances up to 200km. The performance of the proposed GMM is evaluated through a set of comprehensive residual analyses. Furthermore, we compared the proposed GMM with recently published GMMs with the observed data for CEUS. The proposed GMM could apply in long-term and short-term US Geological Survey National Seismic Hazard Maps and for the hazard evaluation of induced seismicity.

... The standard practice in Israel adopts a GMM developed for the western United States: amendment 5 to SII 413 (Standards Institution of Israel [S.I.I.], 2013) uses the Campbell and Bozorgnia (2008; hereafter, CB08) model for calculating the seismic hazard maps, whereas the former versions used the Boore, Joyner, and Fumal (1997) model. Although these models represent the state-of-the-art for the time of their development, there are two main drawbacks in their use for local SHA: (1) the field of GMMs has seen major advancements in the 13 yr since CB08 was published, including a vast increase in data, improved methodologies, and better physics-based constraints; and (2) these models were not calibrated to local source, path, or site scaling, such that their use is somewhat arbitrary. ...

Models for estimating earthquake ground motions are a key component in seismic hazard analysis. In data-rich regions, these models are mostly empirical, relying on the ever-increasing ground-motion databases. However, in areas in which strong-motion data are scarce, other approaches for ground-motion estimates are sought, including, but not limited to, the use of simulations to replace empirical data. In Israel, despite a clear seismic hazard posed by the active plate boundary on its eastern border, the instrumental record is sparse and poor, leading to the use of global models for hazard estimation in the building code and all other engineering applications. In this study, we develop a suite of alternative ground-motion models for Israel, based on an empirical database from Israel as well as on four data-calibrated synthetic databases. Two host models are used to constrain model behavior, such that the epistemic uncertainty is captured and characterized. Despite the lack of empirical data at large magnitudes and short distances, constraints based on the host models or on the physical grounds provided by simulations ensure these models are appropriate for engineering applications. The models presented herein are cast in terms of the Fourier amplitude spectra, which is a linear, physical representation of ground motions. The models are suitable for shallow crustal earthquakes; they include an estimate of the median and the aleatory variability, and are applicable in the magnitude range of 3–8 and distance range of 1–300 km.

... Due to the unavailability of strong motion records, various attenuation relationships were adopted to calculate the peak ground acceleration (PGA) acting on dam sites. For this study six separate predictive relationships for horizontal peak ground acceleration were considered [23,24,25,26,27,28]. ...

Strong ground shaking results in the instability of the embankment and loss of strength at the foundations. Earthquakes can result in damages or failures for dam structures, while dams with large reservoirs can induce to earthquakes. Earthquake safety assessment is an important phenomenon in dam engineering and requires more comprehensive seismic studies for understanding the seismic behavior of dams subjected to severe earthquakes. Seismic hazard and seismic design are important aspects for large dam projects. Case studies about the seismic performance of dams under large earthquakes are available in the literature. Especially active faults on or near dam sites can cause to damaging deformation of the embankment. Turkey has so many dams, which are under the influence of near source zone. This study outlines stability analyses of large embankment dams located on active seismic area, discusses the experience on behavior of large embankment dams located on or near active faults in Turkey and introduces results of total risk analyses of the case studies including large embankment dams, namely Ataturk, Altinkaya, Catalan, Ilisu, Keban, Kilickaya, Menzelet, which have structural heights of 70 to 207 m.

... Due to the unavailability of strong motion records, various attenuation relationships were adopted to calculate the peak ground acceleration (PGA) acting on dam sites. For this study six separate predictive relationships for horizontal peak ground acceleration were considered [23,24,25,26,27,28]. Most of large dams in Turkey were analyzed by using these definitions. ...

The concrete-faced rockfill dam (CFRD) has been constructed with increasing frequency in last decade, because of no settlement problems through the use of compacted rockfill. It is advantagely regarded that there can be no pore water pressure due to earthquake shaking, because the embankment does not include water inside. Dam specialists had a decision that CFRD’s have a high resistance to seismic loading when well compacted. However, its dynamic behaviour was questioned after Wenchuan earthquake, occurred on May 12, 2008 in China. Author states that CFRD’s are more critical structures for earthquake case when compared with other types of embankment dams as based on studies which have been carried out for the dams in the locations where are very close to energy sources in Turkey. There are so many dams, which are under the effect of near-source zones in Turkey. One of largest CFRD’s , namely Ilisu dam is now built on Tigris river, Eastern Turkey. This study summarizes a dynamic analysis procedure for CFRD’s subjected to strong seismic excitation and introduces the total risk and seismic stability of nine large existing CFRD’s having structural heights of 60 m to 100 m, in Turkey.

... On the basis of geological and seismological studies, Hamzehloo et al. [93] found 25 source zones in which seismicity parameters were estimated after omitting foreshocks and aftershocks from the catalog. In addition, they applied four attenuation relationships ( [9], [95][96][97]) in their analysis. Figures (13-a, b, c, d) show the calculated PGA and spectral acceleration for the period of 0.2 sec maps for return Yazdani and Kowsari [98], for the first time, used the time-independent Bayesian probability method for seismic hazard analysis in Iran. ...

This is a state-of-the-art paper on the seismic hazard zoning studies performed inIran since the mid-1970s to 2015. Reliable seismic hazard studies depend on havinga robust earthquake catalog, good knowledge of tectonic conditions and relevantattenuation models applied for the hazard calculations. The better input for hazardanalysis results in the more reliable parameters and seismic hazard assessments.The first generations of seismic hazard zoning maps in Iran were developed based onthe deterministic approaches for calculation of maximum intensities (e.g. [1] and[2]). In 1982, Bozorgnia and Mohajer-Ashjai [3] published the first comprehensiveprobabilistic hazard assessment for major cities of Iran. The first PGA zoning map forthe greater Tehran region was also published by Berberian et al. [4]. The nextgenerations of seismic hazard zoning studies were carried out for dam sites, whichwere under construction during the 1980s and 1990s in Iran. A seismic hazardzoning map of Iran for the "design earthquake" (so called 475 years of returnperiod), was published in 1999 as an attachment to the Iranian seismic code forbuildings (Standard No. 2800). In the recent years, a number of detailed hazardzoning maps for the greater cities and specific industrial sites have also been pre-sented. The defined spectral attenuation equations for Iran (e.g. [5-17]) can be usedfor producing spectral zoning maps. These maps can be developed using regionspecific ground-motion prediction equations by considering various ground-mo-tion parameters that involve spectral acceleration, displacement and peak ground-motion values. Therefore, there are still ongoing attempts to develop the probabilis-tic seismic zoning maps for Iran. In this paper, the seismic hazard zoning maps of Irandeveloped in the last 40 years are investigated. It is tried to depict the developmenthistory of the seismic hazard zoning studies for Iran, which have been started sincethe mid-1970s. Briefly, the trend of such studies was started by the application ofdeterministic approaches for estimation of intensity and then was continued usingprobabilistic approaches. Future studies on the seismic hazard zoning in Iran seemsto cover new approaches such as the realistic acceleration and the neo-determinis-tic approaches, time-dependent mapping, intelligent updating of hazard maps aswell as the development of site-specific hazard analysis based on the development ofmore detailed data.

... Due to the modification between bedrock and A-type sites being a linear problem as well as 1-dimensional and hence these sites augmentation can be done by using the quarter wavelength method of Boore [30] directly. Database of kappa factors have been reported by Chandler et al. [31] and has given an equation (Eq. ...

Varanasi (latitude 25°28′ N and longitude 82°96′ E), the cultural capital of India, is presently clustered with a maze of ancient narrow lanes (Gullies) and old buildings. Being a sacred city, it is not well planned and structured, due to lack of adherence to earthquake-resistant building design philosophies and techniques. Consequently, even a smaller magnitude of an earthquake can cause a considerable loss. The city is also near to Faizabad ridge, which has been seismically sedentary for last 300 years. Due to unavailability of earthquake ground motion (G.M.) records in this region, it is necessary to simulate G.M. based on regional seismic data. In this regard, the stochastic approach has been adopted for the synthesis of G.M. at bedrock level. An EXSIM methodology has been used in this study for synthesis of strong G.M. for various identified faults (Allahabad Fault, Azamgarh Fault, Gorakhpur Fault, Deoria Fault, Lucknow Fault, Siwan Fault, Shajhanpur Fault and Great Boundary Fault) around the city. Various stress drops 70, 100, 125, 150, 175 and 200 bars have been taken for simulations to account for uncertainty in stress drop. Acceleration time histories due to various faults for Varanasi city has been simulated and plotted. The maximum PGA estimated was 0.078 g for Azamgarh Fault at 200 bar among all the faults around the city. Further Response Spectra has been plotted for stress drop (70–200 bar).

... In the present study anther for of this relationship, according to a better coordination with the input data is used. This formula is already used by Joyner, Boore and Fumal (1997); Log S a =a 1 (T).M+a 2 (T).M 2 +b(T).Log R+c i (T).S i +σsa(T).P (3) ...

The spectral values of the recorded strong motions in Iran are used to derive the empirical attenuation laws for different response spectral ordinates, on different site conditions. The strong motions are selected based on their peak acceleration value (having a PGA of 0.05g on at least on one component and the good signal quality in the low frequency band of 0.3Hz or lesser). The empirical relationships are established for the spectral acceleration as a function of the moment magnitude, the hypocentral distances, and a constant parameter representing the site conditions. The one and two step approaches for the regressions are applied, and the results are found to be near to each other, while the results for the one step approach are just presented in this paper. The data set consists of 100 three component accelerograms, all recorded during 1975-2003. The new attenuation coefficients are in general agreement with the previous attenuation coefficients established for Iran. However the spectral values obtained from the new law show greater values comparing to that of the previous law (1999). The difference might be inferred according to the selection of greater motions recorded in the nearer distances to the seismic source.

... On the basis of geological and seismological studies, Hamzehloo et al. [93] found 25 source zones in which seismicity parameters were estimated after omitting foreshocks and aftershocks from the catalog. In addition, they applied four attenuation relationships ( [9], [95][96][97]) in their analysis. Figures (13-a, b, c, d) show the calculated PGA and spectral acceleration for the period of 0.2 sec maps for return Yazdani and Kowsari [98], for the first time, used the time-independent Bayesian probability method for seismic hazard analysis in Iran. ...

This is a state-of-the-art paper on the seismic hazard zoning studies performed inIran since the mid-1970s to 2015. Reliable seismic hazard studies depend on havinga robust earthquake catalog, good knowledge of tectonic conditions and relevantattenuation models applied for the hazard calculations. The better input for hazardanalysis results in the more reliable parameters and seismic hazard assessments.The first generations of seismic hazard zoning maps in Iran were developed based onthe deterministic approaches for calculation of maximum intensities (e.g. [1] and[2]). In 1982, Bozorgnia and Mohajer-Ashjai [3] published the first comprehensiveprobabilistic hazard assessment for major cities of Iran. The first PGA zoning map forthe greater Tehran region was also published by Berberian et al. [4]. The nextgenerations of seismic hazard zoning studies were carried out for dam sites, whichwere under construction during the 1980s and 1990s in Iran. A seismic hazardzoning map of Iran for the "design earthquake" (so called 475 years of returnperiod), was published in 1999 as an attachment to the Iranian seismic code forbuildings (Standard No. 2800). In the recent years, a number of detailed hazardzoning maps for the greater cities and specific industrial sites have also been pre-sented. The defined spectral attenuation equations for Iran (e.g. [5-17]) can be usedfor producing spectral zoning maps. These maps can be developed using regionspecific ground-motion prediction equations by considering various ground-mo-tion parameters that involve spectral acceleration, displacement and peak ground-motion values. Therefore, there are still ongoing attempts to develop the probabilis-tic seismic zoning maps for Iran. In this paper, the seismic hazard zoning maps of Irandeveloped in the last 40 years are investigated. It is tried to depict the developmenthistory of the seismic hazard zoning studies for Iran, which have been started sincethe mid-1970s. Briefly, the trend of such studies was started by the application ofdeterministic approaches for estimation of intensity and then was continued usingprobabilistic approaches. Future studies on the seismic hazard zoning in Iran seemsto cover new approaches such as the realistic acceleration and the neo-determinis-tic approaches, time-dependent mapping, intelligent updating of hazard maps aswell as the development of site-specific hazard analysis based on the development ofmore detailed data.

... Dans cette étude une autre forme de cette relation, selon une meilleure coordination avec les données d'entrée est utilisé. Ceci la formule est déjà utilisée par Joyner, Boore et Fumal (1997) ; ...

On ne connaît pas que les côtes iraniennes soient les régions hasardeuses pour l'alea de tsunami. Mais juste après le tsunami dévastateur de l'océan Indien (le séisme de Banda Acheh; M8.0 le tremblement de terre du 26 décembre 2004) et selon dans le monde entier la tentative parmi la communauté scientifique, des études de tsunami a été étudiée sur le littoral sud de la Mer Caspienne au nord d'Iran le littoral sud du Golfe Persique et la Mer de l'Oman. La Mer Caspienne est le plus grand corps intérieur du monde d'eau. Depuis tant tectonique (la faute de tremblement de terre rompant en Mer qu'en secteurs côtiers) et non tectonique (des glissements de terrain sous-marins et des volcans de boue) les sources de tsunami existent dans la Mer Caspienne, le hasard de tsunami est commencé pour être étudié le point de vue de zonage de hasard dans ses régions côtiers du sud. ABSTRACT. We do not know about the Iranian coasts to be the tsunami hazardous regions. But immediately following the devastating tsunami of Indian ocean (the earthquake of Banda Acheh; M8.0 of 26 December 2004) and according to inits importance, the entire world attempt among the scientific community, and the studies of tsunami started on the coastal southern coast of the Caspian Sea and the northern coasts of the Persian Gulf and Oman Sea. The Caspian Sea is the biggest internal body of the water. Since the tectonics cause (the earthquake fault breaking at sea and in coastal regions) and (submarine landslides and mud volcanoes) as the sources of tsunami exist in the Sea, the chance of tsunami is begun being studied the view point of zoning in its sectors of the south. MOTS-CLÉS : Tsunami, Mer Caspienne, Iran, Zonage, sismotectonique.

... Dans cette étude une autre forme de cette relation, selon une meilleure coordination avec les données d'entrée est utilisé. Ceci la formule est déjà utilisée par Joyner, Boore et Fumal (1997) ; ...

7ème Colloque National AFPS 2007 École Centrale Paris Châtenay Malabry 4-6 juillet 2007 Association Française de Génie Parasismique , RESUME: L'atténuation des mouvements forts iraniens est étudiée utilisant la base de données de mouvements forte iranienne. Cette base de données comprend plus de 2000 à trois composants des données bien enregistrées (l'analogue et numérique) pour lequel les paramètres source télésismique étaient disponibles, ou ont calculé des enregistrements de mouvement forts. Les valeurs spectrales des mouvements forts enregistrés en Iran sont utilisées pour tirer les lois d'atténuation empiriques pour la réponse différente des ordonnées spectrales, sur des conditions de site différentes. Les mouvements forts sont choisis basés sur leur valeur d'accélération maximale (ayant un PGA de 0.05g sur au moins sur un composant et la bonne qualité de signal dans la bande de basse fréquence de 0.3Hz ou moindre). Les rapports empiriques sont établis pour l'accélération spectrale comme une fonction du magnitude de moment, la distance hypocentrale et un paramètre constant représentant les conditions de site. ABSTRACT. The attenuation of strong motions in Iran studied using the database of Iranian strong motion data. This database composed of more than 2000 three component accelerograms (analog and digital) for which the teleseismic source parameters were accessible, or they have been estimated based on the available record. The spectral values of the recorded strong motions in Iran are used for the estimation of the empirical attenuation laws for different spectral ordinates and site conditions. The strong motions are selected based on their maximum acceleration values (to be at least 0.05g on one of the components, the good signal quality for the low frequency of 0.3Hz or less). The empirical relationships are established for the spectral accelerations as a function of moment magnitude, hypocentral distance an a constant parameter representing the site conditions. A comparison is performed finally based on the different attenuation laws developed for the Iran using the growing database of strong ground motions. MOTS-CLÉS : loi d'atténuation, mouvement fort, Iran, accélération maximale, valeur spectral, effet de site, qualité de signal.

Seismogenic faults, depending on their structural maturity, may rupture in one segment or as multi segments; they also can show different slips on their segments. Mature faults break in long ruptures with small slip, while immature faults rupture in as short ruptures that are more energetic. On the other hand, The mature fault demonstrate clustering pattern in earthquake recurrence pattern. Also, The ground motions produced by earthquakes on immature faults are larger than those generated by earthquakes on mature faults. In this paper, we defined maturity of major faults in Easter Iran Province, regarding their segmentation, rupture length, displacement vector on the rupture and the history of clustered earthquake sequence on the fault. Then, the response spectrum of ground motions caused by large earthquakes occurred on these faults were calculated. To reduce the effect of unknown wave paths, we used ground motions recorded in the near field. Earthquakes of different mechanisms were selected in magnitude range from Ms=5.7 to 7.1. We compared the obtained response spectrum with ones resulted from the experimental model presented by Boore et al. study of This parameter can help to recognized ground motion potency and Considering it in extracting attenuation equations increases the accuracy of the results of seismic hazard assessment. With attend to structural maturity of faults, we try to present the model for evolution of seismic activity in two East Iran and Zagros.

Foram desenvolvidas leis de atenuação empíricas (GMPE – Ground Motion Prediction Equation) de aceleração de pico (PGA - Peak ground acceleration), de velocidade de pico (PGV - Peak ground velocity) e de resposta espetral (PSA – Pseudo spectral acceleration)
utilizando dados de sismos localizados na região do Arquipélago da Madeira e área adjacente que foram registados nas estações sísmicas das ilhas da Madeira e de Porto Santo. Neste conjunto de dados estão incluídos os eventos de magnitudes ML 5,2 e ML 5,1 que ocorreram recentemente (em 2020-03-07 e 2022-02-16) e que tiveram efeitos macrossísmicos observados no Arquipélago da Madeira, tendo sido sentidos com intensidade igual ou superior a V (escala de Mercalli modificada). As leis de atenuação foram obtidas por aplicação do
método de análise de regressão não linear múltipla aos dados disponíveis.

This document provides guidelines for the terrestrial environment that are specifically applicable in the development of design requirements/specifications for NASA aerospace vehicles, payloads, and associated ground support equipment. The primary geographic areas encompassed are the John F. Kennedy Space Center, FL; Vandenberg
AFB, CA; Edwards AFB, CA; Michoud Assembly Facility, New Orleans, LA; John C. Stennis Space Center, MS; Lyndon B. Johnson Space Center, Houston, TX; George
C. Marshall Space Flight Center, Huntsville, AL; and the White Sands Missile Range, NM. This document presents the latest available information on the terrestrial
environment applicable to the design and operations of aerospace vehicles and supersedes information presented in NASA-HDBK-1001 and TM X-64589, TM X-64757,
TM-78118, TM-82473, and TM-4511. Information is included on winds, atmospheric thermodynamic models, radiation, humidity, precipitation, severe weather, sea state,
lightning, atmospheric chemistry, seismic criteria, and a model to predict atmospheric dispersion of aerospace engine exhaust cloud rise and growth. In addition, a section
has been included to provide information on the general distribution of natural environmental extremes in the conterminous United States, and world-wide, that may be
needed to specify design criteria in the transportation of space vehicle subsystems and components. A section on atmospheric attenuation has been added since measurements by sensors on certain Earth orbital experiment missions are influenced by the Earth’s atmosphere. There is also a section on mission analysis, prelaunch monitoring,
and flight evaluation as related to the terrestrial environment inputs. The information in these guidelines is recommended for use in the development of aerospace vehicle
and related equipment design and associated operational criteria, unless otherwise stated in contract work specifications. The terrestrial environmental data in these guidelines are primarily limited to information below 90 km altitude. Subject Terms: environment criteria, terrestrial environment, surface extremes, wind, temperature, humidity, precipitation, density, pressure,
atmospheric electricity, cloud cover, control systems, geology, sea state, severe storms, constituents, radiation, diffusion, models

In this study, two metaheuristic optimization algorithms are employed to estimate a mixed model-based ground-motion model (GMM) with several variance components. Two optimization algorithms, particle swarm optimization (PSO) and teaching–learning-based optimization (TLBO), are employed to compute regression coefficients and uncertainties of the GMM by considering a one-stage maximum likelihood estimation framework. These optimization models are applied to a complex predictive equation in a way that the results best fit a ground-motion dataset. Uncertainties and the regression coefficients of a functional form of a predictive equation are estimated and compared with other models to show the strengths and the limitations of the proposed approaches. The obtained results provide reliable solutions and demonstrate good accuracy compared to previous search algorithms based on a given dataset of ground-motions. We estimated error metrics for the predicted data, and the results show that using the proposed algorithms provides better results compared to the existing search algorithms.

The Gulf of California (GoC) is an extensional province where the North America and Pacific plates limit. The boundary is an echelon set of normal and transform faults that produce low and moderate seismicity (M \(\sim\) 5). Castro et al. (J S Am Earth Sci: 106:103087, 2021) reports a Gutenberg–Richter law with a minimum magnitude catalog completeness of 3.6 and b value of 0.86 that are typical for active regions. However, earthquakes with magnitude 7.1 (e.g., 2012/04/12 earthquake) have been reported in the Pescadero transform fault (Sumy et al. in Bull Seismol Soc Am: 103(1):487–506, 2013; Huesca-Pérez et al. in Bull Seismol Soc Am, 2022). The importance of applying a maximum acceleration analysis in this region is to assess the danger associated with earthquakes and their destructive potential. In this work, a semiempirical methodology for making maximum acceleration maps is proposed by using Green’s function method and Brune’s source time function model. It has the advantages of being physical, as opposed to probabilistic, and a method that is deterministic and based on first principles, as well as open to improvement. A consequence of this model is that the effective stress of the rupture is directly proportional to the scalar moment. We show observed accelerations minus predicted accelerations calculated by both methods: the semiempirical and the probabilistic methods. Numerically, the probabilistic method gives a slightly better numerical result due to the fact that the attenuation relationships are more accurate to represent the rupture process but it is obtained using regression analysis. Then, we compare it with the traditional probabilistic seismic hazard analysis (PSHA). Differences are observed, which makes it evident that the probabilistic hazard analysis includes a fluctuating part of the maximum acceleration. We see that both methods have particular advantages.

Urban areas are becoming risky areas for users day by day. Especially as a result of the global climate crisis, which has recently threatened the world, disasters caused by natural-human effects are frequently experienced in cities. The hazards that cause disasters are not only natural but also human impact is at the forefront. In recent years, many different concepts and approaches have been developed to find solutions to urban disasters and to make cities more livable. The purpose of these concepts and approaches; to increase the defense mechanism of cities against increasing disasters. Some of those; disaster resilience, urban resilience, climate change resilient cities, etc.
The aim of the study; for by Ercis, which has a high risk of disasters caused by natural-human effects, to identify potential risk areas performing multiple hazard analysis and to develop proposals within the scope of relevant protection and planning tools in order to ensure the resilience of the city against these hazards.
Considering the disaster data obtained from AFAD in the study area, the hazards that have been experienced in the area and that are likely to be experienced have been determined. These hazards have been mapped and areas with high disaster risk in terms of all hazards have been identified. Multi-criteria decision making method was used in the study. All analyzes within the scope of the study were made in the ARCGIS environment.
The hazards that come to the fore in the study and pose a serious risk for the study area are identified as flood-flood and earthquake hazards. In particular, the frequency of the flood risk was determined to be high compared to other hazards. However, the earthquake hazard risk has been determined to be high because the earthquake hazard also causes serious loss of life. Areas with high slope and elevation, close to fault lines and rivers are generally determined as areas with high disaster risk.
As a result, it is very important for Erciş, which has a high disaster potential, to reduce disaster damage and increase the awareness of users on this issue. In particular, raising the awareness of area users about hazards and risks is very important in reducing the impact of disasters. In addition, it is essential to identify areas with high disaster risk as priority disaster response areas and to include them in spatial plan decisions. It is also very important for areas with high disaster risk to be included in the 1/25000 scale environmental plan as priority intervention areas. The inclusion of areas with high disaster risk, especially at local scales, in the 1/5000 scale master development plans and 1/1000 scale implementation development plans is an important issue in terms of establishing guidelines and planning codes to ensure resilience.

The development of modern and applicable Attenuation relationship is one of the major concerns of Seismologists as it is a requirement for Seismic Hazard assessment to estimate ground motions. It have been developed for many of relationships for several regions of the world and have been initially limited to considering magnitude and distance into derivation the relationship.
In modern Attenuation relationships, also known as Ground Motion Prediction Equations (GMPEs), the site effect is used in order to increase the accuracy of calculation for earthquake engineering applications represented by the shear wave velocity within the first 30 meters of the surface (VS30) which used in seismic Soil classification.
In this study, 619 velocity and 139 acceleration recordings from 52 earthquakes of low magnitudes (3< M <5) at 24 stations of the National Seismic Network were analyzed to develop Prediction Equations of Horizontal Ground Motion component for acceleration and velocity (PGAh and PGVh (in Syria using Regression analysis depending on Vs30 at each site, and determining the accuracy of the analysis by determining the values of Residuals for both PGV and PGA which ranged between 1 and -1.
The results gave a good fit with PGVh analysis match with the previous studies at this studies so that the data fits the resulted relationship and it’s suitable to use in expanded studies about Prediction Equations for Ground Motion parameters in syria while, it gave a weak fit with PGAh analysis which is usual in the study about this topic due to high acceleration values.

Deteriorating infrastructure and risks from natural and man-made hazards (such as earthquakes, wind, blasts) call for a rapid assessment of the integrity of structures to help with decision making regarding/concerning their public safety immediately after a significant event. It is also necessary to assess structural safety/conditions periodically on the basis of measured data and/or visual inspections in order to facilitate necessary repairs, replacements and other maintenance and retrofitting measures. The application of SHM techniques can lead to significant improvements in understanding the structural performance under seismic loads as well as during post-earthquake reconnaissance and rapid emergency response. Therefore, there is a need for development of accurate, reliable and robust damage detection and localization algorithms that use vibration-based data to obtain necessary information about the instantaneous and long-term dynamic behavior of structures in order to assess its integrity without using recovering to finite element modelling (FEM) or any other complex parametric or non-parametric tools. The research described in this report is concerned with the testing, improvement and verification of existing system identification and damage detection algorithms to be implemented into an open source structural health monitoring (OpenSHM) software. The report starts by providing the framework in which further research will be carried out, and by outlining the main objectives of the work. It then continues to describe two main contributions made in the course of this study so far: wave propagation and modal parameter-based system identification techniques using ambient, low-and high-intensity shaking data from a full-scale seven-story reinforced concrete building section tested at the NEES@UCSD shake table. Finally, the outline of future studies is presented together with the tentative work programme. 3

Earthquake is a sudden release of energy due to faults. Natural calamities like earthquakes can neither be predicted nor prevented. However, the severity of the damages can be minimized by development of proper infrastructure which includes microzonation studies, appropriate construction procedures and earthquake resistant designs. The earthquake damaging effect depends on the source, path and site conditions. The earthquake ground motion is affected by topography (slope, hill, valley, canyon, ridge and basin effects), groundwater and surface hydrology. The seismic hazard damages are ground shaking, structural damage, retaining structure failures and lifeline hazards. The medium to large earthquake magnitude (< 6) reported in Ethiopia are controlled by the main Ethiopian rift System. The spatial and temporal variation of earthquake ground motion should be addressed using the following systematic methodology. The general approaches used to analyze damage of earthquake ground motions are probabilistic seismic hazard assessment (PSHA), deterministic seismic hazard assessment (DSHA) and dynamic site response analysis. PSHA considers all the scenarios of magnitude, distance and site conditions to estimate the intensity of ground motion distribution. Conversely, DSHA taken into account the worst case scenarios or maximum credible earthquake to estimate the intensity of seismic ground motion distribution. Furthermore, to design critical infrastructures, DSHA is more valuable than PSHA. The DSHA and PSHA ground motion distributions are estimated as a function of earthquake magnitude and distance using ground motion prediction equations (GMPEs) at top of the bedrock. Site response analysis performed to estimate the ground motion distributions at ground surface using dynamic properties of the soils such as shear wave velocity, density, modulus reduction, and material damping curves. Seismic hazard evaluation of Ethiopia shown that (i) amplification is occurred in the main Ethiopian Rift due to thick soil, (ii) the probability of earthquake recurrence due to active fault sources. The situation of active fault is oriented in the N-S direction. Ethiopia is involved in huge infrastructural development (including roads, industrial parks and railways), increasing population and agricultural activity in the main Ethiopian Rift system. In this activity, socio-economic development, earthquake and earthquake-generated ground failures need to be given attention in order to reduce losses from seismic hazards and create safe geo-environment.

The paper develops a framework to analyze the interactions among seismic soil liquefaction significant factors using the interpretive structural model (ISM) approach based on cone penetration test. To identify the contextual relationships among the significant factors, systematic literature review approach was used bearing in mind the selection principle. Since multiple factors influence seismic soil liquefaction, determining all factors in soil liquefaction would be extremely difficult, as even a few seismic soil liquefaction factors are not easy to deal with. This study highlighted two main characteristics of seismic soil liquefaction factors. First, the seismic soil liquefaction factors–peak ground acceleration F2 (amax), equivalent clean sand penetration resistance F5 (qc1Ncs), and thickness of soil layer F11 (Ts) influenced soil liquefaction directly and were located at level 2 (top level) in the ISM model, meaning they require additional seismic soil liquefaction factors except thickness of soil layer F11 (Ts) to collaboratively impact on soil liquefaction potential. The multilevel hierarchy reveals that depth of soil deposit F10 (Ds) is formed the base of ISM hierarchy. Secondly, Matrice d’impacts croisés multiplication appliqués à un classement (MICMAC) analysis has been employed for evaluating these identified factors in accordance with driving power and dependence power. Factors with a higher driving power should be given special consideration. Autonomous soil liquefaction factors have no reliance on other soil liquefaction factors and interfere less. In order to identify the significant factors that affect seismic soil liquefaction susceptibility, the model built in this study clearly illustrates the complex relationships between factors and demonstrates the direct and indirect relationships.

RESUME Les données des mouvements forts en Iran sont utilisées pour établir les lois d'atténuation empiriques pour différents paramètres de mouvements forts: A max , V max et D max. Les variables explicatives sont la magnitude, la distance hypocentrale et les conditions de site. La base de données se compose de 468 accélérogrammes en 3 composantes. Les effets de site observés à partir de ces régressions ne sont pas très importants pour l'atténuation des mouvements forts mais sont en accord avec la classification de site qu'on a déjà faite pour l'Iran. Les lois d'atténuation sont présentées pour les régions de l'Iran central-Alborz, pour le Zagros et pour l'ensemble des données iraniennes. ABSTRACT The Iranian strong motion data are used to establish the empirical attenuation laws for different strong motion parameters: PGA, PGV and PGD. The independent variables are magnitude, hypocentral distance and site conditions. The data base consists of 468 three-component accelerograms. The site effects prove not to affect too much the attenuation of strong motion parameters, but they are in accordance with the site calssification aleady done for Iran. The attenuation laws are presented for the regions of Central Iran-Alborz, Zagros and for entire of the data base.

Analysis of regional and teleseismic broadband body waves and long-period surface waves from the 1989 Loma Prieta earthquake demonstrates that a fairly simple average fault model explains most characteristics of seismic wave radiation over a broad period range (1 to 300 sec), but there are some systematic period-dependent characteristics that are not yet understood. The model dependence of the surface-wave results suggests that it may be possible to reconcile the duration estimates with improved earth models, but the discrepancy is quite large. The systematic discrepancies in source duration, centroid depth, and seismic moment, despite the consistency in source orientation, raise the possibility of a deep, relatively slow co-seismic slip component, but trade-offs with modeling assumptions preclude us from confirming this hypothesis at present. -from Authors

Seismic signals from the 1979 Imperial Valley earthquake were recorded at 9 strong-motion stations in the N Baja California array operated jointly by US and Mexican research interests. Seven of these stations were occupied by three-component digitally recording accelerographs, and the other two by three-component film- recording accelerographs. In this report, we summarize the peak accelerations and velocities observed for all components and, where possible, the P and S wave arrival times. Four of the stations lacked absolute timing, and one station triggered on the S wave rather than the P wave. Near the US-Mexican border, most instruments recorded peak horizontal accelerations of approx 0.3g; the minimum was 0.17g at the farthest station. The general pattern of strong motion shows considerable complexity.-Authors

Probabilistic and statistical methods are being more widely used in seismic risk analyses. These procedures allow the maximum usage of geologic and seismological input into the evaluation of probable risk levels expected at a site. The seismic parameters used in an analysis must be based upon as complete and accurate a data set as possible and the relationships derived from the data must be consistent and representative of that data base. Several case histories are presented. Each one demonstrates some of the difficulties inherent in most data sets and the methods available to overcome them.

The Managua earthquake occurred at a shallow depth of focus beneath the center of Managua, producing a maximum intensity of MM IX in the center of the city. The epicenter of the main shock is determined to within several kilometers by use of the strong-motion accelerogram recorded at the ESSO refinery. Such accuracy is unprecedented for a large Central American earthquake, and makes the Managua earthquake valuable as a calibration event for minimizing the bias in location of other earthquakes in Nicaragua. The character of the distribution of P-wave residuals and the location of the earthquake well inland from the Benioff zone in Nicaragua suggest that much of the bias in epicenters calculated for earthquakes in the vicinity of Managua is due to station effects rather than source effects. P-wave first-motions are consistent with a left-lateral strike-slip fault as the earthquake source.

Teleseismic P, SV, and SH waves recorded by the WWSS and Canadian networks from the 1971 San Fernando, California earthquake (ML = 6.6) are modeled in the time domain to determine detailed features of the source as a prelude to studying the near and local field strong-motion observations. Synthetic seismograms are computed from the model of a propagating finite dislocation line source embedded in layered elastic media. The effects of source geometry and directivity are shown to be important features of the long-period observations. The most dramatic feature of the model is the requirement that the fault, which initially ruptured at a depth of 13 km as determined from pP-P times, continuously propagated toward the free surface, first on a plane dipping 53°NE, then broke over to a 29°NE dipping fault segment. This effect is clearly shown in the azimuthal variation of both long period P- and SH-wave forms. Although attenuation and interference with radiation from the remainder of the fault are possible complications, comparison of long- and short-period P and short-period pP and P waves suggest that rupture was initially bilateral, or, possibly, strongly unilateral downward, propagating to about 15 km depth. The average rupture velocity of 1.8 km/sec is well constrained from the shape of the long-period wave forms. Total seismic moment is 0.86 × 10^(26) dyne-cm. Implications for near-field modeling are drawn from these results.

The 5.1 M_L Santa Barbara earthquake of 13 August 1978 occurred at 22h54m 52.8s UTC. The epicenter was located 3 km southeast of Santa Barbara at 34° 23.9′N latitude and 119°40.9′W longitude with a focal depth of 12.7 km. The main shock was followed between 13 August and 30 September by 373 aftershocks that were located with the Caltech-USGS array. The aftershock zone extended 12 km WNW from the epicenter and was 6 km wide in the N-S direction, and it had a very clear temporal development. During the first 20 min of activity, all the aftershocks were located in a cluster 7 km WNW of the main shock epicenter. During the next 24 hr, the aftershock zone grew to 11 km in the WNW direction and 4 km in the N-S direction. During succeeding weeks, the zone extended to 12 by 6 km. This temporal-spatial development relative to the main shock epicenter may indicate that the initial rupture propagated 7 km unilaterally to the WNW, and the initial rupture plane may have been considerably smaller than the eventual aftershock zone. This smaller area suggests that the stress drop may have been significantly greater than that derived from the final aftershock zone.
In cross section, the aftershock hypocenters outline a nearly horizontal plane (dipping 15° or less) at 13 km depth. The main shock focal mechanism indicates NNE-SSW compression and vertical extension. The preferred fault plane strikes N80°W and dips 26°NNE, indicating north-over-south thrusting with a component of left-lateral movement. Focal mechanisms for 40 aftershocks also indicate compression in the general N-S direction. For most of these events, the north-dipping nodal plane dips between 7° and 45°, with most dipping 25° or more, which is significantly steeper than the plane delineated by the hypocenters themselves. These observations are consistent with a tectonic model in which much of the slip during the Santa Barbara earthquake occurred on a nearly horizontal plane. The after shocks then might represent movement on a complex series of imbricate thrust faults that flatten into the plane of primary slip. Hence, the Santa Barbara earthquake may be taken as evidence for mid-crustal horizontal shearing in the western Transverse Ranges.

Seismic records from the GDSN (SRO, ASRO, DWWSSN, RSTN) and IDA networks were used to obtain long-period (T > 45 sec) focal mechanisms for 35 earthquakes in Western North America (longitude: −140° to −110°; latitude: +30° to +60°) employing the centroid-moment tensor method of Dziewonski et al. (1981) and Dziewonski and Woodhouse (1983). The same algorithm was applied to all events, the smallest (M0 = 6.4 × 1023 dyne-cm) being an aftershock to the 1979 Imperial Valley, California, earthquake and the largest (M0 = 8.5 × 1026 dyne-cm), the 1980 Eureka, California, earthquake. All events were analyzed with and without the constraint Mrθ = Mrφ = 0 on the moment tensor; an ad hoc criterion on the relative variance reduction was employed to determine a favored solution. Our solutions show general agreement with other published results, as well as with tectonic structures. Agreement with results obtained using the abundant local and regional data confirms the adequacy of the method in determining long-period source parameters and verifies its applicability in regions where local and regional data are scarce or nonexistent.
In some cases, disagreement between our solution and results from first motion studies appears to be related to source complexities. Our moment tensor represents the total stress release of the composite event.
A consistent westward movement of the centroid locations reflects lateral heterogeneities in the crust and mantle.

The Santa Barbara earthquake of 13 August 1978, provides an opportunity to perform a broadband investigation of body waves for a well-recorded, moderate size (M_L = 5.1) event. The long- and short-period teleseismic body waves are modeled in the time domain to construct a source time function which is consistent in the period range of 1 to 20 sec. The long-period records indicate an overall duration of 6 sec while the short-period records reveal the fine-scale character of the slip history consisting of two sharp pulses separated by about 1 sec. The source mechanism determined from this analysis is a moderately dipping (30°NE) thrust with significant left-lateral slip. The moment was determined to be 1.1 × 10^(25) dyne-cm.
The earthquake was also reasonably well recorded on accelerographs in the near-field. The modeling of the strong motion displacements was a two step procedure: (1) the displacements were modeled alone, and (2) in an attempt to achieve consistency between the local and far-field time functions, the qualitative features of the teleseismic short-period time function were used to predict the displacements. If the two sources in the short-period time function are allowed to have different mechanisms, the displacements can be modeled quite well. This suggests that the overall faulting process was rough, and the multiple source character suggested at high frequencies is due to high-stress drop asperities. The two sources are modeled as asperities separated by 1.5 km; the first source has a mechanism consistent with the teleseismic solution while the second source is more steeply dipping. The total moment determined from the strong motion data is 3.5 × 10^(24) dyne-cm or one-third the long-period moment. This is consistent with other recent studies which suggest that the high-frequency strong ground motion is controlled by the distribution of asperities even though the sum of their moments may be small compared to the overall moment. This study also shows the importance of teleseismic short periods in predicting the local displacements.

Strong‐motion attenuation relations are commonly derived from earthquake ground motion collected on triggered recorders. Parametric attenuation relations are estimated from these data using standard least squares methods. The variance of ground acceleration is relatively large and for any given earthquake, there is a distance range for which only stations with larger than average amplitudes will trigger recording. Consequently observed accelerations at these distances are higher than the mean ground acceleration and a bias may be introduced into an attenuation relation regression by non‐detection data censoring.

Recent ground motion relations which predict pga, pgv and psrv for rock sites in ENA are based on a stochastic model whose parameters are indicated by seismological studies of earthquake source and attenuation processes. The validity of the model is verified by application to WNA. The choice of model parameters is validated by comparison of model predictions with ground motion data for ENA. For any magnitude, near-source ENA ground motions are enriched in high frequencies relative to WNA motions. Eastern ground motion characteristics have important implications for seismic hazard. High frequency structures in many parts of ENA face a hazard comparable to that in many active areas of California, whereas the hazard for low-frequency structures on rock sites in ENA is relatively modest.