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# Specification of Long-period Ground Motions: Updated Attenuation Relationships for Rock Site Conditions and Adjustment Factors for Near-fault Effects

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... Four attenuation relations commonly used to develop engineering estimates of strong ground motion in WNA are presented [Abrahamson and Silva, 1997;Campbell and Bozorgnia, in press;Sadigh et al., 1993Sadigh et al., , 1997]. All of these relations are empirically based, meaning that they were developed from a regression analysis of strong-motion recordings. ...
... The attenuation relation of Sadigh et al. [1993Sadigh et al. [ , 1997 can be represented by the expression: The relation can be used to estimate ground motion for generic soil, equivalent to the condition S Soil = 1, or generic rock, equivalent to the condition S Rock = 1 (Table 5.4). The regression coefficients for generic rock are listed in Tables 5.11 and 5.12 and those for generic soil in Table 5.13. ...
... Where predicted spectra for nominal hard rock in WNA are compared to those for ENA hard rock, WNA firm rock (nominally V S 30 = 760 m/sec) is used for this comparison. This latter value for the 30-m velocity is used by Frankel Sadigh et al. [1993Sadigh et al. [ , 1997 Rock --Atkinson and Boore [1995,1997] --S Deep = 0 ( V S 30 = 2800) Toro et al. [1997] --ENA hard rock ( V S 30 = 2800) Ambraseys et al. [1996] S C = 1, S D = 0 (Site Class C) Dahle et al. [1990] --Site Class B Yamazaki [1995, 1996] S 1 = 0, S 2 = 0, S 3 = 0, S 4 = 0 S 1 = 1, S 2 = 0.5, S 3 = 0.5, S 4 = 0 - Crouse [1991aCrouse [ , 1991b -Soil - Youngs et al. [1997] -Soil -Spudich et al. [1999] S Soil = 0 (rock) --Note: For those attenuation relations that represent only one site condition or whose reference site condition is not represented by a specific site parameter, the name of the reference site class or the approximate value of the 30-m velocity is given in parentheses. Blank cells indicate that the attenuation relation was not used to evaluate that site condition. ...
Chapter
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Only engineering models that directly predict ground-motion amplitude or that predict the modulation of this amplitude from such effects as fault geometry and source directivity are discussed in this chapter. Duration is an important aspect of strong ground motion, especially for the inelastic response of structures, but much less attention has been paid to predicting duration and, therefore, no consensus engineering models are available. Generally speaking, the inelastic behavior of structures is included in structural design through the use of time histories and structural ductility factors, which are the topics of other chapters in this book.
... We compared our new ground-motion relations with four ground-motion relations that are widely used to estimate horizontal response spectra for seismological and engineering analyses in nonextensional regions of western North America (Sadigh et al., 1993(Sadigh et al., , 1997Abrahamson and Silva, 1997;Campbell, 1997Campbell, , 2000Campbell, , 2001. The Sadigh et al. (1997) relation addresses the average horizontal component for both soil and rock. ...
... The Sadigh et al. (1997) relation addresses the average horizontal component for both soil and rock. The Sadigh et al. (1993) relation addresses the horizontal and vertical components for rock only. Only the relations of Sadigh et al. (1993), Abrahamson and Silva (1997), and Campbell (1997 address the vertical component. ...
... The Sadigh et al. (1993) relation addresses the horizontal and vertical components for rock only. Only the relations of Sadigh et al. (1993), Abrahamson and Silva (1997), and Campbell (1997 address the vertical component. All of these relations rep-resent a seismically active, shallow-crustal tectonic environment, consistent with our study. ...
Article
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In this study we used strong-motion data recorded from 1957 to 1995 to derive a mutually consistent set of near-source horizontal and vertical groundmotion (attenuation) relations for peak ground acceleration and 5%-damped pseudo-acceleration response spectra. The database consisted of up to 960 uncorrected accelerograms from 49 earthquakes and 443 processed accelerograms from 36 earthquakes of N-w 4.7-7.7. All of the events were from seismically and tectonically active, shallow crastal regions, located throughout the world. Some major findings of the study are (1) reverse- and thrust-faulting events have systematically higher amplitudes at. short periods, consistent with their higher dynamic stress drop; (2) very firm soil and soft rock sites have similar amplitudes, distinctively different from amplitudes on firm soil and firm rock sites; (3) the greatest differences in horizontal ground motion among the four site categories occur at long periods on firm rock sites, which have significantly lower amplitudes due to an absence of sediment amplification, and at short periods on firm soil sites, which: have relatively low amplitudes at large magnitudes and short distances due to nonlinear site effects; (4) vertical. ground motion exhibits similar behavior to horizontal motion for firm rock sites at long periods but has. relatively higher short-period amplitudes at short distances on firm soil sites due to a lack of nonlinear site effects, less anelastic attenuation, and phase conversions within the upper sediments. We used a relationship similar to that of Abrahamson and Silva (1997) to model hanging-wall effects but found these effects to be important only for the firmer site categories. The ground-motion relations do not include recordings from the 1999 M-w > 7 earthquakes in Taiwan and Turkey because there is, still no consensus among strong-motion seismologists as to why these events had such low ground motion. If these near-source amplitudes are later found to be atypical, their inclusion could lead to unconservative engineering estimates of ground motion. The study is intended to be a limited update of the ground-motion. relations previously developed. by us in 1994 and 1997, with the explicit purpose of providing engineers and seismologists with a mutually consistent set of near-source ground-motion relations to use in seismic hazard studies. The U.S. Geological Survey and the California Geological Survey have selected the updated relation as one of several that they are using in their 2002 revision of the U.S. and California seismic hazard maps. Being a limited update, the study does not explicitly address such topics as peak ground velocity, sediment depth, rupture directivity effects, or the use of the 30-m velocity or related National Earthquake Hazard Reduction Program site classes. These are topics of ongoing research and will be addressed in a future update.
... The Landers attenuation relationships were compared to two sets of contemporary attenuation relationships: one set that excluded recordings from the 1989 Loma Prieta and 1992 Landers earthquakes (Sadigh et al., 1986(Sadigh et al., , 1993Joyner and Boore, 1988;Campbell, 1993), and another set that included recordings from these as well as other recent earthquakes (Boore et al., 1993;Campbell and Bozorgnia, 1994). These attenuation relationships are representative of those commonly used in the seismic evaluation and design of structures in the western United States. ...
... As a matter of convenience, the attenuation relationships used for the comparisons are identified throughout the remainder of the article by the initials of the last names of the authors followed by the last two digits of the year in which they were published. This corresponds to the following naming convention: SEY86: JB88: BJF93: C93: SCACP93: CB94: Sadigh et al. (1986) Joyner and Boore (1988) Boore et al. (1993) Campbell (1993) Sadigh et al. (1993) Campbell and Bozorgnia (1994 All of the selected attenuation relationships used widely differing measures of source-to-site distance. C93 and CB94 defined their distance measure as the closest distance to seismogenic rupture, identical to that used in this study. ...
... Recent studies of selected earthquakes have shown that long-period amplitudes of near-source horizontal response spectra for components oriented normal to the causative fault are larger than those oriented parallel to the fault (e.g., Somerville and Graves, 1993;Sadigh et al., 1993). This effect has been found to be especially significant for strike-slip faults. ...
Article
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A total of 167 ground-level accelerograms recorded during the 28 June 1992 Ms 7.6 (Mw 7.3) Landers, California, earthquake were used to study the dependence of peak horizontal acceleration and 5%-damped horizontal response spectra on distance, azimuth, and site geology. A comparison of these recordings with ground-shaking amplitudes predicted by contemporary attenuation relationships indicated that: 1) relationships developed prior to the Landers earthquake did a reasonably good job at predicting the Landers ground motions within about 60 km of the fault, but underpredicted the ground motions at further distances by as much as a factor of 2 to 3; and 2) relationships developed after the Landers earthquake did a reasonably good job at predicting the Landers ground motions within the distance ranges for which they were applicable. -from Authors
... Unlike the distance measures defined by Campbell (1981), Sadigh and others (1986, 1993), Idriss (1991a,b), Abrahamson and Silva (1995, 1996), and Shakal and Bernreuter (1981), R SEIS avoids ambiguities associated with identifying and predicting the location of asperities for large earthquakes and the shallowest extent of rupture for moderate-size earthquakes, which are often accompanied by limited surface cracking but no clear identification of surface rupture. Also, Anderson and Luco (1983) have found from theoretical ground motion modeling studies that R SEIS is analytically superior to the distance measure proposed by Joyner and Boore (1981) and later used by Boore and others (1993, 1994) for characterizing the attenuation of ground motion from dipping faults. ...
... Hard Rock is defined as primarily Cretaceous and older sedimentary deposits, metamorphic rock, crystalline rock, and hard volcanic deposits (e.g., basalt). The approximate relationship between the site classifications defined above and similar classifications defined in terms of shear-wave velocity (e.g., Boore and others, 1993; Borcherdt, 1994) and simpler Soil and Rock site classifications (e.g., Sadigh and others, 1986, 1993; Idriss, 1991a,b; Abrahamson and Silva, 1995, 1996) are given in Table 2. ...
... Some studies have found that the dispersion in the predicted value of PGA is dependent on earthquake magnitude (e.g., Sadigh and others. 1986, 1993; Idriss, 1991a,b; Abrahamson and Silva , 1995, 1996), whereas others have found it to be a function of PGA (e.g., Donovan and Bornstein, 1978). Campbell and Bozorgnia (1994a) investigated both of these hypotheses by plotting the running value of the standard error of estimate of ln(A H ) as a function of mean earthquake magnitude and me ...
Article
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A consistent set of empirical attenuation relationships is presented for predicting free-field horizontal and vertical components of peak ground acceleration (PGA), peak ground velocity (PGV), and 5% damped pseudo-absolute acceleration response spectra (PSA). The relationships were derived from attenuation relationships previously developed by the author from 1990 through 1994. The relationships were combined in such a way as to emphasize the strengths and minimize the weaknesses of each. The new attenuation relationships are considered to be appropriate for predicting free-field amplitudes of horizontal and vertical components of strong ground motion from worldwide earthquakes of moment magnitude (MW) ≥ 5 and sites with distances to seismogenic rupture (RSEIS) ≤ 60 km in active tectonic regions.
... We compared our new ground-motion relations with four ground-motion relations that are widely used to estimate horizontal response spectra for seismological and engineering analyses in nonextensional regions of western North America (Sadigh et al., 1993(Sadigh et al., , 1997Abrahamson and Silva, 1997;Campbell, 1997Campbell, , 2000Campbell, , 2001. The Sadigh et al. (1997) relation addresses the average horizontal component for both soil and rock. ...
... The Sadigh et al. (1997) relation addresses the average horizontal component for both soil and rock. The Sadigh et al. (1993) relation addresses the horizontal and vertical components for rock only. Only the relations of Sadigh et al. (1993), Abrahamson and Silva (1997), and Campbell (1997 address the vertical component. ...
... The Sadigh et al. (1993) relation addresses the horizontal and vertical components for rock only. Only the relations of Sadigh et al. (1993), Abrahamson and Silva (1997), and Campbell (1997 address the vertical component. All of these relations rep-resent a seismically active, shallow-crustal tectonic environment, consistent with our study. ...
... Comparison of the worldwide laws usually used in Algeria [35][36][37] with the attenuation law proposed by Laouami [7] (Fig. 16) shows that: (i) the Ambraseys and Bommer law [35] fits well the proposed law up to 30 km, and is overestimating it at greater distances, (ii) the Sadigh et al. [36] law is underestimating the proposed law up to 30 km and fits it well at greater distances, and (iii) the Ambraseys law [37] does not fit the proposed attenuation law at all. ...
... Comparison of the worldwide laws usually used in Algeria [35][36][37] with the attenuation law proposed by Laouami [7] (Fig. 16) shows that: (i) the Ambraseys and Bommer law [35] fits well the proposed law up to 30 km, and is overestimating it at greater distances, (ii) the Sadigh et al. [36] law is underestimating the proposed law up to 30 km and fits it well at greater distances, and (iii) the Ambraseys law [37] does not fit the proposed attenuation law at all. ...
... At all stations, a directionality effect of the fault induces significantly higher PGA on the E-W than on the N-S component. Furthermore, an analysis of the seismic motion anisotropy, based on the azimuthal distribution of both the standard deviation and the maximum acceleration of the projected movement, gives average azimuths Distance (km) Maximum Acceleration (g) Laouami attenuation law Ambraseys and Bommer, 1991Ambraseys,1995Sadigh and al., 1993. Comparison between the proposed mean Algerian attenuation law [7] with the worldwide laws. ...
Article
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The Algiers–Boumerdes region has been struck by a destructive magnitude 6.8 (M w) earthquake on May 21, 2003. The study presented in this paper is based on main shock strong motions from 13 stations of the Algerian accelerograph network. A maximum 0.58g peak ground acceleration (PGA) has been recorded at 20 km from the epicenter, only about 150 m away from a PGA of 0.34g, with both a central frequency around 5 Hz, explained by a strong very localized site effect, confirmed by receiver function technique results showing peaks at 5 Hz with amplitudes changing by a factor of 2. Soil amplifications are also evidenced at stations located in the quaternary Mitidja basin, explaining the higher PGA values recorded at these stations than at stations located on firm soil at similar distances from the epicenter. A fault-related directionality effect observed on the strong motion records and confirmed by the study of the seismic movement anisotropy, in agreement with the N65 fault plan direction, explains the SW–NE orientation of the main damage zone. In the near field, strong motions present a high-frequency content starting at 3 Hz with a central frequency around 8 Hz, while in the far field their central frequency is around 3 Hz, explaining the high level of damage in the 3-to 4-story buildings in the epicentral zone. The design spectra overestimate the recorded mean response spectra, and its high corner frequency is less than the recorded one, leading to a re-examination of the seismic design code that should definitively integrate site-related coefficient, to account for the up to now neglected site amplification, as well as a re-modeling of the actual design spectra. Finally, both the proposed Algerian attenuation law and the worldwide laws usually used in Algeria underestimate the recorded accelerations of the 6.8 (M w) Boumerdes earthquake, clearly showing that it is not possible to extrapolate the proposed Algerian law to major earthquakes.
... años y la magnitud máxima posible, que define la magnitud el terremoto más grande que físicamente puede generarse de acuerdo a las propiedades y a las características sismotectónicas, se estima a partir del potencial sísmico de las fuentes lineales que se ubican dentro de un área determinada, Polidor (1986), Audemard, et. al. (1995) Campbell, 1993; Sadigh et. al., 1993 6.4. Relación de atenuación de Idriss, 1993. La ecuación derivada por Idriss (1993), particularizada para roca es: [ ] 20) R ...
... rados en la corteza a pequeñas y medianas profundidades y una (1) para caracterizar los eventos generados en zonas de subducción, aplicable a la zona del Nido de Bucaramanga ( Jaramillo, 2000). Las relaciones para determinar las aceleraciones máxima del terreno seleccionadas para terremotos corticales son las de Boore, et. al., 1993;Campbell, 1993;Sadigh et. al., 1993y la de Idriss, 1993 , et. al., 1993. La ecuación predice la más grande componente horizontal aleatoria del movimiento del terreno, con la expresión: ...
Article
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This paper shows the probabilistic seismic hazard analysis to the Western region of Venezuela. The study considers four different earthquake levels: 50% probability of being exceeded in 30 years (frequent), 50% probability of being exceeded in 50 years (occasional), 10% probability of being exceeded in 50 years (rare) and 10% probability of being exceeded in 100 years (very rare). The area is contained between -73W and -68W in longitude and between 7N and 12N in latitude. One of the significant outcomes of the study was the preparation of an upto-date and refined earthquake catalog of the region, from 1610 to 2000, with 6,078 independent events. Based in geologic evidence, geotectonic province, historic and instrumental seismicity, and the spatial variation of the parameters of the seismic recurrence equation, the seismic sources were modeled as 14 areas sources. We have decided to use the stationary Poisson model and the truncated exponential relationship as magnitude distribution relationship. Several ground motion attenuation relationships to characterize the fault type and the near fault effects were used. The results indicate that the highest relative predicted ground motion for competent or rock site, are concentrated within district of Carache (Trujillo state) and Torres (Lara state) for each one of the design levels studied. Based on iso-acceleration map for 10% probability of being exceeded in 50 years, the levels reached within these zones are somewhat over 0,40g.
... Recent empirical attenuation relation studies have generally found that peak horizontal accelerations from thrust earthquakes are 20 to 30% larger than from strike-slip earthquakes for the same magnitude and closest distance (e.g., Campbell 1993;Idriss 1991;Sadigh et aL, 1993;Boore et al., 1994). This effect of earthquake mechanism on the ground motion has been called the style-of-faulting factor. ...
... They used empirical recordings from 11 reverse-oblique and reverse events with M -> 6.0 (Table 4). The residuals of the oblique and reverse event peak accelerations were computed from the Sadigh et al. (1993) and Sadigh (1987) attenuation relations for rock and soil, respectively, and are shown in Figure 6. The residuals from the Northridge earthquake are also shown in this figure. ...
Article
Systematic differences in ground motion on the hanging wall and foot-wall during the Northridge earthquake are evaluated using empirical data. An em-pirical model for the hanging-wall effect is developed for the Northridge earthquake. This empirical model results in up to a 50% increase in peak horizontal accelerations on the hanging wall over the distance range of 10 to 20 km relative to the median attenuation for the Northridge earthquake. In contrast, the peak accelerations on the footwall are not significantly different from the median attenuation over this distance range. Recordings from other reverse events show a similar trend of an increase in the peak accelerations on the hanging wall, indicating that this systematic difference in hanging-wall peak accelerations is likely to be observed in future reverse events.
... The effect of source mechanism in predictive attenuation relations was recognized and pointed out many times by many researchers. McGarr (1984), Campbell (1984), Sadigh et al. (1993), Boore et al. (1997 , and Anooshehpoor and Brune (2002) showed that thrust faults exhibit higher PGAs than those from other source mechanisms. Accordingly all the available information on the focal mechanisms of the earthquakes of our data set was collected from Papazachos and Papazachou (2002), from Papazachos et al. (2001c), as well as from the online catalog of the institutes Istituto Nazionale di Geofisica (I.N.G.), Eidgenössische Technische Hochschule (E.T.H.), and Harvard. ...
... This is important issue in order to avoid introducing nonlinear effects in the predictive relations from magnitude-conversion relations (e.g.,Fukushima, 1996;Papazachos et al., 2001a). The effect of source mechanism in predictive attenuation relations was recognized and pointed out many times by many researchers.McGarr (1984), Campbell (1984),Sadigh et al. (1993), Boore et al. (1997, and Anooshehpoor andBrune (2002)showed that thrust faults exhibit higher PGAs than those from other source mechanisms. Accordingly all the available information on the focal mechanisms of the earthquakes of our data set was collected fromPapazachos andPapazachou (2002), from Papazachos et al. (2001c), as well as from the online catalog of the institutes Istituto Nazionale di Geofisica (I.N.G.), Eidgenössische Technische Hochschule (E.T.H.), and Harvard. ...
Article
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In the present article new predictive relations are proposed for the peak values of the horizontal components of ground acceleration, velocity, and displace-ment, using 619 strong motion recordings from shallow earthquakes in the broader Aegean area, which are processed using the same procedure in order to obtain a homogeneous strong motion database. The data set is derived from 225 earthquakes, mainly of normal and strike-slip focal mechanisms with magnitudes 4.5 M 7.0 and epicentral distances in the range 1 km R 160 km that have been relocated using an appropriate technique. About 1000 values of peak ground acceleration (PGA), velocity (PGV), and displacement (PGD) from horizontal components were used to derive the empirical predictive relations proposed in this study. A term ac-counting for the effect of faulting mechanisms in the predictive relations is intro-duced, and the UBC (1997) site classification is adopted for the quantification of the site effects. The new relations are compared to previous ones proposed for Greece or other regions with comparable seismotectonic environments. The regression anal-ysis showed a noticeable (up to 30%) variance reduction of the proposed relations for predicting PGA, PGV, and PGD values compared to previous ones for the Aegean area, suggesting a significant improvement of predictive relations due to the use of a homogeneous strong motion database and improved earthquake parameter infor-mation.
... Their simulations predicted higher near-field ground motions than those extrapolated from empirical data. The simulations predicted ground motions that were comparable in amplitude to the ground motions predicted by empirical attenuation relationships for shallow-crustal reverse-faulting earthquakes (e.g., Sadigh et al., 1993). Thus, for short distances, Youngs et al. (1997) suggested that higher ground motions be considered than those empirically predicted. ...
... Thus, for short distances, Youngs et al. (1997) suggested that higher ground motions be considered than those empirically predicted. Based on this recommendation, the 1996 National Hazard Maps also included the Sadigh et al. (1993) empirical attenuation relationship for reverse faulting for modeling ground motions from Cascadia subduction zone interface events. ...
Article
Abstract The number,of strong ground motion recordings available for regression analysis in developing empirical attenuation relationships has rapidly grown,in the last 10 years. However, the dearth of strong-motion data from the Cascadia subduc- tion zone has limited this development,of relationships for the Cascadia subduction zone megathrust, which can be used in the calculation of design spectra for engi- neered structures. A stochastic finite-fault ground-motion model,has been used to simulate ground motions for moment magnitude (M) 8.0, 8.5, and 9.0 megathrust earthquakes along the Cascadia subduction zone for both rock-and soil-site condi- tions. The stochastic finite-fault model,was validated against the 1985 M 8.0 Mi- choacan, Mexico, and the 1985 M 8.0 Valpariso, Chile, earthquakes. These two subduction zone megathrust earthquakes were recorded at several rock sites located near the fault rupture. For the Cascadia megathrust earthquakes, three different rup- ture geometries were used to model the M 8.0, 8.5, and 9.0 events. The geometries only differ in their respective fault lengths. A fault dip of 9 to the east with a rupture width of 90 km,was selected to represent average properties of the Cascadia sub- duction zone geometry. A regional crustal damping,and velocity model was used with the stochastic finite-fault model,simulations. Ground motions were computed for 16 site locations. The parametric uncertainties associated with the variation in source, path, and site effects were included in the development of the ground motions. A functional form was fit to the ground-motion model simulations to develop region- specific attenuation relationships for the Cascadia megathrust rupture zone for both rock and soil site conditions. The total uncertainty was based on a combination,of the modeling,and parametric uncertainties (sigmas). These newly developed atten- uation relationships for Cascadia subduction zone megathrust earthquakes can be used in both the probabilistic and deterministic seismic-hazard studies for engineer- ing design for the Pacific Northwest.
... In this study, empirical attenuation relationships developed on the basis of statistical analysis of strong motion data recorded at locations having a similar tectonic environment were used. They are given by the following formulas (Sadigh et al. 1993 where R is the closest distance to the rupture area, M is moment magnitude, a h is maximum peak ground acceleration in ground surface, and r is the standard error in ln(a h ). In our study area the attenuation model chosen is that of Ambraseys et al. (2005): ...
Article
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The aim of this study is to conduct a probabilistic seismic hazard analysis and spatial variation of seismic hazard at the surface level for Northeast of Algeria, covering 4°E–9°E, 33°N–38°N. The most recent peak ground acceleration (PGA) attenuation relationship, along with the updated seismic catalog and the best knowledge on the seismic activity in the study area have been used to estimate the seismic hazard and its uncertainty. Two types of seismic source models, linear sources and areal sources, were considered to model the seismic sources. Different sets of ground motion prediction equations were used for different tectonic provinces to characterize the attenuation properties. The hazard estimation at bedrock level was carried out using a probabilistic approach and the results obtained from various methodologies were combined into a logic tree framework. In this paper, we generate PGA maps with 10% probability of exceedance in 50 years, for a rock site condition. The seismic site characterization of Algeria was done using topographic slope map derived from Digital elevation model data. We estimate the seismic hazard from the seismicity catalog and not from faults with recurrence rates obtained from geologic data. The hazard estimation at surface level, is achieved through the use of appropriate site amplification factors corresponding to various site classes based on topographic gradient. Spatial variation of surface level PGA for return periods of 100, 475 years and 2000 years are presented as contour maps. The maps obtained in this study are based on the assumption that the process of earthquake occurrence is inherently Poissonian, so that the probabilistic ground motion is time-independent.
... Amplification factors were evaluated by normalizing response spectral accelerations computed from recordings by reference spectral accelerations derived from the Sadigh et al. (1993) rock attenuation relationship. The database used was the southern California database of Steidl and Lee (2000). ...
... In this study, empirical attenuation relationships developed on the basis of statistical analysis of strong motion data recorded at locations having a similar tectonic environment were used. They are given by the following formulas of (Sadigh et al. 1993): where R is the closest distance to the rupture area, M is moment magnitude, a h is maximum peak ground acceleration in ground surface and σ is the standard error in ln(a h ), and Ambraseys and Bommer (1991) give the following: where r is the closest distance to the surface projection of the rupture surface, M s is the surface magnitude and h is the depth; P ranges from 0 (for 50% percentile) to 1 (for 84% percentile). ...
Article
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This paper presents a seismic hazard evaluation and develops an earthquake catalog for the Constantine region over the period from 1357 to 2014. The study contributes to the improvement of seismic risk management by evaluating the seismic hazards in Northeast Algeria. A regional seismicity analysis was conducted based on reliable earthquake data obtained from various agencies (CRAAG, IGN, USGS and ISC). All magnitudes (Ml, Mb) and intensities (I0, IMM, IMSK and IEMS) were converted to Ms magnitudes using the appropriate relationships. Earthquake hazard maps were created for the Constantine region. These maps were estimated in terms of spectral acceleration (SA) at periods of 0.1, 0.2, 0.5, 0.7, 0.9, 1.0, 1.5 and 2.0 sec. Five seismogenic zones are proposed. This new method differs from the conventional method because it incorporates earthquake magnitude uncertainty and mixed datasets containing large historical events and recent data. The method can be used to estimate the b-value of the Gutenberg-Richter relationship, annual activity rate λ (M) of an event and maximum possible magnitude Mmax using incomplete and heterogeneous data files. In addition, an earthquake is considered a Poisson with an annual activity rate λ and with a doubly truncated exponential earthquake magnitude distribution. Map of seismic hazard and an earthquake catalog, graphs and maps were created using geographic information systems (GIS), the Z-map code version 6 and Crisis software 2012.
... The relationship between the vertical and horizontal components of strong ground motion in terms of intensity and frequency content has been investigated by many researchers. Selected studies on the subject include Campbell (1982), Niazi and Bozorgnia (1989, 1991, Abrahamson and Litehiser (1989), Trifunac and Lee (1989), Bozorgnia and Niazi (1993), Sadigh et al. (1993), Bozorgnia et al. (1995), Ambraseys and Simpson (1996), Abrahamson and Silva (1997), Campbell (1997), Elnashai and Papazoglou (1997), , Amirbekian and Bolt (1998), Ansary and Yamazaki (1998), Beresnev et al. (2002), Berge-Thierry et al. (2003), Campbell and Bozorgnia (2003), Bozorgnia and Campbell (2004), Kalkan and Gülkan (2004), Ambraseys et al. (2005), Bindi et al. (2010), Edwards et al. (2011), Gülerce and Abrahamson (2011), Bommer et al. (2011), Poggi et al. (2012), and Akkar et al. (2014). Also, for the first time in the United States, the National Earthquake Hazard Reduction Program (NEHRP) Seismic Provisions (BSSC 2009) adopted a modified version of the simplified V/H spectrum proposed by Bozorgnia and Campbell (2004) to use in developing a vertical design spectrum if desired by the engineer. ...
Article
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We present a ground motion model (GMM) for the vertical-to-horizontal (V/H) ratios of peak ground acceleration, peak ground velocity, and 5%-damped pseudo-acceleration response spectra at periods ranging from 0.01 s to 10 s. The V/H GMM includes formulations for the median V/H ratio and for the aleatory within-event, between-event, and total standard deviations. The V/H model is based on the GMMs we have developed for the vertical and "average" horizontal components of ground motion using a mathematical formation that accounts for the correlation between these two components. We validated the V/H model against the NGA-West2 empirical database. We consider our V/H model to be valid for worldwide shallow crustal earthquakes in active tectonic regions for moment magnitudes ranging from 3.3 to 8.5, depending on the style of faulting, and for fault rupture distances ranging from 0 km to 300 km. Our V/H model incorporates period-dependent effects of magnitude saturation, style of faulting, hypocentral depth, fault-rupture dip, geometric attenuation, regionally dependent anelastic attenuation and site response, hanging-wall geometry, and magnitude-dependent between-event and within-event aleatory variabilities. The V/H ratios predicted from the model show a strong dependence on spectral period and site response.
... In order to perform probabilistic seismic hazard analysis (PSHA) it is necessary to have attenuation equations which relate, in probabilistic terms, magnitude and source-to-site distance with the intensity measure of interest, usually peak ground or spectral accelerations. The lack, until recently, of strong motion data in Algeria, and the pressing need for studies of seismic hazard in different potentially seismic regions, motivated the use of American and European attenuation laws (Sadigh et al., 1993;Ambraseys and Bommer, 1991) as considered most appropriate to the Algerian context. In this study, it has been intended to derive the attenuation relationships for PGA and PSA parameters using the earthquake records database which includes more than 1,000 records obtained since 1980. ...
Conference Paper
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This paper deals with the development of the Algerian attenuation law based on local and regional database. Since the installation of the Algerian accelerographs network (335 stations), several earthquakes were recorded thus forming a very useful database including more than 1000 records (3<Ms<6.9 and 7< D hyp <160 Km). One of the most important applications was to derive an attenuation relationship for Algeria. The considered spectral attenuation model accounts for geometrical spreading, anelastic attenuation, and geological site conditions. The regression method, introduced by joyner and Boore (1981), is a two-step inversion [Fukushima and Tanaka, 1990; Fukushima and Tanaka, 1992]. The attenuation model describes the evolution of spectral acceleration according to magnitude, hypocentrale distance, and category of the site. Spectral attenuation laws were derived from 1317 horizontal components homogeneously processed including Algerian strong motion records (48%), European records (42%) and American records (12%). Two models are studied, the first one considers Algerian data only, called local model, and the second one consider the whole data called regional model. The obtained results show that the PGA standard deviation decreases from 0.331 (local data) to 0.314 (regional data), and the local model overestimates the predicted acceleration for larger magnitude. The residual values between observed and predicted spectral accelerations are studied and do not exhibit any bias. The proposed regional model is in good agreement with classical published GMPE's.
... The prediction of seismic risk depends intimately on the attenuation relationship. Several relationships have been investigated for the case of Algeria on the basis of existing attenuation laws (Joyner and Boore 1981;Ambraseys and Bommer 1991;Sadigh et al. 1993;Ambraseys 1995;Ambraseys et al. 2005;Mébarki 2009). Domestic attenuation laws have also been investigated and developed (Benouar 1994;CGS 1998). ...
Article
Located at the North-Eastern part of Algeria (Tellian Atlas), Constantine has crucial administrative, economic, scientific and cultural importance. It has continuously experienced significant urban evolutions during the different periods of its history. The city is located in an active seismic region within Algeria and has been struck in the past by several moderate and strong earthquakes. The strongest earthquake recorded since the beginning of instrumental seismology took place on October 27, 1985 with a magnitude M $$_\mathrm{S}=$$ 5.9. Constantine presents a high seismic risk, because of its dense housing and high population density (2,374 inhabitants/km $$^{2})$$ . This requires a risk assessment in order to take preventive measures and reduce the losses in case of potential major earthquake. For this purpose, a scenario based approach is considered. The building damage assessment methodology adopted for the Algerian context is adapted from HAZUS approach. In the present case, the effective Algerian seismic code response spectrum (RPA 99/2003) is considered as a seismic hazard model. The prediction of the expected damages is performed for a set of almost 29,000 buildings.
... Attenuation models for subduction zone earthquakes are not included because our instrumental and seismotectonic data indicate that most earthquakes within approximately a 600-km radius from Bangkok belong to the shallow crustal type. The first group of new models to be considered are four empirical models developed for Western North America (WNA) by Boore et al. (1997), Abrahamson and Silva (1997), Campbell and Bozorgnia (1994), Sadigh et al. (1993). The second group are two new empirical models for Europe (EU) developed from regression analyses of European and Italy strong-motion data by Ambraseys and Bommer (1992) and Sabetta and Pugliese (1987), respectively. ...
Article
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A seismic hazard assessment of Bangkok is conducted. The results are presented in the form of predicted peak ground accelerations for various levels of probability of exceedance in a 50-year period and the corresponding elastic response spectra. The results indicate that Bangkok, though located at a remote distance from seismic sources, is still at risk of damaging earthquake ground motions similar to those found in Mexico City during the 1985 Michoacan earthquake. The risk is essentially caused by three factors. First, several regional seismic sources that may contribute significantly to the seismic hazard of Bangkok are capable of generating large earthquakes. Second, the attenuation rate of ground motions in this region appears to be rather low and well represented by attenuation models of Central and Eastern North America. Third, the surficial deposits in Bangkok have the ability to amplify earthquake ground motions about 3 to 4 times.
... ( WUS ) . The records were selected by searching an up - to - date data base of strong motion records for rock sites ( Sadigh et al . 1993 ) to find the records whose average horizontal spectrum was similar to a smoothed empirical spectral shape for the desired magnitude and distance ranges . The records chosen and their characteristics are given in Table 2 . 2 . ...
... Four attenuation relations characterizing events generated in crustal faults at small to medium depths, and one relation for subduction zone events, applicable to the Nido of Bucaramanga, in Colombia were used in the study. The relationships used in the first category were drawn from Boore et al. (1993), Campbell (1993, Sadigh et al. (1993), and Idriss (1993), while Crouse (1991) was used for the second category. The results of the probabilistic seismic hazard model in west Venezuela were obtained using the EZ-FRISK software (Risk Engineering 1999). ...
Conference Paper
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Until recently, the focus of FEMA’s Hazus earthquake model has been US centric, largely due to a lack of standardized building/infrastructure data formats applicable elsewhere. In a combined effort between FEMA Region 8 and the Universidad de Los Andes, Venezuela, the Hazus earthquake model was adapted to conduct earthquake loss estimations for Venezuela. The required population totals and demographic distributions were developed using Oak Ridge National Labs Landscan 2008 population data and the census 2001 data from the country. The accuracy of the model was further enhanced for Mérida State by the inclusion of geologic data maps and risk assessment data from other investigations. To identify possible scenarios we used a USGS ShakeMap scenario, representing the historical earthquake that occurred in Mérida in 1674 with an estimated magnitude Ms7.5. Countless minor seismic tremors are continually registered but there is an increasing probability of a damaging earthquake.
... rados en la corteza a pequeñas y medianas profundidades y una (1) para caracterizar los eventos generados en zonas de subducción, aplicable a la zona del Nido de Bucaramanga (Jaramillo, 2000). Las relaciones para determinar las aceleraciones máxima del terreno seleccionadas para terremotos corticales son las de Boore, et. al., 1993; Campbell, 1993; Sadigh et. al., 1993 de Sadigh, et. al., 1993. La ecuación predice la aceleración máxima horizontal y es válida para sismos con magnitud entre 4 y 8, y distancias al sitio de hasta 100 km. ...
Article
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This paper shows the probabilistic seismic hazard analysis to the Western region of Venezuela. The study considers four different earthquake levels: 50% probability of being exceeded in 30 years (frequent), 50% probability of being exceeded in 50 years (occasional), 10% probability of being exceeded in 50 years (rare) and 10% probability of being exceeded in 100 years (very rare). The area is contained between –73W and -68W in longitude and between 7N and 12N in latitude. One of the significant outcomes of the study was the preparation of an upto-date and refined earthquake catalog of the region, from 1610 to 2000, with 6,078 independent events. Based in geologic evidence, geotectonic province, historic and instrumental seismicity, and the spatial variation of the parameters of the seismic recurrence equation, the seismic sources were modeled as 14 areas sources. We have decided to use the stationary Poisson model and the truncated exponential relationship as magnitude distribution relationship. Several ground motion attenuation relationships to characterize the fault type and the near fault effects were used. The results indicate that the highest relative predicted ground motion for competent or rock site, are concentrated within district of Carache (Trujillo state) and Torres (Lara state) for each one of the design levels studied. Based on iso-accelerationmap for 10% probability of being exceeded in 50 years, the levels reached within these zones are somewhat over 0,40g.
... rados en la corteza a pequeñas y medianas profundidades y una (1) para caracterizar los eventos generados en zonas de subducción, aplicable a la zona del Nido de Bucaramanga (Jaramillo, 2000). Las relaciones para determinar las aceleraciones máxima del terreno seleccionadas para terremotos corticales son las de Boore, et. al., 1993; Campbell, 1993; Sadigh et. al., 1993 de Sadigh, et. al., 1993. La ecuación predice la aceleración máxima horizontal y es válida para sismos con magnitud entre 4 y 8, y distancias al sitio de hasta 100 km. ...
Article
Full-text available
This paper shows the probabilistic seismic hazard analysis to the Western region of Venezuela. The study considers four different earthquake levels: 50% probability of being exceeded in 30 years (frequent), 50% probability of being exceeded in 50 years (occasional), 10% probability of being exceeded in 50 years (rare) and 10% probability of being exceeded in 100 years (very rare). The area is contained between –73W and -68W in longitude and between 7N and 12N in latitude. One of the significant outcomes of the study was the preparation of an upto-date and refined earthquake catalog of the region, from 1610 to 2000, with 6,078 independent events. Based in geologic evidence, geotectonic province, historic and instrumental seismicity, and the spatial variation of the parameters of the seismic recurrence equation, the seismic sources were modeled as 14 areas sources. We have decided to use the stationary Poisson model and the truncated exponential relationship as magnitude distribution relationship. Several ground motion attenuation relationships to characterize the fault type and the near fault effects were used. The results indicate that the highest relative predicted ground motion for competent or rock site, are concentrated within district of Carache (Trujillo state) and Torres (Lara state) for each one of the design levels studied. Based on iso-acceleration map for 10% probability of being exceeded in 50 years, the levels reached within these zones are somewhat over 0,40g.
... Field (2000) evaluated amplification factors as a direct function of V s-30 using a non-reference site approach in which amplification factors were derived as a term within a southern California attenuation relationship. Steidl (2000) also used a non-reference site approach, evaluating site factors as a function of V s-30 using residuals from the Sadigh et al. (1993) attenuation relationship for rock sites (similar to the Sadigh et al. 1997 relation). The amplification factors from the Harmsen and Field studies are independent of PHA r . ...
Article
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We develop empirical relationships to predict nonlinear (i.e., amplitude-dependant) amplification factors for 5% damped response spectral acceleration as a continuous function of average shear wave velocity in the upper 30 m, Vs-30. We evaluate amplification factors as residuals between spectral accelerations from recordings and modified rock attenuation relationships for active regions. Amplification at low- and mid-periods is shown to increase with decreasing Vs-30 and to exhibit nonlinearity that is dependent on Vs-30. The degree of nonlinearity is large for NEHRP Category E (Vs-30< 180 m/s) but decreases rapidly with Vs-30, and is small for Vs-30>similar to 300 m/s. The results can be used as Vs-30-based site factors with attenuation relationships. The results also provide an independent check of site factors published in the NEHRP Provisions, and apparent bias in some of the existing NEHRP factors is identified. Moreover, the results provide evidence that data dispersion is dependent on Vs-30.
... • Kenneth Campbell and Yousef Bozorgnia (Campbell, 1997;Campbell and Bozorgnia, 2003). • Brian Chiou and Robert Youngs, representing the model of Sadigh et al. (Sadigh, et al., 1993;1997). • I.M. Idriss (Idriss, 1991). ...
Article
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The "Next Generation of Ground Motion Attenuation Models" (NGA) project is a partnered research program conducted by Pacific Earthquake Engineering Research Center-Lifelines Program (PEER-LL), U.S. Geological Survey (USGS), and Southern California Earthquake Center (SCEC). The project has the objective of developing updated ground motion attenuation relationships through a comprehensive and highly interactive research program. Five sets of updated attenuation relationships are developed by teams working independently but interacting throughout the development process. The main technical issues being addressed by the NGA teams include magnitude scaling at close-in distances, directivity effects,  polarization of near-field motion (fault- strike-normal component vs. fault-strike-parallel component), nonlinear amplification by shallow soil, and sedimentary basin amplification. The attenuation relationships development is also facilitated by the development of an updated and expanded database of recorded ground motions; conduct of supporting research projects to provide constraints on the selected functional forms of the attenuation relationships; and a program of interactions throughout the development process to provide input and reviews from both the scientific research community and the engineering user community. An overview of the NGA project components, process, and products developed by the project is presented in this paper.
... • Norman Abrahamson and Walter Silva (Abrahamson and Silva 1997) • David Boore and Gail Atkinson (Boore et al. 1997) • Kenneth Campbell andYousef Bozorgnia (Campbell 1997, Campbell andBozorgnia 2003) • Brian Chiou and Robert Youngs, representing the model of Sadigh et al. (1993Sadigh et al. ( , 1997 • I. M. Idriss (Idriss 1991) ...
Article
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The "Next Generation of Ground-Motion Attenuation Models" (NGA) project is a multidisciplinary research program coordinated by the Lifelines Program of the Pacific Earthquake Engineering Research Center (PEER), in partnership with the U.S. Geological Survey and the Southern California Earthquake Center. The objective of the project is to develop new ground-motion prediction relations through a comprehensive and highly interactive research program. Five sets of ground-motion models were developed by teams working independently but interacting with one another throughout the development process. The development of ground-motion models was supported by other project components, which included (1) developing an updated and expanded PEER database of recorded ground motions, including supporting information on the strong-motion record processing, earthquake sources, travel path, and recording station site conditions; (2) conducting supporting research projects to provide guidance on the selected functional forms of the ground-motion models; and (3) conducting a program of interactions throughout the development process to provide input and reviews from both the scientific research and engineering user communities. An overview of the NGA project components, process, and products is presented in this paper.
... The effect of source mechanism in predictive attenuation relations was recognized and pointed out many times by many researchers. McGarr (1984), Campbell (1984), Sadigh et al. (1993), Boore et al. (1997 , and Anooshehpoor and Brune (2002) showed that thrust faults exhibit higher PGAs than those from other source mechanisms. Accordingly all the available information on the focal mechanisms of the earthquakes of our data set was collected from Papazachos and Papazachou (2002), from Papazachos et al. (2001c), as well as from the online catalog of the institutes Istituto Nazionale di Geofisica (I.N.G.), Eidgenössische Technische Hochschule (E.T.H.), and Harvard. ...
Article
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A method for improving the accuracy of hypocenter parameters estimation of past and future earthquakes together with the upper mantle velocity structure in the broader Aegean area is presented. The method involves the correction of the seismic wave travel times at regional stations based on a calibration with well-located local earthquakes. The employed data set consists of travel times of earthquakes recorded from both local networks and a sufficient number of regional stations. The earthquake hypocenter parameters estimated from local networks, which are assumed to have been determined accurately are used to compute expected travel times at regional stations. From the comparison of the expected and the observed travel times of seismic waves we calculate “absolute” residuals for each one of regional stations located within the area of interest. These “absolute” residuals are considered to reflect not only the various errors participating in the estimation of the earthquake hypocenter parameters but also the divergence of the thickness of the crust from an average crustal model and the variations of the velocities of Pn and Sn waves for a specific path. The “absolute” residuals are processed through an inversion technique, which results in the estimation of time corrections and velocity variations of Pn waves for every node of the grid (1x1 square windows) into which the examined area has been divided.
... The truncated exponential recurrence model (Cornell and Van Marke, 1969) for seismic source areas and the characteristic model (Young & Copersmith, 1984) for specific faults. In terms of ground motion attenuation we used the worldwide developed attenuation laws which fit the Algerian data (Ambraseys & Bommer, 1991; Sadigh & al., (1993). The two attenuations laws has been given an equal weight of 50% in the model. ...
Article
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This paper present results of the probabilistic seismic hazard analysis carried out in the Oran region, situated in the Northwest of Algeria. This part of Algeria was historically struck by strong earthquakes, it was particularly affected during the October 9, 1790 Oran earthquake of intensity (IX-X). The main purpose of this work is to assess seismic hazard on hard rock in order to provide engineers and planners a basic tool for seismic risk mitigation. The probabilistic approach is used in order to take into account uncertainties in seismic hazard assessment. Seismic sources are defined on the basis of recent results of seismotectonics studies. Source parameters are assessed for each seismic source either on the basis of seismicity data or geological data. The attenuation of ground shaking motion with distance is estimated by using attenuation relationships developed world-wide which fit the Algerian data. Different choices of source parameters values as well as attenuation relationships are assigned an appropriate weight in the framework of a logic tree model. Results are presented as relationships between values of peak ground acceleration (PGA) and annual frequency of exceedance, and map of hazard for a return period of 500 years. A maximum peak ground acceleration of 0.40g is obtained for the Oran site.
Book
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Este libro es producto del trabajo en el campo de la Ingeniería Sismológica que el autor ha realizado durante más de veinte años. Incluye apartes de los apuntes de clase de los profesores del autor de la Universidad Politécnica de Cataluña, Barcelona, España y del International Institute of Seismology and Earthquake Engineering, Tsukuba, Japón. También apartes de las clases que el autor ha dictado en las Universidades Colombianas: Pontificia Universidad Javeriana, Universidad de La Salle, Universidad Industrial de Santander-UIS y la Universidad de Cuenca en Ecuador. Existe relativamente poca literatura en castellano en el tema de la Ingeniería Sismológica, la cual es una especie de interfase entre la Sismología y la Ingeniería Civil. En algunas ocasiones los resultados de los estudios sismológicos son difíciles de interpretar y utilizar, de otro lado los ingenieros geotecnistas y estructurales se rigen por las normas existentes, a veces sin prestar mayor atención a las múltiples limitaciones de las mismas. Este libro presenta de manera simplificada los aspectos más importantes en el estudio de los sismos y su interpretación para el uso en el diseño de estructuras.
Article
The main objective of this study was to assess spatial prediction of slopes movement susceptibility in the Bousselam upstream basin, northeast of Algeria, using a linear indexing model and Geographic Information Systems. First, the locations of 1109 slope instabilities, which occurred in the last three decades, were mapped upon data from various sources such as follows: remote sensing, aerial photographs interpretation, and internal reports compilation. This slope movement inventory was randomly segmented into training and validation datasets (75 % of the known events locations were used for training and building the model and the remaining 25 % for its validation). Second, nine natural and anthropogenic causing factors were mapped as independent variables: geological factors (lithology and faults density), morphometric factors (slope, aspect, and elevations), environmental factors (precipitations, seism, and stream network density), and the land use factor (roads and rail network density). Third, the relative value of each categorical variable involved in the slope movements emergence was assessed (categorization of evaluation criteria, standardization of factors, and weighting of variables). Then, a global index value of slopes movement susceptibility was calculated for each cell in the study area by using a linear indexing model. Finally, the slopes movement susceptibility map was categorized into five hierarchic classes and validated using the validation dataset that was not used in the model building. The area under the curve was included to assess prediction capability of the adopted model (sensitivity = 0.83 and 1 − specificity = 0.74). The resulted susceptibility map may be used for preliminary land planning purposes. Keywords Setif Analytic-heuristic Susceptibility Natural breaks Land use planning
Article
The main objective of this study was to assess spatial prediction of slopes movement susceptibility in the Bousselam upstream basin, northeast of Algeria, using a linear indexing model and Geographic Information Systems. First, the locations of 1109 slope instabilities, which occurred in the last three decades, were mapped upon data from various sources such as follows: remote sensing, aerial photographs interpretation, and internal reports compilation. This slope movement inventory was randomly segmented into training and validation datasets (75 % of the known events locations were used for training and building themodel and the remaining 25%for its validation). Second, nine natural and anthropogenic causing factors were mapped as independent variables: geological factors (lithology and faults density), morphometric factors (slope, aspect, and elevations), environmental factors (precipitations, seism, and stream network density), and the land use factor (roads and rail network density). Third, the relative value of each categorical variable involved in the slope movements emergence was assessed (categorization of evaluation criteria, standardization of factors, and weighting of variables). Then, a global index value of slopes movement susceptibility was calculated for each cell in the study area by using a linear indexing model. Finally, the slopes movement susceptibility map was categorized into five hierarchic classes and validated using the validation dataset that was not used in the model building. The area under the curve was included to assess prediction capability of the adopted model (sensitivity=0.83 and 1−specificity=0.74). The resulted susceptibility map may be used for preliminary land planning purposes. Keywords Setif . Analytic-heuristic . Susceptibility . Natural breaks . Land use planning
Article
The main objective of this study was to assess spatial prediction of slopes movement susceptibility in the Bousselam up stream basin, northeast of Algeria, using a linear indexing model and Geographic Information Systems. First, the locations of 1109 slope instabilities, which occurred in the last three decades, were mapped upon data from various sources such as follows: remote sensing, aerial photographs interpretation, and internal reports compilation. This slope movement inventory was randomly segmented into training and validation datasets (75 % of the known events locations were used for training and building the model and the remaining 25%for its validation). Second, nine natural and anthropogenic causing factors were mapped as independent variables: geological factors (lithology and faults density), morphometric factors (slope, aspect, and elevations), environmental factors (precipitations, seism, and stream network density), and the land use factor (roads and rail network density). Third, the relative value of each categorical variable involved in the slope movements emergence was assessed (categorization of evaluation criteria, standardization of factors, and weighting of variables). Then, a global index value of slopes movement susceptibility was calculated for each cell in the study area by using a linear indexing model. Finally, the slopes movement susceptibility map was categorized into five hierarchic classes and validated using the validation dataset that was not used in the model building. The area under the curve was included to assess prediction capability of the adopted model (sensitivity=0.83 and 1−specificity=0.74). The resulted susceptibility map may be used for preliminary land planning purposes.
Technical Report
It is a well-known fact that critical structures are required to be designed for the vertical effects of ground motions as well as the horizontal effects. We developed a new model for the spectral ratio of vertical to horizontal components of earthquakes (V/H ratio) for Central and Eastern North America (CENA). The proposed V/H ratio model has the advantage of considering the earthquake magnitude, source to site distance, and the shear-wave velocity of soil deposits in the upper 30m of the site for PGA and a wide range of periods (0.001 to 10.0 seconds). The model evaluation is based on a comprehensive set of regression analysis of the newly compiled Next Generation Attenuation (NGA-East) database of available CENA recordings with M ≥ 3.4 and RRUP < 1000 km. The median value of the geometric mean of the orthogonal horizontal motions rotated through all possible nonredundant rotation angles, known as the GMRotD50 (Boore et al., 2006), is used along with the vertical component to perform regression using the nonlinear mixed effect regression. We excluded the earthquakes and recording stations in the Gulf Coast region due to their different ground-motion attenuation (Dreiling et al., 2014). To compute V/H ratios for the Gulf Coast region, we refer the readers to the study of Haji-Soltani et al. (2017) as an independent study performed on the Gulf Coast data. Moreover, we excluded the NEHRP site class E (soft-soil) sites from consideration because of their complex site-response characteristics and their potential for nonlinear site effects. Finally, we compared the predicted ratios from the proposed model with recently published V/H ratio models. We suggest our model be used for developing the vertical response spectra for CENA sites.
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The city of Boumerdès, located in Northern Algeria, was badly affected during the May 21, 2003 Zemmouri (Mw = 6.8) earthquake where extensive liquefaction has been reported. The aim of this paper is to assess and to map the liquefaction potential for Boumerdès. We collected and used data from 154 boreholes, 10 down-hole tests, 56 standard penetrations tests (SPT), and inventory of 35 water level points. This data has been analyzed in the framework of geographical information systems (GIS). We assessed the liquefaction potential index (LPI) by considering a seismic hazard scenario corresponding to amax = 0.48 g calculated, using a probabilistic approach, for a return period of 500 years. LPI values have been correlated to compile the liquefaction hazard map that indicates the quantitative characteristics of the liquefiable layers and the induced disruption probability area. Results show that the main part of the city of Boumerdès belongs to a low liquefaction potential area except for a narrow corridor along the Corso waterway, where the liquefaction potential is moderate to high. The obtained results are compatible with the geological, geotechnical and hydrogeological susceptibility to liquefaction of the area. The results also show a good agreement with the observations made after the May 21, 2003 Zemmouri earthquake. The obtained liquefaction hazard maps may serve as useful tools for land management and planning in the city of Boumerdès and as an example of liquefaction hazard assessment that may be applied in other populated cities in northern Algeria’s seismic prone areas.
Article
The main objective of this study was to assess spatial prediction of slopes movement susceptibility in the Bousselam upstream basin, northeast of Algeria, using a linear indexing model and Geographic Information Systems. First, the locations of 1109 slope instabilities, which occurred in the last three decades, were mapped upon data from various sources such as follows: remote sensing, aerial photographs interpretation, and internal reports compilation. This slope movement inventory was randomly segmented into training and validation datasets (75 % of the known events locations were used for training and building the model and the remaining 25 % for its validation). Second, nine natural and anthropogenic causing factors were mapped as independent variables: geological factors (lithology and faults density), morphometric factors (slope, aspect, and elevations), environmental factors (precipitations, seism, and stream network density), and the land use factor (roads and rail network density). Third, the relative value of each categorical variable involved in the slope movements emergence was assessed (categorization of evaluation criteria, standardization of factors, and weighting of variables). Then, a global index value of slopes movement susceptibility was calculated for each cell in the study area by using a linear indexing model. Finally, the slopes movement susceptibility map was categorized into five hierarchic classes and validated using the validation dataset that was not used in the model building. The area under the curve was included to assess prediction capability of the adopted model (sensitivity = 0.83 and 1 − specificity = 0.74). The resulted susceptibility map may be used for preliminary land planning purposes.
Article
The embankment portion of the Keenleyside Dam on the Columbia River in southeastern British Columbia has been assessed as being susceptible to seismically-induced liquefaction. This paper describes a probabilistic seismic hazard analysis (PSHA) carried out as the first step in a comprehensive risk analysis of the dam. The PSHA incorporated both aleatory and epistemic uncertainties by including alternative, weighted seismogenic zone and source models, recurrence parameters and attenuation relationships. Mean ground motion hazards were de-aggregated to determine magnitude contributions for use in computing probabilities of liquefaction in the risk analysis. It was found to be important to de-aggregate the hazard for the spectral period corresponding to the fundamental vibration period of the dam, rather than de-aggregating the PGA hazard only.
Article
Caltrans' Seismic Design Criteria (SDC) has been adopted as the minimum seismic standard for ordinary bridges on California's highways. The SDC is a compilation of new and existing seismic criteria that had been previously documented in a variety of Caltrans documents. The SDC extends the capacity design philosophy introduced in the 1980 Caltrans Bridge Design Specifications. The most significant departure from the previous procedure is that ductile members are now designed by comparing the displacement demand to the displacement capacity. The demands are generated by a linear elastic analysis, and the capacities are determined from a curvature analysis that incorporates the nonlinear behavior of the structural elements. The demand/capacity methodology supplants the previous method based on reducing the elastic dynamic forces by a force reduction factor. In this paper, the significant features of Caltrans' SDC are described.
Article
Probabilistic Seismic Hazard Analysis (PSHA) reflecting an outcropping reference firm rock site condition (Vs30=760 m/sec) was performed at two BC Hydro dam (hard rock) sites. This reference firm rock condition is consistent with assumptions made in the development of the most recent ground motion prediction equations (GMPEs) for these locations as part of a SSHAC Level 3 project. The next step is the development of frequency and amplitude dependent relative amplification factors (for 5% damped response spectra) between the hard rock dam sites and the firm rock reference site. These factors accommodate potential linear or nonlinear site response using equivalent-linear analysis in a frequency domain random vibration theory methodology. The uncertainty in parameters (e.g. near-surface velocity and dynamic properties) is accounted for when developing the site specific hazard curves. Third, site-specific motions are computed by scaling the reference firm rock site motions with the amplification factors. Probabilistic methods have been developed that accurately preserve the reference site hazard level and result in site-specific hazard curves. These fully probabilistic approaches represent a viable and preferred mechanism to properly incorporate the site-specific aleatory (randomness) and epistemic (uncertainty) variability of the site properties to achieve desired hazard levels. A parallel analysis develops V/H ratios for the calculation of the vertical hazard using the site-specific horizontal motions scaled by empirical and analytical V/H ratios. The site response analyses at two BC Hydro dam sites produced site-specific hazard curves as well as horizontal and vertical response spectra which reflect the desired exceedance frequencies.
Article
Accelerometric records of the Chi-Chi earthquake from sites on the hanging wall exhibit larger acceleration than those from the footwall. Based on ground accelerations recorded at 79 near-field stations (10 hanging-wall stations and 69 footwall stations, respectively) and precise mapping of fault-rupture traces, the hanging-wall/footwall effects of the Chi-Chi earthquake have been fully studied. We show that the hanging-wall effects cannot be simply accounted for by a proper choice of distance metric. The closest distance to the rupture plane (Drup) is then selected to develop an empirical ground-motion model by using the data collected during the mainshock of the Chi-Chi earthquake that struck Taiwan. With the exception of some sites immediately next to the rupture traces (Drup ≤ 5 km), the acceleration residuals between this empirical model and the recorded data at the footwall stations are close to zero for stations in the distance range from 5 to 50 km. On the other hand, the average acceleration amplification on the hanging wall is equal to the natural logarithmic values of 0.64 ± 0.4 for all hanging-wall sites within 20 km of Drup. The hanging-wall/footwall effects have also been evaluated for several response spectral periods. It is observed that both the horizontal and vertical components of spectral acceleration are apparently amplified for sites on the hanging wall at a distance from 5 to 20 km for spectral periods 0.02 to 0.5 sec, whereas the vertical component has less amplification than the horizontal in all the spectral periods considered. The horizontal component of spectral acceleration at the hanging-wall sites also shows a larger value for the long-period motion, relative to the footwall, for periods larger than 1.0 sec. The hanging-wall effects are relatively constant, at low frequencies, as the distance extends to about 20 km. This observation cannot be explained by the simplified empirical model. Rather, it suggests that waves trapped in the hanging-wall wedge may have been involved.
Article
The purpose of the investigations presented herein has been to show a developed and verified method for presentation of seismic action by a time history. These investigations are related to Eurocode 8, Part 2, Bridges, and have involved the use of recorded accelerogrammes obtained from occurred earthquakes. The method introduces optimization by which, for a period equal to the natural period of vibration of a structure, the ratio between the square root of the sum of squares of the spectra computed from both horizontal components of a single record—SRSS and the code spectrum is computed. While performing this task, pairs of horizontal components for which this ratio is equal or greater than 1.0 (up to a tolerance value) are selected for nonlinear dynamic analysis, provided that the scaling factor is limited. Verification of the method is given for a base isolated bridge on E-75 motorway, with a natural period of 1.4 s. Also, some important recommendations and discussions related to the presentation of the code spectrum by a time history are given.
Article
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The focus of the Hazus earthquake model has been largely U.S. centric due to a lack of standardized building-infrastructure data formats applicable elsewhere. In a combined effort between FEMA Region VIII and the Universidad de Los Andes, Venezuela, the present study uses the Hazus 2.1 software to simulate earthquake loss estimations for Venezuela. Population totals and demographic distributions were developed using Oak Ridge National Labs Landscan 2008 population data and the census 2011 for Venezuela. The accuracy of the model was further enhanced for Mérida State, located in western Venezuela, by collecting, incorporating, and developing region and specific inventories including soil maps, liquefaction and landslide susceptibility studies, demographic data, and building inventory information. We used USGS ShakeMaps scenarios for two potential earthquake events with peak ground accelerations proposed within Performance Based Seismic Engineering of Buildings, VISION 2000 recommendations. The region has not witnessed an earthquake with a magnitude greater than M 7 in the last 120 years. Given the historical record of seismicity and the seismotectonics in the region, it becomes increasingly important to understand the potential implications from moderate to large earthquakes in Mérida State, Venezuela.
Article
Probabilistic seismic-hazard assessments use attenuation relations that give some measure of earthquake ground motion as a function of distance, magnitude, and sometimes other parameters. Among the various relations that have been presented, an ambiguity exists with respect to whether the amplitudes of strong motion on rock show a distance-dependent magnitude saturation. Given a high degree of scatter in a limited number of observations, current empirical data cannot resolve this issue. Therefore, a series of synthetic ground-motion simulations have been conducted to elucidate the magnitude dependence of the distance decay for rock sites. Three different techniques are used: one based on empirical Green's functions, one based on theoretical Green's functions with a simple source representation, and one based on theoretical Green's functions with a composite source representation. All three techniques imply that ground motion decays less rapidly with distance for larger magnitude earthquakes, so that there is a distance-dependent magnitude saturation. Intuitively this can be explained as follows: at longer distances the Green's functions are more complex due to various arrivals spread out over a longer duration of time. A larger earthquake, with more subevents spread over a greater time period, will have constructive interference among the various arrivals from each subevent, and the longer durations of the subevent signals at larger distances will cause a proportionately greater increase in the amplitude than what typically occurs at shorter distances. Five different attenuation relations are evaluated on the basis of this prediction, and the implications with respect to probabilistic seismic-hazard assessment are tested in Field and Peterson (2000).
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Accelerometric records of the Chi-Chi earthquake from sites on the hanging wall exhibit larger acceleration than those from the footwall. Based on ground accelerations recorded at 79 near-field stations (10 hanging-wall stations and 69 footwall stations, respectively) and precise mapping of fault-rupture traces, the hanging-wall/footwall effects of the Chi-Chi earthquake have been fully studied. We show that the hanging-wall effects cannot be simply accounted for by a proper choice of distance metric. The closest distance to the rupture plane (D rup) is then selected to develop an empirical ground-motion model by using the data collected during the mainshock of the Chi-Chi earthquake that struck Taiwan. With the exception of some sites immediately next to the rupture traces (D rup 5 km), the acceleration residuals between this empirical model and the recorded data at the footwall stations are close to zero for stations in the distance range from 5 to 50 km. On the other hand, the average acceleration amplification on the hanging wall is equal to the natural loga-rithmic values of 0.64 0.4 for all hanging-wall sites within 20 km of D rup . The hanging-wall/footwall effects have also been evaluated for several response spectral periods. It is observed that both the horizontal and vertical components of spectral acceleration are apparently amplified for sites on the hanging wall at a distance from 5 to 20 km for spectral periods 0.02 to 0.5 sec, whereas the vertical component has less amplification than the horizontal in all the spectral periods considered. The horizontal component of spectral acceleration at the hanging-wall sites also shows a larger value for the long-period motion, relative to the footwall, for periods larger than 1.0 sec. The hanging-wall effects are relatively constant, at low frequencies, as the distance extends to about 20 km. This observation cannot be explained by the simplified empirical model. Rather, it suggests that waves trapped in the hanging-wall wedge may have been involved.
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