Hiroaki Yamanaka

• Tokyo Institute of Technology

This technical report explains details on the results of the investigation to build a subsurface structural model and a selection of earthquake data at the target site of the blind prediction exercise for “The 6th International Association of Seismology and Physics of the Earth’s Interior/International Association of Earthquake Engineering Internat...

The on-site P-wave earthquake early warning (EEW) based on the site-specific ratios of S-waves to P-waves has been applied to large-sized offshore earthquakes, and the efficiency of the method has been validated. However, the method requires the P-waves including earthquake ground motions radiated from a large slip area while avoiding the inclusion...

We have conducted an observation of earthquake ground motion for an acquisition of basic data for building of models for sedimentary layers and earthquake sources to predict long-period strong motion of anticipated earthquakes in Lima, Peru. The observation instrument which consists of a 3-component accelerometer, a high-sensitivity vertical veloci...

A numerical investigation of surface wave propagation in the surface wave exploration of river embankments is implemented using 3D shallow soil models with different subsurface shapes and S-wave velocities. The focus is on the effects of surface and subsurface irregularities on the propagation and dispersion characteristics of Rayleigh waves genera...

In this study, we compared observations and predictions submitted by participants for blind prediction experiments for ground motions using aftershocks, foreshock, and mainshock of the 2016 Kumamoto earthquake sequence, Japan, to improve our understanding of the quality of state-of-the-art methods on the reproducibility of the effects of surface ge...

We propose a simple method for 1D S-wave velocity (Vs) profile estimation using a measured surface S-wave velocity (V1) and peak frequency of the observed microtremor horizontal-to-vertical spectral ratio (HVSR). In this method, the S-wave velocity profile is presented as linear velocity increase with depth in sediments over a bedrock layer that ha...

Recently, an array microtremor survey which is one of the non-destructive geophysical methods has been widely applied in Japan and overseas, to estimate the S-wave velocity profile of the subsurface structure. To improve the quality of data and reduce the variability of results that depend on the measurers and analysts, there are guidelines indepen...

1D velocity profiles at a strong motion station in the northern part of the Kumamoto plain, Japan, were submitted in Step-1 of the blind prediction exercise of strong ground motions in the sixth international symposium on effects of surface geology on seismic motion (ESG6). Individual participants were requested to estimate a 1D S-wave velocity pro...

S-net is a large-scale ocean bottom (OB) network in the Japan Trench area, consisting of inline-type 150 observatories equipped with seismometers and pressure gauges. Among them, 41 observatories have been buried about one meter beneath the seafloors in the shallow water regions (water depth <1500 m). We analyzed the strong-motion data recorded at...

In this study, to understand the seasonal variation of the result of surface wave and microtremor array explorations in areas where freezing occurs in the surface soil during the winter, we conducted both explorations throughout the year at the same site at Kitami Institute of Technology, located in Kitami City, Hokkaido, a cold region in northern...

We studied an applicability of the electrical survey to model shallow subsurface properties used in evaluating site amplification characteristics in the freezing season. The electrical surveys were carried out repeatedly for 1 year in Kitami city, Hokkaido, to evaluate the effects of freezing soil on the electrical property of soil. Apparent resist...

The Kima area is located in the southeastern part of Aswan city where the Aswan wastewater treatment plant and one of the giant factories in the Middle East for chemical and fertilization. The area is very close to the main active seismic zone in South Egypt, where November 7, 2010 earthquake (M 4.6( occurred. The earthquake was felt strongly and c...

Microtremor array measurements, and passive surface wave methods in general, have been increasingly used to non-invasively estimate shear-wave velocity structures for various purposes. The methods estimate dispersion curves and invert them for retrieving S-wave velocity profiles. This paper summarizes principles, limitations, data collection, and p...

Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence...

To evaluate the effects of changes in the physical soil properties on seismic motions of a surface layer due to freezing, in this study, we attempted to extract the features of seasonal variation related to ground motion characteristics by data analysis of weight-drop measurements and borehole seismic observations in the near-surface, in Kitami, Ho...

In the Kanto Basin, Japan, it has been reported that the dominant periods of long-period ground motions vary depending on the areas where earthquakes occurred. This suggests that the characteristics of long-period ground motions are closely related to their propagation paths in the sedimentary layers. We, firstly, investigated the azimuthal depende...

The response spectra of multidimensional analyses are compared with one-dimensional (1D) local models to couple the irregular soil stratification effect at a site. In recent studies, the surface motion 2D/1D or 3D/1D spectra ratios are defined as the spectral aggravation factors for each region of a site. Particularly in alluvial basins, where the...

We propose a new waveform inversion method to estimate the 2D S-wave velocity structure of deep sedimentary layers using broadband Love waves. As a preprocessing operation in our inversion scheme, we decompose earthquake observation records into velocity waveforms for periods of 1 s each. Then, we include in the inversion only those periods for whi...

ZET: Eskişehir ovası ülkemizde hızlı yapılaşma riski altında olan ve bunun sonucunda olası artan sismik riskin değerlendirilmesi yönünde en yoğun çalışılan bölgelerin başında gelir. Yapılan jeolojik ve jeofizik araştırmalar, ova içinde genel olarak sismik hızların düşük olduğu zemin gruplarına ve yer yer 650-1000m'ye ulaşan ana kaya derinliklerine...

We had conducted a temporary strong ground motion observation around the Fujikawa-kako fault zone in the eastern part of Shizuoka prefecture, Japan, for understanding of earthquake ground motion features in the area. In this paper we explain the outline of the strong motion observation and characteristics of observed ground motions. We calculated r...

This paper presents the S-wave H/V spectral ratios and discusses the peak frequencies at the S-net sites. S-net is a large-scale ocean-bottom network for earthquakes and tsunamis in the Japan trench area (Aoi et al. 2020). It is important to understand the site amplification properties based on earthquake records to estimate the ground motions for...

The response spectra of multidimensional analyses are compared with the one-dimensional (1D) local models to couple the irregular soil stratification effect in a site. In recent studies, the surface motion spectra ratios of 2D/1D or 3D/1D are defined as spectral aggravation factors for each region in a site. Particularly in alluvial basins, where t...

This paper reports the results of a case study of the application of the microtremor exploration method in western Turkey. We have conducted microtremor surveys at strong motion stations in Aydin and Denizli provinces to derive shallow S-wave velocity profiles. Array records of vertical microtremor motion were acquired at 12 and 15 stations in Aydi...

The autocorrelation of ambient noise is used to capture reflected waves for crustal and sedimentary structures. We applied autocorrelation to strong-motion records to capture the reflected waves from sedimentary layers and used them for tuning the S-wave velocity structure of these layers. Because a sedimentary-layered structure is complicated and...

This article investigates the stress drop variability of shallow normal-faulting earthquakes in western Anatolia through strong-motion simulations. For this purpose, source characteristics of three moderate to large magnitude events are constrained by the empirical Green’s function simulation in a broadband frequency range. Recordings of ten strong...

Abstract We investigated the cause of destructive ground motion during the 2018 Hokkaido eastern Iburi earthquake. We conducted strong motion observations of aftershocks and microtremors and the surface wave method in the damaged areas of the town of Mukawa, Hokkaido prefecture, Japan. The ground accelerations were continuously recorded during a pe...

A large acceleration with a peak amplitude of 2700 cm/s² was recorded at the K-NET Tsukidate station (MYG004) during the 2011 off Pacific Coast of Tohoku Earthquake. Nonetheless, there was little structural damage around the station. In this study, we estimate the engineering bedrock’s motion variability due to the main shock, deconvolved from the...

Depremler sırasında zemin tabakalarında oluşan deformasyon seviyeleri, yapı-zemin etkileşiminde önemli rol oynamaktadır. Kuvvetli yer hareketi kayıtları kullanılarak yapılan bir boyutlu (1D) dinamik analizlerle yüzeye yakın zemin tabakaları için hesaplanan kayma şekil değiştirmeleri, küçük genlikli titreşimler-mikrotremor verisi analiz sonuçlarının...

If seismic interferometry is to be applied to a strong ground motion record, the number of available records is limited, compared with the number of ambient noise records. To begin with, we investigated the characteristics of the autocorrelation function for various strong motion records, and the influence of the component of strong motion records...

The fundamental vibration period of a building is a crucial parameter for earthquake engineering. The equivalent seismic lateral force is determined from a design spectrum in most static design methods. Accordingly, the earthquake force is a function of the fundamental vibration period of the building. The fundamental period of an existing building...

We performed spectral inversions using ground motion data observed by K-NET, KiK-net, SK-net, and the earthquake observation network of the East Japan Railway Company in the Tokyo metropolitan area, Japan, to evaluate the effects of site amplification factors of both S- and P-waves for the future use of an on-site earthquake early warning system ba...

We have explored 1D S-wave velocity profiles of shallow and deep soil layers over a basement at strong motion stations in Eskisehir Province, Turkey. Microtremor array explorations were conducted at eight strong motion stations in the area to know shallow 1D S-wave velocity models. Rayleigh wave phase velocity at a frequency range from 3 to 30 Hz w...

As well known, local soil condition at a specific site affects the significant features of strong ground motion such as amplitude, frequency range and time duration. The effects of site condition depend on the properties of the motion characteristics, material properties, topography and geometry of the field. The bedrock slope at the basin sides al...

We conduct numerical experiments to estimate the variability of 1D linear and nonlinear soil amplifications due to the uncertainty in shallow S-wave velocity profiles derived from surface-wave phase velocity inversions using the Markov-chain Monte Carlo method. We first generate synthetic, observed phase velocities of Rayleigh waves for two-and thr...

On 24 May 2014, a Mw 6.9 earthquake occurred in the west of Gokceada Island, northern Aegean Sea. The earthquake was close to Canakkale, Enez, Tekirdag cities, and damaged 300 buildings in the Marmara Region, NW Turkey. We simulated its broadband (0.1–10 Hz) ground motions including 1D deep and shallow structures soil amplification effects at the 1...

Abstract To evaluate local site effects in Kumamoto City, we installed six temporary seismic stations along a 6-km north–south survey line in the city immediately after the 2016 Kumamoto earthquake foreshock (Mj 6.4), which occurred on April 14, 2016. Seismic data from the 2016 Kumamoto earthquake (Mj 7.3), which occurred on April 16, 2016, were su...

In this study, edge effect on the spatial variation of surface ground motion was evaluated by conducting one (1D) and two-dimensional (2D) dynamic analyses on the numerical model of Duzce basin. Duzce is a province in northwestern Turkey and was hit by a devastating earthquake in November 1999. In order to estimate the seismic behavior of Duzce bas...

The 9 August 1912 Murefte earthquake (Mw 7.3) occurred on the Ganos Fault in the North Anatolian Fault Zone in the western Marmara Region (NW Turkey). The maximum intensity was X in the Medvedev-Sponheuer-Karnik (MSK-1981) scale around the Ganos Fault. The 1912 Murefte earthquake was simulated by using 1D velocity structures to determine the charac...

We conducted microtremor array surveys for shallow S-wave velocity profiles at 20 sites in Bursa, Yalova and Kocaeli provinces in the north-western part of Turkey to provide fundamental data to assess the seismic hazard in the area. All of the measurement sites were positioned very close to strong motion stations belonging to the Disaster and Emerg...

Since 1939, devastating earthquakes with magnitude greater than seven ruptured North Anatolian Fault (NAF) westward, starting from 1939 Erzincan (Ms=7.9) at the eastern Turkey and including the latest 1999 Izmit-Golcuk (Ms=7.4) and the Duzce (Ms=7.2) earthquakes in the eastern Marmara region, Turkey. On the other hand, the west of the Sea of Marmar...

Observed ground motion records were analyzed for estimating site effects in Lima Metropolitan Area, Peru in the frequency range from 1.0 to 20.0 Hz. The spectral inversion method was applied to separate the three effects – path, source and site amplification. This technique is the most appropriate for analyzing site response since amplification is...

Bogotá, a megacity with almost 8 million inhabitants is prone to a significant earthquake hazard due to nearby active faults as well as subduction megathrust earthquakes. The city has been severely affected by many historical earthquakes in the last 500 years, reaching MM intensities of 8 or more in Bogotá. The city is also located at a large lacus...

Simultaneous estimation of effects of source, propagation path, and local site amplification was carried out using observed strong motion records in a frequency range from 0.8 to 20 Hz for the purpose of empirical evaluation of the local site effects in different geological conditions in the northwestern part of Turkey. The analyzed data are S-wave...

We conducted microtremor array exploration of shallow S-wave velocity profiles at 28 sites in Hatay and Kahramanmaras, in the southern part of Turkey, to provide fundamental data to assess seismic hazards in the two areas. A total of 16 and 12 sites were located in Hatay and Kahramanmaras Provinces, respectively. We temporarily installed two small...

We have conducted observation of earthquake ground motion due to aftershocks of the 2016 Kumamoto earthquake at 26 temporary stations in damaged areas of Kumamoto city, Mashiki town, Nishihara village and Minami-Aso village (partly in Aso city) in Kumamoto prefecture, Japan. Continuous recordings of ground acceleration were acquired in a period of...

Shallow S-wave velocity VS profiles were estimated for 26 temporary strong motion observation sites surrounding the epicenters of a sequence of the 2016 Kumamoto earthquake. The microtremor array method was used to gather the dispersion characteristics of Rayleigh waves. VS profiles were obtained by inverting the dispersion curves for each site and...

An irregularly layered subsurface structure (hereafter irregular site) amplifies earthquake motions sometimes more than a stratified media (hereafter flat site) due to, for example, a focusing effect of seismic waves. An exploration of a depth distribution of a structural boundary is too costly at each site in practice. A preliminary examination is...

It is important to learn from historical earthquakes for earthquake hazard assessments. The Marmara region of northwestern Turkey with a large population faces a high probability of being exposed to a large earthquake. The 1912 Murefte Earthquake with a magnitude of greater than 7 caused significant damage in a wide area in the western part of the...

Jakarta has been selected as a study area for seismic microzonation by considering its population and its infrastructure growth, seismicity and geological setting. One of the important factors in seismic hazard analysis is the characteristics of the ground overlying bedrock, and, as yet, this has not been studied for Jakarta. This study was intende...

We have conducted a microtremor survey for shallow S-wave velocity profiles to be used for seismic hazard evaluation in the Bandung Basin, Indonesia. In the survey, two arrays were deployed temporarily at each of 29 sites, by installing seven vertical sensors in triangular configurations with side lengths from 1 to 16 m. Records of vertical microtr...

During the 2011 Tohoku Earthquake, the peak ground accerelation (PGA) with high value of above 1000 cm/s2 was observed at K-NET Hitachi and K-NET Hokota, located in the coastal region of Ibaraki prefecture which is close to the southern edge of the fault, and the PGA close to 1000 cm/s2 was also observed at KiK-net Iwase, located in the boundary be...

The strong ground motion which has a large peak ground velocity of more than 100cm/s was observed at CCHG site in Small-Titan network during the 2011 off the Pacific coast of Tohoku earthquake. In this paper, we specified the interpretation of site amplification of CCHG site. First, S-wave velocity structure at CCHG site was estimated from the arra...

To understand the generating factor of strong ground motions for a period of 2 to 3 seconds observed in the western part of Tokyo Bay during the 2011 off the Pacific coast of Tohoku earthquake, we estimated shallow and deep S-wave velocity structures at 6 sites near the seismic stations by array microtremors observations. As a result, the existence...

Focusing on variation of peak period of horizontal to vertical spectral ratios (HVSRs) of microtremors due to time and space at flat engineering bedrock sites, we evaluate experimental variation coefficients and discuss the reason of the variation. The continuous microtremor measuments resulted in significant daily variation of peak periods of HVSR...

The 2014 Northern Nagano Earthquake, occurred on 22 November 2014, caused the heavy damage to wooden houses especially in the Horinouchi and Mikkaichiba districts in Hakuba, Nagano prefecture, even though the maximum intensity was 6 lower observed during the event. However, we do not know the feature of the strong ground motion in the districts bec...

The main scope of the InterPACIFIC (Intercomparison of methods for site parameter and velocity profile characterization) project is to assess the reliability of in-hole and surface-wave methods, used for estimating shear wave velocity. Three test-sites with different subsurface conditions were chosen: a soft soil, a stiff soil and a rock outcrop. T...

Integrated Earthquake Simulator (IES) have been developed to provide reasonable earthquake disaster information that is important to reduce damage from earthquakes. In order to predict earthquake disaster with high reliability, a multiple shear spring (MSS) model was applied to the multi degree of freedom (MDOF) model implemented in IES. MSS model...

The long-period ground motions were dominant in the Kanto Basin during the the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0). However, it is suggested that they are relatively small in spite of the large scale of this Magnitude as compared with shallow moderate events. One reason of less amplifications of long-period ground motions obser...

The Marmara Sea region has a giant risk of the earthquake disaster expected to be occurred along the North Anatolian Fault zone. The site amplification of the sedimentary layers is known to has a significant contribution to the strong ground motion. We therefore need to estimate the S-wave velocity structures for the strong ground motion prediction...

Strong ground motion which has the large PGV over 100cm/s was observed at CCHG in Small-Titan network during the 2011 off the Pacific coast of Tohoku earthquake. In this paper, we purpose to evaluate the characteristics of strong ground motions by evaluating the site amplifications at CCHG. We carried out array observations of microtremors to estim...

Heavy damage was experienced in Hakuba village, Nagano prefecture during the 2014 Nagano-ken Hokubu earthquake, Japan. In particular many wooden houses were collapsed in Horinouchi and Mikkaiichiba district in the village. Characteristics of ground shaking during the main shock are not known in the damaged area due to no availability of strong moti...

In this study, we aimed to explore the S-wave velocity structure of shallow soils using microtremors in order to estimate site responses in Tekirdag and surrounding areas (NW Turkey). We collected microtremor array data at 44 sites in Tekirdag, Marmara Ereglisi, Corlu, and Muratlı. The phase velocities of Rayleigh waves were estimated from the micr...

This study introduces a practical method for evaluating structural damage based on a large-scale simulation targeting expansive areas, like whole cities. In such a seismic simulation that deals with numerous building structures, it is desirable to estimate the damage based on a stochastic evaluation considering the uncertainty of structural propert...

A procedure for estimation of Rayleigh wave phase velocities from microtremor observations, using an array with a reference station, is investigated in this study. Simultaneous observation of microtremors at a reference station and at a strong motion observation array in the Kanto Basin, Japan, was carried out. We first calculated cross correlation...

S-wave velocity profiles of sedimentary layers in Tacna, southern Peru, based on analysis of microtremor array data and earthquake records, have been determined for estimation of site amplification. We investigated vertical component of microtremors in temporary arrays at two sites in the city for Rayleigh wave phase velocity. A receiver function w...

Conference Paper-Abstract

Microtremor array measurements have been carried out to estimate the detailed S-wave velocity structures of shallow soil structures in the Tachikawa-fault zone. Array measurements of vertical microtremors were used to retrieve phase velocity of Rayleigh wave. Through the inversion of the phase velocities, we have estimated the S-wave velocity struc...

Near-surface characterization has now gained significance among exploration geophysicists, and many methods are being proposed to retrieve the 2D structures of shallow soils. Because most of these methods are based on the modal inversion of the surface waves, they can only be applied to laterally homogeneous or smoothly heterogeneous soil models. W...

We proposed a new waveform inversion method to estimate a 2-D velocity structure of deep sedimentary layers from Love wave in earthquake records. In this method, first, we conduct particle motion analysis to investigate the characteristics of Love wave propagation in earthquake records observed at strong motion stations located along a target line...

We estimate several scenarios for source models of megathrust earthquakes likely to occur on the Nazca-South American plates interface in southern Peru. To do so, we use a methodology for estimating the slip distribution of megathrust earthquakes based on an interseismic coupling (ISC) distribution model in subduction margins and on information abo...

Jakarta is located on a thick sedimentary layer that potentially has a very high seismic wave amplification. However, the available information concerning the subsurface model and bedrock depth is insufficient for a seismic hazard analysis. In this study, a microtremor array method was applied to estimate the geometry and S-wave velocity of the sed...

Microtremor exploration was performed around seismic recording stations at five sites in Lima city, Peru in order to know the site amplification at these sites. The Spatial Autocorrelation (SPAC) method was applied to determine the observed phase velocity dispersion curve, which was subsequently inverted in order to estimate the 1-D S-wave velocity...

In the 2010 Maule, Chile, earthquake (M-w 8.8), many high-rise buildings in downtown Concepcion (CONC) sustained severe damage. The accelerogram observed at CONC had large amplitudes and long periods. The spectra contained strong peaks with periods around 2 s, whereas the spectra from a neighboring site (CCSP) did not exhibit strong peaks. Because...

During the 2011 Earthquake off the Pacific Coast of Tohoku, high acceleration records with a PGA of 2.7 G were reported at the K-NET Tsukidate station (MYG004), where a maximum seismic intensity of 7 on the Japan Meteorological Agency (JMA) scale was observed. However, no major damage to the wooden houses in the area surrounding the station was rep...