scholarly journals Modeling 3D S-wave velocity structure of Kanto basin for estimation of earthquake ground motion

2006 ◽  
Vol 59 (6) ◽  
pp. 549-560 ◽  
Author(s):  
Hiroaki Yamanaka ◽  
Nobuyuki Yamada
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Velocity Structure ◽  
Earthquake Ground Motion ◽  
S Wave ◽  
Kanto Basin

Exploration of Deep S-Wave Velocity Structure in Niigata and Shonai Plains to Estimate Long-period Earthquake Ground Motion

2009 ◽  
Vol 61 (4) ◽  
pp. 191-205
Author(s):  
Hiroaki SATO ◽  
Hiroaki YAMANAKA ◽  
Sadanori HIGASHI ◽  
Kiyotaka SATO ◽  
Yoshiaki SHIBA ◽  
...  
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Velocity Structure ◽  
Earthquake Ground Motion ◽  
S Wave ◽  
Long Period

scholarly journals Inversion of Love Waves in Earthquake Ground Motion Records for Two-dimensional S-wave Velocity Model of Deep Sedimentary Layers

2020 ◽  
Author(s):  
Kentaro Kasamatsu ◽  
Hiroaki Yamanaka ◽  
Shin’ichi Sakai
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Velocity Structure ◽  
Principal Component ◽  
Love Waves ◽  
Earthquake Ground Motion ◽  
Inversion Method ◽  
S Wave ◽  
Near Surface ◽  
Strong Ground Motion Prediction

Abstract We have proposed a new waveform inversion method to estimate a 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 at periods of 1 s interval. Then, we verify an assumption of 2D propagations of Love waves with polarization features based on a principal component analysis to select the segments applied for the inversion. A linearized iterative inversion analysis for the selected Love wave segments filtered at period of every 1 s allows a detailed estimation of boundary shapes of interfaces over the seismic bedrock with an S-wave velocity of approximately 3 km/s. We demonstrate the technique’s effectiveness with applications to observed seismograms in the Kanto plain, Japan. Differences between the estimated and existing structural models are remarkable at basin edges. A regional variation of the near-surface S-wave velocities in our model is similar to a distribution of surface geological classifications. Since a subsurface structure at a basin edge strongly affects earthquake ground motions in a basin with generations of surface waves, our method can provide a detail model of a complex S-wave velocity structure at an edge part for a strong ground motion prediction.

scholarly journals Inversion of Love waves in earthquake ground motion records for two-dimensional S-wave velocity model of deep sedimentary layers

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Kentaro Kasamatsu ◽  
Hiroaki Yamanaka ◽  
Shin’ichi Sakai
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Velocity Structure ◽  
Principal Component ◽  
Love Waves ◽  
Earthquake Ground Motion ◽  
Inversion Method ◽  
S Wave ◽  
Detailed Model ◽  
Strong Ground Motion Prediction

AbstractWe 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 which the assumption of 2D propagation holds, which we propose to determine through a principal component analysis. A linearized iterative inversion analysis for the selected Love wave segments filtered for periods of 1 s each allows a detailed estimation of the boundary shapes of interfaces over the seismic bedrock with an S-wave velocity of approximately 3 km/s. We demonstrate the effectiveness of the technique with applications to observed seismograms in the Kanto Plain, Japan. The differences between the estimated and existing velocity structure models are remarkable at the basin edges. Our results show remarkable differences from previous existing structural models, particularly near the basin edges while being in good agreement with the surface geology. Since a subsurface structure at a basin edge strongly affects the earthquake ground motions in a basin with the generation of surface waves, our method can provide a detailed model of a complex S-wave velocity structure at an edge part for strong ground motion prediction.

Estimation of site amplification and S-wave velocity profiles in metropolitan Manila, the Philippines, from earthquake ground motion records

2011 ◽  
Vol 42 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Hiroaki Yamanaka ◽  
Kaoru Ohtawara ◽  
Rhommel Grutas ◽  
Robert B. Tiglao ◽  
Melchor Lasala ◽  
...  
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Site Amplification ◽  
Velocity Profiles ◽  
The Philippines ◽  
Earthquake Ground Motion ◽  
S Wave ◽  
Ground Motion Records

Tuning S-Wave Velocity Structure of Deep Sedimentary Layers in the Shimousa Region of the Kanto Basin, Japan, Using Autocorrelation of Strong-Motion Records

2020 ◽  
Vol 110 (6) ◽  
pp. 2882-2891
Author(s):  
Kosuke Chimoto ◽  
Hiroaki Yamanaka
Keyword(s):  
Wave Velocity ◽  
Velocity Structure ◽  
Strong Motion ◽  
S Wave ◽  
Reflected Waves ◽  
Arrival Times ◽  
Strong Motion Records ◽  
Kanto Basin ◽  
Determination Of Parameters

ABSTRACT 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 generates many reflected waves, it is important to identify the boundary layer from which the waves reflected. We used spectral whitening during autocorrelation analysis to capture the reflected waves from the seismic bedrock with an appropriate smoothing band, which controls the wave arrival from the desired layer boundary. The effect of whitening was confirmed by the undulation frequency observed in the transfer function of the sedimentary layers. After careful determination of parameters for spectral whitening, we applied data processing to the strong-motion records observed at the stations in the Shimousa region of the Kanto Basin, Japan, to estimate the arrival times of the reflected waves. The arrival times of the reflected waves were found to be fast in the northern part of the Shimousa region and slow in the western and southern parts. These arrival times are consistent with those obtained using existing models. Because we observed a slight difference in the arrival times, the autocorrelation function at each station was used for tuning the S-wave velocity structure model of the sedimentary layers using the inversion technique. The tuned models perfectly match the autocorrelation functions in terms of the arrival time of the reflected waves from the seismic bedrock.

Improvement of the objective function in the velocity structure inversion based on horizontal-to-vertical spectral ratio of earthquake ground motions

2020 ◽  
Vol 224 (1) ◽  
pp. 1-16
Author(s):  
Mianshui Rong ◽  
Xiaojun Li ◽  
Lei Fu
Keyword(s):  
Objective Function ◽  
Ground Motion ◽  
Velocity Structure ◽  
Strong Motion ◽  
Earthquake Ground Motion ◽  
Inversion Method ◽  
Observation Data ◽  
S Wave ◽  
Inversion Methods ◽  
Underground Velocity Structures

SUMMARY Given the improvements that have been made in the forward calculations of seismic noise horizontal-to-vertical spectral ratios (NHVSRs) or earthquake ground motion HVSRs (EHVSRs), a number of HVSR inversion methods have been proposed to identify underground velocity structures. Compared with the studies on NHVSR inversion, the research on the EHVSR-based inversion methods is relatively rare. In this paper, to make full use of the widely available and constantly accumulating strong-motion observation data, we propose an S-wave HVSR inversion method based on diffuse-field approximation. Herein, the S-wave components of earthquake ground motion recordings are considered as data source. Improvements to the objective function has been achieved in this work. An objective function with the slope term is introduced. The new objective function can mitigate the multisolution phenomenon encountered when working with HVSR curves with multipeaks. Then, a synthetic case is used to show the verification of the proposed method and this method has been applied to invert underground velocity structures for six KiK-net stations based on earthquake observations. The results show that the proposed S-wave EHVSR inversion method is effective for identifying underground velocity structures.

scholarly journals Estimation of S-wave velocity structure and its application to ground motion simulation

2002 ◽  
Vol 27 ◽  
Author(s):  
Basant Kafle ◽  
Hiroaki Yamanaka
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Structural Model ◽  
Velocity Structure ◽  
Seismic Refraction ◽  
Inversion Method ◽  
Subsurface Structure ◽  
S Wave ◽  
Period Range ◽  
Array Measurements

Microtremor array is the most inexpensive and easy to perform technique for the estimation of S-wave velocity structure. Microtremor array measurements have been carried out in the Shizuoka Prefecture, Japan to estimate S-wave velocity structure up to the basement. Phase velocities at wide period range were determined by frequency-wavenumber spectral analysis of vertical microtremor array records. The determined phase velocity is inverted to obtain one-dimensional S-wave velocity profile by genetic algorithm inversion method. A four layer S-wave velocity model with a basement velocity of 3.5 km/s was constructed. Simulation of ground motion has been carried out with two-dimensional finite difference method. Simulation of subsurface structural model was derived from the microtremor array measurement and previous seismic refraction survey. Two profiles were taken for simulation one from Hamaoka to Ryuhyoh and another from Hamaoka to Shimada. 2-D effect of subsurface structure is observed in the propagation of ground motion in the basin. The importance of determination of 2-D subsurface structure for the estimation of ground motion is shown.

Simplified Dispersion Curves of Earthquake Love Wave for Rotational Seismic Motion Estimation

2014 ◽  
Vol 580-583 ◽  
pp. 1639-1644
Author(s):  
Yue Wei Liu ◽  
Hong Nan Li
Keyword(s):  
Ground Motion ◽  
Wave Velocity ◽  
Love Wave ◽  
Velocity Structure ◽  
Matrix Theory ◽  
Corner Frequency ◽  
Apparent Velocity ◽  
S Wave ◽  
Seismic Ground Motion ◽  
Seismic Motion

In the simulation of the rotational seismic ground motion, the apparent velocity of Love wave is always assumed to be equal to the S wave velocity of top layer of the site approximately, with the dispersion of surface wave not being fully considered. In this paper, the effect of the velocity structure to the Love wave dispersion is discussed based on the stiffness matrix theory. It shows that to assume the velocity to be equal to the S wave velocity of the top layer may greatly overestimate the low frequency rotational seismic motion. A simplified dispersion curve, is suggested for rotational seismic ground motion simulation. The shape of the bilinear curve is shaped by 3 parameters. They are the corner frequency, the minimum phase velocity and the velocity ratio. The parameters are affected by the velocity structure of the site.

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