scholarly journals Evaluation of Site Amplification Factor of Observation Sites in Ishikawa Prefecture

2007 ◽  
Vol 7 (2) ◽  
pp. 96-109
Author(s):  
Hayato NISHIKAWA ◽  
Masakatsu MIYAJIMA ◽  
Syohei DOUSHITA ◽  
Masaru KITAURA
Keyword(s):  
Amplification Factor ◽  
Site Amplification ◽  
Ishikawa Prefecture ◽  
Site Amplification Factor

A Method to Directly Estimate S-Wave Site Amplification Factor from Horizontal-to-Vertical Spectral Ratio of Earthquakes (eHVSRs)

2020 ◽  
Vol 110 (6) ◽  
pp. 2892-2911
Author(s):  
Eri Ito ◽  
Kenichi Nakano ◽  
Fumiaki Nagashima ◽  
Hiroshi Kawase
Keyword(s):  
Amplification Factor ◽  
Strong Motion ◽  
Spectral Ratio ◽  
Site Amplification ◽  
Body Waves ◽  
Correction Function ◽  
Site Classification ◽  
Frequency Range ◽  
S Wave ◽  
Site Amplification Factor

ABSTRACT The main purpose of the site classification or velocity determination at a target site is to obtain or estimate the horizontal site amplification factor (HSAF) at that site during future earthquakes because HSAF would have significant effects on the strong-motion characteristics. We have been investigating various kinds of methods to delineate the S-wave velocity structures and the subsequent HSAF, as precisely as possible. After the advent of the diffuse field concept, we have derived a simple formula based on the equipartitioned energy density observed in the layered half-space for incident body waves. In this study, based on the diffuse field concept, together with the generalized spectral inversion technique (GIT), we propose a method to directly estimate the HSAF of the S-wave portion from the horizontal-to-vertical spectral ratio of earthquakes (eHVSRs). Because the vertical amplification is included in the denominator of eHVSR, it cannot be viewed as HSAF without correction. We used GIT to determine both the HSAF and the vertical site amplification factor (VSAF) simultaneously from strong-motion data observed by the networks in Japan and then deduced the log-averaged vertical amplification correction function (VACF) from VSAFs at a total of 1678 sites in which 10 or more earthquakes have been observed. The VACF without a category has a constant amplitude of about 2 in the frequency range from 1 to 15 Hz. By multiplying eHVSR by VACF, we obtained the simulated HSAF. We verified the effectiveness of this correction method using data from observation sites not used in the aforementioned averaging in the frequency range from 0.12 to 15 Hz.

Empirical Site Amplification Modelling for Horizontal and Vertical Ground Motions in Taiwan

2020 ◽  
Author(s):  
Chun-Hsiang Kuo ◽  
Shu-Hsien Chao ◽  
Che-Min Lin ◽  
Jyun-Yan Huang ◽  
Kuo-Liang Wen
Keyword(s):  
Ground Motion ◽  
Amplification Factor ◽  
Ground Motions ◽  
Free Field ◽  
Site Amplification ◽  
Amplification Factors ◽  
Taipei Basin ◽  
Vertical Ground Motions ◽  
Vertical Ground ◽  
Site Amplification Factor

<p>Site amplification behavior are important in ground motion prediction. Seismic waves were amplified and caused significant building damages in the Taipei Basin by the 1986 Hualien offshore (subduction interface) and the 1999 Chi-Chi earthquakes (crustal), for which both of the epicentral distances were nearly 100 km. To understand local site amplifications in Taiwan, empirical site amplification factors for both horizontal and vertical ground motions are studied using recently constructed strong motion and site databases for the free-field TSMIP stations. Records of large magnitude earthquakes of M<sub>W</sub> larger than 5.5 from 1991 to 2016 were selected for this study. Site amplification factors at site conditions with Vs30 between 120 m/s to 1600 m/s and bedrock accelerations up to 0.8 g were evaluated using ratios of spectral accelerations at different periods. The reference site condition, i.e. the engineering bedrock, is assumed as Vs30 of 760 m/s (B/C boundary) in this study. Our empirical site amplification form are borrowed from the site response function of ASK14 and CY14 ground motion models in NGA-West2 project with slight modification. Therefore our site amplification model includes a linear amplification term and a nonlinear deamplification term. The coefficients of the empirical models were obtained by a nonlinear regression analysis using the selected Taiwan data. Site amplification factor is a function of Vs30 and spectral intensity in the model. Similar linear site amplification factor to the NGA models is derived in our model; however, more significant soil nonlinearity behavior than the NGA models is likely captured from the empirical data. The amplification factor in vertical component is smaller than that in horizontal.</p>

scholarly journals Variation Evaluation of Path Characteristic and Site Amplification Factor of Earthquake Ground Motion at Four Sites in Central Japan

2021 ◽  
Vol 11 (5) ◽  
pp. 7658-7664
Author(s):  
T. Nagao
Keyword(s):  
Ground Motion ◽  
Amplification Factor ◽  
Hazard Analysis ◽  
Strong Motion ◽  
Site Amplification ◽  
Earthquake Ground Motion ◽  
Constraint Condition ◽  
Central Japan ◽  
Source Characteristic ◽  
Site Amplification Factor

The considered parameters in seismic design vary, with the Earthquake Ground Motion (EGM) having the largest variation. Since source characteristic, path characteristic, and Site Amplification Factor (SAF) influence the EGM, it is crucial to appropriately consider their variations. Source characteristic variations are mainly considered in a seismic hazard analysis, which is commonly used to evaluate variations in EGM. However, it is also important to evaluate variations in path characteristic and SAF with only a few studies having individually and quantitatively examined the variations of these two characteristics. In this study, based on strong-motion observation records obtained from four sites in central Japan, the three characteristics were extracted from seismograms using the concept of spectral inversion. After removing the source characteristic, the path characteristic and SAF were separated, and the variations in these two characteristics were quantified. To separate and obtain each characteristic from the observed record, one constraint condition must be imposed, whereas the variations in the constraint condition must be ignored. In that case, the variations in the constraint condition are included in the variations of the separated characteristics. In this study, this problem was solved by evaluating the variation in the constraint condition, which is the SAF at a hard rock site, by the use of the vertical array observation record at the site.

Seismic site amplification factor (DAF): Geometrical limits of 1D modelling

1998 ◽  
Author(s):  
P. P. Bruno ◽  
E. Carrara ◽  
V. di Fiore ◽  
A. Rapolla ◽  
N. Roberti
Keyword(s):  
Amplification Factor ◽  
Site Amplification ◽  
1D Modelling ◽  
Site Amplification Factor

scholarly journals Study on Site Amplification Factor Correction for Earthquake Early Warning System

2019 ◽  
Author(s):  
Quancai Xie ◽  
Qiang Ma ◽  
Jingfa Zhang ◽  
Haiying Yu
Keyword(s):  
Early Warning ◽  
Amplification Factor ◽  
Spectral Ratio ◽  
Site Amplification ◽  
Seismic Intensity ◽  
Earthquake Early Warning ◽  
Filter Method ◽  
Recursive Filter ◽  
Earthquake Early Warning System ◽  
Site Amplification Factor

Abstract. The site amplification factor was usually considered as scalar values, such as amplification of peak ground acceleration or peak ground velocity, increments of seismic intensity in the conventional earthquake early warning system. This paper focus on evaluation of infinite impulse recursive filter method that could produce frequency-dependent site amplification and compare the performance of the scalar value method with the infinite impulse recursive filter method. Firstly, the strong motion data of IBRH10 and IBRH19 of Kiban Kyoshin network (Kik-net）from 2004 to 2012 were processed and selected carefully. The relative spectral ratio of IBRH10 surface acceleration to IBRH10 borehole acceleration, the relative spectral ratio of IBRH19 surface acceleration to IBRH19 borehole acceleration, the relative spectral ratio the IBRH10 surface and borehole acceleration to the IBRH19 surface and borehole acceleration were calculated using the traditional spectral ratio method. Secondly, the relative spectral ratio were modelled using the infinite impulse recursive filter method. The simulated IBRH19 surface acceleration and Fourier spectrum were obtained by filtering the IBRH19 borehole data. The seismic intensity residual were calculated for both the observation and simulation data, it shows that 98.6 % of these seismic intensity residuals are less than 0.5, 100 % of these seismic intensity residuals are less than 1. Similarly, the simulated IBRH10 Surface acceleration and Fourier spectrum were obtained by filtering the IBRH19 surface acceleration time series. The seismic intensity residual were calculated for both the observation data and the simulation data. The statistical data shows that 69.7 % of these seismic intensity residuals are less than 0.5, 98.1 % of these seismic intensity residuals are less than 1. Through these comparisons, we can find that these simulations show better performance than the ARV method and station correction method. It also shows good performance than the average level and the highest level of all the 11 years Japan Meteorological Agency (JMA) earthquake early warning system. Thirdly, compare different simulation cases, it can be easily found that this method could produce different amplification factor for different earthquakes. It could produce the frequency-depend site amplification factor. It highly improve the situation that the scalar value site amplification methods which could not produce different amplification factor for different earthquakes. This method pays attention to the amplitude and ignore the phase characteristic, this problem may be improved by the seismic interferometry method. This paper makes deep evaluation of the infinite impulse recursive filter method. Although there are some problems needed to consider carefully and solve, it shows good potential to be used in the future earthquake early warning systems for more accuracy modelling the site amplification factor.

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