An Inversion of Lg-Wave Attenuation and Site Response from Seismic Spectral Ratios in the Eastern China Region

2014 ◽  
Vol 104 (3) ◽  
pp. 1389-1399 ◽  
Author(s):  
X.-Y. Zhu
Keyword(s):  
Wave Attenuation ◽  
Site Response ◽  
Eastern China ◽  
Spectral Ratios ◽  
Lg Wave ◽  
China Region

An Inversion of Site Response and Medium Parameters of Shaanxi Area Using Records of the Wenchuan Aftershocks

2011 ◽  
Vol 80-81 ◽  
pp. 606-610
Author(s):  
Hui Cheng Shao ◽  
Xing Yun Zhu ◽  
Ci Jian Luo
Keyword(s):  
Wave Attenuation ◽  
Site Response ◽  
Joint Inversion ◽  
Low Frequency ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Inversion Method ◽  
Digital Network ◽  
Lg Wave ◽  
Weihe Basin

In this paper, Lg wave records of 43 strong aftershocks in the northern segment of Wenchuan aftershock area recorded by 25 stations of Shaanxi digital network are used. Based on spectral ratio method, a joint inversion method is used to obtain parameters of Lg wave attenuation and site response. In the range of 0.5~7 Hz, the Lg wave attenuation coefficient corresponding to UD, EW and NS components are γ(f)=0.0045f0.327,γ(f)=0.0034f0.417 and γ(f)=0.0036f0.393, respectively. The results show that all stations have site effects lower than 5 in the low frequency, the stations in the Weihe basin as Lint, Jyat and etc do not show obvious amplification, but the stations in the Qinling Mountain show obvious amplification in the high frequencies. At the same time, the results mentioned above are also compared with the that retrieved from small earthquakes.

Seismic site response in the greater Vancouver, British Columbia, area: spectral ratios from moderate earthquakes

1999 ◽  
Vol 36 (2) ◽  
pp. 195-209 ◽  
Author(s):  
John F Cassidy ◽  
Garry C Rogers
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
River Delta ◽  
Data Sets ◽  
Fraser River ◽  
Spectral Ratios ◽  
Data Set ◽  
Seismic Site Response ◽  
Fraser River Delta ◽  
S Period

Three-component, digital recordings of two recent moderate earthquakes provide valuable new insight into the response to seismic shaking in the greater Vancouver area, particularly on the Fraser River delta. The 1996 M = 5.1 Duvall, Washington, earthquake (180 km southeast of Vancouver) triggered strong-motion seismographs at seven sites and the 1997 M = 4.3 Georgia Strait earthquake (37 km west of Vancouver) triggered instruments at 13 sites in the greater Vancouver area. The latter data set is especially important because it contains the first three-component recordings made on bedrock in greater Vancouver. Both data sets represent weak ground motion, with peak horizontal accelerations of 0.5-1.5% gravity (g) for the Duvall earthquake, and 0.2-2.4% g for the Georgia Strait earthquake. Using the method of spectral ratios, we estimate the site response for each of the strong-motion instrument soil sites. On the Fraser River delta amplification is observed over a relatively narrow frequency range of 1.5-4 Hz (0.25-0.67 s period), with peak amplification of 4-10 (relative to competent bedrock) for the thick soil delta centre sites, and about 7-11 for the delta edge sites. Relative to firm soil, the peak amplification ranges from 2 to 5 for the thick soil delta centre sites, and 2 to 6 for the delta edge sites. At higher frequencies, little or no amplification, and in many cases slight attenuation, is observed.Key words: seismic site response, Fraser delta, earthquakes.

The accuracy of soil response estimates using soil-to-rock spectral ratios

1996 ◽  
Vol 86 (2) ◽  
pp. 519-523
Author(s):  
Igor A. Beresnev ◽  
Kuo-Liang Wen
Keyword(s):  
Site Response ◽  
Soft Soil ◽  
Strong Motion ◽  
Finite Depth ◽  
Spectral Ratios ◽  
Site Specific ◽  
Soil Response ◽  
Strong Motion Records ◽  
The Real ◽  
Specific Amplification

Abstract Spectral ratios between soft soil and reference rock sites are often used to predict the sedimentary site response to earthquakes. However, their relationship with the genuine site-specific amplification function is often unclear. We compare the soil-to-rock spectral ratios between the stations that are 3.3 km apart with the “genuine” response given by the ratios between the surface and 17 and 47 m downhole. Data from the SMART1 array in Taiwan are used. The “weak” and “strong” motion records are addressed separately to allow for nonlinear soil response. The soil-to-rock spectral ratios are nearly identical to the “true” amplification at the frequencies from 1 to 10 Hz, if the finite depth of the borehole is taken into account. They correctly capture the strong-motion deamplification effect. However, the soil-to-rock spectral ratios are roughly 1.4 times more uncertain than surface-to-47-m ratios. In summary, the soil-to-rock spectral ratios can be considered as the reliable estimates of the real site response.

Feasibility of the use of Microtremors in Estimating Site Response during Earthquakes: Some Test Cases in Italy

1991 ◽  
Vol 7 (4) ◽  
pp. 551-561 ◽  
Author(s):  
Antonio Rovelli ◽  
Shri K. Singh ◽  
Luca Malagnini ◽  
Alessandro Amato ◽  
Massimo Cocco
Keyword(s):  
Ground Motion ◽  
Seismic Waves ◽  
Site Response ◽  
Spectral Ratio ◽  
Test Cases ◽  
Spectral Ratios ◽  
Cultural Noise ◽  
Maximum Amplification

We explore the feasibility of the use of microtremors in estimating the amplification of seismic waves at soft sites in Italy. Microtremors were measured at three soft sites and nearby hard sites at night when the cultural noise was minimum. These soft sites were selected as those showing the largest amplifications of ground motion during earthquakes as compared to the records on the hard sites or with respect to the predicted spectra. We compare the soft-to-hard site microtremor spectral ratios with the corresponding acceleration spectral ratios. A rough estimate of the shape and level of spectral amplification is obtained from the microtremor data in all three cases. However, the details of the soft-to-hard site spectral ratio are not reproduced and some differences appear in (a) the frequency at which the maximum amplification occurs, and (b) the bandwidth of the significant amplification. More testing of the method is needed before its wider use for microzonation in Italy can be recommended.

Monte-Carlo Simulation of the Theoretical Site Response Variability at Turkey Flat, California, Given the Uncertainty in the Geotechnically Derived Input Parameters

1993 ◽  
Vol 9 (4) ◽  
pp. 669-701 ◽  
Author(s):  
Edward H. Field ◽  
Klaus H. Jacob
Keyword(s):  
Monte Carlo ◽  
Physical Model ◽  
Site Response ◽  
Input Parameter ◽  
Model Parameters ◽  
Spectral Ratios ◽  
Parameter Uncertainties ◽  
Theoretical Predictions ◽  
High Degree ◽  
Geotechnical Studies

In the weak-motion phase of the Turkey Flat blind-prediction effort, it was found that given a particular physical model of each sediment site, various theoretical techniques give similar estimates of the site response. However, it remained to be determined how uncertainties in the physical model parameters influence the theoretical predictions. We have studied this question by propagating the physical parameter uncertainties into the theoretical site-response predictions using monte-carlo simulations. The input-parameter uncertainties were estimated directly from the results of several independent geotechnical studies performed at Turkey Flat. While the computed results generally agree with empirical site-response estimates (average spectral ratios of earthquake recordings), we found that the uncertainties lead to a high degree of variability in the theoretical predictions. Most of this variability comes from poor constraints on the shear-wave velocity and thickness of a thin (∼2m) surface layer, and on the attenuation of the sediments. Our results suggest that in site-response studies which rely exclusively on geotechnically based theoretical predictions, it will be important that the variability resulting from input-parameter uncertainties is recognized and accounted for.

Lg Wave Attenuation in the Isparta Angle and Anatolian Plateau (Turkey)

2012 ◽  
Vol 170 (3) ◽  
pp. 337-351 ◽  
Author(s):  
Sakir Sahin ◽  
Xueyang Bao ◽  
Niyazi Turkelli ◽  
Eric Sandvol ◽  
Ugur Teoman ◽  
...  
Keyword(s):  
Wave Attenuation ◽  
Anatolian Plateau ◽  
Isparta Angle ◽  
Lg Wave
Sign in / Sign up

Export Citation Format

Share Document