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摘要:
A total of 32 free-field accelerograms recorded at rupture distances of less than 300 km during Ludian MS6.5 earthquake in 2014 were used to analysis the spatial distribution of peak ground acceleration (PGA) and peak ground velocity (PGV), and compare the Ludian earthquake ground motions with the four NGA-West2 and one China Sichuan-Tibet area ground motion attenuation models. The results show that, the fastest attenuation direction of PGA and PGV is consistent with the main fault rupture direction. For most Ludian station recordings within the entire rupture distances, the PGA, PGV and spectral acceleration (Sa(T=0.1, 5.0 s)) are beyond +/- 1 standard deviation of the prediction curves of the four NGA-West2 models. The average intra-event residuals of the PGA, PGV and Sa(T=5.0 s) ranged from -1.43 to -0.74. The average intra-event residuals of Sa(T=0.01 similar to 5.0 s) showed a systematic negative within the entire rupture distances. The spatial contours of intra-event residuals for PGA predicted by the four NGA-West2 models are almost the same, and the regions of maximum positive and maximum negative intra-event residuals are mainly distributed with the source-to-site azimuth approximating to -90 degrees and 90 degrees, which are perpendicular to the main fault rupture direction. The terrain of these two areas is relatively flat, and the station sites VS30 in these areas are relatively large. As a whole, four NGA-West2 models will significantly overestimate the spectral acceleration within the entire rupture distances from the Ludian earthquake, especially in short period (T<1.0 s). The China Sichuan-Tibet area ground-motion model considering the actual seismic data in this area will also overestimate the spectral acceleration of the Ludian earthquake to a certain extent, but compared with the four NGA-West2 models, its predicted values will be closer to the actual observed values.
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来源 :
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
ISSN: 0001-5733
年份: 2020
期: 8
卷: 63
页码: 2999-3014
1 . 4 0 0
JCR@2022
ESI学科: GEOSCIENCES;
ESI高被引阀值:22
JCR分区:4