Structure of the Upper Crust in Japan from S-Wave Attenuation Tomography
| 作者: |
Pei, S.P., et al. |
| 期刊名称: |
Bulletin of the Seismological Society of America |
| 发表年度: |
2009 |
| 卷: |
99 |
| 期: |
1 |
| 联系作者: |
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| 页码: |
428-434 |
| 摘要: |
Seismic attenuation (Q-value) can be estimated by extracting the amplitude-frequency information contained in seismic waveforms. We apply the attenuation tomography method of Pei et al. (2006) using M-L amplitude data to estimate attenuation within the upper crust in Japan. More than 60,000 Sg-wave maximum amplitude readings from 5559 events, recorded by 971 stations, were selected from the dense High-Sensitivity Seismography Network (Hi-net) under the condition that epicentral distance is less than 2 degrees and event depth is less than 10 km. The lateral S-wave Q variations of the upper crust at 1 Hz in Japan were obtained. The results indicate that low Q-values exist in the central Japanese islands, with almost the same distribution as volcanoes, while high Q-values exist mainly between the front of volcanoes and the Japanese east coast. In addition, a low Q was found between the eastern coast and the subducted trench. Most large crustal earthquakes occur in or around zones of low Q or the boundaries between areas of low and high Q, which will be very helpful in estimating the risk of large earthquakes.
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