- journal_title：Bulletin of the Seismological Society of America
- Contributor：Shunping Pei ; Zhongxiong Cui ; Youshun Sun ; M. Nafi Toksöz ; Charlotte A. Rowe ; Xing Gao ; Junmeng Zhao ; Hongbing Liu ; Jiankun He ; F. Dale Morgan
- Publisher：Seismological Society of America
- Date：2009-
- Format：text/html
- Language：en
- Identifier：10.1785/0120080029
- journal_abbrev：Bulletin of the Seismological Society of America
- issn：0037-1106
- volume：99
- issue：1
- firstpage：428
- section：Short Notes
Seismic attenuation (<em>Qem>-value) can be estimated by extracting the amplitude-frequency information contained in seismic waveforms. We apply the attenuation tomography method of ef-ref-11-1" class="xref-bibr">Pei <em>et al.em> (2006) using <em>Mem>L amplitude data to estimate attenuation within the upper crust in Japan. More than 60,000 <em>Sgem>-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 2º and event depth is less than 10 km. The lateral <em>Sem>-wave <em>Qem> variations of the upper crust at 1 Hz in Japan were obtained. The results indicate that low <em>Qem>-values exist in the central Japanese islands, with almost the same distribution as volcanoes, while high <em>Qem>-values exist mainly between the front of volcanoes and the Japanese east coast. In addition, a low <em>Qem> was found between the eastern coast and the subducted trench. Most large crustal earthquakes occur in or around zones of low <em>Qem> or the boundaries between areas of low and high <em>Qem>, which will be very helpful in estimating the risk of large earthquakes.