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Qp Structure in the Taiwan Area and Its Correlation to Seismicity

Kuang-Jung Chen, Yih-Hsiung Yeh, Chuen-Tien Shyu
1996 Terrestrial, Atmospheric and Oceanic Sciences  
S-wave amplitude data from the Taiwan Telemetered Seismographic Network (TTSN) and the Central Weather Bureau Seismographic Network (CWBSN) are used in a tomographical inversion for a three-dimensional S wave attenuation structure beneath the Taiwan area. The data consist of three-dimensional, digital seismograms of 137 earthquakes with magnitudes between 3.0 and 5.0. The S-wave attenuation structure is obtained through the use of the damped least-squares method from attenuation time value (t*)
more » ... ion time value (t*) and travel times. Attenuation time value is calculated by using the spec tral decay method under the assumption that t* is independent of frequency. S-wave spectra are corrected for a ro2 source spectrum model. The fre quencies of instrument response above 25 Hz or below 4 Hz usually have large uncertainty. Therefore, the least-squares line fitting is performed in the frequency band of 4 to 25 Hz. The results here show that the distribu tion pattern of the Q8 values in the Taiwan area correlates well with seis micity. In the upper crust (depths of between 0 to 15 km), the region of lower Q s area correlates with higher seismicity. However, in the lower crust and upper mantle (15 to 75 km), the area of higher seismicity correlates with the regions of higher Q s values. (
doi:10.3319/tao.1996.7.4.409(acct) fatcat:zk4hxm5pkbfohioqiwl4ym6d3u