HR: 17:30h
AN: S54B-07    [Abstracts]
TI: Slowness-Azimuth Corrections for IMS Primary Arrays in China
AU: * Hao, C
EM: haochunyue@gmail.com
AF: Institute of Geophysics, China Earthquake Administration, No.5 MinZuXueYuan NanLu HaiDian District, Beijing, 100081, China
AU: He, D
AF: Institute of Geophysics, China Earthquake Administration, No.5 MinZuXueYuan NanLu HaiDian District, Beijing, 100081, China
AU: Zhang, B
AF: Institute of Geophysics, China Earthquake Administration, No.5 MinZuXueYuan NanLu HaiDian District, Beijing, 100081, China
AU: Zheng, Z
EM: zheng.z@126.com
AF: Institute of Geophysics, China Earthquake Administration, No.5 MinZuXueYuan NanLu HaiDian District, Beijing, 100081, China
AB: As the primary stations of CTBT seismic network, Hailar (ps12) and Lanzhou (ps13) arrays had been established for 6 years till the end of this year. In this study, the slowness-azimuth correction was used for the two arrays to improve the location accuracy. The slowness-azimuth correction is to compare the azimuth and slowness obtained from the waveform processing using array techniques to the theoretical values based on the event locations and the velocity model. We used earthquakes recorded by the two arrays from 2003 to 2006 and the event locations from NEIC earthquake catalogue and iasp91 velocity model were chosen as reference events and velocity model here. The two arrays were corrected by the using of teleseismic P phases and the major regional and local phases based on the NEIC earthquake catalogue list. Hailar array shows small corrections and random in orientation while Lanzhou array shows bigger corrections and systematic bias was found that the array shows positive residuals for event paths from South-East and negative residuals for event paths from North- West that may be attributed to local structure. After correction, the two arrays clearly improved the single array location abilities and the standard deviations of azimuth and slowness residuals drop from 10.2 to 5.8 deg and from 1.3 to 0.6 s/deg respectively for Hailar array. For Lanzhou array, these values drop from 26.4 to 11.5 deg and from 3.1 to 1.2 s/deg respectively. The variation ranges of azimuth and slowness residuals is from 105.9 to 53.5 deg and from 12.4 to 4.4 s/deg for Hailar array, while for Lanzhou array, these numbers drop from 167.9 to 64.0 deg and from 14.0 to 6.1 s/deg respectively after correction.
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 9900 CORRECTIONS
SC: Seismology [S]
MN: 2007 Fall Meeting