HR: 0800h
AN: S51B-1003    [Abstracts]
TI: The Effect of Data Recorded at Nearby Stations on Relative Location Algorithms
AU: * Zhang, T
EM: zhangtz45@163.com
AF: Institute of Geophysics, CEA, No.5 Mingyuannanlu, Haidian District, Beijing, 100081 China
AU: Huang, Y
EM: yhuang@globalmminfo.com
AF: Institute of Geophysics, CEA, No.5 Mingyuannanlu, Haidian District, Beijing, 100081 China
AU: Wu, B
EM: wubte@163.com
AF: Institute of Geophysics, CEA, No.5 Mingyuannanlu, Haidian District, Beijing, 100081 China
AB: The Double-difference Earthquake location algorithm (DD) is proposed later than other relative algorithms, such as master event location, hypocentroid decomposition location, multiplet relocation and so on. Compared with other relative location algorithms, the only change in DD is that the partial derivatives of the travel time, for two events with respect to their location and original time, respectively, are calculated for the current two hypocenter locations, instead of for the common position (the location of master event, or the average position of events and so on). Because two partial deviations are taken the same for other relative location algorithms, the distance between events have to be much less than the distance from events to station, which is not necessary for DD. Under some conditions, DD can use the data recorded at nearby stations (the distance between events is comparable with the distance from events to station). And because it the DD method allows us get more accurate absolute locations of events, especially the depths of events, which behave more like absolute location method. On Feb. 24 of 2003, an Ms 6.8 earthquake hit the Jiashi region of Xingjiang Uigur municipality in China, which is one of the most disastrous events in Xingjiang. To monitoring the aftershock activity a temperate network was built in the epicentral region from March 14 to the end of April. Combining the data recorded at 5 mobile stations and 3 regional stations, we relocated the aftershocks of Jiashi Ms6.8 earthquake by DD method. The maximum separation of two events in a pair is taken as 10 km, while the minimum station-event distance is about 20km for mobile stations. The other relative location algorithms are not suitable in this case. The result shows that the distribution of aftershocks is more concentrated along almost east-west direction, which is more consistent with the intensity distribution and focus mechanism. The depth distribution moves to 15-25km from about 10km, which is reasonable because of 15 km sediment layer distributed in this region.
DE: 7205 Continental crust (1219)
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: Fall Meeting 2005