RESEARCH OF THE TIME AND SPACE DISTRIBUTION FOR THE JIASHI EARTHQUAKE SEQUENCE IN XINJIANG FROM 1997 TO 2003

We analyzed and studied the catalog of Jiashi earthquake sequence. The result showed: The Jiashi earthquake sequence from 1997 to 2003 was composed by three phases of occurring earthquakes, the different phases had themselves characteristics, the frequency of M6 earthquakes was high in first phase, the frequency of M5 earthquakes was high in second phase, the earthquake intension was high in the third phase, and the main characteristic before the obvious change of Jiashi earthquake sequence was high b value; The developing course of Jiashi earthquake sequence is from SW direction to NE direction to SE direction, the distribution of M6 earthquakes' aftershocks before Apr. 16, 1997 isn't obvious, the aftershocks of most of the later M6 earthquakes in the south of the main earthquakes, the aftershocks' distribution was different between the Jiashi M6.8 earthquake in Feb. 24, 2003 and the other M6 earthquakes, the reason can be the especial construct; The expansion of the aftershocks of Jiashi M6 earthquakes before 1998 wasn't obvious, the obvious expansion trend occurred in the aftershocks of the M6 earthquake in Aug. 27, 1998, the obvious expansion occurred in the aftershocks of the M6 earthquake in Feb.24,2003; the focal depths of the Jiashi strong earthquakes cluster were from 17km to 31km, the focal depths were about 27km after Apr.16,1998, this showed the first fracture of the Jiashi earthquake sequence started from the crust, but the main fracture started from the middle crust; the distribution characteristic of Jiashi earthquake is from shallow to deep, the M5 earthquakes in three phases also had the same characteristic, most of the M5 earthquakes' occurred in the high-speed region.