The great March 25, 1998, Antarctic Plate earthquake: Moment tensor and rupture history

被引:56
作者
Henry, C [1 ]
Das, S [1 ]
Woodhouse, JH [1 ]
机构
[1] Univ Oxford, Dept Earth Sci, Oxford OX1 3PR, England
关键词
D O I
10.1029/2000JB900077
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We use broadband body and mantle wave data to study the 1998 Antarctic intraplate earthquake. The: centroid moment tensor (CMT) has a large non-double-couple component. There exist two pure double-couple constrained solutions that fit the data almost equally well. The frequent practice of taking the "best double-couple" gives a far from optimal solution. We use P and SH body waves to determine the rupture parameters of the first and larger of the two observed subevents. The best rupture plane, with strike 96 degrees, dip 69 degrees, and rake -18 degrees, is compatible with only one of the two CMT solutions: strike 96 degrees, dip 64 degrees, rake -23 degrees, centroid location (63.1 degrees S, 148.4 degrees E, 10 km depth), centroid time 0313:02 UT, and M-0 = 1.3 x 10(21) N m (M-w = 8.0). The first subevent is a simple, primarily westward propagating similar to 140-km rupture, of similar to 45-s duration, with average velocity greater than or similar to 3 km s(-1); it has' a seismic moment of 1.2 x 10(21) N m (M-w = 8.0), with 75% of its moment released between 10 and 27 s, and a stress drop of similar to 240 bars. The rupture is physically bounded by two fracture zones at 147.5 degrees E and 150 degrees E. The second subevent lasted from 70 to 90 s on a fault extending from 210 to 270 km west of the epicenter, with a moment of 0.3-0.6 x 10(21) N m (M-w = 7.6-7.8). This is a spectacular example of dynamic stress triggering over a 100-km separation distance with a time delay of similar to 40 s. The complex pattern of aftershocks is primarily controlled by preexisting fracture zones on the ocean floor.
引用
收藏
页码:16097 / 16118
页数:22
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