New Constraints on Tectonics of Interior Alaska: Earthquake Locations, Source Mechanisms, and Stress Regime
New Constraints on Tectonics of Interior Alaska: Earthquake Locations, Source Mechanisms, and Stress Regime
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阿拉斯加内陆构造的新约束：地震位置、震源机制和应力机制
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
R. Hansen
中科院分区：
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作者：
N. Ratchkovski;R. Hansen
我们使用联合震源测定法（JHD）重新定位了1988 - 1999年发生在阿拉斯加中部的3611次地壳地震。新的地震位置提供了更多关于Kantishna群结构的细节，并为2000年11月29日Minto Flats地震带的ml 5.6地震的余震序列提供了更好的位置。1995年mw6.0 Minto Flats地震和1996年10月22日mw5.8地震在Denali断层附近的余震的JHD位置也可用。编制了1988 ~ 2000年发生的4.0级以上地震的矩张量解和3.4级以上地震的P波初动解共196个断层平面解目录。利用区域宽带数据计算矩张量解。这个目录被用来计算地壳中的主应力方向。应力方向在阿拉斯加中部发生变化。其中，最大主应力方向自西向东由SE-NW向SSW-NNE方向顺时针旋转。这些应力方向与阿拉斯加南部板块辐合转移的应力场一致。此外，我们在矩张量反演过程中测试了不同的速度结构，以确定计算格林函数的速度模型。矩张量反演研究表明，当震中距离在50 ~ 300 km之间时，利用单个宽带台站的三分量记录可以获得可靠的矩张量解。
We used the joint hypocenter determination (JHD) method to relocate 3611 crustal earthquakes that occurred from 1988 to 1999 in central Alaska. The new earthquake locations provide more details on the structure of the Kantishna cluster and better locations for the aftershock sequence of the 29 November 2000 M L 5.6 earthquake in the Minto Flats seismic zone. The JHD locations for the aftershocks of the 1995 M W 6.0 Minto Flats earthquake and 22 October 1996 M W 5.8 earthquake near the Denali fault are also available. A catalog of 196 fault-plane solutions consisting of the moment tensor solutions for the earthquakes with magnitude 4.0 or above and P -wave first-motion solutions for the earthquakes with magnitude 3.4 and above that occurred from 1988 to 2000 was composed. Moment tensor solutions were calculated using regional broadband data. This catalog was used to calculate principal stress orientations in the crust. The stress orientations change across central Alaska. In particular, the maximum principal stress orientation rotates clockwise from SE-NW to SSW-NNE direction as one moves from west to east. These stress orientations are consistent with the stress field transferred from the plate convergence in southern Alaska. In addition, we tested different velocity structures in the moment tensor inversion procedure to identify velocity models for calculating the Green's functions. The moment tensor inversion study shows that it is possible to obtain a reliable moment tensor solution for moderate-sized earthquakes ( M L ≥ 4) using three-component records from a single broadband station when the epicentral distances are between 50 and 300 km.
Manuscript received 8 June 2001.