Horizontal deformation in the Imperial Valley, California, between 1934 and 1980
Horizontal deformation in the Imperial Valley, California, between 1934 and 1980
复制标题
1934 年至 1980 年间加利福尼亚州因皮里尔谷的水平变形
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
E. L. Timmerman
中科院分区：
文献类型：
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作者：
R. Snay;M. Cline;E. L. Timmerman
在1979年10月15日帝国谷6.6级地震前四个月，国家海洋调查局/国家大地测量局进行了三角测量。1980年2月至3月重复了该测量，以测量同震位移。这些数据与1934-1935年、1939年、1941年、1954-1955年和1967年进行的三角测量相结合，提供了一段时间内地壳变形的历史记录，其中还包括1940年埃尔森特罗7.1级地震。总的数据集进行了分析的位错模型，所观察到的表面变形滑动规定的地质断层。根据该模型，1941-1980年10 km及以上深度的断层滑动量为1.9±0.3 m。这个值大约是1941-1980年帝国断层在0- 10公里深度范围内滑动估计值1.0±0.1米的两倍。这种差异可以用一系列的可能性来解释，包括：（1）某些深断层滑动是由于1940年地震的后效造成的，在这种情况下，深、浅滑动相等的地震周期不是大地震之间的间隔，而是延迟了几年：（2）深滑动应等同于几个平行断层上的浅滑动;（3）地壳经历了永久的非弹性变形;（4）深部变形是由滑动以外的机制调节的。
A triangulation-trilateration survey was performed by the National Ocean Survey/National Geodetic Survey four months prior to the October 15, 1979, Imperial Valley M 6.6 earthquake. The survey was repeated in February–March 1980 to gauge the coseismic displacement. These data combined with triangulation surveys performed in 1934–1935, 1939, 1941, 1954–1955, and 1967 provide a historical record of crustal deformation over a time period that also includes the 1940 El Centro M 7.1 earthquake. The total data set was analyzed in terms of a dislocation model that relates the observed surface deformation to slip on prescribed geologic faults. According to the model, the 1941–1980 fault slip at depths 10 km and greater is 1.9±0.3 m. This value is approximately twice the 1.0±0.1 m estimated for the 1941–1980 slip on the Imperial fault in the 0- to 10-km depth range. This discrepancy can be explained by a range of possibilities including the following: (1) some of the deep fault slip is due to aftereffects of the 1940 earthquake, in which case the seismic cycle over which deep slip and shallow slip are equal is not the interval between large earthquakes but is delayed a few years; (2) the deep slip should be equated to the shallow slip over several parallel faults; (3) the crust experienced permanent inelastic deformation; and (4) deep deformation is accommodated by a mechanism other than slip.