Strain rate patterns from dense GPS networks
Strain rate patterns from dense GPS networks
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DOI：
10.5194/nhess-9-1177-2009
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发表时间：
2009-07
影响因子：
4.6
通讯作者：
M. Hackl;R. Malservisi;S. Wdowinski
中科院分区：
文献类型：
--
作者：
M. Hackl;R. Malservisi;S. Wdowinski
抽象的。地壳应变速率张量的知识提供了断层应变累积等地球动力学过程的描述，这是地震危险性评估以及人为变形的重要参数。在过去的二十年里，GPS等基于卫星的大地测量的观测次数和精度大大增加，提供了点的位移和速度的测量值。在这里，我们提出了一种从密集的GPS网中获得全连续应变速率张量的方法。张量分析提供了变形的不同方面，如最大剪切应变率(包括其方向)和膨胀应变率。这些参数适用于表征电流变形的机制。利用SCEC和UNAVCO提供的速度场，我们能够定位南加州的主要活动断裂，并根据断裂机制对其进行表征。我们还表明，最近在研究区发生的大地震事件严重污染了测量的速度场，而速度场似乎受到地震后瞬时形变的强烈影响。最后，我们将这种方法应用于冰岛两次地震的同震位移数据，结果表明，由这些数据得到的应变场为破裂的位置和震源机制提供了重要信息。
Abstract. The knowledge of the crustal strain rate tensor provides a description of geodynamic processes such as fault strain accumulation, which is an important parameter for seismic hazard assessment, as well as anthropogenic deformation. In the past two decades, the number of observations and the accuracy of satellite based geodetic measurements like GPS greatly increased, providing measured values of displacements and velocities of points. Here we present a method to obtain the full continuous strain rate tensor from dense GPS networks. The tensorial analysis provides different aspects of deformation, such as the maximum shear strain rate, including its direction, and the dilatation strain rate. These parameters are suitable to characterize the mechanism of the current deformation. Using the velocity fields provided by SCEC and UNAVCO, we were able to localize major active faults in Southern California and to characterize them in terms of faulting mechanism. We also show that the large seismic events that occurred recently in the study region highly contaminate the measured velocity field that appears to be strongly affected by transient postseismic deformation. Finally, we applied this method to coseismic displacement data of two earthquakes in Iceland, showing that the strain fields derived by these data provide important information on the location and the focal mechanism of the ruptures.