Coseismic deformation from the 1999 Mw 7.1 Hector Mine, California, earthquake as inferred from InSAR and GPS observations
Coseismic deformation from the 1999 Mw 7.1 Hector Mine, California, earthquake as inferred from InSAR and GPS observations
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DOI：
10.1785/0120000933
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发表时间：
2002-05-01
影响因子：
3
通讯作者：
Rivera, L
中科院分区：
文献类型：
--
作者：
Simons, M;Fialko, Y;Rivera, L
利用干涉合成孔径雷达(InSAR)和全球定位系统(GPS)观测资料，研究了发生在加州东部剪切带的1999年M-W 7.1赫克托矿震的静态形变。干涉去相关、相位和方位偏移量测量表明了地表和近地表滑动的区域，我们使用这些区域来约束地表破裂的几何形状。推断的几何图形在空间上是复杂的，具有多股。断裂带的南三分之一由三个近平行的段组成，长约20公里，沿N45°W向延伸。中央部分是最简单的，只有一条线穿过金银山，走向北纬10度。断裂带的北部三分之一以多个展布为特征，方向与南部和中部的走向近平行。整个破裂的平均走向约为北纬30度。干涉图显示了沿走向的显着应变变化，这与地面滑动测量的变化一致。为了减少计算负担，采用变分辨率数据采样程序，对InSAR和GPS数据进行了断层几何形状和滑动分布的反演。我们比较了假设弹性半空间和层状弹性空间的结果。这两个弹性模型的结果是相似的，尽管分层空间模型预测的深度滑动比半空间模型预测的更多。分层模型预测，在3到6公里的深度处，最大同震滑动超过5英寸。与初步报告相反，赫克托矿破裂的北部容纳了最大滑动。我们的模型对地表断层错距和总地震矩的预测与现场制图结果和最近的地震模型都是一致的。推断的浅层滑动亏损是一个谜，可能表明在地震期间或地震后不久，地壳最上部几公里处发生了分布的非弹性屈服。
We use interferometric synthetic aperture radar (InSAR) and Global Positioning System (GPS) observations to Investigate static deformation due to the 1999 M-w 7.1 Hector Mine earthquake, that occurred in the eastern California shear zone. Interferometric decorrelation, phase, and azimuth offset measurements indicate regions of surface and near-surface slip, which we use to constrain the geometry of surface rupture. The inferred geometry is spatially complex, with multiple strands. The southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a N45degreesW direction. The central segment is the simplest, with a single strand crossing the Bullion Mountains and a strike of N10degreesW. The northern third of the rupture zone is characterized by multiple splays, with directions subparallel to strikes in the southern and central. The average strike for the entire rupture is about N30degreesW. The interferograms indicate significant along-strike variations in strain which are consistent with variations in the ground-based slip measurements. Using a variable resolution data sampling routine to reduce the computational burden, we invert the InSAR and GPS data for the fault geometry and distribution of slip. We compare results from assuming an elastic half-space and a layered elastic space. Results from these two elastic models are similar, although the layered-space model predicts more slip at depth than does the half-space model. The layered model predicts a maximum coseismic slip of more than 5 In at a depth of 3 to 6 km. Contrary to preliminary reports, the northern part of the Hector Mine rupture accommodates the maximum slip. Our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models. The inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake.