Collaborative Research: Modeling of 3-D Viscoelastic Stress Transfer in the California Crust: Implications for Earthquake Triggering and Seismic Hazard Migration

研究人员建议进行一系列三维数值模拟实验，重点是最近加州的三个地震序列：（1）1992年兰德斯地震，它在触发1999年赫克托煤矿事件中的潜在作用，以及它们对南部圣安德烈亚斯断层的综合影响;（2）1983年科林加和1985年Kettleman山盲冲地震及其对延迟圣安德烈亚斯断层帕克菲尔德段地震破裂的潜在影响;以及（3）洛杉矶地区最近的一系列历史地震，包括1933年长滩、1952年克恩县、1971年圣费尔南多、1987年惠蒂尔海峡和1994年北岭地震，及其对洛杉矶地区地震灾害迁移的影响。 最近，研究人员已经成功地为上述加州层序的一个小子集开发了初步的3-D粘弹性模型。 该项目将使他们能够进行更全面的调查，通过（1）扩展模型，包括所有相关的地震，（2）验证模型解决方案的鲁棒性及其对地壳流变学和断层几何假设的敏感性，以及（3）将模型结果与大地测量观测结果进行比较。 这种模拟研究的结果，加上空间大地测量学和地震监测能力的进步，应该为我们提供一个更清楚的了解加州地壳的地震特性，地震触发的机制，以及在加州地震灾害迁移的破坏。 这是加州大学伯克利分校（安迪·弗里德）和WHOI（林健）之间的合作项目。 Freed将使用I-deas粘弹性建模代码进行三维建模实验，而Lin将负责将I-deas解决方案与GENPro边界元代码的独立结果进行比较，并分析研究区域的大地测量和地震数据以约束建模。

Burgmann Lin The investigators propose to perform a set of 3-D numerical modeling experiments, focusing on three recent California earthquake sequences: (1) the 1992 Landers earthquake, its potential role in triggering the 1999 Hector Mine event, and their combined effects on the southern San Andreas fault; (2) the 1983 Coalinga and 1985 Kettleman Hills blind-thrust quakes and their potential effects on delaying seismic rupture on the Parkfield segment of the San Andreas fault; and (3) the most recent sequence of historical quakes in the Los Angeles region, including the 1933 Long Beach, 1952 Kern County, 1971 San Fernando, 1987 Whittier Narrows, and 1994 Northridge events, and their implications on seismic hazard migration in the Los Angeles region. Recently the investigators have successfully developed preliminary 3-D viscoelastic models for a small subset of the above California sequences. This project will allow them to carry out a much more comprehensive investigation through (1) extending the models to include all relevant quakes, (2) verifying the robustness of the model solutions and their sensitivity to assumptions in crustal rheology and fault geometry, and (3) comparing the model results with geodetic observations. Results of this modeling investigation, together with advances in space geodesy and seismic monitoring capabilities, should provide us with a much clearer understanding of the seismic properties of the California crust, the mechanisms of earthquake triggering, and the regularities in seismic hazard migration in California. This is a collaborative project between the UC Berkeley (Andy Freed) and WHOI (Jian Lin). Freed will lead 3-D modeling experiments using the I-deas viscoelastic modeling code, while Lin will lead tasks of comparing the I-deas solutions to independent results from the GENPro boundary-element code and analyzing the geodetic and earthquake data in the study regions to constrain modeling.