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

林伯曼研究人员建议进行一系列三维数值模拟实验，重点放在最近加州的三个地震序列上：(1)1992年的兰德斯地震，它在触发1999年赫克托煤矿事件中的潜在作用，以及它们对圣安德烈亚斯断层南部的综合影响；(2)1983年的科林加和1985年的凯特尔曼山盲冲地震及其对延缓圣安德烈亚斯断裂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年的长滩地震、1952年的克恩县地震、1971年的圣费尔南多地震、1987年的惠蒂尔纳罗斯地震和1994年的北岭地震，以及它们对洛杉矶地区地震危险性迁移的影响。最近，研究人员成功地为上述加州序列的一小部分开发了初步的3-D粘弹性模型。该项目将使他们能够通过以下方式进行更全面的调查：(1)扩展模型以包括所有相关地震，(2)验证模型解的稳健性及其对地壳流变学和断层几何学假设的敏感性，以及(3)将模型结果与大地测量结果进行比较。这次模拟调查的结果，加上空间大地测量和地震监测能力的进步，应该会使我们对加州地壳的地震性质、地震触发机制和加州地震灾害迁移的规律有更清楚的了解。这是加州大学伯克利分校(Andy Freed)和WHOI(林健饰)的合作项目。Freed将使用i-deas粘弹性建模程序领导三维建模实验，而Lin将领导将i-deas解与GENPro边界元程序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的任务。

Lin BurgmannThe 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.