Surface Rupture Earthquakes and the Mechanics of Earthquake Faulting

地表破裂地震和地震断层力学

• 批准号: 1213768
• 负责人: Steven Wesnousky
• 金额: $ 16.89万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213768&HistoricalAwards=false
• 关键词: Surface; Rupture; Earthquakes; Mechanics; Earthquake

The proposed work will develop new observations and data from historical groundrupturing earthquakes to improve understanding of the earthquake rupture process. Priorobservations have worked to define the role of fault geometry in rupture propagation, addressedand discounted self-similarity in the description of surface rupture slip distributions, shownclearly that fault rupture is not consistently uni- or bi-lateral, that earthquakes do not consistentlyinitiate on the section of fault ultimately recording maximum slip, and thatthe relationshipbetween average coseismic slip and rupture length for large strike-slip earthquakes appears torequire coseismic slip at progressively greater depths below the seismogenic layer as a functionof rupture length. Previous work was been limited by time and funding to a set of about threedozen large continental earthquakes which shared the characteristics that there existed (1) mapsof the surface rupture trace, (2) maps of the nearby active faults that did not rupture, and (3)measurements of coseismic offset at many points along the strike of the rupture to define thesurface slip distribution. The resulting compilation has already become a heavily cited andwidely used resource for the larger earthquake physics community. This work will extendprevious analyses to a list of more than twice as many earthquakes that have produced surfaceruptures but for which documentation may not simultaneously satisfy all three criteria. Thepremise of this proposal is that many observations and insights are yet to be gained in followinga similar approach and extending the analysis to these additional surface rupturing earthquakes.Broader Significance:Placing observational bounds on our efforts to understand the physics of the earthquakeprocess is at the heart of quantifying earthquake hazard imposed by mapped active faults; this isthe broadest and most practical impact of the proposed research. Other researchers havedeveloped numerical models of earthquake rupture behavior, but knowing how well they predictreal earth behavior depends on observational data from real ground ruptures. Research questionsinclude how far a rupture can jump from one fault to another, how angle deviations in a faulttrace affect rupture, how deep into the crust rupture extends, and how surface rupture correlateswith expected ground motions. As a practical example, the empirical observations will improvetools to define the expected endpoints and thus rupture lengths of earthquakes in California.Funding will also contribute to the training of a graduate-level geoscience student.

这项拟议的工作将从历史上接地地震中发展出新的观测和数据，以提高对地震破裂过程的理解。以前的观测已经确定了断层几何在破裂传播中的作用，在描述地表破裂滑移分布时解决了和折扣的自相似性，清楚地表明断层破裂不是一致的单侧或双侧的，地震并不总是在最终记录最大滑移的断层上开始，而且对于大型走滑地震来说，平均同震滑动与破裂长度之间的关系似乎需要在孕震层以下逐渐变深的同震滑动作为破裂长度的函数。以前的工作受限于时间和资金，仅限于一组大约30多次大陆大地震，这些地震具有以下特征：(1)地表破裂痕迹图，(2)附近没有破裂的活动断裂图，(3)沿破裂走向的许多点的同震偏移量测量，以确定地表滑动分布。由此产生的汇编已经成为一个被大量引用和广泛使用的资源，供更大的地震物理界使用。这项工作将把以前的分析扩展到两倍以上的地震，这些地震产生了表面喷发，但其记录可能不同时满足所有三个标准。这一建议的前提是，在遵循类似方法并将分析扩展到这些额外的地表破裂地震方面，还没有获得许多观察和见解。更广泛的意义：为我们理解地震过程的物理过程设定观测界限是量化绘制的活动断层造成的地震危险的核心；这是拟议研究的最广泛和最实际的影响。其他研究人员已经开发了地震破裂行为的数值模型，但要知道它们对地球行为的预测有多好，取决于来自真实地面破裂的观测数据。研究问题包括：破裂可以从一个断层跳到另一个断层的距离有多远，断层轨迹中的角度偏差如何影响破裂，地壳破裂延伸的深度有多深，以及地表破裂与预期的地面运动之间的关系。作为一个实际例子，经验观察将改进工具，以确定加州地震的预期终点，从而确定破裂长度。基金还将有助于培养研究生水平的地球科学专业学生。