Collaborative Research: Improving the Chronology of Deformation and Earthquakes at La Rinconada, Argentina: Testing Segmentation and Recurrence Patterns of Blind Thrust Regimes

了解隐伏逆冲断层（没有到达地球的断层）的地震潜力？的表面）对于人口密集的地区如美国的洛杉矶和西雅图以及世界各地地震活跃区域内的其他人口中心具有重大的地震危险暗示。关于破坏性地震断层的长期行为的关键问题包括地震的规模和频率以及它们在时间和空间上的变化。 更好地了解过去地震的时间和规模是用于预测未来事件，描述当地和区域地震危险以及告知公众和应急规划人员的重要信息。然而，人口稠密的地区很难研究，因为混凝土、建筑物和发展模糊了活动断层的表达。在这项研究中，一个活跃的断层系统附近的圣胡安阿根廷，它承担在美国的大都市地区的盲断层的结构相似性，但有一个优点，该地区基本上是不受干扰的，正在调查，以更好地了解几个活跃的盲逆冲断层的地表表现和地震历史。 该项目的重点是对从河流阶地和冲积层中收集的大量样品进行测年，这些样品因地震断层而变形和断裂。根据这些新的数据，将确定过去五次大地震在盲断层系统上发生的时间。新的年龄数据将允许与早期工作中记录的附近断层系统的地震历史进行比较，这些断层是该地区1944年和1977年破坏性地震的原因。该项目将测试单个断层上的地震频率是否是准周期性的（因此是可预测的），这些断层系统是否会产生在时间上聚集的地震，并测试过去的一些地震是否可能破坏了一个更大的震源区，或者是否被限制在与历史事件相同的震源范围内。与该项目早期阶段的结果一样，阿根廷合作者和其他人将使用该项目的新结果来限制地震危险，告知地震工程师，并教育公众有关地震危险。

Understanding the earthquake potential of blind thrust faults (faults that do not reach the Earth?s surface) has major seismic hazard implications for heavily populated areas such as Los Angeles and Seattle in the United States as well as other population centers within seismically active regions around the World. Key questions regarding the long-term behavior of destructive earthquake faults include what are the size and frequency of earthquakes and how do those vary in time and space. Better knowledge of the timing and sizes of past earthquakes is essential information used to forecast future events, to characterize local and regional seismic hazards, and to inform the public and emergency planners. Heavily populated areas, however, are difficult to study because concrete, buildings, and development obscure the expression of active faults. In this study, an active fault system near San Juan Argentina, which bears structural similarities to blind faults within metropolitan regions in the United States, but has the advantage that the area is largely undisturbed, is being investigated to better understand the surficial expression and earthquake history of several active blind thrust faults. This project is focused on dating of a large suite of samples collected from river terraces and alluvium deformed and faulted by the earthquake faults. From these new data, the timing of the past five large earthquakes on the blind fault system will be established. The new age data will allow comparison with the earthquake history of nearby fault systems documented in earlier work, faults that were responsible for damaging earthquakes in 1944 and 1977 in the region. This project will test whether earthquake frequency on individual faults is quasi-periodic (and therefore predictable), whether these fault systems produce earthquakes that cluster in time, and test whether some past earthquake may have ruptured a larger source region or have been confined to the same source dimensions as the historical events. Like the results from an earlier phase of this project, the Argentinean collaborators and others will use the new results from this project to constrain seismic hazard, inform earthquake engineers, and educate the public about earthquake hazards.