Collaborative Research: Paleoseismology of the M7.3 1915 Pleasant Valley Earthquake Ruptures

该项目利用地质学来评估1915年内华达州普莱森特谷7.3级地震断层上过去发生大地震的规模和频率，形成了科学，教育和推广合作计划的基础。通过对单个地震的累积研究，研究界获得了观测结果，以了解地震破裂及其在活动构造过程中的作用。在该项目中获得的信息将被纳入国家灾害地图，以减少未来地震中建筑基础设施和生命线的故障和生命损失。三个研究所的合作旨在为本科生和研究生提供机会，在积极的研究项目的框架内学习地震科学的方法和概念，导致教育和研究的在线和课堂材料的开发，在农村内华达州大学校园和内华达州大学之间建立联系，里诺。三个参与机构中有两个的主要研究人员是早期职业女性研究人员。这项研究将考虑近代历史上发生的少数几次大型大陆地震之一，并消除我们对盆地和山脉以及中央内华达州地震带活动构造的集体理解中的一个重大空白。这项研究将量化过去地震的时间和产生1915年Mw7.3地震的断层的平均滑动率。使用现代加速器质谱放射性碳、光激发发光和地球宇宙成因测年方法，结合本文提出的古地震挖沟调查，将产生以下观测结果：1）评估盆地和山脉内部沿沿着中央内华达州地震带滑动速率升高的向北程度，2）为了确定普莱森特山谷事件的过去历史是否表现出在南部的中央内华达州地震带中观察到的事件的重复聚类，3）解决1915年断裂的链是否在过去的地震中表现出相同的行为，4）将晚更新世期间的地质滑动速率与现代大地测量学进行比较，5）交叉检查应用于相同沉积物的多种测年技术，以及6）对普莱森特山谷冲积扇沉积的时间进行定量限制，作为评估具有相同地貌和土壤特征的相邻山脉前缘断层滑动速率的可能工具。总之，很少有大陆正断层地震破裂，可以收集有关破裂和复发特征的观测资料。这项研究将为比较和对比1915年断裂与之前发生在1915年断层和地球仪周围其他地方的断裂的特征提供基础。收集到的数据将对地震复发的概念模型和地震过程的物理学进行观测，这些模型构成了地震危险性分析的基础。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

This project to use geology to assess the past size and frequency of occurrence of large earthquakes on the fault that produced the magnitude 7.3 1915 Pleasant Valley earthquake in Nevada forms the underpinnings of a collaborative program of science, education and outreach. It is through the cumulative study of individual earthquakes that the research community gains observations to understand earthquake ruptures and their role in active tectonic processes. The information gained in this project will be incorporated into the National Hazard Maps designed to reduce failure of building infrastructure and lifelines and loss of life in future earthquakes. The collaboration of three institutes is designed to provide the opportunity for undergraduate and graduate students to learn methods and concepts bearing on earthquake science in the framework of an active research project, lead to the development of online and classroom materials for education and research, create links between rural Nevada college campuses and the University of Nevada, Reno. Principal investigators at two of the three participating institutions are early career female researchers.The study will consider one of the few large continental earthquakes that occurred in recent history and remove a significant void in our collective understanding of active tectonics in the Basin and Range and the Central Nevada Seismic Belt. This research will quantify the timing of past earthquakes and the average rate of slip on the fault that produced the Mw 7.3 1915 earthquake. The use of modern Accelerator Mass Spectrometry radiocarbon, Optical Stimulated Luminescence, and Terrestrial Cosmogenic dating methods in conjunction with paleoearthquake trenching investigations proposed herein will yield observations to 1) assess the northward extent to which slip rate is elevated along the Central Nevada Seismic Belt within the interior of the Basin and Range, 2) to determine whether the past history of events in Pleasant Valley exhibits repeated clustering of events that is observed in the Central Nevada Seismic Belt to the south, 3) address whether or not strands of the 1915 rupture separated by a 4 kilometer step in trace exhibited the same behavior in past earthquakes, 4) compare geologic rates of slip during the late Pleistocene as compared to modern geodesy, 5) cross-check multiple dating techniques applied to the same sediments, and 6) develop quantitative constraints on the timing of alluvial fan deposition in Pleasant Valley as a possible tool for assessing fault slip rates on adjacent range fronts exhibiting the same geomorphic and soil characteristics. In sum, there are few continental normal fault earthquake ruptures on which to gather observations bearing on the characteristics of rupture and recurrence. This study will provide the basis to compare and contrast characteristics of the 1915 ruptures to those that occurred before, both on the 1915 fault and elsewhere around the globe. The data collected will place observational bounds on conceptual models of earthquake recurrence and the physics of earthquake processes that form the underpinnings of seismic hazard analysis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.