Collaborative Research: Multi-cycle Rupture History of the San Andreas Fault in the Carrizo Plain

合作研究：卡里索平原圣安德烈亚斯断层的多旋回破裂历史

• 批准号: 0409500
• 负责人: Lisa Grant Ludwig
• 金额: $ 24.02万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409500&HistoricalAwards=false
• 关键词: Collaborative; Research; Multi; cycle; Rupture

One of the most basic questions in earthquake physics, earthquake hazards, and neotectonics is "What controls the space-time pattern of seismicity?" A more fundamental question that must be answered first is "What is the space-time pattern of seismicity?" This question can only be answered by observing fault behavior at multiple temporal and spatial scales. Paleoseismic investigations provide data on the multi-cycle rupture history of a portion of a fault. The San Andreas fault is the largest source of seismic hazard in California. Data on the rupture history of the San Andreas fault form the basis of numerous models of fault behavior and seismic hazard. The high slip rate, short recurrence interval, great length and accessibility of the San Andreas fault make it the best target in the U.S. (and perhaps the world) for observational testing of fault behavior models. This project involves collecting a multi-cycle rupture history from a proven paleoseismic site along one of the most scientifically important and hazardous faults in the world: the San Andreas fault. There are only 4 sites along the southern San Andreas fault that have a rupture chronology of at least 5 events. One of these sites is the Bidart Fan in the Carrizo Plain. The Carrizo Plain is one of the best places to study the rupture history of the SAF because it has a proven paleoseismic record with excellent slip rate and slip per event measurements, and the potential to significantly enlarge the data set by increasing the length of the earthquake record. Previous work at the Bidart Fan shows that it contains a lengthy, datable record of surface ruptures. A total of four trenches have been excavated in the SAF zone on the Bidart Fan. These trenches yield a composite chronology consisting of 10 surface ruptures of the Bidart Fan over the last 3,000 years. The most recent 5 earthquakes are reasonably well dated, but uncertainty in the dates of the five earlier ruptures is much greater. Therefore, these five early earthquakes are the primary target of this project. Additional trenches placed across the Bidart Fan are revealing a better spatial and temporal record of deposition across the fan, leading to improved dates of previously documented earthquakes. Radiocarbon dates of samples will be obtained from University of California, Irvine's new Keck Accelerator Mass Spectrometry facility devoted to carbon isotopes using improvements in the application of radiocarbon dating to paleoseismology made at the Lawrence Livermore National Laboratory. This project includes a similar effort to improve the event record in the Carrizo Plain. It is doubling the temporal record of surface ruptures in the Carrizo Plain and providing a major paleoseismic site on the San Andreas fault for developing and testing models of fault behavior.

地震物理学，地震危害和新神经学中最基本的问题之一是“是什么控制地震的时空模式？”首先必须回答的一个更基本的问题是“地震性的时空模式是什么？”只能通过在多个时间和空间尺度上观察断层行为来回答这个问题。旧目的研究提供了一部分故障的多周期破裂病史的数据。圣安德烈亚斯（San Andreas）断层是加利福尼亚州最大的地震危险来源。关于圣安德烈亚斯断裂破裂历史的数据构成了许多断层行为和地震危险模型的基础。 San Andreas断层的高滑动速率，短复发间隔，长度和可及性使其成为美国（甚至是世界）的最佳目标，用于观察错误行为模型。该项目涉及从世界上最重要和最危险的断层之一沿着经过验证的旧遗址收集多周期破裂历史：圣安德烈亚斯的断层。圣安德烈亚斯南部断层沿线只有4个地点，它们的年表破裂至少为5个事件。这些站点之一是Carrizo平原上的Bidart风扇。 Carrizo平原是研究SAF的破裂历史的最佳场所之一，因为它具有良好的壁式记录，具有出色的滑动速率和每个事件测量值的滑动速度，并且有可能通过增加地震记录的长度来显着扩大数据集。 Bidart风扇的先前工作表明，它包含了表面破裂的冗长数据记录。在比达特风扇的SAF区域中，总共挖了四个战es。这些沟渠产生的复合年代学在过去3，000年中由Bidart风扇的10个表面破裂组成。最近的5次地震过时了，但五个较早破裂的日期的不确定性要大得多。因此，这五个早期地震是该项目的主要目标。在Bidart风扇上放置的其他沟渠揭示了整个风扇的空间和时间记录，从而改善了先前记录的地震日期。样品的放射性碳日期将从加利福尼亚大学获得欧文大学的新凯克加速器质谱设施，该设施利用在劳伦斯·利弗莫尔国家实验室（Lawrence Livermore National Laboratory）上应用的放射性碳日期应用于碳同位素的碳同位素。该项目包括类似的努力来改善Carrizo Plain的活动记录。它使Carrizo平原上表面破裂的时间记录增加了一倍，并在San Andreas断层上提供了一个主要的古呼位点，用于开发和测试故障行为的模型。