Collaborative Research: Slip-per-event Rupture History of the San Andreas Fault in the Carrizo Plain: Was the 1857 Earthquake Characteristic?

合作研究：卡里索平原圣安德烈亚斯断层的每次滑动破裂历史：1857 年地震有特点吗？

• 批准号: 0711518
• 负责人: Lisa Grant Ludwig
• 金额: $ 27.01万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711518&HistoricalAwards=false
• 关键词: Collaborative; Research; Slip; per; event

On January 9, 1857 the magnitude 7.8 Fort Tejon earthquake ruptured a 400 km long section of the southern San Andreas Fault including the Carrizo section. The Carrizo section of the San Andreas Fault has been proposed to rupture only during the largest earthquakes, and thereby to control the occurrence of great characteristic earthquakes on the southern San Andreas Fault with centuries-long recurrence times in the Carrizo Plain. Recent findings suggest a more complex rupture pattern with significantly shorter recurrence times and possibly clustered earthquakes. Reported measurements of slip-per-event for the last 5 or 6 earthquakes, when combined with new dates of earthquakes, yield slip rates up to 50 mm/yr, well above widely accepted values of approximately 35 mm/yr. The mismatch suggests that either the strain released is not directly proportional to the time between ruptures, thereby casting doubt on time-predictable and slip-predictable elastic strain models, or some of the reported slip-per-event measurements represent cumulative slip for multiple events. Resolution of this conundrum should lead to fundamental insights into fault mechanics, as well as more effective methods for forecasting future large earthquakes. The goal of this project is to measure the slip from several recent well-dated ruptures of the San Andreas Fault in the Carrizo Plain. The challenge is in linking slip measurements with dates of earthquakes. Several methods will be applied, including three-dimensional paleoseismic excavation of the Bidart fan site, high precision radiocarbon dating, analysis of geomorphic offsets using high resolution airborne laser swath mapping data, and compilation of archival field data from unpublished studies. Results of this research could have significant impact on seismic hazard mitigation and planning for major earthquakes. The San Andreas Fault is the major source of seismic hazard and risk in the densely populated and economically important state of California, and its proven potential to generate a large earthquake makes it a significant threat to the nation. Data from this research will help to assess the probability, and forecast the location and magnitude of the next damaging San Andreas earthquake in southern California.

1857年1月9日，幅度7.8堡堡地震破裂了圣安德烈亚斯南部断层的400公里长，其中包括卡里佐（Carrizo）部分。仅在最大的地震期间，就提出了圣安德烈亚斯断层的Carrizo部分破裂，从而控制了南部圣安德烈亚斯（San Andreas）断层发生的巨大特征地震，在卡里佐平原（Carrizo Plain）长达数百年的复发时间。最近的发现表明，更复杂的破裂模式，复发时间明显较短，可能是聚集的地震。报道了最近5或6次地震的每一个地震的测量值，当与新的地震日期结合使用时，屈服速率高达50 mm/yr，远高于大约35 mm/yr的广泛接受的值。不匹配表明，释放的菌株与破裂之间的时间不成比例，从而对时间预测和可预测的可预测弹性应变模型或一些报告的每项活动测量值表示疑问，代表了多个事件的累积滑移。解决这一难题的解决应导致对断层力学的基本见解，以及预测未来大地震的更有效方法。该项目的目的是衡量卡里佐平原（Carrizo Plain）最近发生的几起圣安德烈亚斯（San Andreas）断层破裂的损失。挑战在于将滑移测量与地震日期联系起来。将采用几种方法，包括使用高分辨率空中激光器绘图数据对Bidart Fan站点的三维paperosic发掘，高精度放射性碳测定，分析地貌偏移的分析以及未公开研究的档案现场数据的汇编。这项研究的结果可能会对减轻地震危害和大地震计划产生重大影响。圣安德烈亚斯（San Andreas）的断层是人口稠密且经济上重要的加利福尼亚州的地震危害和风险的主要来源，其可证明的产生大地震的潜力使其对国家构成了重大威胁。这项研究的数据将有助于评估概率，并预测南加州的下一次破坏性圣安德烈亚斯地震的位置和幅度。