RUI: Investigating Disagreements Between Geologically and Geodetically Estimated Slip Rates for the San Bernardino and San Gorgonio Pass Sections of the San Andreas Fault

RUI：调查圣安德烈亚斯断层的圣贝纳迪诺和圣戈戈尼奥山口部分的地质和大地测量滑移率之间的差异

• 批准号: 0844400
• 负责人: Sally McGill
• 金额: $ 30.85万
• 依托单位: University Enterprises Corporation at CSUSB
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0844400&HistoricalAwards=false
• 关键词: RUI; Investigating; Disagreements; Between; Geologically

Investigating disagreements between geologically and geodetically estimated slip rates for the San Bernardino and San Gorgonio Pass sections of the San Andreas fault. This award is supporting work aimed at better understanding the rate of slip along the southern San Andreas fault, in a region where highly discordant rates have been reported over different time intervals. The Holocene or latest Pleistocene slip rate (15 to 25 millimeters/year) of the San Bernardino section of the San Andreas fault is 3 to 5 times greater than rates based on elastic modeling of geodetic data (generally less than or equal to 5 millimeters/year). This is one of the largest known discrepancies between present rates of strain accumulation and the rate of Holocene to latest Pleistocene strain release. Does this discrepancy indicate that this section of the fault is no longer as active as it once was? Or is it a result of non-uniform rates of strain accumulation throughout the earthquake cycle? Geodetic data are sparse from the San Bernardino Mountains, along the northeast side of this section of the fault. Thus, before these questions about the cause of the rate discrepancy can be fully resolved, it is important to know to what extent the apparently low rate of geodetic strain accumulation may be an artifact of limited geodetic data in the region. Such information has important implications for assessing hazard associated with fault movement along this part of the San Andreas Fault System. To address these questions, researchers from California State University, San Bernadino an colleagues from the University of Arizona are collecting new survey-mode Global Positioning System (GPS) data from this region in order to provide a refined estimate of the present rate of elastic strain accumulation along the San Bernardino and San Gorgonio Pass sections of the San Andreas fault. Professor Sally McGill (California State University, San Bernardino) leads a team of undergraduate students and high school teachers (accompanied by some of their students) in an annual, week-long campaign to collect new survey-mode GPS data. During each summer from 2009-2011 the team collects 4 to 5 days of GPS data from 25 sites in the San Bernardino Mountains and vicinity. These data are processed and modeled by Sigrún Hreinsdóttir and Rick Bennett (University of Arizona), along with contemporaneous GPS data from up to 25 nearby stations from the Plate Boundary Observatory (PBO) and Southern California Integrated Geodetic Network (SCIGN) networks. This project supports undergraduate students, high school teachers and high school students at a variety of levels. Each summer, eight undergraduate students and six high school teachers with some of their students participate in the week-long data collection campaign. McGill works with the teachers to develop posters and lesson plans that bring their research experience back into the classroom. Each year, two of the undergraduate students develop research projects using the GPS data and continue working on the project throughout the summer, analyzing the time-series and conducting one-dimensional elastic and elastic-viscoelastic modeling for fault slip rates. They present results at professional meetings and are encouraged toward graduate school in the Earth sciences. Special efforts are made to recruit these students from populations that are under-represented in the geosciences, which is facilitated by the fact that California State University, San Bernardino is a Hispanic-serving institution at which 36 percent of the 52 geology majors are from under-represented groups. The education and outreach component of this proposal is being evaluated by an external consultant, Robert deGroot.

调查圣安德烈亚斯断层的圣贝纳迪诺和圣戈尔戈尼奥山口段的地质学和大地测量学估计滑动率之间的分歧。该奖项支持旨在更好地了解南部圣安德烈亚斯断层沿着滑动速率的工作，该地区在不同的时间间隔内报告了高度不一致的速率。 圣安德烈亚斯断层圣贝纳迪诺段的全新世或更新世晚期滑动速率（15至25毫米/年）比基于大地测量数据弹性建模的速率（通常小于或等于5毫米/年）大3至5倍。 这是目前已知的应变累积速率与全新世至更新世晚期应变释放速率之间最大的差异之一。 这种差异是否表明断层的这一部分不再像以前那样活跃？ 或者是整个地震周期中应变累积速率不一致的结果？ 沿着这段断层东北侧的圣贝纳迪诺山脉的大地测量数据很稀少。因此，在完全解决这些关于速率差异原因的问题之前，必须了解大地应变积累速率明显较低在多大程度上可能是该区域有限的大地测量数据造成的。这些信息对于评估与圣安德烈亚斯断层系统沿着断层运动相关的危险具有重要意义。为了解决这些问题，加州州立大学圣贝纳迪诺分校的研究人员和亚利桑那大学的同事正在收集该地区新的调查模式全球定位系统（GPS）数据，以提供对圣安德烈斯断层圣贝纳迪诺和圣戈尔戈尼奥山口部分目前弹性应变积累速率的精确估计。 Sally麦吉尔教授（加州州立大学，圣贝纳迪诺）带领一个由本科生和高中教师组成的团队（由他们的一些学生陪同）参加为期一周的年度活动，收集新的调查模式GPS数据。 从2009年到2011年的每个夏天，该团队从圣贝纳迪诺山脉及其附近的25个地点收集了4到5天的GPS数据。 这些数据由Sigrún Hreinsdottir和Rick班尼特（亚利桑那大学）处理和建模，沿着来自板块边界观测站（PBO）和南加州综合大地测量网络（SCIGN）多达25个附近台站的同期GPS数据。该项目支持不同层次的本科生、高中教师和高中生。 每年夏天，八名本科生和六名高中教师与他们的一些学生参加为期一周的数据收集活动。 麦吉尔与教师合作开发海报和教案，将他们的研究经验带回课堂。 每年，两名本科生使用GPS数据开发研究项目，并在整个夏天继续研究该项目，分析时间序列并对断层滑动率进行一维弹性和弹性粘弹性建模。 他们在专业会议上展示成果，并被鼓励进入地球科学研究生院。 特别努力从地球科学代表性不足的人群中招收这些学生，这是由于加州州立大学，圣贝纳迪诺是一所西班牙裔服务机构，其中52个地质专业中有36%来自代表性不足的群体。 外部顾问Robert deGroot正在评价这项建议的教育和外联部分。