The Strength of Strike-Slip Faults: Space-Geodetic Constraints for a Ridge-Transtensional System in the Gulf of California

走滑断层的强度：加利福尼亚湾海脊-张拉系统的空间大地测量约束

• 批准号: 1019847
• 负责人: Falk Amelung
• 金额: $ 11.57万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1019847&HistoricalAwards=false
• 关键词: Strength; Strike; Slip; Faults; Space

This project is a space-geodetic study of the Ballenas Transform Fault in the Gulf of California, which is part of the North America-Pacific plate boundary. The research team will acquire campaign GPS and interferometric synthetic aperture radar data and use finite element modeling methods to study the accumulation and release of tectonic strain to test for crustal strength variations along the fault. Strength variations are expected because the heat flow varies with distance from two incipient mid-ocean ridge basins in the north and south, and because of significant variations in crustal structure on both sides of the fault (undeformed Baja California versus the Gulf of California extensional province). The fault, situated in a oceanic channel, affords a special opportunity to study strength variation for because: 1) the transform fault has a very high slip rate of approximately 46 mm/yr; 2) the fault accommodates the entire North America-Pacific plate relative motion without any other strike-slip faults in its vicinity and therefore no overlapping strain patterns; 3) the August 2009 magnitude 6.9 earthquake and its regular earthquake repeat time (every 55 years) allows for a clear definition of the state of the fault within the earthquake cycle which is very important for models of the strain accumulation.This study has important implications for seismic hazard estimates for all major transform faults such as the San Andreas Fault system in California further to the north. Seismic hazard estimates are commonly based on models that ignore strength variations. This study will provide new data on how crustal strength variations affect strain accumulation.

该项目是对加利福尼亚湾的Ballenas变换断层的太空地理研究，该湾是北美太平洋板块边界的一部分。研究团队将获取运动GPS和干涉合成孔径雷达数据，并使用有限的元素建模方法研究构造菌株的积累和释放，以测试沿断层的地壳强度变化。预期强度变化是因为热流随远离两个初期的北部和南部的中洋山脊盆地的距离而变化，并且由于断层两侧的地壳结构的显着变化（未经构造的Baja California与加利福尼亚扩展省的海湾）。该断层位于海洋通道中，为研究强度变化提供了一个特殊的机会，因为：1）变换断层的滑移速率非常高约46 mm/yr； 2）故障可容纳整个北美太平洋板块相对运动，其附近没有任何其他走滑断层，因此没有重叠的应变模式； 3）2009年8月的6.9地震及其常规地震重复时间（每55年一次）允许对地震周期内断层状态进行明确的定义，这对于菌株积累的模型非常重要。这项研究对所有主要变换断层（如加利福尼亚州的San Andreas断层系统）具有重要意义。地震危害估计通常基于忽略强度变化的模型。这项研究将提供有关地壳强度变化如何影响应变积累的新数据。