Estimating Frictional Properties of Faults from Geodetic Data

根据大地测量数据估计断层的摩擦特性

• 批准号: 0911467
• 负责人: Kaj Johnson
• 金额: $ 12.1万
• 依托单位: Indiana University
• 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: 2009-07-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911467&HistoricalAwards=false
• 关键词: Estimating; Frictional; Properties; Faults; Geodetic

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)Large faults that generate earthquakes exhibit a wide range of slip behaviors including stick-slip motion resulting in episodic earthquakes, stable and steady sliding without fast earthquake slip, and oscillatory or non-steady slip sliding without earthquakes. This range in slip behaviors can be understood and modeled through the application of friction laws derived from laboratory sliding experiments with natural or synthetic rock samples. The friction parameters obtained from these experiments are implemented in numerical models of faults imbedded in the earth in order to predict the slip behavior of faults. Small changes in the friction parameters implemented in these models can lead to dramatically different sliding behaviors. For example, small changes in parameters can change from stick-slip, earthquake producing slip behavior to steady, stable sliding behavior without earthquakes. Knowledge of the distribution of these parameters on faults is therefore essential for earthquake hazard assessment. The object of this work is to use measurements of motions of the Earth?s surface near faults to infer friction parameters on faults. Measurements from the Hayward fault in the eastern San Francisco Bay Area and from the San Andreas fault near San Juan Bautista will be compared with numerical models of fault slip. Data from these locations recorded transient slip episodes on the faults triggered by distant earthquakes. Also, various existing methodologies for modeling fault creep will be systematically examined to assess the influence of simplifying assumptions on model inferences and therefore provider a clearer understanding of how well the frictional properties of faults can be resolved using such approaches.Models incorporating rate-state friction have been remarkably successful in explaining a wide range of observations reflecting the nature of fault slip including afterslip, decay rates of aftershocks, episodic slip at subduction zones, spontaneous silent earthquakes, as well as general features of the earthquake cycle. Numerical studies invoking rate-state friction employ laboratory-derived friction parameters which are often assumed, for simplicity, to vary only with depth. It remains unclear to what extent the laboratory friction values are relevant to real faults.

该奖项是根据 2009 年美国复苏和再投资法案（公法 111-5）资助的，产生地震的大断层表现出多种滑动行为，包括导致阵发性地震的粘滑运动、稳定且稳定的滑动而没有快速地震滑动，以及没有地震的振荡或非稳定滑动。这种滑动行为的范围可以通过应用从天然或合成岩石样品的实验室滑动实验中得出的摩擦定律来理解和建模。从这些实验中获得的摩擦参数应用于埋藏在地球中的断层的数值模型中，以预测断层的滑动行为。这些模型中实现的摩擦参数的微小变化可能会导致滑动行为显着不同。例如，参数的微小变化可以从粘滑、地震产生的滑动行为转变为稳定、稳定的无地震滑动行为。因此，了解这些参数在断层上的分布对于地震灾害评估至关重要。这项工作的目的是利用断层附近地球表面运动的测量来推断断层上的摩擦参数。 旧金山湾区东部的海沃德断层和圣胡安包蒂斯塔附近的圣安德烈亚斯断层的测量结果将与断层滑动的数值模型进行比较。来自这些地点的数据记录了由遥远地震引发的断层上的瞬态滑动事件。此外，还将系统地检查各种现有的断层蠕变建模方法，以评估简化假设对模型推论的影响，从而更清楚地了解使用此类方法可以如何很好地解决断层的摩擦特性。包含速率状态摩擦的模型已经非常成功地解释了反映断层滑动性质的广泛观测结果，包括后滑、余震的衰减率、俯冲带的偶发性滑动、自发的无声地震以及地震周期的一般特征。涉及速率状态摩擦的数值研究采用实验室导出的摩擦参数，为简单起见，通常假设这些参数仅随深度变化。目前尚不清楚实验室摩擦值与实际故障的相关程度如何。