Analysis of the Shallow Slip Deficit Using Sub-Pixel Image Correlation: Implications for Fault Evolution, Slip Rates, and Seismic Hazards

使用子像素图像相关分析浅层滑移缺陷：对断层演化、滑移率和地震灾害的影响

• 批准号: 1147436
• 负责人: James Dolan
• 金额: $ 42.5万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1147436&HistoricalAwards=false
• 关键词: Analysis; Shallow; Slip; Deficit; Using

This research project is focused on understanding the distribution of fault slip near the Earth's surface during earthquakes through the use of a powerful new technology (COSI-corr sub-pixel image correlation), which facilitates tracking of the location and amount of surface deformation along and around faults in much more detail than was possible using previously available methods. Previous studies suggest that the slip that occurs along faults during earthquakes is larger at depth than near the surface, leading to what has been termed a surface slip deficit. Determining the cause(s) of this surface slip deficit provides the basic rationale for this research. Using the COSI-corr image correlation technique, scientists from the University of Southern California and Caltech will examine the distribution of slip near the surface along more than a dozen large-magnitude earthquakes that occurred during the past few decades. The results will facilitate the mapping of on-fault versus off-fault deformation patterns in earthquakes, allowing correlation of these observations with basic features of the fault zone, such as the amount of total slip a fault has accommodated in its lifetime, which may prove to be good predictors of the percentage of slip that will occur on faults during future earthquakes.The results of this research have basic implications for the understanding of the seismic hazards posed by major fault systems. Currently, forecasts of the probability of the future occurrence of earthquakes are based largely on the slip rate of the fault, that is, the rate at which the blocks on either side of the fault slide past each other over the course of many earthquakes. Such rates are mainly derived from the analysis of offset surface features, and usually do not include any deformation that might be distributed around the main fault trace. Thus, significant off-fault deformation may yield underestimates of the rate of movements on faults, and thus on seismic hazard. In addition, these data will allow the researcher to test models of possible preferred propagation direction of seismic ruptures, which will be of profound importance for determining in advance the regional distribution of strong ground motions. The anticipated results will also allow assessment of models for the likelihood that seismic ruptures will (or will not) propagate through structural complexities along the fault, an issue of basic importance for estimating in advance the sizes of future earthquakes. The results will thus provide the basis for the development of statistical measures of on-fault versus off-fault slip and rupture behavior that will be used in next-generation hazard assessment strategies to provide more accurate estimates of future seismic hazard.

该研究项目的重点是通过使用强大的新技术（COSI-CORR子像素图像相关性），了解地震期间地球表面附近的断层滑动的分布，这有助于跟踪沿着位置和表面变形的位置和数量使用先前可用的方法，围绕故障的详细信息要多得多。先前的研究表明，在地震期间沿着断层发生的破裂的深度比表面附近大，导致所谓的表面滑动不足。确定此表面滑动不足的原因为这项研究提供了基本的基本原理。使用COSI-CORR图像相关技术，来自南加州大学和加州理工大学的科学家将检查过去几十年来发生的十多个大型地震，沿着表面附近的滑动分布。结果将有助于地震中的on损坏与OFF故障变形模式的映射，从而使这些观察值与故障区域的基本特征相关联，例如，总滑动的量在其寿命中已容纳了，这可能证明是成为对未来地震期间断层上会发生的滑移百分比的良好预测指标。这项研究的结果对理解主要断层系统造成的地震危害具有基本意义。当前，对地震未来发生概率的预测主要基于断层的滑动速率，即断层两侧的块在许多地震过程中彼此滑行的速度。这样的速率主要来自对偏移表面特征的分析，通常不包含任何可能分布在主要故障迹线周围的变形。因此，明显的OFF型变形可能会低估断层运动速率，从而低估地震危险。此外，这些数据将使研究人员能够测试地震破裂的可能优选传播方向的模型，这对于事先确定强大地面运动的区域分布非常重要。预期的结果还将允许对模型进行评估，即地震破裂将（或不会）通过沿断层的结构复杂性传播，这是提前估算未来地震大小的基本重要性问题。因此，结果将为开发跨失调滑移与破裂行为的统计度量的制定提供基础，这些措施将用于下一代危害评估策略，以提供对未来地震危害的更准确估计。