Pixel-Tracking on High-Resolution Imagery Spanning the Darfield, New Zealand Earthquake

该项目旨在评估破坏性地震（如去年新西兰基督城附近地区发生的两次地震）对基础设施的破坏以及发生余震的可能性。在这种情况下，这两个事件的密切时间关联导致我们在第二次地震之前从广泛的卫星平台获得了比通常更多的地震前图像。我们建议使用视觉检查和图像映射以及自动相互关联（像素跟踪）的组合来表征与每次地震相关的同震和震后破坏和变形。我们还将模拟每次地震的特征，以便评估应力变化对邻近断层的影响。我们的主要目标是1)量化与达菲尔德和克赖斯特彻奇事件相关的不断演变的压力，2)识别和绘制附近断层上触发滑动的任何观测结果，3)绘制液化，滑坡和探测沿班克斯半岛以及萨姆纳和利特尔顿周围的早期滑坡，4)生成两次地震的滑动分布，以解释断层几何形状的未知方面，并修正先前对相邻断层引起的库仑应力变化的估计。本提案中的工作将有助于推进基于图像的卫星大地测量学领域，该领域有许多NSF感兴趣的演示应用，包括地震科学、冰川学、地下水管理、滑坡预测和减灾等。这两个地震在时间和空间上接近（但不是立即）发生的特殊序列引起了研究附近断层上地震相互作用模式的研究人员的极大兴趣。目前，利用卫星图像研究地震在几个方面受到限制。同震和震后变形研究依赖于少数平台和传感器类型（例如SPOT图像、SAR、LANDSAT），而其他通常更高分辨率的观测类型通常被纳入GIS软件包中，并通过视觉检查寻找破坏迹象（例如建筑物倒塌、洪水、液化）。我们的研究可能会将这些数据类型用于限制变形的大小，这将加快救援人员的潜在响应时间，并有助于智能部署可以监测可能受到初始地震压力的相邻断层部分的仪器。

This project is aimed at assessing damage to infrastructure and the potential for aftershocks immediately after destructive earthquakes such as the two that hit the region around Christchurch, New Zealand, during the past year. In this case, the close temporal association of the two events resulted in a case where we have more pre-seismic imagery from a wide range of satellite platforms before the second earthquake than is usual. We propose to use a combination of visual inspection and mapping of the images and automated cross-correlation (pixel-tracking) to characterize the coseismic and postseismic damage and deformation associated with each earthquake. We will also model the characteristics of each earthquake in order to assess the impact of stress changes on neighboring faults. Our primary goals are to 1) Quantify the evolving strain associated with the Darfield and Christchurch events, 2) Identify and map any observations of triggered slip on nearby faults, 3) Map liquefaction, landslides and detect incipient slumps along the Banks Peninsula and around Sumner and Lyttelton, and 4) Generate a slip distribution for both earthquakes that accounts for unknown aspects of the fault geometry and revise previous estimates of Coulomb stress change induced on neighboring faults.The work in this proposal will help advance the field of image-based satellite geodesy, which has many demonstrated applications of interest to NSF, including earthquake science, glaciology, groundwater management, landslide forecasting and mitigation, etc. This particular sequence of two earthquakes occurring in close (but not immediate) temporal and spatial proximity is of great interest to researchers studying the modes of interaction between earthquakes on nearby faults. The use of satellite imagery to study earthquakes at the present time is limited in several ways ? coseismic and postseismic deformation studies rely on a small number of platforms and sensor types (e.g. SPOT imagery, SAR, LANDSAT), while other, often more high-resolution observation types are typically ingested into GIS software packages and inspected visually for signs of damage (e.g., building collapse, flooding, liquefaction). Our study may open up these data types for use in constraining the magnitude of deformation as well, which would speed up the potential response time for relief workers, and aid in the intelligent deployment of instruments that can monitor adjacent sections of fault that may be stressed by the initial earthquake.