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

该项目旨在评估对基础设施的破坏以及在破坏性地震后立即发生余震的可能性，例如去年袭击新西兰克赖斯特彻奇周围地区的两次破坏性地震。在这种情况下，两次地震在时间上的密切联系导致了我们在第二次地震之前从广泛的卫星平台上获得了比平时更多的地震前图像。我们建议使用图像的目视检查和绘图以及自动互相关(像素跟踪)相结合的方法来表征与每一次地震相关的同震和震后破坏和变形。我们还将模拟每一次地震的特征，以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演化应变，2)识别和绘制附近断层上任何触发滑动的观测结果，3)绘制液化、滑坡和探测班克斯半岛以及萨姆纳和利特尔顿周围的早期滑坡，以及4)生成这两次地震的滑动分布，这解释了断层几何形状的未知方面，并修正了先前对邻近断层引起的库仑应力变化的估计。这项建议中的工作将有助于推进基于图像的卫星大地测量领域，这一领域已被证明对国家科学基金会感兴趣的许多应用，包括地震科学、冰川学、地下水管理、滑坡预测和缓解，这一发生在时间和空间上接近(但不是直接)的两次地震的特殊序列对研究附近断层上地震之间的相互作用模式的研究人员非常感兴趣。目前利用卫星图像研究地震在几个方面受到限制？同震形变研究和震后形变研究依赖于少量的平台和传感器类型(例如SPOT图像、SAR、陆地卫星)，而其他通常更高分辨率的观测类型通常被吸收到地理信息系统软件包中，并通过视觉检查损坏的迹象(例如，建筑物倒塌、洪水、液化)。我们的研究可能会开放这些数据类型，用于约束形变的大小，这将加快救援人员的潜在反应时间，并有助于智能地部署仪器，这些仪器可以监测可能受到初始地震压力的邻近断层部分。

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.