RAPID: Sparta Earthquake Surface Deformation Characterization

该项目将结合地球科学方法来描述与2020年8月9日北卡罗来纳州斯巴达镇发生的5.1级地震相关的地貌变化。这些方法将包括飞越该地区，进行高分辨率激光成像探测和测距系统(LiDAR)，以获得高垂直精度的震后景观调查。地表地质和地球物理观测将与激光雷达相结合，从而能够精确定位和测量地震在地表或附近造成的影响。从该项目获得的信息将对地震风险分析至关重要，并可用于减少未来地震中建筑基础设施和生命线的故障和生命损失。将开展与当地社区的外联活动，以扩大对地球科学，特别是地震的了解。首席调查员和联合调查员将与美国地质调查局和北卡罗来纳州地质调查局合作，将这项研究的结果与他们的努力结合起来。该项目由一名女性早期职业科学家领导，不同的研究生(女性、拉丁裔和非洲加勒比人)将从该项目的工作中获得广泛的知识和经验。2020年8月8日在北卡罗来纳州斯巴达附近发生的5.1兆瓦地震在斯巴达镇(强度为VI级)以及美国东南部、中西部和东北部地区有强烈震感，远至威尔明顿(北卡罗来纳州)、亚特兰大(佐治亚州)、辛辛那提(俄亥俄州)和华盛顿特区都有MMI-II级地震。这场不同寻常的中等地震造成了地表的位移(破裂)，这是欧洲占领后，美国东部第一次发现地表破裂。此外，5级地震破裂地表的情况极为罕见。8月9日和随后几周进行了记录其特征的工作。初步观察表明，地表形变可能与地下预先存在的不连续面重新激活有关，而这些不连续面的构造活动尚不清楚。地表断层表现为沿走向可追踪约2.2公里的狭窄形变带。沿着地表破裂的长度，变形通过反向位移和/或褶皱/弯曲来调节，产生最大垂直位移约20厘米，平均8-10厘米的陡峭。该项目将完成表面破裂的整个长度的表征。该项目将获取高分辨率激光雷达数据，并将继续正在进行的获取地面激光雷达扫描测量数据、高分辨率航空图像和地下地球物理测量数据的工作。将收集更多的地质和地貌观测，即通过地质挖掘，以可能记录古地震活动的地区为目标。这种数据的相互关联将有助于回答有关斯巴达地震动力学的基本问题。该项目将对了解与美国东部中等地震活动有关的地震风险做出重大贡献，很可能对类似的板内环境也是如此。这项研究将提供机会，了解地表的变形是如何调节的，地表破裂是如何发生的，以及地表附近的哪些预先存在的构造能够传播地震活动。为此，将包括地下调查在内的遥感数据和实地观测相结合将是至关重要的。世界其他地区已经开展了几项与地质变形、地下结构、古地震学、地震学和遥感相关的地震活动研究，但不是针对MW5.1，因此这有助于使这项研究独一无二。该奖项反映了≥的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project will combine geoscience methods to characterize the movement of the landscape associated with the magnitude 5.1 earthquake that shook the town of Sparta in North Carolina on August 9, 2020. These methods will include flying across the area undertaking a high-resolution laser imaging detection and ranging system (LiDAR) to obtain a post-earthquake landscape survey with high vertical accuracy. Surface geology and geophysical observations will be integrated with LiDAR, allowing the precise location and measurement of effects caused at or near the surface by the earthquake. The information gained from this project will be crucial for earthquake hazard analysis and may be applied to reduce failure of building infrastructure and lifelines and loss of life in future earthquakes. Outreach activities with the local communities will be undertaken to broaden understanding of geoscience and specifically earthquakes. The Principal investigators and co-investigators will collaborate with the U.S. Geological Survey and the North Carolina Geological Survey to integrate the results of this study with their efforts. The project is led by a female early career scientist, and diverse graduate students (female, Latinx and African-Caribbean) will gain broad knowledge and experience from working on this project. The Mw 5.1 08/09/2020 earthquake, near Sparta, North Carolina was strongly felt in the town of Sparta (Intensity VI) and across the Southeastern, Midwest, and Northeastern USA, with MMI–II recorded as far away as Wilmington (NC), Atlanta (GA), Cincinnati (OH) and Washington DC. This uncommon moderate earthquake caused a displacement (rupture) of the ground surface, being the first time that a surface rupture was recognized in the eastern USA, after European occupation. Moreover, it is extremely rare for M5 earthquakes to rupture the surface. Efforts to document its characteristics were undertaken on August 9 and the weeks following. Preliminary observations suggest that the surface deformation may be associated to re-activation of sub-surface pre-existent discontinuities, whose tectonic activity is poorly understood. The surface fault is expressed by a narrow zone of deformation, traceable for approximately 2.2 kilometers along strike. Along the length of the surface rupture, the deformation is accommodated by reverse displacement and/or folding/flexure generating a scarp with a maximum vertical displacement of approximately 20 centimeters and average of 8–10 centimeters. This project will complete the characterization of the surface rupture on its entire length. The propject will acquire a high-resolution LiDAR data, and will continue the ongoing acquisition of terrestrial LiDAR scan survey data, high resolution aerial imagery, and subsurface geophysical survey data. Additional geologic and geomorphic observations will be collected, namely through geological excavations that will target areas with potential record for paleoseismicity. This cross-correlation of data will help answer fundamental questions on the Sparta earthquake dynamics. This project will make a strong contribution to the knowledge about seismic risk associated to moderate seismicity in the Eastern United States and very likely for similar intraplate settings. This research will provide the opportunity of understanding how deformation in the surface was accommodated, how the surface rupture occurred and what pre-existing structures near the surface are capable to propagate seismicity. For that, the combination of remote data and field observations which will include sub-surface surveys will be essential. Several studies of seismicity Mw≥6.0 correlating geological deformation, sub-surface structures, paleoseismology, seismology and remote sensing have been undertaken in other regions of the world; however not for a Mw 5.1 and as such this helps make this study unique.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.