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日撼动北卡罗来纳州斯巴达镇的5.1级地震相关的景观运动特征。这些方法将包括飞越该地区，利用高分辨率激光成像探测和测距系统（LiDAR）获得高垂直精度的震后景观调查。地面地质和地球物理观测将与激光雷达相结合，允许精确定位和测量地震在地表或地表附近造成的影响。从该项目中获得的信息对地震危害分析至关重要，并可用于减少未来地震中建筑物基础设施和生命线的损坏和生命损失。将与当地社区开展外展活动，以扩大对地球科学，特别是地震的了解。主要研究人员和共同研究人员将与美国地质调查局和北卡罗来纳地质调查局合作，将这项研究的结果与他们的努力相结合。该项目由一名女性早期职业科学家领导，不同类型的研究生（女性、拉丁裔和非洲-加勒比裔）将从该项目中获得广泛的知识和经验。2020年8月9日，北卡罗来纳州斯巴达附近发生了5.1级地震，在斯巴达镇（强度VI）以及美国东南部，中西部和东北部都有强烈的震感，MMI-II记录远至威尔明顿（NC），亚特兰大（GA），辛辛那提（OH）和华盛顿特区。这次不寻常的中等地震引起了地表的位移（破裂），这是欧洲占领后美国东部首次发现地表破裂。此外，5级地震使地表破裂的情况极为罕见。8月9日及其后几周进行了记录其特征的工作。初步观测表明，地表变形可能与地下先前存在的不连续性的重新激活有关，而这些不连续性的构造活动尚不清楚。地表断层表现为一个狭窄的变形带，沿走向可追溯约2.2公里。沿着地表破裂的长度，变形通过反向位移和/或折叠/弯曲来调节，形成最大垂直位移约为20厘米，平均为8-10厘米的陡崖。该项目将完成地表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，并将继续获取地面激光雷达扫描调查数据、高分辨率航空图像和地下地球物理调查数据。额外的地质和地貌观测将被收集，即通过地质挖掘，将目标区域与潜在的古地震活动记录。这种相互关联的数据将有助于回答有关斯巴达地震动力学的基本问题。该项目将对美国东部中等地震活动相关的地震风险知识做出重大贡献，并且很可能在类似的板内环境中。这项研究将为了解地表的变形是如何被调节的，地表破裂是如何发生的，以及地表附近的哪些预先存在的结构能够传播地震活动提供机会。为此，将远程数据和包括地下调查在内的实地观测相结合将是必不可少的。世界其他地区开展了若干Mw≥6.0级地震活动性研究，涉及地质变形、地下构造、古地震、地震学和遥感；然而，不是为m5.1，正因为如此，这有助于使这项研究独特。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.