The 18 March 2020 Mw 5.7 Magna, Utah, earthquake was the largest earthquake in Utah since the 1992 ML 5.8 St. George earthquake. The geologic setting of the Magna earthquake is well documented by recent geologic mapping at 1:24,000 scale and 1:62,500 scale at and near the epicenter northeast of Magna, Utah. Subsurface fault modeling from surficial geologic mapping, structural cross sections, deep borehole data, and geophysical data reveals a complex system of faulting concentrated in the hanging wall of the Weber and Salt Lake City segments of the Wasatch fault zone including the Harkers fault, the West Valley fault zone, and the newly interpreted Saltair graben. Based on geologic and geophysical data (seismic and gravity), we interpret the mainshock of the Magna earthquake as having occurred on a relatively gently dipping part of the Salt Lake City segment, with aftershocks concentrated in the Saltair graben and West Valley fault zone. Postearthquake rapid reconnaissance of geological effects of the Magna earthquake documented liquefaction near the earthquake epicenter, along the Jordan River, and along the Great Salt Lake shoreline. Subaerial and subaqueous sand boils were identified in regions with roadway infrastructure and artificial fill, whereas collapse features were noted along the shores of the Great Salt Lake. Potential syneresis cracking and pooling in large areas indicated fluctuating groundwater likely related to earthquake ground shaking. The moderate magnitude of the Magna earthquake and minimal geological effects highlight the critical importance of earthquake research from multidisciplinary fields in the geosciences and preparedness on the Wasatch Front.

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2020年3月18日Mw 5.7麦格纳（犹他州）地震的地质背景，地面影响和拟议的结构模型

2020年3月18日，犹他州麦格纳5.7级地震是自1992年ML 5.8圣乔治地震以来犹他州最大的地震。麦格纳地震的地质环境在最近的地震地图上得到了很好的证明，在犹他州麦格纳东北震中及附近，比例为1：24,000和1：62,500。根据表面地质图，结构断面，深孔数据和地球物理数据进行的地下断层建模揭示了一个复杂的断层系统，集中在沃萨奇断层带的韦伯和盐湖城部分的悬挂壁上，包括哈克斯断层，西部山谷断层带和新解释的Saltair地带。根据地质和地球物理数据（地震和重力），我们将麦格纳地震的主震解释为发生在盐湖城部分相对缓和的部分，余震集中在Saltair en陷和West Valley断层带。震后对麦格纳地震地质影响的快速勘测表明，地震震中附近，约旦河沿岸以及大盐湖海岸线沿线发生了液化。在具有道路基础设施和人工填充物的区域中发现了地下​​和水下沙沸腾，而在大盐湖沿岸则发现了塌陷特征。大面积潜在的脱水收缩和合并表明地下水的波动可能与地震地面震动有关。