The New Madrid seismic zone has been the source of multiple major (M ~7.0–7.5) earthquakes in the past 2 ka, yet the surface expression of recent deformation remains ambiguous. Crowleys Ridge, a linear ridge trending north‐south for 300+ km through the Mississippi Embayment, has been interpreted as either a fault‐bounded uplift or a nontectonic erosional remnant. New and previously published seismic reflection and shallow resistivity data show discontinuities at the ridge margins in Plio‐Pleistocene strata, yet the timing of most recent faulting and the lateral extent of these faults remain unknown. To assess Pleistocene‐to‐recent tectonic activity of Crowleys Ridge, we perform landscape‐scale geomorphic analyses, such as relief, slope, hypsometry, and drainage basin shape, on a 10‐m digital elevation model (DEM). North‐to‐south variations in geomorphic indices indicate Pleistocene‐to‐recent tectonic uplift of the southern ridge. Moreover, mapping on a <1‐m lidar‐derived DEM reveals scarps on late Pleistocene geomorphic surfaces. The scarps are primarily located along the southern ridge, trend parallel to the ridge margin discontinuously for 0.1–1 km, and vertically offset <56 ka surfaces 0.4 m with up to 6 m of tilting. These landscape‐scale patterns and scarps, integrated with discontinuities in the seismic reflection and resistivity data, provide evidence of low‐rate (<0.2 mm/year) late Quaternary tectonic activity along the southern segment of Crowleys Ridge. The interpretations agree with recent tectonic models suggesting southern Crowleys Ridge is a compressional step over in a right‐lateral fault system within the Reelfoot Rift.

中文翻译：

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新马德里地震带克劳利山脊晚第四纪变形的证据

在过去的2 ka里，新马德里地震带曾是多次大地震（M〜7.0-7.5）的发源地，但是最近变形的表面表现仍然是模棱两可的。Crowleys山脊是一条贯穿密西西比河向北延伸300+ km的线性山脊，已被解释为断层抬升或非构造性侵蚀残余。新的和先前发布的地震反射和浅层电阻率数据显示，上新世地层的脊缘处存在不连续性，但是最近断裂的时间和这些断裂的横向范围仍然未知。为了评估Crowleys Ridge的更新世至最近的构造活动，我们在10米的数字高程模型（DEM）上进行了景观尺度的地貌分析，例如地貌，坡度，水势测定和流域盆地形状。地貌指数从北到南的变化表明南部山脊更新世至最近的构造隆升。此外，在<1 m的由激光雷达得出的DEM上进行映射，可以发现晚更新世地貌表面上的赤道。陡坡主要分布在南部山脊上，在不连续的情况下平行于山脊边缘延伸0.1-1 km，垂直偏移<56 ka表面0.4 m，最大倾斜6 m。这些景观尺度的格局和陡坡，加上地震反射和电阻率数据的不连续性，为克劳利山脊南部的低第四纪晚期构造活动提供了低速率（<0.2毫米/年）的证据。这些解释与最近的构造模型相吻合，表明南部克劳利山脊是Reelfoot裂谷内右断层系统的一次压缩性跨越。