Relationship between waterfall distribution and seismic hazards in large earthquake-prone areas

Waterfalls represent the forefront of erosion in a watershed and describe the process of landform change. Although many geomorphological and geological studies have been conducted on the formation and development of knickpoints, their relationship with phenomena that cause large-scale landform changes, such as earthquakes, has not been clarified. Although the distribution and formation of waterfalls have previously reflected large-scale geomorphological phenomena, no studies have captured this information from the engineering perspective of disaster management. This study identified the factors that influence the distribution of waterfalls and highlighted their potential applications in disaster management. The relationship between the distribution of waterfalls, topographical features, and data on seismic hazards for the 1923 Kanto earthquake epicenter area, which recorded a magnitude of 7.3, are displayed. The distribution data of 3972 waterfalls, including 651 waterfalls with heights greater than 10 m, were consolidated and analyzed for topographical features and information related to earthquakes. A clear relationship was identified between the distance from the fault zone and the number of waterfalls. In contrast, areas where no faults were found were identified despite the concentration of waterfalls and epicenters. It is conceivable that undiscovered blind active faults potentially exist in these areas. The integration of geophysical investigations, including the analysis of seismic wave propagation characteristics, may provide an approach for detecting active faults based on surface geomorphic features.