干旱区生态环境知识资源中心

Shallow moonquakes are thought to be of tectonic origin. However, the geologic structures responsible for these moonquakes are unknown. Here we report sites where moonquakes possibly occurred along young lobate scarps in the Schrodinger basin. Our analysis of Lunar Reconnaissance Orbiter and Chandrayaan-1 images revealed four lobate scarps in different parts of the Schrodinger basin. The scarps crosscut small fresh impact craters (<10-30m) suggesting a young age for the scarps. A 28km long scarp (Scarp 1) yields a minimum age of 11Ma based on buffered crater counting, while others are 35-82Ma old. The topography of Scarp 1 suggests a range of horizontal shortening (10-30m) across the fault. Two scarps are associated with boulder falls in which several boulders rolled and bounced on nearby slopes. A cluster of a large number of boulder falls near Scarp 1 indicates that the scarp was seismically active recently. A low runout efficiency of the boulders (2.5) indicates low to moderate levels of ground shaking, which we interpret to be related to low-magnitude moonquakes in the scarp. Boulder falls are also observed in other parts of the basin, where we mapped >1500 boulders associated with trails and bouncing marks. Their origins are largely controlled by recent impact events. Ejecta rays and secondary crater chains from a 14km diameter impact crater traversed Schrodinger and triggered significant boulder falls about 17Ma. Therefore, a combination of recent shallow moonquakes and impact events triggered the boulder falls in the Schrodinger basin.