Undulations in Subducted Oceanic Crust Correlate With Shallow Tremor Distribution in the Kuril Trench Off Hokkaido

Abstract

Recent research has shown that shallow tremors tend to occur in spatial association with heterogeneous conditions, which are formed by seamounts or ridges on the subducted oceanic crust. In the southern Kuril Trench, shallow tremors have been observed on the western side, although no apparent heterogeneity in the subducted oceanic crust has been identified. To investigate structures spatially associated with these shallow tremors, we processed reflection seismic data acquired along seven profiles. We examined structures ranging from the seafloor to the top of the oceanic crust, within a depth of up to 20 km. Our results reveal that undulations observed at the top of the subducted oceanic crust are related to the distribution and number of shallow tremors. The undulations would play a crucial role in the distribution of shallow tremors.