Catalog of small repeating earthquakes for the Japanese Islands

Abstract

AbstractGroups of repeating earthquakes, which occur in approximately the same location and possess a similar focal mechanism, have been extracted in various tectonic environments worldwide. Their recurrence interval has been used to estimate the spatiotemporal evolution of aseismic slip along major tectonic boundaries. Furthermore, slight changes between the waveforms of repeating earthquakes have been analyzed to delineate temporal changes in the local seismic velocity structure. Here, we construct a long-term catalog of small repeating earthquakes in the central Japan since 1981 and throughout the Japanese Islands since 2001 (2001–2019) based on waveform similarity and relative source locations. Most of the long-duration sequences are located near the strongly coupled areas of the Philippine Sea and Pacific plates as they subduct from the Ryukyu–Nankai–Sagami and Kuril–Japan trenches, respectively. Many of the repeating sequences that occur in shallow crustal environments are short-lived. This repeating earthquake catalog allows us to estimate the slip history along each tectonic boundary. We believe that this and similar catalogs will be useful for future investigations of source processes, temporal slip and stress changes along faults, and local velocity structures, thereby providing new insights into earthquake generation mechanisms.