Co‐Occurrence of Low and Very Low Frequency Earthquakes Explained From Dynamic Modeling

Very low‐frequency earthquakes (VLFs) are characterized by longer source duration and smaller stress drop than regular earthquakes of similar magnitude. Recent studies have shown their frequent correlation with low‐frequency earthquakes (LFEs) on shared faults. The underlying source processes governing the occurrence of VLFs and their interaction with LFEs remain elusive. Here, we employ a slip‐weakening model for slow earthquakes. By comparing the source parameters of simulations and observations, it is suggested that VLFs are slow self‐arresting earthquakes that self‐terminate within the nucleation patch. Additionally, we adopt a composite model to reproduce the records of the simultaneous occurrences of a VLF and an LFE in the Nankai area. Our results present the possibility that VLFs, LFEs, and regular earthquakes can be distinguished using a unified dynamic framework.