Changes of Event Size Distribution During Episodes of Shallow Tectonic Tremor, Nankai Trough

Abstract Slow earthquakes follow a power‐law size distribution with an exponential taper for the largest events. We investigated changes in of shallow tectonic tremor events during two prolonged episodes (>1 month) along Nankai trough and found that slope distributions increased while cut‐off magnitudes decreased late each episode, as activity waned. Interpreting these two‐dimensional probabilistic cell automaton model slow earthquakes, we decrease event ignition probability or increase energy dissipation slip can qualitatively explain observed changes. These imply accumulated stress pore‐fluid pressure on fault interface occurred episode. Because source migrates parameters be attributed to spatial variations temporal characteristics.