The Response of Repetitive Very‐Long‐Period Seismic Signals at Aso Volcano to Periodic Loading

Abstract Triggering of volcano seismic activity and eruptions by tides, atmosphere pressure, rainfall, earthquakes have been in constant debate. However, there is limited evidence concerning the triggering very‐long‐period signals (VLPs), which are closely linked to conduit dynamics. Persistent repetitive VLP event beneath Aso volcano, historically termed long‐period tremor (LPT), manifests episodic pressurization depressurization events a crack‐like shallow conduit. Here we show that LPT display no appreciable spectral peaks associated with major diurnal/semidiurnal tidal constituents or barometric pressure. Instead, passing surface waves ∼0.01 m/s from 2011 Tohoku earthquake elevated preferentially increased likelihood events. We suggest hydrothermal reservoir near source behaves like confined (unconfined) aquifer against short‐period (long‐period) stress. A high stress rate ∼10 2 Pa/s sufficient enhance permeability plug/wall promotes