资源环境科技发展态势分析平台

Earthquakes are known to precede volcanic activity, including long-period or very long period (VLP) volcanic seismicity. However, the relationships among earthquakes, VLP seismicity, and volcanic eruptions are not well understood. Here we present the locations of VLP seismicity at Aso volcano, Japan, between January 2015 and December 2016, a period that includes the M-w 7.0 Kumamoto earthquake and phreatomagmatic eruptions. By using a differential-time backprojection method developed in this study to accurately locate VLP events, we clearly identified two distinct VLP clusters. Whereas the eastern cluster was active during eruptions, the western cluster displayed intense VLP seismicity only for a few months after the earthquake. The western cluster may be associated with opening of new fractures during the earthquake. This study explores the mechanisms that can relate earthquake to volcanic activities and provides a new approach to analyze the dynamic behaviors inside volcanoes that may yield useful information for hazard evaluation.

Plain Language summary The relationship between earthquake and volcanic seismicity is studied by analyzing continuous seismic data recorded between January 2015 and December 2016, a period that includes the M-w 7.0 Kumamoto earthquake and volcanic eruptions at Aso. This study focuses on analyzing very long period (VLP) seismic event with a period of 15 s that can be explained by pressure fluctuation within hydrothermal systems. The intense activity of long-period event could be an indication of impending eruptions. By using our developed localization method, we revealed two clusters of VLP sources, namely, eastern and western clusters. The eastern cluster was always active during an active period of Aso volcano. However, the western cluster showed intense VLP seismicity only for a few months after the earthquake. The western cluster could be associated with opening of new cracks triggered by the Kumamoto earthquake. This study suggests a strong relationship between distant large earthquake with volcanic seismicity that could be useful for disaster mitigation. Moreover, monitoring of temporal and spatial evolution of VLP sources may be considered as a tool to study the response of volcanic activity to ground shaking from large earthquake.