资源环境科技发展态势分析平台

Deep low-frequency earthquakes (DLFEs) are ubiquitous seismic activities in the deep parts of volcanoes. Owing to the low signal-to-noise ratio, the seismic activities of DLFEs have not been characterized in detail; particularly, the linkage between DLFEs and shallow volcanic activity has not been understood sufficiently. In this study, numerous DLFEs have been successfully detected beneath the Hakone volcano, central Japan, by cross-correlating a template to the continuous seismic signals. The resulting seismic catalog reveals that DLFEs are activated prior to notable earthquake swarms in the shallow part of a volcano and to the crustal expansion caused by a pressure source at a depth of 7 km. Results indicate that the activation of DLFEs reflects the feeding of magmatic fluid from depth. The subsequent increment in the magmatic-fluid pressure triggers shallow volcanic activities.