Detection of short-term slow slip events along the Nankai Trough via groundwater observations

Abstract

In order to develop new tools or techniques to detect short-term slow slip events (S-SSEs) along subduction zones, we attempted to detect S-SSEs by conducting groundwater pressure observations. At ANO station, which is a groundwater observation station operated by the Geological Survey of Japan, the National Institute of Advanced Industrial Science and Technology, for earthquake prediction research, groundwater pressures changed due to six S-SSEs that occurred near ANO from June 2011 to April in 2013. The fault models of these S-SSEs, which were estimated mainly by observing the crustal strains and tilts, explained the changes in the groundwater pressures. If the strain sensitivity of the observed groundwater pressure or level is larger than 1 mm/nstrain and the noise level is smaller than 50 mm/day, it is possible to detect S-SSEs that occur in southwest Japan by conducting groundwater pressure or level observations. Key Points S-SSEs can be detected by conducting groundwater observations The conditions for detecting S-SSEs via groundwater observations are shown Our results will be useful for forecasting large earthquakes ©2013. American Geophysical Union. All Rights Reserved.