Continuous Observation of Crustal Movement by the Japan Meteorological Agency

Abstract

The Japan Meteorological Agency (JMA) has continuously observed crustal movement using primarily volumetric strainmeters and multi-component strainmeters of the borehole type. The main purpose of the observations is to detect any precursory slip of the anticipated Tokai earthquake. Strain observations in the Tokai region are expected to play an important role in providing information about the Tokai earthquake. Tidal strain, atmospheric pressure effects, precipitation effects, and geomagnetic effects are removed from the observed data in real time. The corrected strain is monitored 24 hours a day. Although strain change that had continued over several years due to a long-term slow slip event was not detected, strainchanges continuing for several days to several months due to volcanic activities as well as short-term slow slip events have been detected. The fact that strain changes due to short term slow slip events have been detected suggests that strain observation in the Tokai region has the ability to detect a precursory slip.