Appraisal of the detectivity of hypothetical preslip of the Tonankai and Nankai Great Earthquakes using the integrated groundwater observatories of the Geological Survey of Japan, AIST

Abstract

    The detectability of hypothetical "preslip" of the great Tonanaki and Nankai earthquakes is investigated using the integrated groundwater observatories currently being established by the Geological Survey of Japan, AIST. The detectability is calculated in terms of three characteristic parameters of the preslip, i.e., time constant (slip duration), spatial extent, and direction of the preslip. If it is assumed that the crustal deformation caused by the hypothetical preslip follows the elastic dislocation theory, and the noise level of the line strain observation of the network is 2×10^-8, it is expected to detect preslip with a moment magnitude of greater than 6.5 in the wide area of the network when the characteristic time constant (duration of preslip) and the spatial extent of preslip are about 1 day and 12 km×10 km, respectively. The detectability gets worse when either of the quantities is larger.