| We conducted a detailed near-surface geophysical survey at Mashiki Town stricken by the 2016 Kumamoto Earthquakes. The survey comprised “Hybrid Surface Wave Survey” (HSWS), capacitively coupled resistivity (CCR) measurement, and GPR. A total of 5 short lines were set to intersect a branched surface rupture. Notable results were as follows. First, GPR successfully imaged a number of step-like dislocations in the surficial zones up to 3 m deep around the surface rupture. The resistivity structure showed relative upthrow of ESE side. HSWS delineated a kink structure of a low velocity lens at the surface rupture. Additional seismic reflection data processing was applied to HSWS records. As a result, a reverse faulting structure of about 100 meters wide was clearly imaged. |
