The resistivity structure around the hypocentral area of the Ebino earthquake swarm in Kyushu district, Japan

Wide band and dense MT soundings on the hypocentral area of the Ebino earthquake swarm, which occurred in 1968, in southern Kyushu were performed to examine the existence of fluid in the hypocentral area, which possibly caused the earthquake swarm. The regional strike and the induction arrow were calculated first. Then a two-dimensional resistivity structure beneath the surveyed area is calculated by using an inversion technique. The best fitted model shows that the hypocentral area is relatively more resistive than the surrounding area. We conclude that a large mass of fluid is not likely to exist in the hypocentral area.