| This paper describes the results of a shear wave seismic reflection survey of the southern part of the epicentral area of the Northern Miyagi earthquake (Mj 6.4), which struck on July 26, 2003. The epicenters were on northern Miyagi Prefecture, about 350 kilometers north of Tokyo in Japan, and located about ten kilometers underground. After the earthquake shocks, we conducted a shear-wave seismic reflection survey using a shear-wave vibrator to locate and delineate the geological structure in the subsurface adjacent to the epicenters. We set a 4.2-km long survey line along the coast of Ishinomaki Bay. The seismic section after migration based on CMP reflection processing delineated the fold of the Neogene strata in the subsurface between Asahiyama Hill and Ishinomaki Bay. The geological interpretation shows that the Asahiyama Flexure is identified with the fold and extends into Ishinomaki Bay. The Asahiyama Flexure is more active than that estimated from the paleo-seismology. |
