Permalink : http://hdl.handle.net/2115/44463

JaLCDOI : 10.14943/gbhu.73.117

Since 2005, The Headquarters for Earthquake Research Promotion（HERP）has been publishing National Seismic Hazard Maps for Japan to provide useful information for disaster prevention countermeasures for the country and local public agencies, as well as promote public awareness of disaster prevention of earthquakes. In the course of making the year 2009 version of the map, which is the commemorate of the tenth anniversary of the settlement of the Comprehensive Basic Policy, the methods to evaluate magnitude of earthquakes, to predict strong ground motion, and to construct underground structure were investigated in the Earthquake Research Committee and its subcommittees. Within approximately 100 active fault zones that were evaluated by HERP, there are 6 megafault systems that extend more than 80 km, which are longer than the fault length in the database used to evaluate the scaling relations by Matsuda（1975）. In order to predict the magnitude of earthquakes occurring on mega-fault systems, we examined the scaling relations for mega-fault systems using nine earthquakes of which source processes were analyzed by waveform inversion. As a result, we found that the data fit in between the scaling relations of seismic moment and rupture area by Somerville et al.（1999）and Irikura and Miyake（2001）. We also found maximum displacement of surface rupture is two to three times larger than the average slip on the seismic fault. Using this relation, the seismic moment on mega-fault systems can be adjusted.