Japan Geoscience Union Meeting 2015

Presentation information

Oral

Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS31] Crustal Deformation

Mon. May 25, 2015 4:15 PM - 6:00 PM 304 (3F)

Convener:*Yusaku Ohta(Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University), Masayuki Murase(Department of Geosystem, College of Humanities and Sciences, NIHON University), Chair:Hisashi Suito(Geospatial Information Authority of Japan), Teruyuki Kato(Earthquake Prediction Research Center, Earthquake Research Institute, The University of Tokyo)

[SSS31-P09] Abnormal strain distribution in Hokkaido, Japan, inferred from the 2003 Tokachi-oki earthquake

3-min talk in an oral session

*Kentaro ISHIMORI1, Mako OHZONO2 (1.Department of Earth and Environmental Sciences Graduate School, Yamagata University, 2.Faculty of Science, Yamagata University)

To extract the abnormal strain distribution caused by heterogeneous subsurface structure in Hokkaido, Japan, we compared observed coseismic crustal deformation with theoretical crustal deformation of the 2003 Tokachi-oki earthquake (M8.0). Observed data is extracted by the difference of the daily coordinates, which is provided by GSI (F3 solutions), before and after the event. Theoretical data is calculated from dislocation model (Okada, 1992), which assumes deformation in uniform elastic half-space, using fault parameters provided by GSI. The observed coseismic displacement is explained by calculations well, except for several areas. Dilations are also roughly agreed with each other. However, several areas show deformation excess and deformation deficit with respect to theoretical model. Especially, in Hidaka region, which is high seismic velocity region (kita et al., 2012), corresponds to deformation excess area, and Kamuikotan region, which has thick sediment layer, corresponds to deformation deficit area. These results might imply the effect of the heterogeneous subsurface structure around the region.