Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Zhao, D. Articles by Hasegawa, A. Search for Related Content GeoRef GeoRef Citation

Tomographic Imaging outside a Seismic Network: Application to the Northeast Japan Arc

¹ College of Information and Engineering
Chengdu University of Technology
Chengdu 610059, China
 (Z.W.)
² Research Center for Prediction of Earthquakes and Volcanic Eruptions
Graduate School of Science
Tohoku University
Sendai 980-8578, Japan
 (D.Z., N.U., A.H.)

The conventional local tomography can determine the 3D seismic velocity structure right beneath a seismic network, but it cannot determine the 3D structure outside a seismic network. In this study we show that such a limitation of tomography can be overcome if many earthquakes occur outside a seismic network. In the northeast Japan arc earthquakes occur actively from the Japan Trench to the Pacific coast. We detected and used sP-depth phase to relocate the suboceanic earthquakes accurately, and then used P- and S-wave arrival times from the relocated suboceanic events and the earthquakes under the northeast Japan land area to determine the 3D P- and S-wave velocity and Poisson’s ratio structures of the entire northeast Japan arc from the Japan Trench to the Japan Sea coast. Our results exhibit strong lateral heterogeneities under the forearc region. The mainshock hypocenters of large interplate earthquakes (M 7.0–8.2) mainly cluster near the boundaries of high and low velocity and Poisson’s ratio above the subducting Pacific slab. A few large earthquakes are located in areas with high velocity and low Poisson’s ratio. These results suggest that lateral heterogeneities on the slab boundary can affect the rupture nucleation of large thrust earthquakes and the degree of interplate seismic coupling.