Syntheses of the regional stress fields of the Japanese islands |
| |
| Authors: | Tetsuzo Seno |
| |
| Institution: | Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan |
| |
| Abstract: | The principal stresses in northern Honshu and in central-southwest Japan are synthesized on the basis of the ridge push, slab pull and across-arc variation of differential forces due to crust/plate structural variation. Assuming a more compressive north–south horizontal stress in central Japan-northern Honshu than that of southwest Japan, the calculated principal stress profiles explain the observed stress fields in these areas: namely, a strike–slip fault type for southwest-central Japan and a reverse fault type for northern Honshu, both having east–west σHmax. Kyushu is characterized by the gradient of horizontal stresses both in the east–west and north–south directions, which cannot be explained by simple plate interactions or by crust/plate structural variation. Combined with other lines of evidence for existence of mantle upwelling in the East China Sea west of Kyushu, it is proposed that the stress gradient is produced by the viscous drag exerted by the flow spread laterally from the upwelling plume. The eastward movement of Kyushu and southwest Japan relative to Eurasia revealed by the recent Global Positioning System measurements conducted by the Geographical Survey Institute of Japan would be partly explained by this basal drag. |
| |
| Keywords: | central Japan Kyushu northern Honshu ridge push slab pull southwest Japan stress fields upwelling plume viscous drag |
|
|
