HR: 1330h
AN: T52A-0231    [PDF]
TI: Collisional Deformation, In Situ Stress, and Topographic Relief in Central Japan
AU: * Townend, J
EM: john.townend@vuw.ac.nz
AF: Victoria University of Wellington, School of Earth Sciences P.O. Box 600, Wellington, 6015 New Zealand
AU: Zoback, M D
EM: zoback@pangea.stanford.edu
AF: Stanford University, Department of Geophysics, Stanford, CA 94305-2215 United States
AB: By amalgamating travel time and first motion data from three Japanese seismic networks, we have obtained a comprehensive focal mechanism catalog with which to investigate tectonic stress directions throughout most of Japan. The axis of maximum horizontal compressive stress agrees well with the axis of greatest contractional strain rate in central and southwest Japan once the effects of interseismic strain accumulation have been removed from geodetic observations according to an elastic dislocation model of subduction thrust locking. This residual deformation is presumed to be independent of deformation associated with strain accumulation and release in the subduction zone earthquake cycle, and to represent net geologic deformation of the upper plate. Moreover, it is broadly confined to the area of pronounced topography in central Japan, and is consistent in both spatial extent and principal strain rate directions with the deformation expected for horizontal motion of the Amurian plate with respect to northeastern Honshu. We conclude that the state of crustal stress in central Japan and the concentration of neotectonic deformation within the Japanese Alps are controlled by crustal collision and are relatively insensitive to earthquake processes on the main subduction zone thrusts beneath.
DE: 1208 Crustal movements--intraplate (8110)
DE: 7230 Seismicity and seismotectonics
DE: 8123 Dynamics, seismotectonics
DE: 8150 Plate boundary--general (3040)
DE: 8164 Stresses--crust and lithosphere
SC: Tectonophysics [T]
MN: 2003 Fall Meeting