HR: 1340h
AN: G43B-1200    [Abstracts]
TI: Vertical land displacements in Hokkaido, northern Japan
AU: * Thomson, K H
EM: k.h.thomson@durham.ac.uk
AF: Department of Geography, Durham University, Science Laboratories South Road, Durham, DH1 3LE, United Kingdom
AU: Long, A J
EM: a.j.long@durham.ac.uk
AF: Department of Geography, Durham University, Science Laboratories South Road, Durham, DH1 3LE, United Kingdom
AU: Horton, B P
EM: bphorton@sas.upenn.edu
AF: Department of Earth and Environmental Science University of Pennsylvania, 240 South 33rd Street, Philadelphia, PA 19104-6316, United States
AU: Sawai, Y
EM: yuki.sawai@aist.go.jp
AF: Active Fault Research Center, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology Site 7,1-1-1 Higashi, Tsukuba, Ibaraki, 305-8567, Japan
AB: Pleistocene marine terraces along the north-eastern coast of Hokkaido island (Japan) are deformed as a result of the subduction of the Pacific Plate along the Kuril Trench. The morphology of Hokkaido, with terraces and coastal environments that extend orthogonal to the trench, provides a unique opportunity to test models of land movement over a variety of temporal scales. Current models suggest that the spatial pattern and rate of long- term deformation is constant over the last few interglacial cycles, and fossil shorelines from Hokkaido indicate that the region has experienced long-term uplift at a maximum rate of 76-90 cm/kyr around the Shiretoko Peninsula, 200 km from the Kuril Trench. In contrast, present-day land movements record subsidence along the eastern coast of Hokkaido, at a maximum rate of ca. 8 mm/yr (120 km from the trench). In this paper we compare vertical rates of deformation derived from different data sources over a range of time scales. We use continuous Global Positioning System observations and tide gauge measurements to reconstruct current and recent interseismic deformation around Hokkaido. Century-scale deformation over the last earthquake cycle (from c. AD 1650 to present) is evaluated with microfossil-based reconstructions of former sea-levels, whilst Holocene crustal movements are assessed by comparing calibrated sea-level index points with geophysical model predictions of relative sea-level. We apply forward elastic dislocation modelling using our estimates of crustal deformation on Hokkaido to investigate the characteristics of the Kuril subduction zone. Our work demonstrates the value of different types of palaeoseismic data for reconstructing spatial and temporal variations in the behaviour of the Kuril subduction zone and thus contribute to improved understand of seismic hazard in this part of the Pacific Ocean.
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8036 Paleoseismology (7221)
SC: Geodesy [G]
MN: 2007 Fall Meeting