HR: 0800h
AN: T11D-1287    [Abstracts]
TI: Crustal shortening rate inferred from Late Quaternary fluvial terraces across the central part of the northeastern Japan arc
AU: * Matsu'ura, T
EM: matsuura-t@aist.go.jp
AF: Geological survey of Japan, Site 7, 1-1-1, Higashi, Tsukuba, 305-8567 Japan
AB: Crustal shortening and strain rates of the central part of the NE Japan arc are estimated using late Quaternary fluvial terraces. Fluvial terraces are correlated to marine isotope stages (MISs) by tephrochronology and 14C dating. The latest and older accumulation terraces are recognised and correlated to MIS 2-4 or 4, and MIS 6, respectively. Regional uplift rates are estimated as 0.17 +/- 0.01 m/kyr (outer arc) and 0.28 +/- 0.03 m/kyr (inner arc) using the relative heights of accumulation terrace surfaces. Assuming that the regional isostatic uplift is caused by crustal shortening, the shortening rates are 0.26 cm/yr (outer arc) and 0.40 cm/yr (inner arc). The strain rates are 0.03 ppm/yr (outer arc) and 0.05 ppm/yr (inner arc). These long-term rates are nearly one order of magnitude smaller than the short-term (several-year) strain rate obtained using global positioning system data. Keywords fluvial terrace; crustal shortening; northeastern Japan; late Quaternary
DE: 8100 TECTONOPHYSICS
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting