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Lithospheric loading by the 1896 Riku-u earthquake, northern Japan: implications for plate flexure and asthenospheric rheology.

Journal of Geophysical Research

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Abstract

Under favorable circumstances the time-dependent aseismic deformation resulting from the loading of the lithosphere by the stress drop of large dip slip earthquakes can be used to determine both the effective elastic plate thickness and the asthenospheric viscosity. The deformation has several similarities with the deflection of the lithosphere by surface loads and with movements due to postglacial rebound. Level changes obtained in the 80 years since the M = 7.5, 1896 Riku-u earthquake, an intraplate thrust event in northern Honshu, provide convincing evidence that asthenospheric readjustments are responsible for the observed movements. Leveling surveys crossing the zone of surface faulting have been repeated five times since 1900 and delineate a localized depression that has subsided at a continually decreasing rate. The depression is centered close to the 1896 faulting, and its shape and width, about 75 km, are matched by our model using a plate thickness of 30 km. The decaying subsidence rate constrains the viscosity of the uppermost asthenosphere to be 1 x 1020 P. A linear viscous rheology matches the observed decay quite well, although measurements are sparse during the several decades following the earthquake. -Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Lithospheric loading by the 1896 Riku-u earthquake, northern Japan: implications for plate flexure and asthenospheric rheology.
Series title:
Journal of Geophysical Research
Volume
85
Issue:
B11
Year Published:
1980
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Geophysical Research
First page:
6429
Last page:
6435