Department of Earth Sciences, Toyama University
Department of Earth Sciences, Toyama University
抄録(英)
This paper presents an analysis of transform fault (TF) events along the Eltanin fracture zone (FZ) and the Udintsev FZ, the Pacific-Antarctic Ridge. We redetermined fault plane solutions and seismic moments of 12 TF events by moment tensor inversion (FITCH et al. : J. Geophys. Res., 85,3817,1980) using Claerbout's Robust modelling (CLAERBOUT and MUIR : Geophysics, 38,826,1973). Corrections for physical dispersion and instrumental response were made by a simple method same as that of CHUNG and KANAMORI (Phys. Earth Planet. Inter., 23,134,1980). Conclusions are as follows : (1) Events for which fault plane solutions were well-constrained were all left-lateral strike-slip fault events, which is consistent with the concept of the transform fault. (2) Total amount of the seismic moments released at the Eltanin FZ, the Pacific-Antarctic Ridge, is 6-7×(10)^<26>dyn・cm, including all of the TF events of the surface wave magnitude Ms greater than 5.8. The estimate is 8-10% of an amount of 7.5×(10)^<26>dyn・cm predicted by a simple plate kinematics with parameters of a TF length of 1300km, a crustal thickness of 10km, a rigidity of 4×(10)^<11>dyn・cm, a spreading rate of 9cm/yr and the period of 16 years. This indicates that the main part of transform fault movements was released aseismically at the Eltanin FZ. The conclusion (2) seems to be a proof for the conclusion that the fast-spreading center like the Pacific-Antarctic Ridge is hot and plastic because hot mantle materials are being supplied by the fast-moving mantle-convection current.
雑誌書誌ID
AA00733561
雑誌名
Memoirs of National Institute of Polar Research. Special issue
Mode of seismic moment release at the Pacific-Antarctic Ridge (abstract)
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KJ00000012100
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概要
