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Geodetic inversion for the fault model of the 1994 Shikotan Earthquake
Author(s) -
Ozawa Shinzaburo
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl02049
Subject(s) - geodetic datum , geology , akaike information criterion , inversion (geology) , seismology , geodesy , magnetic dip , fault plane , fault model , fault (geology) , geophysics , mathematics , physics , statistics , tectonics , quantum mechanics , electronic circuit
The fault parameters of the 1994 Shikotan earthquake were determined by inverting all available geodetic data using an iterative linearized least‐squares method. A one‐fault inversion shows that a shallow‐dip fault‐plane model does not reproduce the minor deformation observed on Shikotan island, while a steep‐dip model can fit all the data well. Multifault inversion shows that a fault‐plane divided into two subfaults lengthwise is the best fitting model based on Akaike's Information Criteria [ AIC ] for shallow‐dip faulting mechanism. This model yields a very high stress drop, 40 MPa, on the deeper subfault. For a steep‐dip model, a fault plane divided into two subfaults sideways gives the minimum AIC . All the computations for models consisting of two to eight subfaults show that the chi‐square values of the shallow‐dip models are about 10% higher than those of the steep‐dip models. Considering the high stress drop, the larger chi‐square value, and the requirements of a complex subfault system for the shallow‐dip model, we reach the conclusion that the steep‐dip model is more suitable to explain the geodetic observations.