The October 4, 1994 Shikotan (Kurile Islands) tsunamigenic earthquake: An open problem on the source mechanism

On October 4, 1994, an earthquake of magnitude M-w = 8.2 occurred in the we stern part of the Kurile Islands, generating a tsunami that has been well r ecorded along the entire coast of Japan. Previous works have shown that thi s earthquake does not represent a low angle thrust event, normally expected in a subduction zone, rather an intra-plate event rupturing through the sl ab. On the basis of the accepted mechanism, two fault models, representativ e of the nodal plane ambiguity, have been suggested. The goal of this work is to verify whether the tsunami simulations are able to rule out one of th e two proposed fault models. Taking into account both fault models together with a heterogeneous slip along the fault, we have performed numerical sim ulations of the tsunami. All source models produce tide-gauge records in ag reement with the observed ones. The limit of resolution of the performed si mulations, estimated by means of a perturbed bathymetry, does not allow us to distinguish the best source model.