W Phase Inversion and Tsunami Inundation Modeling for Tsunami Early Warning: Case Study for the 2011 Tohoku Event

Abstract

Centroid moment tensor solutions for the 2011 Tohoku earthquake are determined by W phase inversions using 5 and 10 min data recorded by the Full Range Seismograph Network of Japan (F-net). By a scaling relation of moment magnitude to rupture area and an assumption of rigidity of 4 × 1010 N m−2, simple rectangular earthquake fault models are estimated from the solutions. Tsunami inundations in the Sendai Plain, Minamisanriku, Rikuzentakata, and Taro are simulated using the estimated fault models. Then the simulated tsunami inundation area and heights are compared with the observations. Even the simulated tsunami heights and inundations from the W phase solution that used only 5 min data are considerably similar to the observations. The results are improved when using 10 min of W phase data. These show that the W phase solutions are reliable to be used for tsunami inundation modeling. Furthermore, the technique that combines W phase inversion and tsunami inundation modeling can produce results that have sufficient accuracy for tsunami early warning purposes.