Deep-Water Characteristics of the Trans-Pacific Tsunami from the 1 April 2014 M w 8.2 Iquique, Chile Earthquake

Abstract

© 2014, Springer Basel.We studied the tsunami generated by the 1 April 2014 Mw 8.2 Iquique (Chile) earthquake using 20 Deep-ocean Assessment and Reporting of Tsunamis (DART) records and applying Fourier and wavelet analyses as well as performing numerical simulations. Deep-water tsunami wave heights were in the range of 0.8–35.0 cm. For the stations located more than 2,200 km from the source, the average wave height was 1.7 ± 1.1 cm. The observed tsunami arrivals were delayed by 1–17 min relative to the simulated ones based on the linear long wave equations, and the delays were proportional to the tsunami travel distances. A small initial depression was observed at DART stations located at distances >10,000 km from the source whereas, traditionally, an initial elevation is expected at stations located seaward of subduction zones. Fourier analyses showed tsunami governing periods of 21.1 ± 1.7 and 14.7 ± 0.7 min, corresponding to a fault length of 60–70 km and a fault width of 40–45 km. While the two 21-min and 15-min signals appeared in most DART stations during ~0.5 h following the conventional arrival times, the 15-min signal was delayed at some far-field stations. Distribution of maximum DART wave heights across the Pacific Ocean did not show a meaningful relation between maximum DART wave heights and directivity or distance from the source.The sea level data used in this study were provided through the USA National Oceanographic and Atmospheric Administration (NOAA). We thank Hiroshi Tsuruoka and Takeo Ishibe at the Earthquake Research Institute (ERI) for assisting in preparation of some figures. Several figures were drafted using the GMT software (Wessel and Smith 1991). We are sincerely grateful to Prof. Alexander Rabinovich, the editor, and two anonymous reviewers for comments that improved this article. This study is supported by the Japan Society for the Promotion of Science (JSPS)