On the Leading Negative Phase of Major 2010–2014 T

Authors: Marie C Eblé George T Mungov Alexander B Rabinovich

Publish Date: 2015/07/11

Volume: 172, Issue: 12, Pages: 3493-3508

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Abstract

Time series observations from instruments sited in the deep ocean and along coastal margins of the Pacific during major tsunami events in the years since 2010 were systematically processed Examination of these records during four events 2010 Chile Maule 2011 East Japan Tohoku 2012 Haida Gwaii and 2014 Chile Iquique show the prevalence of a small negative phase leading the first major positive tsunami wave a phase that is not typically reproduced by current modelling approaches We present leading negative phase signatures in examples from the more than 40 deepocean bottom pressure and approximately 200 tide gauge records investigated for this study High sampling rate time series 15s were given greater weight in our investigation than the more readily available 1min series Careful investigation of tsunami arrival at each deepocean site highlights the role filtering techniques may play in misleading researchers or masking specific tsunami features such as the leading negative phase that is the basis of this study The main focus of this investigation is to characterise the scale and repeatability of the phenomenon in support of recent similar findings rather than to provide a definitive explanation as to the cause In general our findings are in good agreement with and support the theoretical results of Watada et al J Geophys Res Solid Earth 1194287–4310 2014The authors thank the National Data Buoy Center and the National Ocean Service for their dedication in securing quality observations the National Tsunami Warning Center for providing many coastal data sets and Lindsey Wright and NOS Pacific especially Caleb Gostnell for the many hours invested in calling tide gauge backup units and manually downloading the 15s data that are the basis of our investigations We also thank Karen Birchfield for her assistance with graphics and the reviewers for taking the time to provide candid and greatly appreciated comments for manuscript improvement The contribution of Alexander Rabinovich was partially funded under NOAA/PMEL Contract Number WE133R13SE1659 and by the Russian Science Foundation Grant 145000095 This is PMEL contribution 4099

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