Significant tsunami observed at ocean-bottom pressure gauges during the 2011 off the Pacific coast of Tohoku Earthquake

The 2011 Tohoku Earthquake caused a devastating tsunami along the shoreline from the Tohoku to Kanto districts. Although many of the tide gauge stations along the Tohoku coast were saturated or damaged due to the tsunami, two cabled ocean-bottom tsunami sensors installed off Kamaishi successfully re...

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Bibliographic Details
Published in:Earth, planets, and space planets, and space, 2011-01, Vol.63 (7), p.803-808
Main Authors: Maeda, Takuto, Furumura, Takashi, Sakai, Shin’ichi, Shinohara, Masanao
Format: Article
Language:English
Subjects:
Coastlines
Earth and Environmental Science
Earth Sciences
Earthquake damage
Geology
Geophysics/Geodesy
Letter
Marine
Rupture
Seismic phenomena
Slip
Stations
Trenches
Tsunamis
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Summary:The 2011 Tohoku Earthquake caused a devastating tsunami along the shoreline from the Tohoku to Kanto districts. Although many of the tide gauge stations along the Tohoku coast were saturated or damaged due to the tsunami, two cabled ocean-bottom tsunami sensors installed off Kamaishi successfully recorded the tsunami waveform just above the source rupture area. The records indicated a characteristic two-stage tsunami development sequence: a smoothly increasing tsunami amplitude from 0 to 2 m during the first 800 s from the earthquake origin time, and a short-period impulsive tsunami with a peak of more than 5 m in the following 200 s. Such observations strongly suggest the lack of any sea floor upheaval at the stations during the earthquake, and the occurrence of an extremely large slip in the shallow portion of the subducting Pacific Plate near the trench axis. The source model derived from the offshore tsunami records indicates that a very large slip of 57 m occurred off Miyagi near the trench axis, south of the rupture area of the 1896 Meiji Sanriku tsunami earthquake, and was the major source of the highly destructive tsunami that subsequently developed.
ISSN:1343-8832
1880-5981
DOI:10.5047/eps.2011.06.005