Tsunami source area of the 2011 off the Pacific coast of Tohoku Earthquake determined from tsunami arrival times at offshore observation stations

Yutaka Hayashi,Kazuhiro Kimura,Kenji Hirata,Kenji Maeda,Hiroaki Tsushima

doi:10.5047/eps.2011.06.042

Yutaka Hayashi, Kazuhiro Kimura + Show 3 more

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https://doi.org/10.5047/eps.2011.06.042

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Abstract

The source area of the tsunami generated by the 2011 off the Pacific coast of Tohoku Earthquake estimated from tsunami arrival times recorded at offshore wave gauges, GPS buoys, cabled ocean-bottom pressure gauges, and tsunami buoys is about 500-km long with a maximum width of approximately 200 km. The 2011 tsunami source area includes several segments of previous recurring large earthquakes. However, the northern and southern parts of the large Japan Trench segment were not included in the source area. The southern off-Boso-Peninsula part of the Japan Trench segment has the potential to generate a large tsunami earthquake in near future.

Highlights

The 2011 off the Pacific coast of Tohoku Earthquake occurred at 05:46:23 on 11 March, 2011 (UTC)
In this study, we modified the tsunami travel times by 1 min corresponding to a distance of 120 km from the epicenter to the contact point of the back-propagation line and the tentatively-determined tsunami source area (Table 1)
The eastern edge of the tsunami source area was along the west side of the Japan Trench, and the southern one was near N36◦

Summary

Introduction

The 2011 off the Pacific coast of Tohoku Earthquake occurred at 05:46:23 on 11 March, 2011 (UTC). The tsunami that accompanied the earthquake was detected at various offshore observation stations, including coastal wave gauges (Nagai, 1998; Nagai et al, 2005), real-time kinematic global positioning system (RTK-GPS) buoys (Kato et al, 2005), cabled deep ocean-bottom pressure gauges (OBPG) Coastal wave gauges and RTK-GPS buoys are part of Japan’s Nationwide Ocean Wave Information Network for Ports and Harbours (NOWPHAS). Several series of large recurring earthquakes with source areas on the plate boundary of the subduction zone under the Japan Trench have been identified by the Earthquake Research Committee (ERC, 2005). Determining which earthquake segments have ruptured during individual earthquakes is of crucial importance in the evaluation of the potential for subduction-related seismic activity along the Japan Trench in the near future

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