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  • Letter
  • Open Access

The tsunami source area of the 2003 Tokachi-oki earthquake estimated from tsunami travel times and its relationship to the 1952 Tokachi-oki earthquake

Earth, Planets and Space201456:BF03353066

  • Received: 16 November 2003
  • Accepted: 26 February 2004
  • Published:


We estimate the tsunami source area of the 2003 Tokachi-oki earthquake (Mw 8.0) from observed tsunami travel times at 17 Japanese tide gauge stations. The estimated tsunami source area ( 1.4 × 104 km2) coincides with the western-half of the ocean-bottom deformation area (2.52 × 104 km2) of the 1952 Tokachi-oki earthquake (Mw 8.1), previously inferred from tsunami waveform inversion. This suggests that the 2003 event ruptured only the western-half of the 1952 rupture extent. Geographical distribution of the maximum tsunami heights in 2003 differs significantly from that of the 1952 tsunami, supporting this hypothesis. Analysis of first-peak tsunami travel times indicates that a major uplift of the ocean-bottom occurred approximately 30 km to the NNW of the mainshock epicenter, just above a major asperity inferred from seismic waveform inversion.

Key words

  • The 2003 Tokachi-oki earthquake
  • tsunami
  • tide gauge records
  • the 1952 Tokachi-oki earthquake