loading page

Enigmatic tsunami waves amplified by repetitive source events in the southwest of Torishima Island, Japan
  • +2
  • Osamu Sandanbata,
  • Kenji Satake,
  • Shunsuke Takemura,
  • Shingo Watada,
  • Takuto Maeda
Osamu Sandanbata
Earthquake Research Institute, The University of Tokyo

Corresponding Author:osm3@eri.u-tokyo.ac.jp

Author Profile
Kenji Satake
University of Tokyo
Author Profile
Shunsuke Takemura
Earthquake Research Institute, the University of Tokyo
Author Profile
Shingo Watada
University of Tokyo
Author Profile
Takuto Maeda
Hirosaki University
Author Profile


On 9 October 2023 (JST), mysterious tsunamis with a maximum wave height of 60 cm were observed in Izu Islands and southwestern Japan, although only seismic events of body-wave magnitudes mb 4–5 have been documented in the southwest of Torishima Island. To investigate the source process, we analyze tsunami waveforms recorded by an array network of ocean-bottom pressure gauges. A stacked waveform of 16 records suggests recurrent arrivals of multiple wave trains. Deconvolution of the stacked waveform by a tsunami waveform from the first event revealed over 10 source events that intermittently generated tsunamis for ~1.5 hours. The temporal history of this sequence corresponds to the origin times of T-phases estimated by an ocean-bottom seismometer, and the mb 4–5 seismic swarm, implying a common origin. Larger events later in the sequence occurred at intervals comparable to the tsunami wave period, causing amplification of later phases of the tsunami waves.
27 Oct 2023Submitted to ESS Open Archive
31 Oct 2023Published in ESS Open Archive