Abstract
Two hazardous typhoons, Lionrock (August 2016) and Jebi (September 2018), destructively affected the coast of Japan and produced extreme sea level variations. The results of field surveys in the impacted regions showed that multiple deaths and extensive floods were caused by the combined effect of low-frequency sea level raise (storm surges) and intensive high-frequency (HF) tsunami-like waves (meteotsunamis). The data from ten tide gauges for the 2016 event and eight gauges for the 2018 event were used to examine the properties of the observed sea levels, to estimate the relative contribution of the two sea level components and to evaluate their statistical characteristics (maximum wave heights, amplitudes and periods of individual components, etc.). For the 2016 event, we found that the surge heights were from 12 to 35 cm and that the mean contribution of surges into the total observed sea level heights was ~ 39%; the meteotsunami amplitudes were from 22 to 92 cm, and they contributed 61% of the total height. For the 2018 event, storm surges were significantly stronger, from 46 to 170 cm, while HF amplitudes were from 38 to 130 cm; their relative inputs were 67% and 33%, respectively. Combined, they formed total flood heights of up to 120 cm (2016 event) and 288 cm (2018 event). Previously, the contribution of storm seiches (meteotsunamis) in coastal floods had been underestimated, but results of the present study demonstrate that they can play the principal role. What is even more important, they produce devastating currents: according to our estimates, current speeds were up to 3 knots (1.5 m/s) during the Lionrock event and more than 5 knots (2.6 m/s) during Jebi; these strong currents appear to be the main reason for the resulting damage of coastal infrastructure. The most important characteristic of the recorded meteotsunamis is their trough-to-crest maximum height. During the 2016 event, these heights at three stations were > 1 m: 171 cm at Erimo, 109 cm at Hachijojima and 102 cm at Ayukawa. The 2018 event was stronger; maximum meteotsunami wave heights were 257 cm at Gobo, 138 cm at Kushimoto, 137 cm at Kumano and 128 cm at Murotomisaki. The 2018 Gobo height of 257 cm is much larger than historical non-seismic seiche maxima for the Pacific coast of Japan (140–169 cm) estimated by Nakano and Unoki (1962) for the period of 1930–1956.
| Original language | English |
|---|---|
| Pages (from-to) | 1639-1672 |
| Number of pages | 34 |
| Journal | Natural Hazards |
| Volume | 106 |
| Issue number | 2 |
| Early online date | 7 Dec 2020 |
| DOIs | |
| Publication status | Published - 1 Mar 2021 |
Bibliographical note
Funding Information:We are grateful to Dr Hiroshi Takagi (Tokyo Institute of Technology, Japan), Mr Takumu Iwamoto (Port and Airport Research Institute, Yokosuka, Japan) and Dr Tomohiro Takagawa (Port and Airport Research Institute, Yokosuka, Japan) for assisting us during the field surveys of the coastal damage from two typhoons examined in this article. We thank Takumu Iwamoto for providing us with the air pressure measurements reported in this study. Tide gauge data were provided by the Japan Meteorological Agency (JMA) through Toshihiro Ueno (JMA, Sapporo District Meteorological Observatory, Japan) and Shigeki Nakagawa and Professor Kenji Satake (both from the University of Tokyo, Japan). The authors gratefully acknowledge Fred Stephenson (Institute of Ocean Sciences, Sidney, BC, Canada) for valuable comments and suggestions. We used the GMT software for drafting some of the figures (Wessel and Smith 1998). For AR, this work was partially supported by the Russian State Assignment of IORAS #0149-2019-0005. MH was funded by the Royal Society, the UK, grant number CHL/R1/180173.
Funding Information:
We are grateful to Dr Hiroshi Takagi (Tokyo Institute of Technology, Japan), Mr Takumu Iwamoto (Port and Airport Research Institute, Yokosuka, Japan) and Dr Tomohiro Takagawa (Port and Airport Research Institute, Yokosuka, Japan) for assisting us during the field surveys of the coastal damage from two typhoons examined in this article. We thank Takumu Iwamoto for providing us with the air pressure measurements reported in this study. Tide gauge data were provided by the Japan Meteorological Agency (JMA) through Toshihiro Ueno (JMA, Sapporo District Meteorological Observatory, Japan) and Shigeki Nakagawa and Professor Kenji Satake (both from the University of Tokyo, Japan). The authors gratefully acknowledge Fred Stephenson (Institute of Ocean Sciences, Sidney, BC, Canada) for valuable comments and suggestions. We used the GMT software for drafting some of the figures (Wessel and Smith ). For AR, this work was partially supported by the Russian State Assignment of IORAS #0149-2019-0005. MH was funded by the Royal Society, the UK, grant number CHL/R1/180173.
Publisher Copyright:
© 2020, The Author(s).
Keywords
- Harbour oscillations
- Meteotsunami
- Seiches
- Statistics
- Storm surge
- Tide gauge records
- Tsunami currents
- Typhoon
ASJC Scopus subject areas
- Water Science and Technology
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)