Why is the Tonga submarine volcanic tsunami observed in Japan farther than Saipan?
Japanese scholar “volcanic shockwave – tsunami amplification due to wave resonance”
(Tokyo = Yonhap News) Correspondent Lee Se-won = An analysis showed that the tsunami (tsunami) that occurred after a submarine volcano erupted near Tonga in the South Pacific was amplified by the interlocking of shock waves and waves of volcanic activity.
The Mainichi Shimbun reported that the shock wave caused by the eruption was transmitted to the atmosphere and a ‘resonance’ that coincided with the speed of transmission of sea waves occurred, which was amplified as it approached the Japanese archipelago approximately 8,000 km away. It was reported on the 17th that the scholars came up with it.
According to the report, experts say that at observation points such as Saipan, the Dominion of the United States, or Pohnpei Island, in Micronesia, which are midway between the submarine volcano and Japan, a change in tide level as high as that of Japan (up to 1.2m) was not observed. interpreted like this
Fumihiko Imamura, a professor at the International Institute of Disaster Science at Tohoku University (tsunami engineering), analyzed that the tsunami was caused by a shock wave called ‘resonance’ accompanied by an undersea volcanic eruption.
It is believed that the shock wave caused the tsunami off the coast of Japan as it vibrated the air and propagated into the sea water.
According to this eruption, when the tide was first observed in Japan, an atmospheric pressure increase of about 2 hPa (hectopascals) was observed.
Kenji Tanaka, a professor at Hiroshima Institute of Technology (meteorology and marine engineering), said that the shock waves spread concentrically at the eruption point at a speed of about 300 meters per second, and went faster than the tsunami directly generated by the eruption, causing waves around the Japan Trench. It was explained that it resonated with
He estimated that there are two major types of tsunami that reached Japan: those observed around 8 am on the 15th and those observed around 11 am on the same day.
Among them, it was interpreted that the first one was due to a shock wave, and the latter was caused by the flow of a large amount of sediment into the sea due to an eruption.
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