Tide level change due to eruption Review of information announcement Tonga eruption received Japan Meteorological Agency

In January, the Japan Meteorological Agency reviewed the method of announcing information on tide level changes due to the eruption, based on the fact that tide level changes were observed along the coasts of various parts of Japan in a large-scale eruption at a submarine volcano in Tonga, South Pacific. rice field.

The possibility of a "tsunami" will be evaluated by newly utilizing observations by meteorological satellites, and more detailed information will be announced.

In a large-scale eruption of a submarine volcano in Tonga in January, tide level changes of several centimeters to a meter or more were observed along the coasts of various parts of Japan.

Subsequent analysis suggests that the pressure wave caused by the impact of the eruption had an effect, but at that time the announcement of tsunami warnings and warnings was delayed, so a meeting of experts summarized the way information should be announced, and the Japan Meteorological Agency 27 It started operation from the day.

According to this, if a large-scale eruption similar to that at that time occurs, we will first announce that there is a risk of a "tsunami" due to atmospheric pressure waves and the estimated time of arrival in Japan.

In addition to information on changes in tide level, we will also utilize image analysis by meteorological satellites, and if pressure waves are observed, we will announce more detailed information such as announcing that "the possibility of tsunami occurrence has increased". It is said.

In addition, if changes in atmospheric pressure and tide level are observed at similar timings, the possibility of a tsunami will increase, and we will issue a tsunami warning even if the standards are not met.

Professor Kenji Satake of the Earthquake Research Institute, the University of Tokyo, who chaired the expert meeting, said, "Tsunami caused by an eruption is a very rare phenomenon, but at least when a large-scale eruption occurs overseas, the possibility of a tsunami will increase. It is important to be aware that there is no doubt that tsunami warnings and warnings may be issued. "