The latest simulations of pumice stones that have been confirmed to have been washed ashore not only in Okinawa and Amami but also in the Izu Islands and Chiba Prefecture have been announced.
It is said that there is a possibility that the Izu Islands will be approached together this weekend ...
Confirmed in Okinawa / Amami → Off Kochi Prefecture → Izu Islands, etc.
In August, a large amount of pumice erupted from the submarine volcano of the Ogasawara Islands arrived in Okinawa and Amami in October, and has a great impact on people's lives such as fishing and tourism.
After that, some of the pumice stones seemed to be on the Kuroshio Current, and in November, drifting objects that seemed to be pumice stones were confirmed off the coast of Kochi Prefecture.
And from around last week, a small amount of pumice stones, which are thought to be from submarine volcanoes, have been found ashore in Shikinejima and Oshima in the Izu Islands, as well as in some of the coasts of Chiba Prefecture.
A pumice stone was found drifting in the Izu Islands on the 15th on a patrol by the Japan Coast Guard.
It was found in and off the bays of Toshima, Niijima, Kozushima, Miyakejima, and Mikurajima, and it was said that it floated in a streak with a width of 1 meter and a maximum length of 100 meters in each place.
What happens after this?
Latest simulation
What will happen to pumice stones after this?
JAMSTEC = Japan Agency for Marine-Earth Science and Technology announced the latest simulation on the 16th.
The simulation is performed using pumice stone data observed by the JAXA satellite and an original ocean current model, and is calculated in three scenarios: when there is no effect considering the influence of the wind, when there is a certain amount, and when it is strong. I'm doing it.
In the simulation, the pumice that was drifting off the Kuroshio Current off the coast of Shikoku on November 5 once meandered to the south and then headed north again toward Honshu.
After reaching the offshore of the Tokai region around the 14th, proceed east and approach the Izu Islands.
And after the 19th of this weekend, a large amount of pumice stones are expected to reach the Izu Islands.
After that, pumice stones continued to approach the Izu Islands until late November, and after temporarily staying and slowing down, they gradually escaped to the eastern offshore.
In the Tokai and Kanto areas, it is expected to pass relatively offshore and the impact on the coast of Honshu is expected to be limited, but if a large amount of pumice arrives, there is concern about the impact on the Izu Islands.
Expert "Izu Islands Possibility of continuous flow of a large amount"
Toru Miyama, Senior Researcher of the Japan Agency for Marine-Earth Science and Technology, said, "Similar to Okinawa, even a small amount of drifting may occur at first in the Izu Islands, but then a large amount may continue to flow. If you find pumice stones in the surrounding waters, It is important to share information promptly and use it for measures at ports and other places. "
The pumice drift simulation will be updated every few days in line with the JAXA satellite observations.
From the residents of the Izu Islands ...
I heard about the impact of pumice stones on the Izu Islands at the Takeshiba Passenger Ship Terminal in Minato-ku, Tokyo.
"I have to use a ship when I leave the island to go to the hospital for treatment of heart disease, so I'm most worried that pumice stones will be washed ashore and will not affect the operation of the ship. If there is, we can't do anything about it. "(Izu Oshima, 83-year-old man)
" I'm worried that the traffic connecting Oshima and Takeshiba will be cut off, and that it will affect the tourism and fishing industries that support Oshima's industry. I'm worried about what happens to people's movements when pumice stones are washed ashore, as long as Corona calms down and the emergency declaration is lifted and tourists return. "(Female, 40s, Izu Oshima)
How did you drift?
Analysis from satellite imagery
How are pumice stones actually drifting?
Ikuhiko Ikegami of the University of Tasmania, who specializes in submarine volcanoes, extracted brownish areas where pumice is drifting from images taken by satellites and analyzed how pumice was drifting.
<August 13> "Fukutoku Okanoba" eruption Pumice stones head west
According to this, pumice stones will flow westward after an eruption occurred at the submarine volcano "Fukutoku Okanoba" in the Ogasawara Islands on August 13.
In early September, it drifted around 300 km east of Minamidaito Island, making a full turn, and then moved further west.
According to Mr. Ikegami, the pumice stones that had been gathered around "Fukutoku Okanoba" gradually spread as they proceeded west.
<End of September> Drifting range expands due to typhoon passage
From around the end of September, it was divided into about 100 lumps, and it became dusty due to the passage of the typhoon at the end of September, which expanded the range of pumice drifting.
<Early October> Reached the area around Minamidaito Island, Okinawa
It reached the area around Minamidaito Island in Okinawa in early October, and reached the main island of Okinawa in late October.
<November> Drifting off the coast of Kyushu and Shikoku
In November, you can see that pumice stones are drifting off the coast of Kyushu and Shikoku.
Last time, when Fukutoku-Okanoba erupted in 1986, 35 years ago, and pumice drifted, pumice was confirmed in Okinawa four months after the eruption, but this time it reached Okinawa in just two months. Therefore, Mr. Ikegami says that the drifting speed may have been about twice as fast.
Mr. Ikegami said, "The background of the pumice moving to the west may have been affected by ocean currents and winds. Normally, pumice spreads and sinks while drifting, but because it moved quickly, it moved to Okinawa. The damage may have increased. "
Where is the pumice stone now?
Expert analysis
In addition, Mr. Ikegami analyzed where the pumice stones reached in the Kanto region from images posted on SNS.
According to it, all of them were confirmed on Izu Oshima, Niijima, Shikinejima, Kozushima, Miyakejima, Mikurajima in the Izu Islands, and also on the coast of Tateyama City, Chiba Prefecture.
According to Mr. Ikegami, this pumice stone is characterized by having something like a blackish dot from gray to whitish color, and researchers call it "chocolate chip" or "cookie and cream" because of its appearance. is.
This is different from the pumice stones that are usually found in the Izu Islands.
Okinawa fishermen still can't go fishing
On the other hand, Okinawa Prefecture still has a large amount of pumice stones washed ashore.
At the fishing port in Kunigami Village in the northern part of the main island, a fence was installed to prevent the inflow of pumice stones, but pumice stones have flowed over it, so fishermen are still unable to go fishing.
Yoshikatsu Yamashiro (77), who has been based in this fishing port for more than 60 years, has been taking high-class fish Akajin and Irabucha, but due to the influence of pumice stones, he is unable to fish for nearly a month and is expected to earn income. Is not ...
In the small fishing boat I own, pumice stones were accumulated in the engine filter, and a large amount of pumice stones were also packed in the drainage port with a diameter of about 10 cm on the side of the ship, and Mr. Yamashiro removed it with a wire. rice field.
Mr. Yamashiro said, "I can't pay the living expenses such as rent and step on and kick, but since it is a natural disaster, there is no place for anger. I want to tell the country etc. to help the fishermen."
Concerns about prolonged impact of Okinawa pumice
There is concern that the pumice stones around Okinawa will have a long-term impact.
In the latest simulation released by JAMSTEC = Japan Agency for Marine-Earth Science and Technology, the number of pumice stones that ride the Kuroshio and go off the Pacific Ocean increases over time, but some tend to stay in the surrounding waters for a while depending on the wind strength. about it.
Ministry of Land, Infrastructure, Transport and Tourism Considers collection technology to share with local governments
The Ministry of Land, Infrastructure, Transport and Tourism is studying technology for recovering pumice stones with experts in marine civil engineering work, and at the meeting on the 16th, the results of verifying whether existing technology can be applied were summarized.
According to this, as the recovery technology from land
,
▽
heavy equipment called backhoe and
▽ suction vehicle used for sludge recovery
▽ scoop etc.
can be applied, and backhoe was the largest in the amount of pumice collected per hour. Was shown.
As the technologies for recovering from a sea ship
pump or suck suspended matter with ▽ water
upon collection of pumice in ▽ booms, etc. are effective way to save in landing nets
pumice pulling the net in ▽ plurality of small vessels It was reported that the method of collecting pumice was also effective.
The Ministry of Land, Infrastructure, Transport and Tourism has decided to share the compiled results with Okinawa and Kagoshima prefectures as well as coastal municipalities that may be washed ashore in the future.