According to Japanese scientists, the largest volcanic eruption recorded in the current geological era occurred 7,300 years ago

About 7,300 years ago, it took place underwater, off the southwest coast of Japan.the largest volcanic eruption of the current geological era. There was an explosion more than three times as much pyroclastic material as the largest known modern eruptionMount Tambora, which exploded in Indonesia in 1815, causing such drastic climate changes that it led to “The Year Without a Summer” in 1816.

The eruption of Kikai-Akahoya He came from submerged caldera in the coastal region south of the Japanese island of Kyushu in southwestern Japan and located on a volcanic front where the Philippine Sea plate subducts the Eurasian plate. He made the boiler at least three large-scale eruptions 140,000, 90,000, and 7,300 years old.

In addition to lava, volcanoes also expel large quantities of pumice, ash and gases in a fast stream known as a pyroclastic flow and its sediments are a valuable source of data about past eruptions.

This eruption expelled a large amount of volcanic products (ash, pumice, etc.) that settled in an area of ​​more than 4,500 square kilometers around the site of the eruption.

An eruption with consequences on a planetary scale

With an estimated volume between 133 and 183 cubic kilometersthe devastating effects of the eruption on people living on nearby islands have been documented by geologists and archaeologists, and analysis of volcanic ash deposits has shown that the explosion It was one of the largest eruptions of the current geological erathe Holocene, which began 11,700 years ago.

However, The origin and size of the explosion were uncertain due to the difficult access to the underwater caldera, to the crater that was created after the eruption of the volcano and to volcanic deposits on the sea floor.

A detailed study of the underwater volcanic deposits around the Kikai caldera in Japan shed light on the mechanisms of deposition as well as the size of the event. A team of scientists from Kobe University in Japan studied the eruption and concluded that it did much larger than previously thought.

The results are part of an article published in Journal of Volcanology and Geothermal Research directed by Nobukazu Seama who combined their findings with previous estimates of volcanic rocks deposited on the sea floor and concluded that the total amount of material drawn from the volcano It is the equivalent of more than 300 cubic kilometers of surface area.

However, this eruption is still ongoing deep below the eruption of the Toba supervolcano in Indonesia about 74,000 years ago, which released more than 2,500 cubic kilometers of magma.

Review Kikai-Akahoya, Seama and their colleagues conducted a seismic survey to map the underwater area around the caldera, about 200 meters below the surface. The data allowed them to isolate the volcanic layer from the seismic study and calculate the total volume of material that the volcano produced.

Researchers they collected deep deposits using a remote-controlled drilling robot and compiled rock samples below to identify the flow corresponding to this eruption, identifying layer containing various volcanic glass.

Kikai-Akahoya caldera it still has a large magma chamber beneath it. If it explodes, it may cause another eruption, although it is unpredictable to know its size because The exact size of this magma chamber is unknown..

Better understanding of risks

Combining historical information from past eruptions, such as Kikai-Akahoya, with studies of more recent underwater eruptions, such as the 2022 Hung Tonga eruption, it can help us build better models for predicting future eruptions.

So we can to better understand the risks and thanks to this knowledge to better produce in space, prevent and mitigate possible impacts on population, heritage and environment, reducing the risk of possible disasters.

Link to news:
Shimizu, S., Nakaoka, R., Seama, N., et al. Submarine pyroclastic deposits from the 7.3 ka caldera-forming Kikai-Akahoya eruption. Journal of Volcanology and Geothermal Research. 2024.