Kikai Caldera - Undersea Super-Volcano

Japan - March. 2020
I had the great privilege of being able to join the crew of the Fukae Maru, a scientific research ship from the Kobe Ocean-Bottom Exploration Center. The expedition team studies the plate tectonics around Japan as well as the Kikai Caldera underwater super-volcano. I boarded the ship with an interpreter in Nagasaki, and we spent 5 days on board as they used sonar and a magnetometer to map out parts of the sea floor.
Kikai Caldera is a massive, mostly submerged caldera 19 kilometers (12 mi) in diameter in the Osumi Islands of Kagoshima Prefecture, Japan.
Kikai Caldera was the source of the Akahoya eruption, one of the largest eruptions during the Holocene (10,000 years ago to present). About 6,300 years ago, pyroclastic flows from that eruption reached the coast of southern Kyushu up to 100 km (62 mi) away, and ash fell as far as Hokkaido. The eruption produced about 150 km³ of material, giving it a Volcanic Explosivity Index of 7 and making it one of the most explosive in the last 10,000 years.
Kikai is still an active volcano. Minor eruptions occur frequently on Mount Io, one of the post-caldera subaerial volcanic peaks on Iojima. Iojima is one of three volcanic islands, two of which lie on the caldera rim. On June 4, 2013, weak tremors were recorded. Shortly after, eruptions began and continued off-and-on for several hours.



The Fukae Maru, docked in Nagasaki.
These are some of the sensors that the team retrieved from Kikai caldera on their last expedition.
Out to sea! It's hard to imagine sail overtop of a super volcano.



The magnetometer. It measures the strength of the Earth's magnetic field. It is towed behind the ship on 150 meters of cable.
The science team deploying the magnetometer.
In the monitoring room where the scientists observe the raw data coming back from their instruments.



The bridge of the Fukae Maru.
This is what a sonar scan of an undersea super volcano looks like.
On board for 5 days, I was filming the operations for a new TV program.



The ship "mowed the lawn" and went back and forth, scanning sections of the sea floor.
I assisted the team with retrieving the magnetometer, afterwards, I got a pic of me with my flag from the Royal Canadian Geographical Society, which I always carry with me.
Goodbye Fukae Maru. We got off the ship in Kobe, and the next day, I flew home from Osaka, just as the Covid-19 pandemic was really ramping up.