Japan's Kikai Caldera Magma Reservoir Found Refilling, Study Shows

Researchers from Kobe University, working with the Japan Agency for Marine‑Earth Science and Technology (JAMSTEC), have identified a large magma‑rich reservoir beneath the largely submerged Kikai caldera that is actively refilling. Seismic surveys using air‑gun arrays and ocean‑bottom seismometers revealed the reservoir lies about 1.5‑3 miles below the sea floor, in the same location that supplied magma for the massive eruption 7,300 years ago that devastated the Jōmon civilization.

Chemical analyses indicate the newly injected magma differs from the ancient eruptive material, suggesting a fresh supply of molten rock. The finding offers a rare opportunity to study how giant supervolcano systems recover after catastrophic eruptions, with implications for other large calderas such as Yellowstone in the United States and Toba in Indonesia.