"Massive Chokai volcano, the largest of NE Honshu, overlooks the Japan Sea. Chokai is composed of two overlapping stratovolcanoes with a conical profile that has given it the local names Akita-Fuji or Dewa-Fuji. The summit of the gently sloping western volcano (Nishi-Chokai) is cut by a large horseshoe-shaped caldera breached to the south, whose floor contains lava domes. The younger eastern volcano (Higashi-Chokai) began forming about 20,000 years ago. It was cut by another large horseshoe-shaped caldera, breached to the north. During an eruption about 2600 years ago it was the source of the voluminous Kisakata debris avalanche, which reached the Pacific coast. Two post-caldera lava domes have been constructed at the upper SE end of the caldera. Intermittent reports of historical eruptions at Chokai date back to the 6th century AD."  -Smithsonian Volcano Archive
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