Izu-Tobu volcano is a group of volcanic vents with cinder cones, lava flows, domes and tephra deposits on the NE Izu peninsula 80 km SW of Tokyo.
The Izu-Tobu volcanic group covers an area of 400 sq km and contains many submarine volcanoes offshore of the peninsula. Most of its erupted magmas are basalt, and a smaller volume is andesite.
Ito city is the largest town (ca. 70,000 inhabitants) located in the volcanic field. It is known for its hot springs and resorts.
The latest eruption of Izu-Tobu volcano was in 1989, when a small submarine crater formed NE of Ito City.
The Izu-Tobu volcano group (Higashi-Izu volcano group) is scattered over a broad, plateau-like area of more than 400 sq km on the east side of the Izu Peninsula. Construction of several stratovolcanoes continued throughout much of the Pleistocene and overlapped with growth of smaller monogenetic volcanoes beginning about 300,000 years ago. About 70 subaerial monogenetic volcanoes formed during the last 140,000 years, and chemically similar submarine cones are located offshore. These volcanoes are located on a basement of late-Tertiary volcanic rocks and related sediments and on the flanks of three Quaternary stratovolcanoes: Amagi, Tenshi, and Usami. Some eruptive vents are controlled by NW-SE- or NE-SW-trending fissure systems. Thirteen eruptive episodes have been documented during the past 32,000 years. Kawagodaira maar produced pyroclastic flows during the largest Holocene eruption about 3000 years ago.
