Tokachi is made of overlapping stratovolcanoes. Several vents have produced 17 historic eruptions. The eruptions cluster into five periods: 1857, 1887 and 1889, 1925-1931, 1952 to 1962, and 1985 and 1989. Most of the eruptions were phreatic, small to moderate in size (VEI=1-2), and about half were explosive. There eruptions generated pyroclastic flows. Only the 1670 eruption produced lava flows. Eruptions in 1926 and 1962 caused damage and fatalities. Hot mudflows during the 1926 eruption mixed with snow and moved down Hurano valley. The mudflows covered 20 km in 26 minutes, destroying 5,080 homes and killing at least 146 people. Falling blocks killed five people in 1962. Fumeroles continue to release steam at Tokachi.

February 11, 2003

On February 8, volcanic tremor occurred for 37 minutes at Tokachi.

This information was summarized from the GVP/USGS Weekly Volcanic Activity Report

All photographs courtesy of and copyrighted by Mike Lyvers.

Looking northeast to neighboring volcanoes. Note ski lift in foreground.

A huge volcanic bomb just below Tokachi's active crater.

Tokachi's active crater.

Tokachi's active crater.

High above the active crater, approaching true summit.

Inactive crater (foreground) with neighbor volcano (distance).

Highly eroded neighboring dormant volcanoes of the Tokachi range.

Source of Information:

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

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