Iwate Volcano | John Seach


Honshu, Japan

39.85 N, 141.00 E
summit elevation 2038 m
complex volcano

Iwate volcano is located 20 km northwest of Morioka City.
There are two volcanic cones; the eastern cone (Higashi-Iwate) is younger than the western cone (Nishi-Iwate).

1998-99 Earthquakes
The 1998–1999 volcanic unrest of Iwate volcano, was marked by 350 deep low-frequency earthquakes and 120 intermediate-depth low-frequency earthquakes, as well as an intense swarm of shallow volcanic earthquakes that began during 1998 April. Shallow seismicity west of the summit began in February 1998 and reached a peak at the end of April. In June the Japan Meteorological Agency announced the possibility of an eruption of the volcano.

On 3rd September 1998 a magnitude 6.1 earthquake hit 12 km SE of the summit of Iwate volcano. Drilling data implied that seismic activity in 1998 was caused by the magma resurgence at depth, and triggered the earthquake along existing faults. Shallow seismic activity of Iwate volcano during 1998–1999 was associated with crustal deformation.

A magnitude 3.6 earthquake occurred at the western edge of Nishi-Iwate on 22nd May 1999.This was followed by the formation of new fumaroles on the north slope of Mts. Ubakura-yama and Kurokura-yama and in the western stream of Ojigokudani. A magmatic component of fumarolic emissions were detected in August and October 1999. Four minutes of volcanic tremor was detected on 4th November 1999, followed by 2 hours of earthquake swarm.

1995 Earthquakes
Intermediate-depth tremor began at Iwate volcano in September 1995.

1919 Eruption
A small phreatic eruption occurred in July 1919 on the western side of Onigajo caldera (O-jigokudani).

Iwate Volcano Eruptions

1919, 1731-32, 1719, 1689, 1687, 1686.