Iwate Volcano

Updated: Aug 4, 2025 20:23 GMT - refresh

complex volcano

Honshu, Japan, 39.85°N / 141°E

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Summit height: 2041 m / 6,696 ft

Current status: normal or dormant (1 out of 5)

Last update: 9 Oct 2024 (Smithsonian / USGS Weekly Volcanic Activity Report)

Iwate (or Iwatesan) volcano is a symmetrical stratovolcano in northern Honshu, Japan, 20 km northwest of Morioka City.
It consists of 2 cones, the older western Nishi-Iwate and the younger eastern summit Higashi-Iwate. The older volcano to the west is truncated by a caldera that resulted from repeated collapse.
The caldera contains a central cone with a 500 m wide crater containing a lake and is breached by a narrow gorge to the NW.
Volcanic activity migrated to the east and built Yakushi-dake, the young, mainly basaltic summit cone of Higashi-Iwate. Yakushi-dake contains a 500 m wide crater and partly buries the eastern rim of the caldera. It is the vent of most recent activity including a lava flow from the eruption in 1732 that traveled down the NE flank.
The last historic activity was a small phreatic eruption from O-jigokudani on the W side of the Onigajo caldera. The eruption caused mudflows.
There are uncertain reports about activity in July 1934.

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News/Updates | Earthquakes

Typical eruption style: explosive
Iwate volcano eruptions: 1934 (?), 1919, 1732, (reported 1719 eruption was in 1732), 1689 (?), 1687, 1686
Radiocarbon- & tephrochronology dated: 1450 ± 100, 1300 ± 50, 150 AD (?), 350 BC (?), 450 BC (?), 1150 BC (?), 1250 BC (?), 1500 BC ± 300, 1650 BC (?), 2000 BC (?), 2050 BC ± 200, 2950 BC ± 50, 3050 BC (?), 3250 BC ± 500, 3750 BC ± 100, 4350 BC ± 500, 4450 BC ± 500, 4850 BC ± 50, 4900 BC ± 100, 5650 BC ± 50, 6300 BC ± 100, 6450 BC ± 1000

Latest nearby earthquakes

Date and Time	Mag / Depth	Distance / Location
Aug 4, 10:04 pm (GMT +9)	0.2 2.1 km	13 km (8.3 mi) to the W	Japan: Northern Iwate Pref	Info
Aug 4, 01:55 pm (GMT +9)	0.4 7.2 km	21 km (13 mi) to the E	Japan: Northern Iwate Pref	Info
Saturday, August 2, 2025 GMT (3 quakes)
Aug 3, 05:40 am (GMT +9)	0.2 5.8 km	25 km (15 mi) to the NE	Japan: Northern Iwate Pref	Info
Aug 3, 05:16 am (GMT +9)	0.3 5.5 km	21 km (13 mi) to the SW	Japan: Northern Iwate Pref	Info
Aug 3, 04:44 am (GMT +9)	0.8 3.7 km	24 km (15 mi) to the NW	Japan: Northern Akita Pref	Info
Thursday, July 31, 2025 GMT (1 quake)
Jul 31, 05:02 pm (GMT +9)	1.2 94 km	23 km (14 mi) to the E	22 km northeast of Morioka, Iwate, Japan	Info
Wednesday, July 30, 2025 GMT (1 quake)
Jul 30, 06:25 pm (GMT +9)	0.2 8.7 km	28 km (18 mi) to the NE	Japan: Northern Iwate Pref	Info
Tuesday, July 29, 2025 GMT (2 quakes)
Jul 30, 08:38 am (GMT +9)	2.8 5 km	9.8 km (6.1 mi) to the W	Japan: Northern Iwate Pref I FELT IT	Info
Jul 29, 08:26 pm (GMT +9)	1.6 4.3 km	14 km (8.7 mi) to the NW	Japan: Northern Iwate Pref	Info

View recent quakes

Background

The western and older volcano Nishi-Iwate contains an oval-shaped 1.8 x 3 km caldera. Nishi-Iwate volcano begin growing about 700,000 years ago and suffered repeated (at least 7) collapse during the past 230,000 years, most recently between 739 and 1615 AD.

Significant volcanic eruptions: Iwate volcano

In the past 10,000 years, Iwate has had at least 26 confirmed volcanic eruptions, out of which 3 are documented by historical records, while the others can be inferred from geological evidence.
Additionally, there are 5 uncertain or discredited eruptions from Iwate volcano.

The table below lists all known eruptions (date in bold face) of Iwate volcano since around 3000 BC. Updates on the most recent volcanic activity of Iwate can be found on the news page of Iwate volcano.

Date	Note	VEI
?? 1934 Jul - 1935	Uncertain Eruption	?
1919 Jul 15 ?	W side of Onigajo caldera (O-jigokudani) Historical obs./docs.	1
1823	Discredited Eruption
1732 Jan 22 - Oct	NE flank of Yakushi-dake Historical obs./docs.	2
1719 Feb	Discredited Eruption
?? 1689 AD Jun 22	Uncertain Eruption	2?
?? 1687 AD Apr 14 - Jul	Uncertain Eruption	2?
1686 AD Mar 26 - Mar 27	Historical obs./docs.	3
1450 ±100 y. AD	Nishi-Iwate and Higashi-Iwate	?
1300 ±50 y. AD	Higashi-Iwate (Myoko-dake)	3
150 ? AD	Higashi-Iwate	?
350 ? BC	Higashi-Iwate	?
450 ? BC	Nishi-Iwate (O-jigokudani area)	?
1150 ? BC	Nishi-Iwate	?
1250 ? BC	Higashi-Iwate	3
1500 ±300 y. BC	Higashi-Iwate	?
1650 ? BC	Nishi-Iwate (O-jigokudani area)	?
2000 ? BC	Nishi-yama	?
2050 ±200 y. BC	Higashi-Iwate	?
2700 ±200 y. BC	Higashi-Iwate	?
2950 ±50 y. BC	Nishi-Iwate	?

Remark:

Our list of volcanic eruptions closely follows the database of eruptions of the Smithsonian's Global Volcanism Project (GVP), the internationally most recognized data source for volcanic eruptions, but also includes significant eruptive episodes or related volcano events. "Volcanic eruptions" are usually to be understood as sequences of individual eruptive episodes that can follow each other, or even overlap (if several vents are involved), and can last many years, decades or even longer. For example, the current activity of Stromboli volcano is understood as a single eruption that has been ongoing since 1934.

Sources: NOAA National Centers for Environmental Information (NCEI), Global Significant Volcanic Eruptions Database. doi:10.7289/V5TD9V7K | Global Volcanism Project / Smithsonian Institution

Eruptions of Iwate volcano

1998 magma intrusion event
There was no eruption, but from February to September 1998, dike intrusions were observed geodetically and seismologically at Iwate volcano. Magma commenced rising beneath the eastern basaltic cone and later migrated laterally westward. ...more info

Iwate Volcano FAQ

+When was the last eruption of Iwate volcano?

The last confirmed eruption of Iwate occurred in 1919.

+How often does Iwate volcano erupt?

Since 1686 AD, Iwate volcano has had at least 3 historically documented eruptions. This means that it erupts on average every 113 years.

+How active is Iwate volcano at present?

Iwate volcano is occasionally active: Since 1900, it has had one eruption, which occurred in 1919.

+When was the largest eruption of Iwate volcano?

The largest eruption of Iwate volcano in historic times occurred in 1686 AD. It ranks as a "vulcanian" eruption with a magnitude 3 on the VEI (Volcanic Explosivity Index) scale.

Latest satellite images

See also: Sentinel hub | Landsat 8 | NASA FIRMS

Latest satellite images

Iwate Volcano Maps

Below is a selection of maps showing the location and surroundings of the volcano at various resolutions based on aerial-imagery / terrain maps. Feel free to use them for non-commercial purposes on your blog or website as long as you credit them with a link back to this page (click to copy it).