Dotsero Volcano

Updated: Nov 5, 2025 16:36 GMT - refresh

maar

Colorado (Canada and USA (mainland)), 39.66°N / -107.04°W

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Summit height: 2230 m / 7,316 ft

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

The small Dotsero maar in NW Colorado, 2 km NE of the small town Dotsero, near the junction of the Colorado and Eagle Rivers west of the Gore Range, is the only volcano in Colorado that has had activity in the past 10,000 years.
It erupted ca. 4000 years ago, producing an explosion crater (maar), lahars, and a 3 km long lava flow.
The crater of Dotsero is 700 m in diameter and 400 m deep with a flat floor covered by debris. It exposes a lithic-rich pyroclastic deposit, a strombolian scoria-fall deposit, lahars deposits, and a lava flow.

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News/Updates | Earthquakes

Typical eruption style: explosive
Dotsero volcano eruptions: 2200 BC ± 300 years

Latest nearby earthquakes

Date and Time	Mag / Depth	Distance / Location

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Background

Although easily accessible by Interstate highway 70 which cuts across a lava flow from Dotsero, this volcanic center is one of the least known in the western United States.
The youngest feature, the Dotsero maar, was erupted along a ridge consisting of evaporites and reddish oxidized sandstones of Pennsylvanian age.
Small scoria cones were constructed along a NNE-SSW line on either side of the maar. Small lahars preceded the eruption of a basaltic lava flow that traveled 3 km down two narrow V-shaped valleys and spread out onto the floodplain of the Eagle River, diverting the river to the south side of the valley.
Older Pleistocene basaltic lava flows occur nearby at Willow Peak, McCoy, and Triangle Peak.
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Source: GVP Dotsero volcano information

Significant volcanic eruptions: Dotsero volcano

No historic eruptions are known from Dotsero volcano, but at least one eruption around 2200 BC can be inferred from geological evidence.

The table below lists all known eruptions (date in bold face) of Dotsero volcano in historic times and during the past 10,000 years. Updates on the most recent volcanic activity of Dotsero can be found on the news page of Dotsero volcano.

Date	Note	VEI	Deaths	Damage
2200 ±300 y. BC		2?

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

Dotsero Volcano FAQ

+When was the last eruption of Dotsero volcano?

The last confirmed eruption of Dotsero occurred around 2200 BC.

+When was the largest eruption of Dotsero volcano?

The largest eruption known from the younger geological history of Dotsero volcano occurred around 2200 BC. It only has a VEI (Volcanic Explosivity Index) of , likely because it was a mainly effusive eruption generating lava flows but very little ash.

Latest satellite images

See also: Sentinel hub | Landsat 8 | NASA FIRMS

Latest satellite images

Dotsero 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).