All About Mt. Omuro

大室山 Mt. Ōmuro

Some facts about Mt. Ōmuro, the most famous volcano in Izu


Google Earth: Ito city and Mt. Ōmuro (bottom center)

I live in Ito, the most populous city on the Izu peninsula. The most defining geographical feature of Ito, is Ōmuro Mountain, a dormant volcano.


South slope of Mt. Omuro in winter
Cinder Cone Features - EarthHow

Local geologists describe Mt. Ōmuro as a scoria cone volcano – aka a cinder cone. “Cinder cones are the most common type of volcano in the world. They are small in comparison to the other types of volcanoes. In fact, they’re only tens to hundreds of meters in size. But at the same time, they’re very steep typically with a bowl-shaped crater at the summit.” (


Scoria - Photo by Jonathan Zander

Everywhere you go around Ito, you see scoria that came from Mt. Ōmuro.


Lava flow from Mt Ōmuro (in brown)
Lava flowed about 4 kilometers to the ocean
Background Photo by Magda Ehlers from Pexels

In late winter, for more than 700 years, the annual yamayaki event takes place at Mt. Ōmuro. Yamayaki literally means “mountain burning.” The original purpose of the event was to produce high quality kaya (sedge grass) that was used for thatched roofs. Over the past 100 years, thatched roofs have virtually disappeared in Japan, but the tradition carries on as a tourism event. The entire mountain burns in about half an hour.

Mt. Omuro Mountain Burning Event

For more information about Mt. Ōmuro and the surrounding area, here are a few websites to visit: is only in Japanese, but you can paste the address into Google Translate and view the content.


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