About Osorezan
Osorezan is a stratovolcano rising to 878 meters (2,881 feet) in Japan's Northwestern Pacific Volcanic Regions. Its last known eruption was in 1787 CE. The volcano has produced 1 recorded eruption.
Geography & Climate
Osorezan is located in Japan, within the Northeast Japan Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 41.28° N, 141.12° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 878 meters above sea level, Osorezan is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.
Geological Context
Osorezan sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Japan near Osorezan, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.
Eruption History Summary
Osorezan has 1 recorded eruption in the geological database, spanning from 1787 CE to 1787 CE.
GVP Reference Summary
Osorezan, on the Shimokita Peninsula in northernmost Honshu, contains a 5-km-wide caldera partly occupied by a shallow lake that drains through the N caldera wall. Dissected lava domes ring the caldera floor. The andesitic-to-dacitic volcano is largely Pleistocene in age, with activity dating back about 800,000 years. The last identified distal tephra deposit was erupted during the late Pleistocene. The only report of historical activity was in a Tohoku district travel document published in 1787, which stated that Yakeyama in Mutsu country (Osoreyama) had erupted. Older residents reported that large fires and clouds were sometimes seen from the summit, accounting for the volcano's local name, Yakeyama, or "Burning Mountain" (Murayama, 1987). Earthquake swarms have been documented during the second half of the 20th century, and magma bodies have been detected beneath the volcano.
— Smithsonian Institution, Global Volcanism Program
1 Recorded Eruption
| Year | VEI | Type | Area |
|---|---|---|---|
| 1787 | — | Confirmed Eruption | — |
Real-Time Data
USGS Alert Level
Thermal Anomalies
Frequently Asked Questions About Osorezan
Is Osorezan an active volcano?+
Osorezan is classified as active based on credible evidence of past eruptions. Although its last known eruption was in 1787 CE, volcanologists consider it capable of erupting again.
When did Osorezan last erupt?+
The most recent recorded eruption of Osorezan occurred in 1787 CE. The eruption was classified as a "Confirmed Eruption." Osorezan has 1 recorded eruption in total.
How high is Osorezan?+
Osorezan has a summit elevation of 878 meters (2,881 feet) above sea level. At 878 meters, it is a relatively low-elevation volcano.
What type of volcano is Osorezan?+
Osorezan is classified as a Stratovolcano. Stratovolcanoes (also called composite volcanoes) are steep, conical volcanoes built up by many layers of hardened lava, tephra, and volcanic ash. They are among the most common and dangerous types, known for explosive eruptions.
Where is Osorezan located?+
Osorezan is located in Japan, in the Northwestern Pacific Volcanic Regions. More specifically, it lies within the Northeast Japan Volcanic Arc. Its exact coordinates are 41.279° latitude, 141.120° longitude.
Is it safe to visit Osorezan?+
Osorezan can generally be visited, but as with any volcano, visitors should check local conditions and any advisory notices before traveling. Japan may have specific regulations for accessing volcanic areas. Guided tours are often the safest and most informative way to experience a volcano.
