Mashu
Caldera in Japan
Key Facts
Elevation
857 m (2,812 ft)
Type
Caldera
Location
43.572°, 144.561°
Region
Kuril Volcanic Arc
Rock Type
Andesite / Basaltic Andesite
Tectonic Setting
Subduction zone
Location
Loading map...
Overview
Mashu is a 6-km-wide Holocene caldera that truncates a stratovolcano constructed on the ESE rim of the large Kussharo caldera. The steep-walled caldera, filled by Lake Mashu, is one of the scenic highlights of Hokkaido. Following caldera collapse about 7,000 years ago, a small andesitic stratovolcano, Kamuinupuri, was formed beginning about 4,000 years ago, creating a reentrant into the SE side of the deep caldera lake.
A large explosive eruption about 1,000 years ago, the latest dated eruption, created a 1. 2 x 1. 5 km crater at the summit of Kamuinupuri.
The small island of Kamuishu in the center of Lake Mashu represents the tip of a mostly submerged dacitic lava dome.
Volcanic Hazards & Risk Assessment
Primary Hazards
- Pyroclastic flows and surges
- Large explosive eruptions (VEI 4+)
- Ash fall and tephra deposits
- Lahars and debris flows
Risk Level
Geological Composition & Structure
Rock Types
Tectonic Setting
Age & Formation
Eruption Statistics & Analysis
| Metric | Value | Global Ranking | Significance |
|---|---|---|---|
| Total Recorded Eruptions | Unknown | Low | Moderately active volcano |
| Maximum VEI | VEI Unknown | Minor | Local impact potential |
| Recent Activity | 946 years ago | Historical | Historically active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in Northwestern Pacific Volcanic Regions
Quick Info
- •Smithsonian ID: 285081
- •Evidence: Eruption Dated
- •Epoch: Holocene
About the Photo
The deep blue waters of 6-km-wide Mashu caldera are seen here from its western rim. The small island of Kamuishu in the center of Lake Mashu (right-center) is the tip of a mostly submerged lava dome. Mashu is a Holocene caldera of a volcano constructed on the ESE rim of the Kussharo caldera. Following caldera collapse, Kamuinupuri (whose lower flanks are visible at the far right) formed beginning about 4,000 years ago.
Copyrighted photo by Shun Nakano, 2001 (Japanese Quaternary Volcanoes database, RIODB, http://riodb02.ibase.aist.go.jp/strata/VOL_JP/EN/index.htm and Geol Surv Japan, AIST, http://www.gsj.jp/).
Authority Sources
Related Volcanoes
Basic Information
This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.