Ranau

Caldera in Indonesia

Key Facts

Elevation

1,854 m (6,083 ft)

Type

Caldera

Location

-4.871°, 103.925°

Region

Sunda Volcanic Arc

Rock Type

Dacite

Tectonic Setting

Subduction zone

Location

Loading map...

Overview

Ranau is an 8 x 13 km Pleistocene caldera partially filled by the crescent-shaped Lake Ranau. The caldera lies along the Great Sumatran Fault that extends the length of Sumatra. Incremental formation of the caldera culminated in the eruption of the voluminous Ranau Tuff about 0.

55 million years ago. A morphologically young post-caldera stratovolcano, Gunung Semuning, was constructed within the SE side of the caldera to a height of more than 1,200 m above the lake surface. The volcano has not been mapped in sufficient detail to determine the age of its latest eruptions, although fish kills and sulfur smells in the late 19th and early 20th centuries may be related to volcanism.

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

Population at RiskModerate

Infrastructure RiskModerate

Aviation RiskSignificant

Geological Composition & Structure

Rock Types

Primary

Dacite

Silica Content

Varied composition

Tectonic Setting

Subduction zone

Formed by oceanic plate subduction, typically producing explosive eruptions due to water-rich magmas.

Age & Formation

Epoch

Holocene

Evidence

Evidence Uncertain

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	Unknown	Historical	Historically active

Monitoring & Alert Status

Monitoring Networks

Global Volcanism Program

International eruption database

Current Status

Normal

No recent activity. Routine monitoring continues.

Nearby Volcanoes in Sunda-Banda Volcanic Regions

Regional Volcanic Activity

The Sunda-Banda Volcanic Regions contains multiple active volcanic systems. Cross-regional magma interactions and tectonic stresses can influence eruption patterns across the entire arc. Monitor regional seismic activity and volcanic alerts.

Quick Info

•Smithsonian ID: 261251
•Evidence: Evidence Uncertain
•Epoch: Holocene

About the Photo

Lake Ranau partially fills the 8 x 13 km Ranau caldera. A morphologically young post-caldera stratovolcano, Gunung Semuning, its summit obscured by clouds below the bottom center lake shore in this NASA Landsat image (N is to the top), was constructed within the SE side of the caldera to a height of more than 1,600 m above the caldera lake surface. The age of the most recent eruptions at Ranau are not known, but fish kills and the smell of sulfur in the late 19th and early 20th centuries may have been related to eruptions within the lake.

NASA Landsat 7 image (worldwind.arc.nasa.gov)