Batur

Geography & Climate

Batur is located in Indonesia, within the Sunda Volcanic Arc of the broader Sunda-Banda Volcanic Regions. Situated at 8.24° S, 115.38° E in the Southern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 1,711 meters above sea level, Batur is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a caldera, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Batur 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 Indonesia near Batur, 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

Batur has 20 recorded eruptions in the geological database, spanning from 1905 CE to 1999 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1974 CE, reaching VEI 2 on the Volcanic Explosivity Index. With an average interval of roughly 5 years between eruptions over a span of 94 years, this is one of the more frequently active volcanoes in the database. This persistent activity suggests a robust and well-supplied magma system beneath the volcano. The most recent eruption in 1999 CE places this volcano within the modern era of volcanological observation.

Significance

Its 20 recorded eruptions make it one of the most prolific volcanoes in our database, reflecting a persistent and well-documented eruptive history that has provided volcanologists with extensive data for understanding eruption patterns and forecasting future activity. Given its recent activity, Batur is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

The historically active Batur is located at the center of two concentric calderas NW of Agung volcano. The outer 10 x 13.5 km caldera was formed during eruption of the Bali (or Ubud) Ignimbrite about 29,300 years ago and now contains a caldera lake on its SE side, opposite the Gunung Abang cone, the topographic high of the complex. The inner 6.4 x 9.4 km caldera was formed about 20,150 years ago during eruption of the Gunungkawi Ignimbrite. The SE wall of the inner caldera lies beneath Lake Batur; Batur cone has been constructed within the inner caldera to a height above the outer caldera rim. The Batur stratovolcano has produced vents over much of the inner caldera, but a NE-SW fissure system has localized the Batur I, II, and III craters along the summit ridge. Recorded eruptions have been characterized by mild-to-moderate explosive activity sometimes accompanied by lava emission. Basaltic lava flows from both summit and flank vents have reached the caldera floor and the shores of Lake Batur in historical time.

— Smithsonian Institution, Global Volcanism Program