Tambora

Geography & Climate

Tambora is located in Indonesia, within the Sunda Volcanic Arc of the broader Sunda-Banda Volcanic Regions. Situated at 8.25° S, 118.00° E in the Southern Hemisphere, the volcano lies within a tropical climate zone. At 2,850 meters above sea level, Tambora rises above the surrounding terrain into montane or subalpine conditions. The elevation creates distinct ecological zones along its flanks, from forested lower slopes to exposed rocky terrain near the summit. 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

Tambora 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 Tambora, 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 trachybasalt / tephrite basanite, 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

Tambora has 7 recorded eruptions in the geological database, spanning from 3910 BCE to 1967 CE. The most powerful recorded event was a super-colossal eruption, among the largest in recorded geological history in 1812 CE, reaching VEI 7 on the Volcanic Explosivity Index. This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1967 CE places this volcano within the modern era of volcanological observation.

Significance

Tambora has produced at least one eruption of VEI 7 or higher, placing it among the most powerful volcanic systems ever documented on Earth. Eruptions of this magnitude eject hundreds of cubic kilometers of material, can cause volcanic winters lasting years, and have historically led to crop failures and famine across continents. With 7 recorded eruptions on file, Tambora has enough documented activity to help scientists identify patterns in its eruptive behavior. Given its recent activity, Tambora is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

The massive Tambora stratovolcano forms the entire 60-km-wide Sanggar Peninsula on northern Sumbawa Island. The largely trachybasaltic-to-trachyandesitic volcano grew to about 4,000 m elevation before forming a caldera more than 43,000 years ago. Late-Pleistocene lava flows largely filled the early caldera, after which activity changed to dominantly explosive eruptions during the early Holocene. Tambora was the source of history's largest explosive eruption, in April 1815. Pyroclastic flows reached the sea on all sides of the peninsula, and heavy tephra fall devastated croplands, causing an estimated 60,000 fatalities. The eruption of an estimated more than 150 km3 of tephra formed a 6-km-wide, 1250-m-deep caldera and produced global climatic effects. Minor lava domes and flows have been extruded on the caldera floor at Tambora during the 19th and 20th centuries.

— Smithsonian Institution, Global Volcanism Program