Ranakah

Geography & Climate

Ranakah is located in Indonesia, within the Sunda Volcanic Arc of the broader Sunda-Banda Volcanic Regions. Situated at 8.64° S, 120.53° E in the Southern Hemisphere, the volcano lies within a tropical climate zone. At 2,288 meters above sea level, Ranakah 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 cluster, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Ranakah 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 Ranakah, 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

Ranakah has 2 recorded eruptions in the geological database, spanning from 1987 CE to 1991 CE. The most powerful recorded event was a severe eruption capable of regional ash fall and pyroclastic flows in 1987 CE, reaching VEI 3 on the Volcanic Explosivity Index. These eruptions span roughly 4 years of volcanic history. The most recent eruption in 1991 CE places this volcano within the modern era of volcanological observation.

Significance

With a maximum recorded VEI of 3, Ranakah has produced eruptions capable of generating pyroclastic flows and significant ash fall in the surrounding area. While not among the largest eruptions globally, VEI 3 events pose serious hazards to local populations and can disrupt regional air travel. Given its recent activity, Ranakah is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

The Anak Ranakah (Child of Ranakah) lava dome was formed in 1987 in an area without previous recorded eruptions at the base of the large older lava dome of Gunung Ranakah. An arcuate group of lava domes extending about 12 km west from Gunung Ranakah to Poco Mandosawa occurs on the outer N flanks of the poorly known Poco Leok caldera on western Flores Island.

— Smithsonian Institution, Global Volcanism Program