Karkar

Geography & Climate

Karkar is located in Papua New Guinea, within the Bismarck Volcanic Arc of the broader Southwestern Pacific Volcanic Regions. Situated at 4.65° S, 145.98° E in the Southern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 1,839 meters above sea level, Karkar is a moderately sized peak that remains accessible to hikers and researchers for much of the year. 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

Karkar 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 Papua New Guinea near Karkar, 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

Karkar has 19 recorded eruptions in the geological database, spanning from 7140 BCE to 2014 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 730 CE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 1643 CE (VEI 3), 730 CE (VEI 4), 520 CE (VEI 4). This level of eruptive frequency indicates a persistently active volcanic system that warrants ongoing monitoring. With eruptive activity as recently as 2014 CE, Karkar remains an actively monitored volcano.

Significance

With a maximum recorded VEI of 4, Karkar has demonstrated the capacity for significant explosive eruptions that can impact regional aviation, agriculture, and communities tens of kilometers from the summit. VEI 4 eruptions produce ash columns reaching 15-25 kilometers into the atmosphere. With 19 recorded eruptions, Karkar has a substantial eruptive history that provides valuable data for understanding volcanic behavior and assessing future hazards in the Southwestern Pacific Volcanic Regions region. Given its recent activity, Karkar is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Karkar is a 19 x 25 km forest-covered island that is truncated by two nested summit calderas. The 5.5 km outer caldera was formed during one or more eruptions, the last of which occurred 9,000 years ago. The steep-walled 300-m-deep, 3.2 km diameter, inner caldera was formed sometime between 1,500 and 800 years ago. Cones are present on the N and S flanks of this basaltic-to-andesitic volcano; a linear array of small cones extends from the northern rim of the outer caldera nearly to the coast. Recorded eruptions date back to 1643 from Bagiai, a pyroclastic cone constructed within the inner caldera, the floor of which is covered by young, mostly unvegetated andesitic lava flows.

— Smithsonian Institution, Global Volcanism Program