Pagan

Geography & Climate

Pagan is located in United States, within the Mariana Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 18.13° N, 145.80° E in the Northern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 570 meters above sea level, Pagan 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

Pagan 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 United States near Pagan, 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 basalt / picro-basalt, 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

Pagan has 20 recorded eruptions in the geological database, spanning from 1864 CE to 2021 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 1981 CE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 1981 CE (VEI 4), 1923 CE (VEI 3), 1873 CE (VEI 3). With an average interval of roughly 8 years between eruptions over a span of 157 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. With eruptive activity as recently as 2021 CE, Pagan remains an actively monitored volcano.

Significance

With a maximum recorded VEI of 4, Pagan 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. 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, Pagan is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Pagan Island, the largest and one of the most active of the Mariana Islands volcanoes, consists of two stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed within calderas, 7 and 4 km in diameter, respectively. North Pagan at the NE end of the island rises above the flat floor of the northern caldera, which may have formed less than 1,000 years ago. South Pagan is a stratovolcano with an elongated summit containing four distinct craters. Almost all of the recorded eruptions, which date back to the 17th century, have originated from North Pagan. The largest eruption during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.

— Smithsonian Institution, Global Volcanism Program