Farallon de Pajaros

Geography & Climate

Farallon de Pajaros is located in United States, within the Mariana Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 20.55° N, 144.89° E in the Northern Hemisphere, the volcano lies within a tropical climate zone. At just 337 meters above sea level, Farallon de Pajaros is a relatively low-elevation volcanic feature. Despite its modest height, it remains an active geological formation with the same underlying magmatic processes as its taller counterparts. 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

Farallon de Pajaros 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 Farallon de Pajaros, 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

Farallon de Pajaros has 16 recorded eruptions in the geological database, spanning from 1864 CE to 1952 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1952 CE, reaching VEI 2 on the Volcanic Explosivity Index. This level of eruptive frequency indicates a persistently active volcanic system that warrants ongoing monitoring. The most recent eruption in 1952 CE places this volcano within the modern era of volcanological observation.

Significance

With 16 recorded eruptions, Farallon de Pajaros has a substantial eruptive history that provides valuable data for understanding volcanic behavior and assessing future hazards in the Northwestern Pacific Volcanic Regions region. Given its recent activity, Farallon de Pajaros is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

The small 2-km-wide island of Farallon de Pajaros (also known as Uracas) is the northernmost and most active volcano of the Mariana Islands. Its relatively frequent eruptions dating back to the mid-19th century have caused the andesitic volcano to be referred to as the "Lighthouse of the western Pacific." The symmetrical, sparsely vegetated summit is the central cone within a small caldera cutting an older edifice, remnants of which are seen on the SE and southern sides near the coast. Flank fissures have fed lava flows that form platforms along the coast. Eruptions have been recorded from both summit and flank vents.

— Smithsonian Institution, Global Volcanism Program