Socorro

Geography & Climate

Socorro is located in Mexico, within the Mathematicians Ridge Volcanic Province of the broader Eastern Pacific Volcanic Regions. Situated at 18.78° N, 110.95° W in the Northern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 1,050 meters above sea level, Socorro is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a shield, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Socorro is situated along a rift zone, where tectonic plates are pulling apart. As the crust thins and fractures, magma rises to fill the gap, creating volcanic activity. Rift volcanism typically produces more fluid lava flows rather than explosive blasts, which means communities near Socorro in Mexico generally face slower-moving hazards like lava flows and ground fissures rather than sudden pyroclastic events. However, rift volcanoes can still generate significant ash emissions and gas releases that affect local air quality. The dominant rock type is trachyte / trachydacite, an intermediate to silica-rich volcanic rock. This composition typically produces more viscous magma, leading to more explosive eruptions with ash columns and pyroclastic flows. Andesitic and dacitic magmas build pressure before erupting, which is why volcanoes with this rock chemistry are often associated with Plinian-style eruptions that can send ash tens of kilometers into the atmosphere and disrupt aviation across entire regions.

Eruption History Summary

Socorro has 6 recorded eruptions in the geological database, spanning from 3090 BCE to 1993 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1951 CE, reaching VEI 2 on the Volcanic Explosivity Index. This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1993 CE places this volcano within the modern era of volcanological observation.

Significance

With 6 recorded eruptions on file, Socorro has enough documented activity to help scientists identify patterns in its eruptive behavior. Given its recent activity, Socorro is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Socorro, the SE-most of the Revillagigedo Islands south of Baja California, is the summit of a massive, predominately submarine basaltic shield volcano capped by a largely buried, 4.5 x 3.8-km-wide summit caldera. A large tephra cone and lava dome complex, Cerro Evermann, forms the summit, and along with other cones and vents, fills much of the Pleistocene caldera. Rhyolitic lava domes have been constructed along flank rifts oriented to the N, W, and SE, and silicic lava flows from summit and flank vents have reached the coast and created an extremely irregular shoreline. Late-stage basaltic eruptions produced cones and flows near the coast. Only minor explosive activity, some of which is of uncertain validity, has occurred from flank vents in historical time dating back to the 19th century. In 1951 a brief phreatic eruption ejected blocks, and the gas column reached 1200 m altitude. A submarine eruption occurred during 1993-94 from a vent 3 km W of the island during which large scoriaceous blocks up to 5 m in size floated to the surface without associated explosive activity.

— Smithsonian Institution, Global Volcanism Program