Toliman

Geography & Climate

Toliman is located in Guatemala, within the Central America Volcanic Arc of the broader Middle America-Caribbean Volcanic Regions. Situated at 14.61° N, 91.19° W in the Northern Hemisphere, the volcano lies within a tropical climate zone. At 3,158 meters above sea level, Toliman 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 composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Toliman 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 Guatemala near Toliman, 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.

GVP Reference Summary

Volcán Tolimán is a large andesitic stratovolcano that rises above the S shore of Lake Atitlán. It was constructed within the Pleistocene Atitlán III caldera, near its inferred southern margin. A shallow elliptical crater truncates the summit, and a subsidiary peak to the SSW also has a shallow crater. In contrast to the tephra-covered surface of Volcán Atitlán immediately to the S, the surface is covered by thick lava flows. Many of the flows were erupted from vents on the flanks and form a highly irregular shoreline on the S side of Lake Atitlán. A lava flow that entered Lake Atitlán from the Cerro de Oro lava dome on the N flank was considered by Newhall et al. (1987) to be less than a few thousand years old based on the thickness of sediment accumulated on the sublacustral part of the flow.

— Smithsonian Institution, Global Volcanism Program