Report on Toliman (Guatemala) — 23 April-29 April 2003

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 April-29 April 2003
Managing Editor: Gari Mayberry

Please cite this report as:

Global Volcanism Program, 2003. Report on Toliman (Guatemala). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 23 April-29 April 2003. Smithsonian Institution and US Geological Survey.

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14.612°N, 91.189°W; summit elev. 3158 m

All times are local (unless otherwise noted)

A landslide on the outer flanks of Tolimán volcano passed through and buried portions of a mountain village at 0418 on 23 April. Regional authorities blamed steep slopes, wet soils, and minor tremors. The disaster struck the village of Chichicaste, which lies along the volcanic front ~300 km W of the capital, Guatemala City. Tolimán and the area stricken sit on the S side of Lake Atitlán, the 18 x 12 km lake filling the depression of Guatemala's famous Atitlán caldera.

As of the afternoon of 23 April, the Guatemalan agency CONRED reported 200 people evacuated, 20 missing, and 6 confirmed dead. Known damage to infrastructure included 40 homes at risk, another 12 with severe damage, and 6 destroyed. The village and environs had been specifically mentioned as vulnerable to landslide hazards in a government report issued in September 2002 following a similar disaster then. Mudslides in highland areas are common during the wet season, an interval that often occurs during late March through September.

Geologic Background. Volcán Tolimán is a large andesitic stratovolcano that rises above the south shore of Lake Atitlán. Tolimán was constructed within the Pleistocene Atitlán III caldera, near its inferred southern margin. A shallow elliptical crater truncates the summit, and a minor subsidiary peak to the SSW also has a shallow crater. In contrast to the tephra-covered surface of its twin volcano to the south, Volcán Atitlán, the surface of Tolimán is draped by prominent thick lava flows. Many of the flows were erupted from vents on the volcano's flanks and form a highly irregular shoreline on the south side of Lake Atitlán. No historical eruptions are known from Tolimán. However, a lava flow that entered Lake Atitlán from the parasitic lava dome of Cerro de Oro on the northern 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.

Sources: Coordinadora Nacional para la Reducción de Desastres (CONRED), Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)