# Volcano Watch — Galeras, Mauna Loa, Decade Volcanoes

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On Thursday an explosion in the crater of Galeras Volcano in Colombia killed six volcanologists attending an international workshop attended by more than 90 scientists, and killed an additional three people not attending the workshop.

On Thursday an explosion in the crater of Galeras Volcano in Colombia killed six volcanologists attending an international workshop attended by more than 90 scientists, and killed an additional three people not attending the workshop.

Some of the participants were on a field excursion to the volcano when the small phreatomagmatic explosion occurred at about 1:40 p.m. Thursday. Of the six volcanologists killed, four were from Colombia, one was from Great Britain and the last from Russia.

Fifteen American scientists attended the workshop and three of them were injured, one seriously, during the explosion. Another scientist from Ecuador was also injured in the blast. Five U.S. Geological Survey scientists had planned to attend the workshop, but the American Embassy in Bogota had denied them permission to travel due to reports of terrorist activity in the area.

Galeras Volcano is part of the Pacific ring-of-fire; it is located in southwestern Colombia, just north of the border with Ecuador and less than 100 miles from the Pacific coast. The volcano rises nearly 14,000 feet above sea level and is a large (25 kilometers in diameter, 300 cubic kilometers in volume), complex volcanic center. The eastern flank lies under the city of Pasto, capital of the state of Narino, and site of the international workshop.

Galeras was recently specified as one of the Decade Volcanoes by the International Association of Volcanology and Chemistry of the Earth's Interior because of the extreme volcanic risk this active volcano poses. All active, and most dormant, volcanoes are hazardous, but many have relatively low risk because no one lives in the potentially affected areas. More than 400,000 people live on the flanks of Galeras.

Galeras began to show signs of unrest in 1988, and an earlier international workshop was held there in 1989 to assist national and local efforts to respond to any volcanic crises and to provide training to other Latin American countries concerned with emergency response to volcanic crises. The earlier workshop was designed as a training activity by the Volcano Disaster Assistance Program of the U.S. Geological Survey, a program funded by the U.S. Geological Survey and Agency for International Development's Office of U.S. Foreign Disaster Assistance Program.

The current workshop was a "Decade Volcano" workshop aimed at increasing monitoring of this dangerous volcano and training of volcanologists in Central and South America. Most of the 33 participants in the group on the rim and inside the crater were gas geochemists who were attempting to standardize their sampling techniques and to calibrate chemical analyses of volcanic gas samples among the many laboratories worldwide.

The eruption was preceded by emission of a small ash plume at 6:43 a.m. the morning of January 14 and by the occurrence of a sequence of seismic tremors. It is unclear why the group apparently failed to heed such early warning signs and proceeded into the crater area. This tragedy points to the importance of international cooperation and the U.S. Geological Survey's role in contributing to volcano monitoring efforts worldwide in order to reduce volcanic risk.

The volcanology community is small and many of the participants at this workshop, including several of those killed, have visited the Hawaiian Volcano Observatory of worked with members of our staff in the past. We shall miss our friends and colleagues.

"Decade Volcano" status was also conferred on two volcanoes in the U.S. because of the high risk they pose: Mt. Rainier in Washington and Mauna Loa in Hawaii. The Hawaiian Volcano Observatory, as part of the Hawaii Center for Volcanology, is currently planning a Decade Volcano workshop for next fall to discuss strategies for improving our monitoring of Mauna Loa Volcano and thereby reducing volcanic risk.