July 28, 1995

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Soufriere Hills, Montserrat

Soufriere Hills Volcano on the island of Montserrat in the Caribbean became active on July 18, 1995. This is the first eruption of the volcano in historic time. Five scientists and technicians from the U.S. Geological Survey's Volcano Crisis Assistance Team, headquartered at the Cascades Volcano Observatory in Vancouver, Washington, are responding to this eruption with additional seismic equipment and expertise. They will join a team from the University of the West Indies and two scientists sent by the French government. The Caribbean Disaster Emergency Agency is assisting in the preparation of contingency plans for different eruption scenarios.

Villagers on Montserrat reported loud rumbling noises, a light ashfall, and a strong sulfurous odor on July 18. The eruption was preceded by three years of elevated seismic activity and a more intense earthquake swarm that began on July 14. The initial eruption was apparently a small phreatic (steam) event which produced minor ash that was distributed about the island by the wind. Satellite imagery analyzed by scientists at NOAA showed no signs of this eruption plume, as would be expected for such a small event. On July 19, observers confirmed that small steam explosions were occurring in an area about 1.5 kilometers northeast from the summit. The explosions were spaced about 20 minutes apart and sent ash and steam about 40 meters high. On July 22, light ashfall occurred in the capital of Plymouth, located about four kilometers west of the summit, and in villages to the southwest of the summit.

The activity, though minor so far, is being taken quite seriously because of the risk to the people and because other similar volcanoes in the region have had large, destructive eruptions in the past. Montserrat is only one of a chain of volcanic islands strung across the Caribbean in a roughly north-south direction. It is north of Guadeloupe Island, home of Soufriere Volcano, which has had nine eruptions since 1660, with the most recent in 1976. Farther south is Micotrin Volcano on the Island of Dominica, which last erupted in 1880. The next active volcano to the south is the infamous Mont Pelee on the island of Martinique. Its eruption in 1902 was the third most deadly in historic time. About 28,000 people were killed by glowing avalanches of hot ash, which raced, at speeds estimated at 150 kilometers per hour, through the city of St. Pierre. La Soufriere Volcano, which erupted in 1718, 1812, 1902, and 1979, lies to the south on the island of St. Vincent. The eruption here in 1902 killed 1,600 people only hours before the more devastating eruption of Mont Pelee on Martinique. Soufriere means "sulfur" in French, hence the inordinate number of volcanoes that bear the same name. The southernmost active volcano in the chain is named Kick 'em Jenny. It is entirely submarine and has had eight small eruptions between 1937 and 1977.

The Hawaiian Volcano Observatory (HVO) owes its origins to the eruption of Mont Pelee in 1902. Dr. Thomas A. Jaggar, Professor of Geology at M.I.T., established the Hawaiian Volcano Observatory in 1912 to learn more about volcanoes in order to prevent future disasters, such as those he had observed in St. Pierre. The motto of his new observatory was "Ne plus haustae aut obrutae urbes" or "No more shall the cities be destroyed." It is a motto that still guides the work of the U.S. Geological Survey's Hawaiian, Cascades, and Alaska Volcano Observatories.