June 10, 2005

Soufriere Hills

Here is a report I had to write for science...enjoy:

For over three hundred years, Montserrat, a small island situated in the West Indies, was the quiet homeland to farmers and immigrants, who fell in love with the scenic terrain. The peaceful island was home to some 13,000 residents, living a comfortable lifestyle, as well as several destinations, popular with tourists from England and the United States. However, the small island of 39 square miles was not a peaceful as it seemed from the surface. Its premier geologic feature, a stratovolcano named Soufriere Hills, located on the southernmost tip of the island, only appeared to be quiet, but underneath the surface, newly formed magma was increasing in activity and pressure.
Since the end of its last eruptive period in the 1600s, the Soufriere Hills have been building pressure due to a subduction zone beneath the island, pushing the plates of the North and South American continents under the Caribbean plate. The heat from the earth melts the rock that makes up the plates and produces magma. As this magma makes its way to the surface of the earth, pressure is built up and must find a way to be released. Geoff Wadge, a geologist from the University of Reading in England, compared this natural phenomenon to a lava lamp. “It accumulates at depth and then blips its way up,” he said. As the magma reaches the surface, accompanied by of various sorts of gasses, they must find a way to release their accumulated pressure. This occurs as a volcanic eruption, a common spectacle throughout the world.
Volcanic eruptions can be anywhere between minor, giving off only steam and a small amount of ash and extreme, producing lava and mud flows while spewing out hardened rock. While Soufriere Hills has never had a tremendously damaging eruption, such as one to the extent of Mount Saint Helens, in Washington State, its eruptions are still quite dangerous and highly destructive. The effects of its ash and lava are not far reaching, but are a constant threat to the nearby towns and villages, covering homes and farms in ash, while crushing windows and cars with rocks and boulders ejected by the volcano. Many cities, including the capital of the island, Plymouth, have fallen victim to pyroclastic flows, setting fire to evacuated stores and homes, already smothered in ash.
The first of the recent series of eruptions, beginning in 1995, caught the inhabitants of the island off guard, but scientists were fully aware of the volcanoes past and present seismic activity. During the 1930s, magma and seismic activity began to dramatically increase, resulting in seasonal earthquakes. Scientists set to work to predict possible eruptions, arriving at several different answers regarding where exactly the volcano would erupt from. They were split. They could not agree on whether the volcano would erupt from the summit, as many volcanoes do, or from the side, through one of the solfataras. Solfataras, also called fumaroles, are vents that release volcanic gas and water vapor, making it a possible exit of a larger amount of matter, equaling an eruption. Aside from the activity, the volcano had an eruptive past. It was fully active in the 1600s, when it was first settled and the mountain named, by the Irish, and several thousand years ago as well. Despite the geologic unrest, immigrants were attracted to the island that reminded them greatly of their motherland and decided to begin their new lives on the petite islet.
Also pointing to an active past is the composition of the volcano. Soufriere Hills is a stratovolcano. A stratovolcano, sometimes called a composite volcano, is constructed of layers of volcanic rock and ash that have settled around the neck, allowing the volcano to grow after each eruption. Often there may be little or no lava traveling away from the vent after an eruption, but when lava is present it is very thick, and quickly becomes solid, preventing lava to flow far away from the opening. Compared to shield volcanoes, stratovolcanoes are exceptionally violent, producing far more explosive eruptions that shoot ash hundreds of feet into the air allowing it to travel very far. Pyroclastic flows released by these types of volcanoes can destroy forests and towns by burning them with hot, toxic gasses. Rocks darting from the volcano, and acid rain formed by the gasses can pose threats to plant and animal life, as well as people and possessions.
For the island of Montserrat, the most recent eruptions have been devastating, as there had not been witnesses to view any other eruption in Soufriere Hills’ past. This set of eruptions began in 1995, when earthquakes began to indicate the waking of the dormant volcano. In 1996, the volcano finally began erupting. By 1997, fierce eruptions spewed ash and rock, threatening the local residence, and forcing Great Brittan, the possessor of the island, to consider evacuating all of the residence. As citizens of the island migrated to the northern region, protected by hills, many minor ash emitting eruptions continued. Pyroclastic flows became rather common, as they reached and destroyed areas that had been considered safe at one time, forcing even more of the population from their homes. The volcano is still active to this day, giving off steam, ash and dangerous fumes, while creating large earthquakes and triggering rockslides. The volcano has undergone so many dramatic eruptions that the crater has caved in several times and had to be rebuilt.
The latest eruptive history of the volcano has shaken the lives of many who live on the island. Everyone has been evacuated from the southern part of the island, the area closest to the volcano. Over 8,000 people have left and moved back to neighboring islands, or to Great Brittan. What remained of the islands industry and production after the 1989, Hurricane Hugo, was ruined further by the beginning of ash fall and destroyed entirely by pyroclastic flows. Everyone who lived on the island, and has continued to live there, has been gathered to the northernmost tip of the island, an area that was not populated until after the eruptions. Even thought the occupants of Montserrat are now safe from pyroclastic flows and rocky debris, they still get frequent ash fall, damaging planes and farms.
The volcano has also taken a toll on the health of the island. Toward the beginning of 1999, scientists discovered and announced the presence of deadly levels of cristobalite. Cristobalite is a fine, colorless mineral that has been ejected by the volcano in vast amounts. The occurrence of this mineral has the potential to give the islanders lung disease, leading to death.
The land’s natural landscape has changed a great deal since the beginning of the eruptions. Areas where trees and plants of all sorts were once plentiful are now barren wastelands, cleared by pyroclastic flows. Ash has covered nearly every part of the island, adding to the soil and creating a blanket over the lush terrain.
The recent eruption of Soufriere Hills has the effected the island of Montserrat and all of the surrounding area a great deal. It has destroyed forests and animal life, homes, and cities. Citizens have had to face the harsh reality that a volcano is more than gorgeous feature, accenting the land, but a realistic danger that can release its disasters at any moment. Though few people have died, many lives have been ruined. People were forced from their homeland to new places. For nearly ten years they have had to live with a dangerous volcano, constantly expelling vast amounts of ash and toxins into their air, and the air of the surrounding islands. Now that nearly everything has been lost the volcano, the remaining residents have very little left to keep them hanging on. Though the people are returning to their enjoyable ways of life they live in a whole new world that has been opened up by the volcano. “We don’t know when the volcano will do something.” Says Matilda Farrell, “The geologists do the best they can, but they don’t know either. Only God is in control. We can only pray that when the next event come, there is no danger to it. We still have to thank God that we have food and shelter and friends.” Along with the hope of returning to their ash covered homes when the volcano seeps back into dormancy, this is all that the inhabitants of Montserrat have to keep them going, hope, and friendship.

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