Mount St.Helens

1. Mount St.Helens

2. Mt. St. Helens EruptionCauses Mt. St. Helens is situated in the Rocky Mountains near the west coast of the USA. It lies near to a destructive plate boundary where the Juan de Fuca Plate is moving south-east and the North American Plate is moving north-east. As the small plate is being forced under the larger plate it is going into the mantle where it melts. When this happens, molten rock rises into the crust. It builds up in the magma chamber and eventually forces its way to the surface.

3. Impact On Landscape After the start of the May 18th eruption, an enormous column of ash thrust 15 miles into the sky. It continued to eject ash for about nine hours. The plume deposited ash and pumice on top of the blast deposit downwind from the volcano. The ash was blown eastward by the wind at about 60 miles per hour. Some of the ash reached the eastern United States within 3 days. Small particles entered the jet stream and circled the Earth within two weeks. The blast killed every form of plant and animal life for a distance of 25km north of the volcano. Even fully-grown fir trees were flattened, up to 30km away. About 7000 animals died , including elk and bears.

4. Impact on the People The damage caused by the eruption ran into the billions and 61 people were killed with 198 needing rescued. Farms were destroyed and the entire area was covered in ash and left in darkness. The ash caused a lot of pollution putting the peoples health at risk. Some people were swept away by land slides.

5. Human Responses • The nature and severity of Mt. St. Helen eruption surprised everyone and its effects were devastating. Although many charities were involved in the relief work, the biggest aid agency was the government and the Federal (national) government. This is called official aid. It fell into three categories: • Aid in preparing for the eruption • The state authorities evacuated people from the exclusion zone, which saved many lives. A few residents, however, refused to leave, as did the scientists, reporters and cameramen who were only there for the eruption.

6. 2.Short term aid after the eruption This involved (a) rescuing stranded people (b) and then clearing up afterwards. The authorities were able to mobilise many people and much equipment quickly to help in these operations. 3. Long term aid This was concerned with returning the area to what it was originally like before the eruption, and this took several years.