Information on Mount Saint Helens

Mt St. Helens   Mt St. Helens was a Hugh volcano, then after the years it worn into a small yet still pretty big mountain. Volcanic eruptions alter the surface of the Earth's lithosphere, the hard, outermost shell of the Earth. Many eruptions have built Mount St. Helens' beautiful cone shape. The May 18, 1980, eruption, however, dramatically changed the volcano's size and shape. It tore off the mountain's top and blasted a giant crater in its side.

The number of well-located earthquakes at Mt. St. Helens has increased again this month, this time from 165 events in May to 318 in June. These quakes were so small, however, that the total seismic energy release was about the same as the month of May. Smaller eruptions have continued since the year 1980. Mostly happening at the bottom of the volcano’s crater, each of the eruptions squeezes out a layer of lava. Scientist believes that the volcano is slowly rebuilding itself into its old form.

On May 18 1980 at 8:30 am, a magnitude of 5.1 shook Mount St. Helens and a bulge surrounding areas slid away in a gigantic rockslide and an avalanche, releasing pressure and triggering a major ash eruption of the volcano. Thirteen hundred feet (400m) of the peak blew outwards. At the end there is 24 squares miles of valley was filled by a debris avalanche. Fifty-seven people were killed or are still missing. More than nine hours of vigorous plume ash erupted, eventually reaching 12 to 15 miles above sea level.

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