Mount Saint HelensMount Saint Helens By Martina

Type of VolcanoType of Volcano Mt. St. Helens is a mountain located in Mt. St. Helens is a mountain located in

Washington, USA. Washington, USA.

It is an active Stratovolcano. A startovolcano, It is an active Stratovolcano. A startovolcano, also called composite volcano, is a tall, conical also called composite volcano, is a tall, conical volcano which has many layers. Those layers are volcano which has many layers. Those layers are made of hardened lava, ash and other volcanic made of hardened lava, ash and other volcanic components. components.

Composite volcanoes form when volcanoes Composite volcanoes form when volcanoes erupt with lava flows and explode by throwing out erupt with lava flows and explode by throwing out their molten material. They are found at plate their molten material. They are found at plate boundaries.boundaries.

History of Mt. St. HelensHistory of Mt. St. HelensThe volcano was named by a British explorer, in The volcano was named by a British explorer, in

honor of his Britannic Ambassador which was called honor of his Britannic Ambassador which was called Baron St. Helens. Baron St. Helens.

Mt. St. Helens is a 40,000 year old volcano. Mt. St. Helens is a 40,000 year old volcano. More than 25,000 years ago the volcano was shaped More than 25,000 years ago the volcano was shaped differently. In fact the dome was smaller and had a differently. In fact the dome was smaller and had a different shape. The pretty big eruptions which different shape. The pretty big eruptions which happened 25,000 years ago, rearranged the shape of happened 25,000 years ago, rearranged the shape of the dome with its hardened lava and ash. the dome with its hardened lava and ash. The biggest eruption of Mt. St. Helens was on May 18, The biggest eruption of Mt. St. Helens was on May 18, 1980. Some eruptions before that are: 1980. Some eruptions before that are: • The one is 1831, which wasn’t very big. The one is 1831, which wasn’t very big. • The one in 1842, which threw ashes very far.The one in 1842, which threw ashes very far.There was another eruption in 1857, which didn’t do any There was another eruption in 1857, which didn’t do any damage. After that, the volcano became dormant, and damage. After that, the volcano became dormant, and stayed like that until May 18, 1980.stayed like that until May 18, 1980.

The Big Eruption: May 18, May 18, 1980 1980

The eruption in 1980 The eruption in 1980 Mt. St. Helens is a very famous volcano Mt. St. Helens is a very famous volcano

because of its catastrophic eruption which because of its catastrophic eruption which took place on May 18, 1980. It was the worst took place on May 18, 1980. It was the worst volcanic disaster in recorded history of USA. volcanic disaster in recorded history of USA. The eruption started at 8:32 am and The eruption started at 8:32 am and continued until 6:30 pmcontinued until 6:30 pm. .

Eruption SequenceEruption Sequence

Description/Measurements Description/Measurements of the Eruptionof the Eruption

When Mount. St. Helens Erupted, lava didn’t come out of it, but only ash did. Before the explosion, the ice and the snow on the top of the mountain started melting. Within three weeks a bugle was created on the northern side of the volcano. Than, small earthquakes with the Richter magnitudes between 2.5 and 4.2, occurred. After the small earthquakes, little amounts of smoke and ash columns about 2,100m high started coming out of the crater of the volcano. From that, people understood that the volcano would erupt sometime soon. On May 18, at 8.32 am, an earthquake with a Richter magnitude of 5.2 (about 1 mile beneath the volcano) shakes Mt. St. Helens. The northern broadside of the volcano detached (Landslide). The landslide traveled 175-250 km/h. The water of the Spirit Lake (a lake located close to the forest) was displaced with the landslide, and 10m high waves covered up houses and camps. The landslide caused an avalanche which covered an area of 62km2. It also caused many mud flows. At the same time an explosion made the crater of the volcano become bigger and also made big amount of ash come out of it. The ash moved 100km/h.

About three hours and 30 minutes after the About three hours and 30 minutes after the eruption, the ash of Mount St. Helens reached eruption, the ash of Mount St. Helens reached Moscow, and 16 hours after the eruption began, the Moscow, and 16 hours after the eruption began, the ash reached central Colorado. ash reached central Colorado.

Before the Eruption, Mount St, Helens was Before the Eruption, Mount St, Helens was 2,950 m tall. When the northern broadside of the 2,950 m tall. When the northern broadside of the volcano detached, Mount. St. Helens became 401m volcano detached, Mount. St. Helens became 401m shorter, which means that after the eruption the shorter, which means that after the eruption the volcano was 2,549m tall. volcano was 2,549m tall.

Human ImpactHuman Impact The eruption killed 57 people, including Harry R. The eruption killed 57 people, including Harry R.

Truman, who became famous because he decided not to Truman, who became famous because he decided not to evacuate before the eruption. evacuate before the eruption. If the eruption occurred one day later, when the loggers If the eruption occurred one day later, when the loggers would be at work, the death toll would have been much would be at work, the death toll would have been much higher. higher.

A film crew was dropped by an helicopter on May A film crew was dropped by an helicopter on May 23, 1980, to film the remains of the volcano. On May 25, 23, 1980, to film the remains of the volcano. On May 25, 1980, there was another eruption, and luckily, the crew 1980, there was another eruption, and luckily, the crew survived and was rescued two days later by National survived and was rescued two days later by National Guard (Kind of army) helicopters. In the eruption, large Guard (Kind of army) helicopters. In the eruption, large amounts of ash came speeding out of the crater along amounts of ash came speeding out of the crater along with deep earthquakes. with deep earthquakes. $1.1 billion = the worth of the damage done by the $1.1 billion = the worth of the damage done by the Eruption Eruption

Environmental EffectsEnvironmental EffectsMt. St. Helens’ eruption in 1980 caused lots of Mt. St. Helens’ eruption in 1980 caused lots of

forests and houses to burn. Even the trees, 32 km away forests and houses to burn. Even the trees, 32 km away were destroyed! About 7,000 important animals for the were destroyed! About 7,000 important animals for the chain (Food chain: Animal eating one animal that is chain (Food chain: Animal eating one animal that is eaten by another animal) died. Also 40,000 salmons eaten by another animal) died. Also 40,000 salmons died because of the mudflows. died because of the mudflows.

The Spirit lake which was displaced by the The Spirit lake which was displaced by the landslide, was 12m underneath mud. The roads also landslide, was 12m underneath mud. The roads also had lots of damage. In fact, 321km of railways, roads had lots of damage. In fact, 321km of railways, roads and highways were destroyed. and highways were destroyed.

BibliographiesBibliographiesBarrows, Calder. Barrows, Calder. The Ecological Impact of a Volcano-The Ecological Impact of a Volcano-Mt. St. HelensMt. St. Helens..http://www.maxwell.syr.edu/plegal/tips/t2prod/barrowhttp://www.maxwell.syr.edu/plegal/tips/t2prod/barrowswq.htmlswq.html

History of Mt. St. Helens. November 11, 2007. http://www.scsc.k12.ar.us/2001Outwest/PacificNaturalHistory/Projects/BookV/Default.htm

Mount St. Helens.Mount St. Helens. November 9, 2007. November 9, 2007. http://http://en.wikipedia.org/wiki/Mt._St._Helensen.wikipedia.org/wiki/Mt._St._Helens

Mount St. Helens-The Sleeping Monster. Mount St. Helens-The Sleeping Monster. November November 12, 2007. 12, 2007. http://www.angelfire.com/pa3/facts/http://www.angelfire.com/pa3/facts/

Shadwick, Brian, and Susan Barlow. Shadwick, Brian, and Susan Barlow. About Science About Science 33. 2003: pp 19-20.. 2003: pp 19-20.

Teacher’s Guide to Stratovolcanoes of the World. November 12,2007. http://www.ngdc.noaa.gov/seg/hazard/stratoguide/intro.html

1980 Eruption of Mount St. Helens. 1980 Eruption of Mount St. Helens. November 10, November 10, 2007. 2007. http://en.wikipedia.org/wiki/1980_eruption_of_Mount_St._Helens#Buildup_to_disaster