Date: Entry: Volcanoes Pg 202-203

1. Volcanic eruptions Constructive force I. Add new rock to existing land II. Make new islands B. Destructive force I. Changes landscape around the volcano

Mount Saint Helens

Mount Saint Helens

When Mt. St. Helens erupted.

2. Anatomy of a volcano Vent – opening that allows magma to escape Magma – melted rock inside volcano Lava – erupted magma outside volcano Volcano – the vent and the mountain that forms around it from cooled lava, ash, cinders, and rock

3. Location of volcanoes Most occur along plate boundaries Area in Pacific Ocean where volcanoes are common called Ring of Fire

C. Hot spots Form in the center of moving plates Example – Hawaiian Islands, Yellowstone

For your viewing pleasure Volcanic Eruption’s

Mt. St Helens

Two years after the 1980 eruption

Pahoehoe flow

Ropey Pahoehoe

Aa lava flow

Lava fountain

Lava meets ocean

Vulcanologists sampling gases

Mount Pinatubo ash plume

Dormant 500 years July 16, 1990 7.8 eq. April 1991 magma started rising to surface 1000s small eqs accrued June 15th massive eruption ejected 5 cu.km vol. Material Ash cloud rose 22 miles Satellites tracked ash cloud several times around globe Pyroclastic flows filled valleys 660 ft. thick 20 million tons of sulphur dioxide into stratosphere global temps dropped .50C.

Ex. Mauna Ulu, Hawaii

Mauna Loa, Hawaii erupting 1984

Mount Etna, Italy

Mount Rainer, Washington

Crater Lake, Oregon

Aniakchak Volcano, Alaska

Devil’s Tower, South Dakota                                       

Clingman’s Dome, Great Smoky Mountain National Park, Tennessee