The Volcano Website

 

The General Info.

    What is a volcano?  Volcanoes are vents in the Earth's surface that release lava, ash, and from within the Earth, the mantle.  The lava that comes pouring out of active volcanoes is caused by very high temperatures and pressure that melt the rocks into magma.  Once magma rises to the surface it is called lava.  Basalt, andesite, and rhyolite are the 3 common volcanic rock types. Basalt is the most common and least harsh, rhyolite is the most harsh.

    Where?  Plate boundaries are where most volcanoes form. Because of the movement of these areas, violent results [such as volcanoes] are likely to happen.  At convergent boundaries plates are coming together.  Plates separating are called divergent.  Plates that slide against each other are called transform-fault. Volcanoes can happen at convergent and divergent boundaries, or at hot spots.  Hot spots heat parts of the plate above it's spot in the mantle.

    How does the plates' movement form volcanoes?  At convergent plates subduction happens, 2 plates collide and 1 goes under the other.  Parts of the plate melts as it gets pushed into the Earth's mantle, forming magma that pours onto the surface as lava [Example: Mt. Saint Helens].  At divergent boundaries hot rock, from the space between the plates, are pushed up to the surface.  Volcanoes created this way are usually under oceans, shield volcanoes.  Shield volcanoes can also form at hotspots.  Volcanoes rise and die down as plates move over hotspots.  This is how island chains usually form [Example: The Hawaiian Islands].

Interesting Fact

    Volcanoes are named after an italian island north of Sicily, Vulcano.

Mt. Saint Helens: a.k.a. "the Fuji of America"

    Mt. Saint Helens is a stratovolcano in Washington.  Its latitude is 46.2N and longitude 122.18W.  Mt. Saint Helens is 2,549 meters [8,364 feet.] This volcano has had continuous activity since 1980.  The activity includes occasional erruptions of steam and ash, and sometimes pyroclastic flows, or clouds of ash. Mt. Saint Helens hasn't always been active though.

    Mt. Saint Helens awoke in 1980 with an eruption from it's sleep since 1857.  Mt. Saint Helens is 40,000 years old- considered to be young.  These eruptions were huge and were the first in the United States since the eruptions at Lassen Peak in 1914.  This volcano provided scientists with great data collection obtaqined from the climatic eruption of May 18, 1980.  This eruption had an energy release of 24 megatons thermal energy.

Mt. Vesuvius

    Mt. Vesuvius is a 300,000 year old volcano near Naples, Italy.  At this location the African Plate meets the Eurasian Plate.  Its latitude is 40.8 and latitude of 14.4E.  This volcano has an elevation of 4,200 feet.  17,000 years ago this stratovolcano formed after the Somma volcano collapsed.

    Mt. Vesuvius has a timeline of violent eruptions.  The first to be described was in A.D. 79 [thought to be on Aug. 24] destroyed 2 towns, Herculaneum and Pompeii.  Since then Mt. Vesuvius has erupted several times, another violent one in 1631, and the last one in 1944.  Two eruptions , that were among the biggest in Europe, occured in 5960B.C. and 3580B.C.  An area of 31 square miles was uplifted in1983-1985.  In some places upto 5.9 feet!  This damaged homes, the harbor, and the tourist industry.  36,000 people had to be moved.

Hazards of Volcanoes

    To be in any area near an active volcano is hazardous.  Between 1980 and 1986 an average of 845 people died- each year, due to volcanic hazards.The number of deaths are increasing because of the amount of people populating around active volcanoes, not becaquse of more volcanic activity.  The list of volcanic hazards include: volcanic earthquakes, directed blasts, tephra, volcanic gases, lava flows, debris avalanches, landslides, tsunamis, and clouds of ash.  For further information and prevention, go toVolcanic Hazards.

Causes of Eruptions

    The reason for eruptions is for the Earth to release pressure, steam, magma, and ash.  This stuff is released because of pressure on a magma chamber.  When the magma chamber has filled it erupts.  There are many factors to determine the kind of eruption.  The amount of water equals how much steam.  The amount of silica equals how gooey the lava is.  For more details and step-by-step pictures go to Volcanoes Online.

Signs That An Eruption Is Likely

    Warnings are usually provided by volcanoes before an eruption.  Although, withoutwarning steam and ash eruptions could occur.  For, eruptions with magma spewing out as lava, you can expect several signs beforehand.  Earthquakes, deformed ground surfaces, and changes in temperature [extreme heat] and chemistry [sulfur] of ground and spring waters are common before such an eruption.  If such signs ocur it could just mean there is volcanic activity, an eruption could be farther off in the future.  For more information go to : When will a volcano erupt?