Saturday, December 15, 2012

It's ALIVE... Volcanoe Classifications

Classifications for volcanoes that are still active are different than that of volcanoes that are dead.

1) Dormant volcano is a volcano that was dead, and may erupt again in the near future.

2) Extinct volcanoes are volcanoes that are likely to never erupt again. There is no seismic activity.

3)Hawaiian eruption is when the volcano produces a huge amount of lava that may shoot into the air like a geyser, or come through a crack and produce a long sheet of lava called a fire curtain.

4)Strombolian eruptions are when the volcano erupts frequently, and noisily, but often the eruptions are mild.

5)Plinian eruptions are when volcano expels gas and dust into the atmosphere which forms ash clouds that travel for hundreds of miles. These eruptions are usually violent and are hundreds of times more powerful than an atomic bomb. Mt. St. Helens was a Plinian eruption.

Saturday, December 1, 2012

Volcanoe Classifications

Wow... we have just learned how a volcano is formed... but did you know that there are many different types of volcanoes? Sure... so let's check out what those are today!

The types of volcanoes are actually classified on how they are formed.
1)Cinder cone volcano - is formed by explosions of small fragments of solidified lava or tephra. These eruptions build up cone shaped domes and typically don't get as big as other volcanoes.
2)Shield volcanoes are formed by molten lava.The lava doesn't cool immediately and so it runs out forming a longer shelf type formation. Usually these volcanoes have a crater at their top. They also get cracks around their base from which molten lava also erupts. This causes the volcano to get very broad in diameter.
3) Composite volcanoes are ones that erupt both lava and cooled rock called cinders. The shape of this volcano is somewhere between the cinder cone and the shield volcano.
4)Calderas are formed when the magma chamber of the volcano was close to the surface and after it had cooled it collapsed. These huge crater type depressions typically fill with water.