Plate tectonics continued. Volcanoes. Apologia Physical Science.

My last post was about plate tectonics.  You can find that here.  I wanted to break the topics included with plate tectonics because there is a lot to learn and/or review.  So first up is volcanoes.

Quick review of the plates.  The idea of plate tectonics is the idea that the continents drifted from place to place breaking apart from each other, grinding against each other, and colliding with each other with resultant mountains, earthquakes, and volcanoes.

When the plates move, it causes friction which in turn cause volcanoes near the edge of the plates. Volcanoes are mountains.  A volcano is formed from magma from within the earth's upper mantle. Volcanoes open downward into a pool of molten rock which is below the earth's surface.  The pressure builds up thus causing an eruption.  Rock fragments and gases are forced up through the opening and spill over and/or fill the air with lava fragments.  As time goes by and a volcano continues to erupt, the volcano increases in size.

Active, dormant, and extinct are the three categories scientist use to categorize volcanoes.

Active volcano in Hawaii.

Active means the volcano has recently erupted and may erupt again soon.

Mauna Kea in Hawaii-dormant. 
Last eruption 2460 BCE

Dormant means the volcano has not erupted in an extended period of time but has the potential to erupt again in the future.

Malheur Butte in Oregon-extinct.

Extinct means the volcano erupted thousands of years ago and will most likely never erupt again.






The extinct volcano (pictured above) named Malbeur Butte in Oregon is rumored to be haunted.  According to the legends, this volcano was once a spot where witches met secretly.  It is said that all kinds of shadowy figures appear at the site of the volcano after dark.  These figures make strange noises to scare visitors away.

Other cool facts you may not know.

There are approximately 1500 active volcanoes with over 80 of those being under the oceans.  These active volcanoes are mostly found in Washington, Oregon, California, Alaska, and Hawaii.

Mauna Lao in Hawaii is currently the world's largest active volcano on earth.

Have you ever heard of the volcano bird?
This is a highly endangered bird known as the Maleo.  The Maleo bird depends on the geothermal energy to help incubate its massively large eggs.  These eggs are approximately five times larger than that of a regular chicken egg.  The female Maleo bird approximately the same size as a duck which makes seeking out volcanic areas to assist in incubating the eggs necessary.

image source

Did you know that the tallest volcano in our solar system is not even on earth?  It is on Mars, of course!  Olympus Mons is a volcano that rises 27 km and measures 550 across.

A volcanic eruption can also trigger a tsunami (a large ocean wave caused by an underwater earthquake/volcanic explosion), earthquakes, rockfalls, mudslides, and flash floods.

Next up: Earthquakes.

Find out more:
Khan Academy has a great collection of videos.
Dynamic earth.
How volcanoes work.
How stuff works, volcanoes and plate tectonics.
Pangaea video
National Geographic