Volcanoes!
VII. Volcanoes
A. Volcano: an opening in Earth’s lithosphere which allows hot magma, volcanic ash and gases to escape from below the planet's surface.
B. Result from tectonic plate movement
1. Divergence
a. Ex. Mid-Atlantic Ridge
2. Subduction
a. Ex. Mt. St. Helens
3. Hotspots
a. Ex. Hawaiian Islands & Yellowstone Caldera
4. NOT at transform or continental collision boundaries
a. No magma at these boundaries
B. Result from tectonic plate movement
1. Divergence
a. Ex. Mid-Atlantic Ridge
2. Subduction
a. Ex. Mt. St. Helens
3. Hotspots
a. Ex. Hawaiian Islands & Yellowstone Caldera
4. NOT at transform or continental collision boundaries
a. No magma at these boundaries
Volcano vocabulary
Cleveland volcano in the Aleutian Islands off of Alaska.
Here are some words you should know:
magma: molten rock that has not reached the surface
lava: molten rock that has come to the surface
vent: opening where magma rises to surface; a volcano may have several vents - a main vent and secondary vents
magma chamber: a large underground pool of magma found beneath the surface of the Earth. The magma in such a chamber is under great pressure, and given enough time, that pressure can gradually break the rock around it creating outlets or vents for the magma.
Ring of Fire: a region around the Pacific tectonic plate boundary where most of the world's volcanoes and earthquakes occur (see below) The Ring of Fire has 75% of the Earth's volcanoes (over 450 volcanoes) and 90% of the Earth's earthquakes.
The picture above is of the one of the volcanoes created by the subduction of the Pacific plate beneath the North American oceanic plate, creating the island arc known as the Aleutian Islands.
Click on the picture above to learn about volcanoes on Nat Geo Volcano 101
magma: molten rock that has not reached the surface
lava: molten rock that has come to the surface
vent: opening where magma rises to surface; a volcano may have several vents - a main vent and secondary vents
magma chamber: a large underground pool of magma found beneath the surface of the Earth. The magma in such a chamber is under great pressure, and given enough time, that pressure can gradually break the rock around it creating outlets or vents for the magma.
Ring of Fire: a region around the Pacific tectonic plate boundary where most of the world's volcanoes and earthquakes occur (see below) The Ring of Fire has 75% of the Earth's volcanoes (over 450 volcanoes) and 90% of the Earth's earthquakes.
The picture above is of the one of the volcanoes created by the subduction of the Pacific plate beneath the North American oceanic plate, creating the island arc known as the Aleutian Islands.
Click on the picture above to learn about volcanoes on Nat Geo Volcano 101
D. Four MAIN types
There are 4 main types of volcanoes: shield, cinder cone, composite (or stratovolcano), and lava dome . If you click on each type, it will take you to another page in my website that describe them in more detail
There are 4 main types of volcanoes: shield, cinder cone, composite (or stratovolcano), and lava dome . If you click on each type, it will take you to another page in my website that describe them in more detail
Where are volcanoes?
As we saw in our Astrojournal exercise, volcanoes typically form at the boundaries of tectonic plates. In particular, they occur where plates are diverging (such as along the mid-Atlantic ridge) and where they are subducting (such as along the Pacific plate). They do not typically form where tectonic plates are sliding past each other (transform movement such as along the California coast). The Ring of Fire is a region around the Pacific tectonic plate boundary where most of the world's volcanoes and earthquakes occur (see picture below) The Ring of Fire has 75% of the Earth's volcanoes (over 450 volcanoes) and 90% of the Earth's earthquakes.
Volcanoes can also form away from tectonic plates boundaries where there are hotspots, or areas where magma may rise closer to the surface. Hawaii's volcanoes are good examples of hotspot volcanoes.
Volcanoes can also form away from tectonic plates boundaries where there are hotspots, or areas where magma may rise closer to the surface. Hawaii's volcanoes are good examples of hotspot volcanoes.
Comparing the size of different volcanoes
_Here's a diagram showing how tiny Mt. Rainier is compared
to the the Big Island of Hawaii. WOW! It doesn't look so tiny in the
picture on the right! The island is actually a mountain that was formed beneath
the ocean. It is taller than the tallest continental mountain, Mt.
Everest, in the Himalayas.
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Nyiragongo Crater: Journey to the Center of the World
You have to check out these AMAZING photos of researchers going right up to the rim of the Africa's Nyiragongo crater - risking their lives to gather data. This is located along the diverging rift where water is already starting to fill in, creating Africa's Great Lake's region. In June 2010, a team of scientists and intrepid explorers stepped onto the shore of the lava lake boiling in the depths of Nyiragongo Crater. Photographer Olivier Grunewald was within a meter of the lake itself, giving us a unique glimpse of it's molten matter. (28 photos total)
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Weekly Volcano Activity Report
The USGS and the Smithsonian post a weekly report on recent volcanic activity around the world. Click on the image to go to that website