Presentation on theme: "A POWERPOINT BY CHANTEL MONCUR. A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. Volcanic eruptions."— Presentation transcript:
A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. Volcanic eruptions have been known to knock down entire forests. An erupting volcano can trigger tsunamis, flash floods, earthquakes, mudflows and rockfalls.
Most volcanoes are 10,000 to 100,000 years old Gasses that are emitted from volcanoes are sometimes really dangerous and can cause pollution problems. Magma is called lava after it comes out of a volcano.
The biggest known volcano in our solar system is on Mars. Its name is Olympus Mons and it measures 600km wide and 21km high. The word volcano actually comes from the roman god of fire, Vulcan.
Mount Vesuvius destroyed the ancient city of Pompeii in AD79. Has erupted many times but the most recent was in 1944. Mount Vesuvius is considered one of the most dangerous volcanoes in the world!
There are more than 1500 active volcanoes on the Earth. We currently know of 80 or more which are under the oceans. Active volcanoes in the U.S. are found mainly in Hawaii, Alaska, California, Oregon and Washington.
A lahar is a type of mudflow or debris flow composed of pyroclastic material, rocky debris, and water. The material flows down from a volcano, typically along a river valley. It is very dangerous because it's consistency and the way it acts is very much like cement. It is liquid when it's moving, but when it stops, it solidifies. This can cause just as much devastation as lava itself.
How are volcanoes formed? Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface. Over time as the volcano continues to erupt, it will get bigger and bigger. Why do volcanoes erupt? The Earth's crust is made up of huge slabs called plates, which fit together like a jigsaw puzzle. These plates sometimes move. The friction causes earthquakes and volcanic eruptions near the edges of the plates.
What is the difference between lava and magma? Magma is liquid rock inside a volcano. Lava is liquid rock (magma) that flows out of a volcano. Fresh lava glows red hot to white hot as it flows. Why does lava take a long time to cool down? Lava cools slowly because lava is a poor conductor of heat. Lava flows slow down and thicken as they harden.
Volcano Experiment: Here is an experiment on how to make a soda bottle volcano with Mentos. Volcano Experiment: Volcano Experiment: Here is another experiment on how to make a baking soda volcano. Volcano Experiment: