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Transcript of Volcanoes
same, except lava is above ground and magma is underground. What causes a volcano to erupt? Volcanoes usually form at the edges of plates. A lot form in the ring of fire. The ring of fire is a band of volcanoes that circles much of the Pacific Ocean. Believe it or not, there are four main types of volcanoes. One type of volcano is called a cinder cone volcano. Cinder cone volcanoes are small, hill sized volcanoes that spew lava out into the air. Another kind is called a shield volcano. It is a kind of volcano that's shaped like a bowl and has grooves in the side from basalt lava. One more type of volcano is called a composite volcano. Composite volcanoes are made up of layers, alternating lava rock and regular rock. Also, they're really big. Some of them can be up to 2,500 meters high! The last kind of volcano is called a lava dome. Lava dome volcanoes are smallish volcanoes. Their eruption doesn't go very far, so most of it spills down the side. That creates a sort of dome around the volcano. Some famous volcanoes are: Mt. Vesuvius, Italy It erupted in 79 CE, and it killed more than 16,000 people. Mt. Etna, Italy. It's not famous for killing lots of people, but for how many times it has erupted. It's erupted about 60 times since 1600 CE. It last erupted on February 19, 2013. And finally, Mt. St. Helens, Washington State. It's mostly famous for it's eruption in 1980, which killed 57 people. It last erupted on July 10, 2008. How do scientists know when a volcano is about to erupt? Well, there are a couple warning signs that tell scientists if a volcano is going to erupt soon. One warning sign is a small earthquake under a volcano. Also, the volcano swells a tiny bit before it erupts. Scientists also use many tools to predict
volcano eruptions. One of the tools that scientists use is called a tiltmeter.A Tiltmeter measures the angle of the volcano slope, and when the volcano swells up bit because of pressure, the tiltmeter warns you. A tiltmeter is so accurate that it can detect one millimeter of a difference on the slope of a volcano. Another way scientists can predict when a volcano is going to erupt is by taking a gas sample. If there is a sudden rise in the amount of So2 in the air above the volcano, then it is going to erupt soon. Scientists have been able to predict many volcano eruptions, such as: Mt Etna (which I told you about earlier) was predicted to erupt between 2007 and 2015. As you now know, it erupted in 2013. And also, Mount Nyiragongo, Africa. It was predicted to erupt a week before it actually erupted. In all, scientists are not completely accurate when it comes to predicting exactly when a volcano will erupt, but they can tell if a volcano is going to erupt soon (like Mount Nyiragongo) or at least give it an amount of time for it to erupt (like Mt Etna). And now... The moment we've all been waiting for... "THE RING OF FIRE" BY DR. RICHARD ALLEY!!!!!!!