Daily Archives: March 17, 2008

Anatomy of Magma

Magma is molten or partially molten rock beneath the Earth’s surface. When magma erupts onto the surface, it is called lava. Magma typically consists of (1) a liquid portion (often referred to as the melt); (2) a solid portion made … Continue reading

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GENERIC FEATURES A volcanic vent is an opening exposed on the earth’s surface where volcanic material is emitted. All volcanoes contain a central vent underlying the summit crater of the volcano. The volcano’s cone-shaped structure, or edifice, is built by … Continue reading

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The Modified Mercalli Scale

In seismology a scale of seismic intensity is a way of measuring or rating the effects of an earthquake at different sites. The Modified Mercalli Intensity Scale is commonly used in the United States by seismologists seeking information on the … Continue reading

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Richter Scale

Seismologists use a Magnitude scale to express the seismic energy released by each earthquake. Here are the typical effects of earthquakes in various magnitude ranges: Earthquake Severity Richter Earthquake Magnitudes Effects Less than 3.5 Generally not felt, but recorded. 3.5-5.4 … Continue reading

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