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Volcanic Eruptions and Hazards

Volcanic Eruptions and Hazards: What is a volcano? A volcano is a vent or chimney that connects molten rock (magma) from within the Earth’s crust to the Earths surface. The volcano includes the surrounding cone of erupted material. | Volcanic Eruptions and Hazards What is a volcano? A volcano is a vent or chimney that connects molten rock (magma) from within the Earth’s crust to the Earths surface. The volcano includes the surrounding cone of erupted material. vent cone magma chamber conduit A volcano is a place on the Earth’s surface where hot, molten rock (called magma) breaks through. As we will see there are many different types of volcanoes and material that is erupted. However, in general a volcano is classed as “active” if it erupts lava, rock, gas or ash, or if it shows seismic (earthquake) activity. A volcano is dormant if it hasnt erupted for a long time (less than 1 million years) but could again one day. An extinct volcano will never erupt again. Presenters; go through the different parts of a volcano: Magma: Molten rock beneath the surface of the earth. Magma chamber: The subterranean cavity containing the gas-rich liquid magma which feeds a volcano. Conduit: A passage followed by magma in a . | Volcanic Eruptions and Hazards What is a volcano? A volcano is a vent or chimney that connects molten rock (magma) from within the Earth’s crust to the Earths surface. The volcano includes the surrounding cone of erupted material. vent cone magma chamber conduit A volcano is a place on the Earth’s surface where hot, molten rock (called magma) breaks through. As we will see there are many different types of volcanoes and material that is erupted. However, in general a volcano is classed as “active” if it erupts lava, rock, gas or ash, or if it shows seismic (earthquake) activity. A volcano is dormant if it hasnt erupted for a long time (less than 1 million years) but could again one day. An extinct volcano will never erupt again. Presenters; go through the different parts of a volcano: Magma: Molten rock beneath the surface of the earth. Magma chamber: The subterranean cavity containing the gas-rich liquid magma which feeds a volcano. Conduit: A passage followed by magma in a volcano. Vent: The opening at the earths surface through which volcanic materials issue forth. Cone: A volcanic cone built entirely of loose fragmented material (pyroclastics) and (or) lava flows erupted from the vent. Erupted material builds up with each eruption forming the cone. How and why do volcanoes erupt? Hot, molten rock (magma) is buoyant (has a lower density than the surrounding rocks) and will rise up through the crust to erupt on the surface. Same principle as hot air rising, e.g. how a hot air balloon works When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts. Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption! Think about shaking a carbonated drink and then releasing the cap. Small amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption Where the magma just trickles out of the volcano (lava flow). Why Do Volcanic .