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Comment: 14:44 - 16:10 (01:26)
Source: Annenberg/CPB Resources - Earth Revealed - 13. Volcanism
Keywords: "Robert Tilling", volcano, prediction, "ground deformation", uplift, "seismic monitoring", earthquake, magma, fracture
Our transcription: It is currently estimated that volcanoes pose a potential threat to more than half a billion people across the globe.
In an effort to lessen the damage from volcanoes, geologists are refining their methods of forecasting eruptions.
Probably all volcanic eruptions are preceded by and accompanied by measurable changes in the physical or chemical state of the volcano.
One of the principal means of monitoring or measuring the changes, at least the physical configuration of the volcano, is by means of what we call "ground deformation studies".
This simply is just a term for measuring the changes in the shape of the volcano.
Most volcanoes will swell up or inflate prior to an eruption, and this causes the volcano in itself, the surface of the volcano, to be uplifted and the sides tilted out and bulge outward.
The other major component in tracking a volcano or monitoring a volcano is the seismic monitoring of earthquakes that occur beneath the ground because as the molten rock forces its way up toward the surface to erupt -- it has to make room for itself; it's got to fracture the rock to move up higher or laterally.
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