Section 2 - Ways that volcanic eruptions can be predicted

A tiltmeter is an instrument designed to measure very small changes from the horizontal level, either on the ground or in structures. [1] A similar term, in less common usage, is the inclinometer. Tiltmeters are used extensively for monitoring volcanos, the response of dams to filling, the small movements of potential landslides, the orientation and volume of hydraulic fractures, and the response of structures to various influences such as loading and foundation settlement. Tilmeters may be purely mechanical or incorporate vibrating-wire or electrolytic sensors for electronic measurement. A sensitive instrument can detect changes of as little as one arc second.
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Seismometers are instruments that detect disturbances in Earth's crust. Used mostly for earthquake detection, they can also measure the turbulence of a volcano's magma activity. The disturbance or activity is recorded on a seismograph, a sheet of paper that shows the intensity of the activity.