A tiltmeter is a device used to measure the slope, or tilt, of the Earth's surface. It works much like a spirit level, with a liquid bubble inside a chamber that responds to changes in tilt.

Volcanologists use a tiltmeter to determine the slope of a volcano's side. This information is used to predict eruptions, such as Mount Pinatubo in 1991.

Tiltmeters are also employed as part of the instrumentation for large dams, as part of a dam safety system to provide information on the dam's condition and an early warning of dam failure.

See also

• Dam safety system
• Differential GPS
• Remote sensing methods
• Rock mechanics ( Applied geomechanics )

External links

• ASDSO: Association of State Dam Safety Officials
• Hawaiian Volcano Observatory's Kīlauea website
• Laboratory for Terrestrial Physics at Goddard Space Flight Center

Measuring instruments