The United States Geological Survey (USGS) uses various seismic tools, including creepmeters, pore pressure monitors, tiltmeters and strainmeters. These instruments keep track of the volcanic and fault activities that can trigger earthquakes.
The USGS employs seismic monitoring devices around the United States, particularly in the western part of the country, including Hawaii. Creepmeters evaluate fault slip by logging the change in position between a pair of monuments erected on opposing sides of a fault. Pore pressure monitors register differences in fluid pressure in deep boreholes that may result from fault movements.
Tiltmeters gauge ground tilt that occurs due to volcanic uplifts or fault slips. Strainmeters are typically placed inside boreholes and used to record crustal strains in areas where volcanic, earthquake and fault activities are prominent.