As of 2015, there are no instruments available that can actually predict an earthquake, but instruments used to detect earthquakes include creepmeters, strainmeters, tiltmeters and pore pressure monitors. These tools are used by the United States Geological Survey in fault lines and volcanoes in the United States. Each tool has a unique and equally important role in helping seismologists determine when earthquakes occur.
Creepmeters record the displacement, or change in distance, between piers, which are two set points located on opposite sides of a fault line. Similarly, strainmeters record changes in pressure in the Earth's crust when movement occurs. Pore pressure monitors show the changes in fluid pressure levels in boreholes, usually caused by seismic activity. Lastly, tiltmeters record the change in Earth's surface rotation in the events of volcanic uplift or fault movement.