Strainmeters can resolve strain changes of less than one part per billion (1 mm in 1000 km) at short periods, which makes them ideal for capturing short-term transient deformation over time intervals ranging from seconds to months; at longer periods, GPS techniques are more stable, and by using GPS and strainmeters together, EarthScope will capture a fuller range of Earth deformation processes. Borehole strainmeters have been used for more than two decades to measure crustal deformation near active faults and volcanoes in the United States, Taiwan, China, Iceland and Japan.