GPS instruments provide scientists with a high precision, 3D data about ground movement over time. CalVO currently monitors its volcanoes daily with about 60 continuous GPS receivers, while many other GPS sites are measured on a campaign basis (annually, or whenever feasible). The sites are clustered around each volcano, with the majority at Long Valley Caldera, which spans the largest area monitored by CalVO. New stations can be added if deformation occurs over a broader region than expected. CalVO's current daily monitoring sites are owned and operated several partners including: USGS-Volcano Science Center, USGS-Earthquake Science Center, NASA Jet Propulsion Laboratory (JPL), Harvard University, and UNAVCO.
Other ground-based instruments, including tiltmeters (which measure tilt of the ground) and strainmeters (which measure the amount of tension or compression in the ground), contribute to the well rounded observation capabilities of CalVO.
InSAR satellite imagery is collected routinely every few days by a number of international satellites. InSAR observes deformation in the direction that the satellite camera is looking and covers a wide area.