Volcano Watch: Another way HVO tracks changes on Hawaiian volcanoes

On the west side of Mauna Loa summit, a campaign GPS (center-right) measures its location for a period of two to three days. This site has been occupied every year by helicopter since 1994. Mauna Kea, Hualalai and Haleakala can be seen in the distance. (S. Conway/Special to West Hawaii Today)

Geodetic surveys measure the change in shape of our volcanoes due to changes in magma supply and storage. The USGS Hawaiian Volcano Observatory has a long history of using many different types of instruments and technologies over the decades to detect these changes.