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Annual Deformation Surveys Completed
for Kilauea and Mauna Loa volcanoes

Map showing displacement vectors between 1999 and 2001 on Mauna Loa and Kilauea volcanoes, Hawaii
Map showing direction and amount of horizontal movement of GPS stations on Mauna Loa and Kilauea volcanoes, Hawai`i. Click for larger-sized map and explanation.

For many years, scientists of the Hawaiian Volcano Observatory have conducted annual surveys of benchmarks on Kilauea and Mauna Loa in order to track how the volcanoes swell, shrink, or otherwise change shape. In collaboration with scientists from Stanford University, we recently completed several different types of surveys to track vertical and horizontal movements of the past year. The results show a pattern of movement similar to that observed by previous surveys.

Kilauea's summit subsides and south flank spreads

In the past year, the summit continued to subside at a maximum rate of 7 cm/yr as magma moved from the summit reservoir to the Pu`u `O`o vent. This short-term rate is a little slower than the long-term rate of about 10 cm/yr since the eruption began in 1983, but the results are not sufficiently different to say that an important change has occurred. The south flank moved seaward at a maximum rate of 7 cm/yr, about the same as that for the past several years. Details of summit subsidence.

No change at Mauna Loa's summit

Very little to no deformation was measured at the summit of Mauna Loa in the past year. The southeast flank extended by 1-3 cm. Before 1993, the summit and upper flanks of the volcano were all moving outward as magma moved into the summit reservoir. Between 1993 and 2000, the summit area subsided by about 7 cm. The reason for this slow subsidence is not clear; nevertheless, the reservoir does not appear to be inflating with new magma at this time. Details of long-term deformation of Mauna Loa.


Archive of previous feature stories

Snow atop Mauna Loa Volcano

Snow blankets summit of Mauna Loa Volcano, Hawai`i
Photograph by D.A. Swanson, 27 February 2002

Snow adorns the upper 1.5 km (5,000 ft) of Mauna Loa Volcano. Rarely does snow reach so far down the mountain. This panorama photograph was taken from the summit area of Kilauea's caldera near the Hawaiian Volcano Observatory. Click on image for a photograph 800 pixels wide or here for 1125 pixels wide.


More Volcano Information from HVO and Beyond

Earthquake seismogramReport a felt earthquake to HVO using this form.
More USGS Volcano Web sites

Volcano WatchCurrent issue of Volcano Watch essay, written weekly by USGS scientists.
National Park ServiceHawai`i Volcanoes National Park, home to HVO. Find visitor information and resources here. Graphic: Kids DoorVolcanoes for kids, from the Volcano World website.