Rapid deformation of Kilauea Volcano: Global positioning system measurements between 1990 and 1996

Campaign Global Positioning System (GPS) measurements from 1990 to 1996 are used to calculate surface displacement rates on Kilauea Volcano, Hawaii. T he GPS data show that the south flank of the volcano, which has generated s everal large earthquakes in the past 3 decades, is displacing at up to simi lar to 8 cm/yr to the south-southeast. The summit and rift zones are subsid ing, with maximum subsidence rates of similar to 8 cm/yr observed a few kil ometers south of the summit caldera. Elastic dislocation modeling of the GP S data suggests that the active sources of deformation include deep rift op ening along the upper east and east rift zone, fault slip along a subhorizo ntal fault near the base of the volcano, and deflation near the summit cald era. A nonlinear optimization algorithm was used to explore the parameter s pace and to find the best fitting source geometry. There is a broad range o f model geometries that fit the data reasonably well. However, certain mode ls can be ruled out, including those that have shallow rift opening or shal low fault slip. Some offshore, aseismic slip on a fault plane that dips bet ween 25 degrees north-northwest and 8 degrees south-southeast is required. Best fitting slip and rift opening rates are 23-28 cm/yr, although rates as low as 10 cm/yr are permitted by the data.