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. The GPS data show that the south flank of the volcano, which has generated several large earthquakes in the past 3 decades, is displacing at up to ;8 cm/yr to the south-southeast. The summit and rift zones are subsiding, with maximum subsidence rates of ;8 cm/yr observed a few kilometers south of the summit caldera. Elastic dislocation modeling of the GPS data suggests that the active sources of deformation include deep rift opening along the upper east and east rift zone, fault slip along a subhorizontal fault near the base of the volcano, and deflation near the summit caldera. A nonlinear optimization algorithm was used to explore the parameter space and to find the best fitting source geometry. There is a broad range of model geometries that fit the data reasonably well. However, certain models can be ruled out, including those that have shallow rift opening or shallow fault slip. Some offshore, aseismic slip on a fault plane that dips between 258 north- northwest and 88 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.