GPS measurements and kinematic models of the surface deformation on Kilauea Volcano, Hawaii

Kilauea Volcano, Hawaii, is both volcanically and seismically active. Kilauea has been erupting at Pu‘u O‘o almost continuously since 1983. The volcano's south flank has been the site of M7.2 (1975) and M6.1 (1989) earthquakes. In chapter 1, campaign GPS measurements from 1990 to 1996 are used to calculate surface displacement rates on Kilauea. The GPS data shows that the south flank of the volcano is rapidly displacing seaward at ∼8 cm/yr. The elastic dislocation sources required to fit the data include deep rift opening and seaward slip along a subhorizontal fault near the base of the volcano. In chapter 2, the dislocation geometry is constrained to the best-fitting model from chapter 1 and an inversion is done for the fault slip-rate and rift opening-rate distribution. In the resulting model, the highest fault slip rates are shown to occur beneath the central south flank. The rift opening rate is greatest beneath Makaopuhi Crater. Areas of rift dilation correlate well with microseismicity on the adjacent regions of the south flank. Strike-slip rates are also estimated along the Upper East Rift zone, with the highest rates occurring at the base of the rift zone. Chapter 3 discusses the most recent fissure eruption in Kilauea's East Rift zone. Models of the GPS data indicate that the intrusion's bottom edge extended only 2.4 km deep. Continuous GPS data revealed rift opening 8 hours prior to the eruption. In the absence of precursory summit extension, the rift intrusion was caused by deep rift dilation and slip on the south flank decollement stressing the shallow rift zone. Chapter 4 discusses the continuous GPS measurements on Kilauea that started in August 1995. The installation of the network and data analysis are described. The data set records the deformation that occurred after the January 30, 1997 fissure eruption, which shows continued rift extension for ∼2 months after the eruption and increased rates of south flank displacement up until June 1998.