Stress Changes Before and During the Pu‘u ‘Ö‘ö-Küpaianaha Eruption

International audienceSurface deformation and earthquake data for Kïlauea Volcano have been analyzed as they pertain to stress interactions before and during the Pu‘u ‘Ö‘ö-Küpaianaha eruption. A newly developed method was used to solve for Coulomb stress changes from earthquake rate changes that facilitates quantitative comparisons between earthquake and deformation data sets. Between the 1975 M7.2 Kalapana earthquake and the start of the Pu‘u ‘Ö‘ö-Küpaianaha eruption in 1983, deformation rates of Kïlauea Volcano were the most rapid ever recorded. During this period, deformation was characterized by expansion of a dike-like magma system within Kïlauea’s rift zones, coupled with aseismic creep over a narrow zone of a low-angle fault located beneath the volcano’s south flank. For the 1976–83 period, the rate of rift opening is estimated to have averaged 40 cm per year on the basis of ground deformation. At the onset of the Pu‘u ‘Ö‘ö-Küpaianaha eruption in January 1983, the dike propagated to the surface to form the eruptive fissures. Deformation data and seismicity stress solutions indicate that a fivefold slowing of stressing rates in Kïlauea’s south flank occurred either in late 1979 or at the start of the of Pu‘u ‘Ö‘ö-Küpaianaha eruption in January 1983, depending on location. The stressing rates before and after the onset of the eruption are consistent with changes in volume of magma stored before and after the onset of the Pu‘u ‘Ö‘ö-Küpaianaha eruption