HR: 13:55h
AN: V12G-02 INVITED     [PDF]
TI: Stresses Associated to the Onset of the Pu'u '\={O}'\={o} K\={u}paianaha Eruption
AU: * Cayol, V
EM: cayol@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, CNRS, Univ. B. Pascal, OPGC, 5, rue Kessler, Clermont-Ferrand, 63000 France
AU: Dieterich, J H
EM: dieterich@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, Cal 94025 United States
AU: Okubo, P
EM: pokubo@usgs.gov
AF: U.S. Geological Survey, Hawaiian Volcano Observatory, Volcano, HI 96718 United States
AU: Miklius, A
AF: U.S. Geological Survey, Hawaiian Volcano Observatory, Volcano, HI 96718 United States
AU: Okamura, A
AF: U.S. Geological Survey, Hawaiian Volcano Observatory, Volcano, HI 96718 United States
AB: Ground deformation and seismicity are used in a complementary way in order to determine stressing processes before and at the onset of the Pu'u \={O}'\={o} K\={u}paianaha eruption. After the magnitude 7.2 Kalapana earthquake and before the start of the ongoing eruption in 1983, deformation of Kilauea volcano was the most rapid ever recorded. Modeling shows that this deformation was characterized by the dilation of a dike-like magma system within Kilauea'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 1976-1983 period, rates of rift zone opening averaged 40 centimeters a year resulting in a magma supply of 0.19 cubic-kilometer per year. The onset of the Pu'u '\={O}'\={o} K\={u}paianaha eruption was associated with a 2.1 meter fissure opening in the east rift-zone and a significant change of the south-flank seismicity pattern and rates. Coulomb stresses associated to the fissure opening are computed using a three-dimensional boundary element method for two different models that fit the deformation data equally well - a model in which the inflating rift dike propagated from a depth of 3 km to the free surface, and a model of an isolated intrusion of a shallow dike. Then, Coulomb stresses are computed independently from earthquake rates using a newly developed method [{\it Dieterich et al.,} 2000]. We find that the Coulomb stresses determined from seismicity agree with the model corresponding to the propagation of the rift dike to the surface. Moreover this model is mechanically consistent with our model for the 1976-1983 period.
DE: 3210 Modeling
DE: 8164 Stresses--crust and lithosphere
DE: 8414 Eruption mechanisms
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting