HR: 1340h
AN: V53A-1138    [Abstracts]
TI: Source Models of the June 17th, 2007 Kilauea Intrusion: Spatio-Temporal Evolution
AU: * Montgomery-Brown, E D
EM: emilyd@stanford.edu
AF: Department of Geophysics Stanford University, 397 Panama Mall, Stanford, CA 94305, United States
AU: Sinnett, D K
EM: dsinnett@stanford.edu
AF: Department of Geophysics Stanford University, 397 Panama Mall, Stanford, CA 94305, United States
AU: Segall, P
EM: segall@stanford.edu
AF: Department of Geophysics Stanford University, 397 Panama Mall, Stanford, CA 94305, United States
AU: Miklius, A
EM: asta@usgs.gov
AF: USGS Hawaiian Volcano Observatory, P.O. Box 51, Hawaii National Park, HI 96718-0051, United States
AU: Poland, M P
EM: mpoland@usgs.gov
AF: USGS Hawaiian Volcano Observatory, P.O. Box 51, Hawaii National Park, HI 96718-0051, United States
AU: Larson, K M
EM: kristinem.larson@gmail.com
AF: University of Colorado, UCB 429, Boulder, CO 80309, United States
AB: The June 17, 2007 intrusion in the upper East Rift Zone (ERZ) of Kilauea volcano, Hawaii was particularly well monitored with continuous GPS, tilt, and InSAR. The first indication of activity was increased seismicity from Kilauea's summit to the bend in the ERZ. The upper ERZ tilted ~70 μ rad sharply down to the south from 02:16 to 07:40 HST, and within minutes the summit crossing GPS baseline began to shorten and eventually decreased by ~14 cm over 2.5 days. Beginning between 08:00 and 0:900, the rift-spanning GPS baseline down rift lengthened by ~1 meter in just over two days. In the two following days, surface cracks were observed in the upper ERZ, and a small amount of new lava was seen on the northeast side of Kane Nui o Hamo. We test distributed source models with a variety of dike geometries that follow observed surface cracks, the axis of InSAR fringes, and the optimal uniform opening model (Sinnett et al., this volume). The sources included are the ERZ dike, the south flank decollement, and the summit magma reservoir. The dike and decollement are modeled as distributed rectangular dislocations, and the summit magma reservoir with a Mogi source. While several models explain most of the data, none fits the details of the data near the western end of the dike, perhaps indicating a complex source geometry, inelastic deformation, or differing mechanisms of pre-, co- and post- intrusion. In the preferred model, following the axis of deformation observed by InSAR, the maximum opening of 2.33 m is between 0-2 km deep under Kane Nui o Hamo, just north of Makaopui crater. Another opening maximum of nearly 2 m occurs about 2 km deep between Pauahi and Mauna Ulu. Seismicity during the intrusion was concentrated below the opening maxima, with some events between them. Unlike previous ERZ intrusions (e.g. Jan. 1997, Owen et al., GRL, 2000) the dike opening does not account for all of the deformation observed at the GPS sites on the southwest flank, nor does it agree with the tilt direction at Kaena Point, indicating possible decollement slip during the intrusion (B. Brooks, pers. comm.). Inversions including a decollement favor slip of up to 30 cm and improve data fits locally, especially in the western part of the network, although the overall amount of data variance explained (~ %70) is similar to the dike-only models. We use the Kalman filter-based Extended Network Inversion Filter (McGuire and Segall, GJI, 2003) to invert kinematic GPS solutions that have been smoothed to reduce multipath (Larson et al., JGR, 2001) and sampled every 4 minutes, and tilt, sampled every 1 minute, for the spatio-temporal slip evolution. The source parameters are the same as the preferred distributed model. Because the dike is short relative to station spacing, lateral resolution of propagation is limited, however, refined models my be able to determine the relative timing of the intrusion and slow slip.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8425 Effusive volcanism
DE: 8485 Remote sensing of volcanoes
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting