HR: 0800h
AN: T21A-0368    [Abstracts]
TI: Stable and transient motion on Kilauea's south flank from InSAR Persistent Scatterers
AU: * Johanson, I A
EM: ijohanson@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd MS 977, Menlo Park, CA 94025, United States
AU: Poland, M P
EM: mpoland@usgs.gov
AF: U.S. Geological Survey - Hawaiian Volcano Observatory, P.O. Box 51, Hawaii National Park, HI 96718, United States
AU: Wicks, C
EM: cwicks@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd MS 977, Menlo Park, CA 94025, United States
AB: Seaward sliding of the south flank of Kilauea volcano on the island of Hawaii occurs at a rapid rate (~10 cm/yr) and is associated with major earthquakes, such as a M7.2 in 1975. These events, as well as `interseismic' sliding, are inferred to occur on a decollement at the interface between oceanic sediments and the volcanic edifice at 7-9 km depth. Large landslide blocks, whose headwalls form the Hilina Pali and the Holei Pali, also accommodate seaward motion of the south flank, but whether they terminate at depth against the basal decollement or move independently in the shallow crust is unclear. Recently, several slow earthquakes (SEQs) have been observed by continuous GPS measurements on Kilauea's south flank. Evidence for the source depth of the SEQ events is ambiguous; slip may occur on the basal decollement or on the sliding plane of a landslide block at shallower depths. These possibilities are difficult to distinguish given the continuous GPS station geometry. InSAR provides an increase in the spatial density of measurements, though it is vulnerable to spurious signals produced by tropospheric water vapor. Using the Persistent Scatterer method can mitigate atmospheric error sources; allowing for a more precise determination of the deformation field than is possible from a single interferogram. We used the Stanford Method for Persistent Scatterers (StaMPS) to identify >250,000 persistent scatterers (PSs) from 28 descending-mode SAR scenes (27 interferograms) acquired between 2003 and 2007 by the European Space Agency's ENVISAT satellite. StaMPS isolates pixels that show consistently good spatial correlation with other PS candidates and then extracts phase change information from all 27 interferograms to produce a time history of deformation at the location of each PS. Atmospheric effects are mitigated by applying a spatially correlated noise (SCN) filter, which removes signals that are long-wavelength in space, but short- wavelength in time. The dataset captures the overall seaward motion of the south flank, as well as small-scale deformation features associated with the surface expressions of the Koa'e and Hilina Fault Zones. Evaluation of the time series suggests that the small-scale deformation features near the Hilina Fault Zone are unaffected by the slow earthquakes, implying that the most shallow part of the sliding plane is not involved in the SEQs. We will attempt to construct a 2D model of flank motion that includes slip on the basal decollement and the landslide blocks that effectively partitions slip between shallow, deep-seated, and transient sources.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1211 Non-tectonic deformation
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 6924 Interferometry (1207, 1209, 1242)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting