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Shallow vs. Deep Sliding on Kilauea's south flank from InSAR Persistent Scatterers

Ingrid Johanson(2), Michael Poland(1) and Charles Wicks Jr.(2)

(1) USGS, Hawaii Volcano Observatory, P.O. Box 51, Hawaii National Park, 96718, United States
(2) U.S. Geological Survey, 345 Middlefield Rd, Menlo Park, 94025, United States

Abstract

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. It is difficult to distinguish between deep and shallow sources 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 >25,000 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. Also, an increase in rate of flank-wide range-change associated with a 2005 slow earthquake is visible in the time history data. 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 and deep-seated sources

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry