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Surface Deformation and Coherence Measurements of Kilauea Volcano, Hawaii, from SIR-C Radar InterferometryThe shuttle imaging radar C/X synthetic aperture radar (SIR-C/X-SAR) radar on board the space shuttle Endeavor imaged Kilauea Volcano, Hawaii, in April and October 1994 for the purpose of measuring active surface deformation by the methods of repeat-pass differential radar interferometry. Observations at 24 cm (L band) and 5.6 cm (C band) wavelengths were reduced to interferograms showing apparent surface deformation over the 6-month interval and over a succession of 1-day intervals in October. A statistically significant local phase signature in the 6-month interferogram is coincident with the Pu'u O'o lava vent. Interpreted as deformation, the signal implies centimeter-scale deflation in an area several kilometers wide surrounding the vent. Peak deflation is roughly 14 cm if the deformation is purely vertical, centered southward of the Pu'u O'o caldera. Delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures, at the level of 12 cm peak-to-peak in the radar line-of-sight direction. Though the phase observations are suggestive of the wide-area deformation measured by Global Positioning System (GPS) methods, the atmospheric effects are large enough to limit the interpretation of the result. It is difficult to characterize centimeter-scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous, spatially distributed measurements of reactivity along the radar line of sight. Studies of the interferometric correlation of images acquired at different times show that L band is far superior to C band in the vegetated areas, even when the observations are separated by only 1 day. These results imply longer wavelength instruments are more appropriate for studying surfaces by repeat-pass observations.
Document ID
19980227532
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rosen, P. A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Hensley, S.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Zebker, H. A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Webb, F. H.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Fielding, E. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Date Acquired
August 18, 2013
Publication Date
October 25, 1996
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 101
Issue: E10
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
Paper-96JE01459
Distribution Limits
Public
Copyright
Other

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