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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1277
DTSTART:20081209T180500Z
DURATION:PT1H0M0S
DTSTAMP:20260506T205350Z
LAST-MODIFIED:20080908T174134Z
LOCATION:4274 Chamberlin (Refreshments will be served)
SUMMARY:A technique for modeling radar interferograms without phase un
 wrapping: Application to the M 5 Fawnskin\, California earthquake of 4
  December 1992\, Chaos & Complex Systems Seminar\, Kurt Feigl\, UW Dep
 artment of Geology and Geophysics
DESCRIPTION:Interferometric analysis of synthetic aperture radar image
 s (InSAR) measures the phase shifts between two images acquired at two
  distinct times. These ambiguous "wrapped" phase values range from  1/
 2 to +1/2 cycles. The standard approach interprets the phase values in
  terms of the change in distance between the ground and the radar inst
 rument by resolving the integer ambiguities in a process known as "unw
 rapping". To avoid unwrapping\, we have developed\, validated\, and ap
 plied a new method for modeling the wrapped phase data directly. The m
 ethod defines a cost function in terms of wrapped phase to measure the
  misfit between the observed and modeled values of phase. By minimizin
 g the cost function with a simulated annealing algorithm\, the method 
 estimates parameters in a nonlinear model. Since the wrapped phase res
 iduals are compatible with a von Mises distribution\, several parametr
 ic statistical tests can be used to evaluate the fit of the model to t
 he data. The method\, named General Inversion for Phase Technique (GIP
 hT)\, can handle noisy\, wrapped phase data. Applying GIPhT to two int
 erferograms in the area of Fawnskin\, California\, we estimate a set o
 f model parameters describing a magnitude 5 aftershock of the 1992 Lan
 ders earthquake. The resulting simulation fits the data well. The phas
 e final residuals have a circular mean deviation less than 0.15 cycles
 /datum. Sampling the final residuals\, we find the circular standard d
 eviation of a phase measurement to be approximately 0.2 cycle\, corres
 ponding to 6 mm in range.
URL:https://www.physics.wisc.edu/events/?id=1277
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