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Toward System-Level Earthquake Probability Modeling: Karen Felzer
Project Title: Application of the InSAR Persistent Scatterers Method to Volcano Deformation
Mendenhall Fellow: Ingrid Johanson , (650) 329-4897, ijohanson@usgs.gov
Duty Station: Menlo Park, CA
Start Date: February 21, 2006
Education: Ph.D., Geophysics, University of California, Berkeley, 2005
Research Advisors: Chuck Wicks, (650) 329-4874,cwicks@usgs.gov;, Dan Dzurisin, (360) 993-8909, dzurisin@usgs.gov; Zhong Lu, (605) 594-6063, lu@usgs.gov; Wayne Thatcher, (650) 329-4810, thatcher@usgs.gov
  Ingrid Johanson

Project Description: In the last decade, interferometric synthetic aperture radar (InSAR) has developed into one of the most exciting tools for measuring ground deformation. The satellite-based InSAR system produces an image of a region showing relative surface motion with sub-centimeter level precision and tens-of-meters spatial resolution.  InSAR is particularly suited to volcano monitoring applications as ground deformation often precedes volcanic or seismic activity.  Furthermore, a SAR satellite’s wide coverage and good resolution provides a density of data that would be cost-prohibitive and possibly dangerous to collect in the field. 

For this project I am working on extending the utility of InSAR measurements over volcanic areas through the implementation of the Persistent Scatterer method (PS).  I am focusing on Kilauea volcano in Hawaii and Shishaldin volcano in the Aleutians.  These two locations not only present interesting geophysical problems, but also challenges for using InSAR whose solutions will be widely applicable.  High relief and seasonal and secular changes in ground cover make volcanic terrains particularly susceptible to geometric and temporal decorrelation.  The PS method can increase the temporal resolution and precision of InSAR measurements in areas that are difficult for traditional InSAR analysis, by extracting range change values from exceptionally stable individual ground targets that are not as affected by decorrelation [Ferretti, et al., 2001; Hooper, et al., 2004].  The technique explicitly constructs time series, with maximum resolution of the satellite repeat time (24 days for RADARSAT, 35 days for ERS1&2), which can constrain kinematic models of volcanic processes. 

Of particular interest on Hawaii is a period of simultaneous inflation on Mauna Loa and effusive eruption on Kilauea suggesting that these two are connected at a shallow level [Miklius and Cervelli, 2003].  The PS method has the potential to greatly increase the density of measurements over the current network of GPS stations and tiltmeters.  A dense distribution of deformation data will be better able to constrain the geometry and kinematics of a sub-surface feature linking the two volcanic centers.

References

Ferretti, A., Prati, C., and Rocca, F., 2001, Permanent scatterers in SAR interferometry: IEEE Trans. Geosci. Remote Sens. (USA), vol. 39, no.1, p. 8-20.

Hooper, A., Zebker, H., Segall, P., and Kampes, B., 2004, A new method for measuring deformation on volcanoes and other natural terrains using InSAR persistent scatterers: Geophysical. Research. Letters, vol. 31, no. 23.

Miklius, A., and Cervelli, P., 2003, Vulcanology: Interaction between Kilauea and Mauna Loa: Nature, vol. 421, no. 6920, p. 229.  


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