Inversion of Wrapped Differential Interferometric SAR Data for Fault Dislocation Modeling

The Differential Synthetic Aperture Radar (SAR) Interferometry technique has dramatically boosted the application of remote sensing in many geophysical disciplines, particularly tectonics. Coseismic interferograms have provided, in many cases, “images of earthquakes,” showing the surface displacement due to the deep fault dislocation. Aside from being visually appealing, interferograms are of fundamental importance for the analysis, by means of appropriate dislocation models, of the geometrical and kinematic characteristics of the fault, which are also parameters of key interest for earthquake risk management. This paper provides a contribution in the general framework of the integration of dislocation models in Differential SAR Interferometry processing. In particular, with reference to coseismic interferograms, it proposes a technique that allows the direct inversion of wrapped interferograms for dislocation model analysis. This option makes it possible to avoid the critical and error-prone processing step of phase unwrapping, carried out in the classical analysis of interferometric data. Examples of inversion of real data, relevant to the 1999 Athens and Izmit earthquakes, demonstrate the feasibility and the advantages of this data processing approach.

ASI-SIGRIS project. ESA Cat1 5605. AO-Greece 2003

P. Berardino, G. Fornaro, R. Lanari and E. Sansosti, “ A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms”, IEEE Trans. Geosci. and Remote Sens, 40 (11), pp. 2375–2383, 2002.
G. Fornaro, A. Pauciullo, F. Serafino, “Deformation Monitoring over large areas with Multipass Differential SAR Interferometry: a new approach based on the use of Spatial Differences”, Int. Journal of Remote Sens.,. vol 30, no. 6, April2009, pp 1455 - 1478.
A. Ferretti, C. Prati, and F. Rocca, “Nonlinear subsidence rate estimation using Permanent Scatterers in Differential SAR Interferometry”, IEEE Trans. Geosci. and Remote Sens., 38 (5), pp. 2202–2212, 2000.
A. Ferretti, C. Prati, and F. Rocca, “Permanent Scatterers in SAR Interferometry”, IEEE Trans. Geosci. and Remote Sens, 39 (1), pp. 8–20, 2001.
M. Moro, M. Chini, M. Saroli, S. Atzori, S. Stramondo and S. Salvi, "Analysis of large, seismically induced gravitational deformations imaged by high resolution COSMO-SkyMed SAR", in press on Geology, doi: 10.1130/G31748.1G. Fornaro, E. Sansosti, A. Pauciullo: “Phase-Difference Based Multi-Channel Phase Unwrapping ”, IEEE Trans. Image Processing., vol.14, pp.960-972, July 2005.
L. Cascini, G. Fornaro, and D. Peduto, “Advanced low- and full- resolution DInSAR map generation for slow-moving landslide analysis at different scales”, Engineering Geology, 112, pp. 29-42, 2010.
F. Amelung, D.L. Galloway, J.W. Bell, H.A. Zebker, and R.J. Laczniak, “Sensing the ups and downs of Las Vegas: InSAR reveals structural control of land subsidence and aquifer-system deformation”, Geology, 27 (6), pp. 483–486, 1999.
R. Lanari, P. Berardino, S. Borgström, C. Del Gaudio, P. De Martino, G. Fornaro, S. Guarino, G.P. Ricciardi, E. Sansosti, and P. Lundgren, “The use of IFSAR and classical geodetic techniques for caldera unrest episodes: application to the Campi Flegrei uplift event of 2000”, J. Volcanology and Geothermal Res., 133, pp. 247 – 260, 2004.
B.A. Bolt, “Earthquakes”, (4th edition) W.H. Freeman & Company, New York, pp. 366, 1999.
R.M. Allen, “Earthquake hazard mitigation: new directions and opportunities”, Treatise on Geophysics, 4, pp. 607-647, 2007.
I. Hunstad, A. Pepe, S. Atzori, C. Tolomei, S. Salvi and R. Lanari, “Surface deformation in the Abruzzi region, Central Italy, from multitemporal DInSAR analysis”, Geophys. J. Int., 2009, doi: 10.1111/j.1365-246X.2009.04284.x
Biggs, J., Wright, T., Lu, Z., & Parsons, B., (2007). Multi-interferogram method for measuring interseismic deformation: Denali Fault, Alaska. Geophysical Journal International, 170 (3), 2007 doi:10.1111/j.1365-246X.2007.03415.x
Fialko, Y., (2006). Interseismic strain accumulation and the earthquake potential on the southern San Andreas fault system, Nature, 441, pp. 968–97, 2006.
Taylor, M. H. & Peltzer, G., (2006). Current slip rates on conjugate strike slip faults in Central Tibet using Synthetic Aperture Radar Interferometry, J. Geophys. Res., B12402, 2006, doi:10.1029/2005JB004014.
D. Massonnet, M. Rossi, C. Carmona, F. Adragna, G. Peltzer, K. Feigl, and T. Rabaute, “The displacement field of the Landers earthquake mapped by Radar Interferometry”, Nature, 364, pp. 138–142, 1993.
R. Burgmann, D. Schmidt, R.M. Nadeau, M. d’Alessio, E. Fielding, D. Manaker, T.V. McEvilly, and M.H. Murray, “ Earthquake Potential Along the Northern Hayward Fault, California”, Science, 289, pp. 1178 – 1182, 2000.
G.J. Funning, B.E. Parsons, T.J Wright, J.A. Jackson, and E.J. Fielding, , “Surface displacements and source parameters of the 2003 Bam (Iran) earthquake from Envisat advanced synthetic aperture radar imagery”, J. Geophys. Res., 110, p. B09406,doi:10.1029/2004JB003338, 2005.
Fialko et al., “Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit”, Nature, 435, 295-299, 2005.
S. Atzori, M. Manunta, G. Fornaro, A. Ganas, and S. Salvi, “Postseismic displacement of the 1999 Athens earthquake retrieved by the Differential Interferometry by Synthetic Aperture Radar time series”, J. Geophys. Res., vol. 113, B09309, 2008.
D. Reale, D. O. Nitti, D. Peduto, R. Nutricato, F. Bovenga, G. Fornaro, “Post-seismic Deformation Monitoring With The COSMO/SKYMED Constellation”, IEEE Geosci. Remote Sens. Lett, doi: 10.1109/LGRS.2010.2100364.
Y. Okada, “Surface deformation due to shear and tensile faults in a half-space”, Bullettin of the Seismological Society of America, vol. 75, no 4, pp. 1135-1154, 1985.
C. W. Chen and H. A. Zebker, ``Phase unwrapping for large SAR interferograms: Statistical segmentation and generalized network models,'' IEEE Trans. Geosci. Remote Sens., 40, pp. 1709-1719, 2002.
M. Costantini, “A novel phase unwrapping method based on network programming”, IEEE Trans. Geosci. Remote Sens., vol. 36, no. 3, pp. 813–821, May 1998.
K.L. Feigl, and C.H. Thurber, “A method for modelling radar interferograms without phase unwrapping: application to the M 5 Fawnskin, California earthquake of 1992 December 4”, Geophys. J. Int., 176, pp. 491-504, 2009.
P. Stoica, and R. L. Moses, Introduction to Spectral Analysis, Upper Saddle River, NJ 07458, Prentice-Hall, 1997.
G. A. Papadopoulos, G. Drakatos, D. Papanastassiou, I. Kalogeras, and G. Stavrakakis, “Preliminary results about the catastrophic earth-quake of 7 September 1999 in Athens, Greece”, Seismol. Res. Lett., 71(3), pp. 318–329, 2000.
G. A. Papadopoulos, A. Ganas, and S. Pavlides, “The problem of seismic potential assessment: Case study of the unexpected earthquake of 7 September 1999 in Athens, Greece”, Earth Planets Space, 54, pp. 9– 18, 2002.
S. Stramondo, F.R. Cinti, M. Dragoni, S. Salvi, and S. Santini, “The August 17, 1999 Izmit, Turkey, earthquake: slip distribution from dislocation modeling of DInSAR and surface offset”, Annals of Geophysics, vol. 45, no 3/4, 2002.
A. Barka, “The 17 August 1999 Izmit earthquake”, Science, 285, pp. 1858-1859, 1999.
Delouis, B., P. Lundgren, J. Salichon, and D. Giardini (2000). Joint inversion of InSAR and teleseismic data for the slip history of the 1999 Izmit (Turkey) earthquake, Geophys. Res. Lett. 27, 3389–3392.
S. Salvi, S. Stramondo, A. Ferretti, G. J. Funning, F. Sarti, A. Mouratidis, "The Sentinel-1 mission for the improvement of the scientific understanding and the operational monitoring of the seismic cycle", under revision on Remote Sens. of Env., 2011