>Return to Research

Use of InSAR and GPS observations to study crustal deformation
 

In collaboration with many colleagues at JPL and elsewhere, we have been active in the technical development and use of satellite geodesy. In particular, we contribute to the continued development of ROI_PAC (23) as well as the next generation radar processing package that we currently call modular ROI_PAC, a.k.a. MROIPAC (a project led by Paul Rosen at JPL). I have also been active in forming and managing the WInSAR data consortium. Finally, we are also trying to encourage NASA to launch a dedicated U.S. InSAR satellite (e.g., 22). From the perspective of a user of InSAR data,we have been working on understanding the appropriate error structure to adopt in our modeling efforts(19, 29), focusing on incorporating a covariance matrix that takes into account orbit-error induced effects as well as tropospheric delay effects. We have also developed computationally efficient algorithms for using the dense spatial coverage provided by InSAR as effectively as possible (15, 29). Our current favored approach is based on a spatially variable averaging and sampling scheme that is driven by maximizing the amount of data used while maintaining a data resolution matrix that is close to being an identity matrix (not to be confused with the model resolution) (29). Our use of GPS data falls into 3 categories: 1. Use of existing data acquired and processed by others and available in the published literature. This mode is exemplified by our studies of the Hector Mine and Antofagasta earthquakes (34, 35, 12, 15)

Interferogram of Long Valley Caldera (CA) showing relative surface displacements over approximately 3 years. Deformation is caused by magma migration around 10 km depth and geothermal drilling. See ref. 7.

2. Use of publicly available raw data that is processed by our collaborators (primarily at JPL). This includes data from the SCIGN network that we used to study tropospheric delays that would affect InSAR data (19). This is also the approach we have adopted in a new effort to study subduction zone dynamics in Japan. In this case, with colleagues at JPL, we are undertaking a complete reprocessing of the over 1000 GPS sites in Japan. For this task, the GPS processor has been ported to take advantage of the multi-CPU Beowulf clusters that are available to us. 3. Install and analyze our own continuous GPS sites. Through the Caltech Tectonics Observatory we are analyzing observations from the SUGAR network in Sumatra installed by Kerry Sieh, and we are building a network in the Central Andes. Data from the Chilean network will provide a compliment to InSAR data coverage.

^S1 Improving Inferred Models of Distributed Fault Slip, R. B. Lohman, M. Simons, Geophys. J. Int., submitted, 2004.

³⁵ Distribution of slip from Mw 11 > 6 earthquakes in the northern Chile subduction zone, M. E. Pritchard, C. Ji, and M. Simons, J. Geophys. Res., 111, doi: 10.1029/2005JB004013, 2006. [PDF]

³⁴An aseismic slip pulse in northern Chile and along-strike variations in seismogenic behavior, M.E. Pritchard and M. Simons, J. Geophys. Res., 111, doi:10.1029/2006JB004258, 2006. [PDF]

³¹Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit , Fialko,Y., Sandwell, D., Simons, M. & Rosen, P., Nature, Vol 435, 19 May 2005, doi:10.1038/nature03425. [PDF]

³⁰ Locations of Selected Small Earthquakes in the Zagros Mountains, R. B. Lohman, M. Simons, G-cubed, Volume 6, Number 1, Q03001, doi:10.1029/2004GC000849, March 2005. [PDF]

²⁹ Some thoughts on the use of InSAR data to constrain models of surface deformation, R. B. Lohman, M. Simons, G-cubed, Vol. 6, No. 1, Q01007, doi:10.1029/2004GC000841, Jan. 25, 2005. [PDF]

²⁷ Surveying Volcanic Arcs with Satellite Radar Interferometry: The Central Andes, Kamchatka, and Beyond, M. Pritchard, M. Simons, GSA Today, Vol. 14, No. 8, August 2004. [PDF]

²⁶ An InSAR-based survey of volcanic deformation in the southern Andes, M. E. Pritchard, M. Simons, GRL, Vol. 31, 2004, L15610, doi:10.1029/2004GL02545, 2004. [PDF]

²⁵ BARGEN continuous GPS data across the eastern Basin and Range province, and implications for fault system dynamics, Niemi, N. A., B. P. Wernicke, A. M. Friedrich, M. Simons, R. A. Bennett, and J. L. Davis, Geophysical Journal International, 159, 842-862, 2004, doi:10.1111/j.1365-246X.2004.02454.x. [PDF]

²⁴ An InSAR-based survey of volcanic deformation in the central Andes, M.E. Pritchard and M. Simons, G-cubed, 5, doi:10.1029/2003GC000610, February 7, 2004. [PDF]

²³ Updated Repeat Orbit Interferometry Package Released, P. A. Rosen, S. Hensley, G. Peltzer, and M. Simons, Eos, 85, February 3, 2004.

²² Plan for Living on a Restless Planet Sets NASA's Solid Earth Agenda, S.C. Solomon et al., Eos, 84, November 11, 2003.

¹⁹ Neutral atmospheric delay in interferometric synthetic aperture radar applications: statistical description and mitigation, T.R. Emardson, M. Simons, and F.H. Webb, J. Geophys. Res., 108, doi:10.1029/2002JB001781, 2003. [PDF]

¹⁵ Coseismic Deformation from the 1999 Mw 7.1 Hector Mine, California, Earthquake as Inferred from InSAR and GPS Observations, M. Simons, Y. Fialko, and L. Rivera, Bull. Seismol. Soc. Am., 92, 1390-1402, 2002. [PDF]

¹³ Location and mechanism of the Little Skull Mountain Earthquake as constrained by satellite radar interferometry and seismic waveform modeling, R. Lohman, M. Simons, and B. Savage, J. Geophys. Res., 107, 10.1029/2001JB000627, 2002. [PDF]

¹² Co-seismic slip from the July 30, 1995, Mw 8.1 Antofagasta, Chile, earthquake as constrained by InSAR and GPS observations, M. Pritchard, M. Simons, P. Rosen, S. Hensley, and F. Webb, Geophys. J. Int., 150, 362-376, 2002. [PDF]

¹¹ Evidence for on-going inflation of the Socorro magma body, New Mexico, from Interferometric Synthetic Aperture Radar Imaging, Y. Fialko and M. Simons, Geophys. Res. Lett., Vol. 28, No.18, 3549-3552, 2001. [PDF]

¹⁰ The complete (3-D) surface displacement field in the epicentral area of the 1999 Mw7.1 Hector Mine earthquake, California, from space geodetic observations, Fialko, Y., M. Simons, and D. Agnew, Geophys. Res. Lett., 28, 3063-3066, 2001. [PDF]

⁹ Deformation and seismicity in the Coso geothermal area, Inyo County, California: Observations and modeling using satellite radar interferometry, Y. Fialko and M. Simons, J. Geophys. Res., 105, 21,781-21,793, 2000. [PDF]

⁷ Finite source modeling of magmatic unrest in Socorro, New Mexico, and Long Valley, California, Y. Fialko, M. Simons, and Y. Khazan, Geophys. J. Int., 146, 191-200, 2001. [PDF]

 

Mark Simons' Paper Collection: Entire paper including figures are all made available online (within the bounds of copyright restrictions).