Assessing pre- and post-deformation in the southern Arava Valley segment of the Dead Sea Transform, Israel by differential interferometry Francesco Sarti a, * ,1 , Yaacov Arkin b , Jean Chorowicz c , Arnon Karnieli d , Teresa Cunha e a ESA/ESRIN, Earth Observation Program, V. Galileo Galilei, Casella Postale 64, Frascati 00044, Italy b Geological Survey of Israel, Jerusalem, Israel c Laboratoire de Tectonique, Case 129, Universite ´ Paris 6, France d The Remote Sensing Laboratory, Jacob Blaustein Institute for Desert Research, Ben Gurion University of the Negev, Beersheba, Israel e Geology Department, Instituto Geologico e Mineiro, Alfragide, Portugal Received 7 October 2002; received in revised form 4 March 2003; accepted 8 March 2003 Abstract Differential radar interferometry, using archived ERS data over the region of the Dead Sea Transform, allows to detect ground movement (subsidence or uplift) in playas within the southern Arava Valley segment of the Dead Sea Rift. These measurements are consistent with a mean displacement rate of about 0.4 cm/month, in the direction of the radar beam, during the 8-month period preceding the Nuweiba earthquake of 22 November 1995. In the 3 years following the earthquake, the measured rate was smaller by a factor of 10. These movements are not related to salt diapirs or water pumping activities in the area. The exact location, along faults, suggests a possible correlation with pre- seismic and post-seismic fault deformation. A simple fault model consistent with the observed phenomena associates the observed subsidence/uplift to right and left stepping en- echelon fault patterns related to inter-seismic tensional accumulation along the faults. Further observations are necessary on this site and similar fault areas to corroborate the correlation between seismic activity and the observed phenomena. Monitoring of these sites should continue with differential Global positioning system (GPS) measurements and radar interferometric analysis using Envisat and Radarsat as well as archived data (including J-ERS). D 2003 Elsevier Science Inc. All rights reserved. Keywords: Interferometry; En-echelon fault; Dead Sea Transform; Dead Sea Rift; Digital elevation model; Global positioning system; Hue intensity saturation 1. Introduction Synthetic Aperture Radar differential interferometry is a well-established technique allowing the precise measurement of ground displacement down to a few millimeters over large areas with a good spatial resolution. This technique is based on the measurement of phase variation between two succes- sive radar acquisitions. Topographic effects are corrected using a digital elevation model that may be produced from a dedicated interferogram. The main general limitations of this technique are the loss of fringe clarity due to a poor surface preservation (coherency loss) and the bias introduced by atmospheric artifacts (Fruneau & Sarti, 2000; Massonnet & Feigl, 1998). Classical examples of application of this technique to ground displacement mapping can be found in the literature (Feigl et al., 2002; Massonnet et al., 1993, 1996; Peltzer et al., 2000). The Dead Sea Transform corresponds to an active, left lateral, fault system (Fig. 1) where several pull- apart mechanisms exist, for example the Dead Sea and Sea of Galilee (Ben-Menahem, 1981; Garfunkel, 1981; Garfunkel, Freund, & Zak, 1981). Chorowicz and Deffontaines (1993) referred to transform faults on a pull-apart model in the Rhine Graben in a similar situation. Khair, Karakaisis, and Papadi- mitriou (2000) discussed the seismic zonation of the Dead Sea Transform; each study contributing to the overall under- standing of the phenomenon. The present study, using ERS radar interferometry, ana- lyzes the deformation of a well-limited region (Arava Valley segment of the Dead Sea Transform) prior to and following the Nuweiba earthquake of 22 November 1995. The epicenter 0034-4257/03/$ - see front matter D 2003 Elsevier Science Inc. All rights reserved. doi:10.1016/S0034-4257(03)00066-X * Corresponding author. Tel.: +39-6-91480-409; fax: +39-6-94180- 552. E-mail address: [email protected] (Y. Sarti). 1 Work performed while seconded at CNES, Radar System Department, Toulouse, France. www.elsevier.com/locate/rse Remote Sensing of Environment 86 (2003) 141 – 149
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Remote Sensing of Environment 86 (2003) 141–149
Assessing pre- and post-deformation in the southern Arava Valley segment
of the Dead Sea Transform, Israel by differential interferometry
Francesco Sartia,*,1, Yaacov Arkinb, Jean Chorowiczc, Arnon Karnielid, Teresa Cunhae
aESA/ESRIN, Earth Observation Program, V. Galileo Galilei, Casella Postale 64, Frascati 00044, ItalybGeological Survey of Israel, Jerusalem, Israel
cLaboratoire de Tectonique, Case 129, Universite Paris 6, FrancedThe Remote Sensing Laboratory, Jacob Blaustein Institute for Desert Research, Ben Gurion University of the Negev, Beersheba, Israel
eGeology Department, Instituto Geologico e Mineiro, Alfragide, Portugal
Received 7 October 2002; received in revised form 4 March 2003; accepted 8 March 2003
Abstract
Differential radar interferometry, using archived ERS data over the region of the Dead Sea Transform, allows to detect ground movement
(subsidence or uplift) in playas within the southern Arava Valley segment of the Dead Sea Rift. These measurements are consistent with a
mean displacement rate of about 0.4 cm/month, in the direction of the radar beam, during the 8-month period preceding the Nuweiba
earthquake of 22 November 1995. In the 3 years following the earthquake, the measured rate was smaller by a factor of 10. These movements
are not related to salt diapirs or water pumping activities in the area. The exact location, along faults, suggests a possible correlation with pre-
seismic and post-seismic fault deformation.
A simple fault model consistent with the observed phenomena associates the observed subsidence/uplift to right and left stepping en-
echelon fault patterns related to inter-seismic tensional accumulation along the faults. Further observations are necessary on this site and
similar fault areas to corroborate the correlation between seismic activity and the observed phenomena. Monitoring of these sites should
continue with differential Global positioning system (GPS) measurements and radar interferometric analysis using Envisat and Radarsat as
well as archived data (including J-ERS).
D 2003 Elsevier Science Inc. All rights reserved.
Keywords: Interferometry; En-echelon fault; Dead Sea Transform; Dead Sea Rift; Digital elevation model; Global positioning system; Hue intensity saturation
1. Introduction
Synthetic Aperture Radar differential interferometry is a
well-established technique allowing the precise measurement
of ground displacement down to a few millimeters over large
areas with a good spatial resolution. This technique is based
on the measurement of phase variation between two succes-
sive radar acquisitions. Topographic effects are corrected
using a digital elevation model that may be produced from
a dedicated interferogram. The main general limitations of
this technique are the loss of fringe clarity due to a poor
surface preservation (coherency loss) and the bias introduced
0034-4257/03/$ - see front matter D 2003 Elsevier Science Inc. All rights reserv
/95)–ERS2 19736 (28/01/99). Apart from relief-correlated effects on the
are visible, aligned along the main fault. Profiles 1–2, 3–4,. . .,13–14 are
nsity Saturation images corresponding to interferograms AQ7, AQ6, AQ8,
Fig. 3. (a) Coverage of the selected data set. In bold gray: portion centered on the Dead Sea Rift and on the Arava Valley. (b) Retained interferometric pairs over
the playas: AQ7: ERS1 19369 (29/03/95)–ERS1 21874 (20/09/95). HA=2500 m, time interval: 5.8 months. AQ6: ERS1 21874 (20/09/95)–ERS1 22876 (29/
11/95). HA=350 m, time interval: 2 months. AQ8: ERS1 22876 (29/11/95)–ERS2 19736 (28/01/99). HA=450 m, time interval: 38 months.
F. Sarti et al. / Remote Sensing of Environment 86 (2003) 141–149144
ERS-1, -2 archives and on the orbit data. Three interfero-
metric combinations (AQ6, AQ7, AQ8) were retained (Fig.
3b) for the detection and discrimination of pre-seismic and