Differential Synthetic Aperture Radar Interferometry

DinSAR1small

Earthquakes, landslides, volcanic eruptions, or, more generally, deformation phenomena of the earth's surface, can be monitored through the use of Synthetic Aperture Radar (SAR) sensors.
 
The SAR is able to revisit the same area at regular intervals, providing information at very high spatial resolution of the observed scene. In the case of ERS 1 / 2 and Envisat European Space Agency (ESA), active since 1992 has set the time to review every 35 days, while for the new generation sensors such as the constellation Cosmo Sky-Med, the interval was reduced to 8 days. Using the technique known as SAR Interferometry (InSAR), in which you compare (they do "interfere") two images acquired from slightly different positions (spatial baseline) you can get three-dimensional images of the Earth's surface, measuring the topography. When images are acquired in different times (temporal baseline), using the Differential SAR Interferometry (DInSAR) technique, it is possible to measure the changes of the surface. These measures are shown by a series of colored bands, the so-called fringes or interferogram. The electromagnetic waves used are characterized by an alternation of crests spaced about 5 cm, this distance is called the wavelength. It is "counting" these crests that the radar is able to understand how far is the object he is observing. Not only that, if the object, which can also be located hundreds of miles away, moving only a few centimeters, the number of crests that characterize the electromagnetic waves will change, allowing you to detect and accurately measure the displacement with centimetric accuracy.
The interferometric techniques produce not only the maps of ground deformation measured along the line of sight of the sensor, but taking advantage of a series of images (instead of only two) acquired over time, allow us to follow the itself temporal evolution of deformation. For example, the measurement of ground deformation in volcanic areas is extremely important because these are often precursors of eruptions, or however indicate an increase of volcanic activity. And when you consider that the first satellites used for this purpose have collected data since 1992,the deformation history of a volcano in the last 19 years can be analyzed with a previously unimaginable detail. Moreover, as a further advantage compared to the more "traditional" techniques especially in case of eruption, these measurement are obtained without any necessity of access to the volcano.
Traditional techniques include manual data collection to be made by measurement campaigns in the area, or the installation, at fixed locations,of GPS receivers. In both cases, the number of measurement points will be limited.
 
A satellite deformation map, however, can cover large areas and with a very high density of measurement.
Earthquakes, landslides, volcanic eruptions, or, more generally, deformation phenomena of the earth's surface, can be monitored through the use of Synthetic Aperture Radar (SAR) sensors.
The SAR is able to revisit the same area at regular intervals, providing information at very high spatial resolution of the observed scene. In the case of ERS 1 / 2 and Envisat European Space Agency (ESA), active since 1992 has set the time to review every 35 days, while for the new generation sensors such as the constellation Cosmo Sky-Med, the interval was reduced to 8 days. Using the technique known as SAR Interferometry (InSAR), in which you compare (they do "interfere") two images acquired from slightly different positions (spatial baseline) you can get three-dimensional images of the Earth's surface, measuring the topography. When images are acquired in different times (temporal baseline), using the Differential SAR Interferometry (DInSAR) technique, it is possible to measure the changes of the surface. These measures are shown by a series of colored bands, the so-called fringes or interferogram. The electromagnetic waves used are characterized by an alternation of crests spaced about 5 cm, this distance is called the wavelength. It is "counting" these crests that the radar is able to understand how far is the object he is observing. Not only that, if the object, which can also be located hundreds of miles away, moving only a few centimeters, the number of crests that characterize the electromagnetic waves will change, allowing you to detect and accurately measure the displacement with centimetric accuracy.The interferometric techniques produce not only the maps of ground deformation measured along the line of sight of the sensor, but taking advantage of a series of images (instead of only two) acquired over time, allow us to follow the itself temporal evolution of deformation. For example, the measurement of ground deformation in volcanic areas is extremely important because these are often precursors of eruptions, or however indicate an increase of volcanic activity. And when you consider that the first satellites used for this purpose have collected data since 1992,the deformation history of a volcano in the last 19 years can be analyzed with a previously unimaginable detail. Moreover, as a further advantage compared to the more "traditional" techniques especially in case of eruption, these measurement are obtained without any necessity of access to the volcano.Traditional techniques include manual data collection to be made by measurement campaigns in the area, or the installation, at fixed locations,of GPS receivers. In both cases, the number of measurement points will be limited.
A satellite deformation map, however, can cover large areas and with a very high density of measurement.

 


Additional Info

  • Ruch J, Acocella V, Storti F, Neri M, Pepe S, Solaro G, Sansosti E (2010). Detachment depth revealed by rollover deformation: An integrated approach at Mount Etna. Geophysical Research Letters, vol. 37.

  • Manconi A, Walter TR, Manzo M, Zeni G, Tizzani P, Sansosti E, Lanari R (2010). On the effects of 3-D mechanical heterogeneities at Campi Flegrei caldera, southern Italy. Journal of Geophysical Research-Solid Earth, vol. 215.

  • di Bisceglie M, Di Santo M, Galdi C, Lanari R, Ranaldo N (2010). Synthetic Aperture Radar Processing with GPGPU, IEEE Signal Processing Magazine, vol. 27, pag. 69-78.

  • Neri, M., Casu, F., Acocella, V., Solaro, G., Pepe, S., Berardino, P., Sansosti, E., Caltabianco, Lundgren, P., Lanari, R. (2009), Deformation and eruptions at Mt. Etna (Italy): A lesson from 15 years of observations, Geophysical Research Letters, vol. 36, ISSN: 0094-8276, doi: 10.1029/2008GL036151.

  • Fernández, J., Tizzani, P., Manzo, M., Borgia, A., González, P.J., Martí, J., Pepe, A., Camacho, A.G., Casu, F., Berardino, P., Prieto, J.F., Lanari, R. (2009), Gravity-driven deformation of Tenerife measured by InSAR time series analysis, Geophysical Research Letters.

  • Trasatti, E., F. Casu, C. Giunchi, S. Pepe, G. Solaro, S. Tagliaventi, P. Berardino, M. Manzo, A. Pepe, G. P. Ricciardi, E. Sansosti, P. Tizzani, G. Zeni, and R. Lanari (2008), The 2004–2006 uplift episode at Campi Flegrei caldera (Italy): Constraints from SBAS-DInSAR ENVISAT data and Bayesian source inference, Geophysical Research Letters, vol. 35, L073078, doi:10.1029/2007GL033091.

  • Casu, F., Manzo, M., Pepe, A., Lanari R. (2008), SBAS-DInSAR Analysis of Very Extended Areas: First Results on a 60,000 km2 Test Site, IEEE Geoscience and Remote Sensing Letters, vol. 5, no. 3, doi:10.1109/LGRS.2008.916199.

  • Tizzani, P., Berardino, P., Casu, F., Euillades, P., Manzo, M., Ricciardi, G. P., Zeni, G., Lanari, R. (2007), Surface deformation of Long Valley caldera and Mono Basin, California, investigated with the SBAS-InSAR approach, Remote Sensing of Environment Journal, 108, pp. 277-289, doi: 10.1016/j.rse.2006.11.015.

  • Casu, F., Manzo, M., Lanari, R. (2006), A quantitative assessment of the SBAS algorithm performance for surface deformation retrieval from DInSAR data, Remote Sensing of Environment Journal, 102, pp. 195-210, doi: 10.1016/j.rse.2006.01.023.

  • Borgia, A., Tizzani, P., Solaro, G., Manzo, M., Casu, F., Luongo, G., Pepe, A., Berardino, P., Fornaro, G., Sansosti, E., Ricciardi, G. P., Fusi, N., Di Donna, G., Lanari, R. (2005). Volcanic spreading of Vesuvius, a new paradigm for interpreting its volcanic activity. Geophysical Research Letters, 32, L03303, doi:10.1029/2004GL022155.

  • Pepe, A., Sansosti, E., Berardino, P., Lanari, R. (2005). On the Generation of ERS/ENVISAT DinSAR Time-Series via the SBAS technique. IEEE Geoscience and Remote Sensing Letters, 2, 3, pp. 265-269.

  • Bonaccorso A. , Sansosti E. , Berardino P.  (2004). Modelled deformation pattern from terrestrial and satellite geodetic data and observed pattern from SAR for inferring magma storage sources at Mt. Etna during the 1991-93 eruption”, Pure and Applied Geophysics (PAGEOPH), Vol. 161, No.7, May.

  • Lanari R., Zeni G., Manunta M., Guarino S., Berardino P., Sansosti E. (2004) “An Integrated SAR/GIS Approach for Investigating Urban Deformation Phenomena: a case study of the city of Napoli, Italy”, International Journal of Remote Sensing, vol. 25.

  • Lundgren, P., Casu, F. , Manzo, M., Pepe, A., Berardino, P., Sansosti, E., Lanari, R. (2004), Gravity and magma induced spreading of Mount Etna volcano revealed by satellite radar interferometry, Geophysical Research Letters, 31, L04602, doi: 10.1029/2003GL018736.

  • Lundgren, P. Berardino, M. Coltelli, G. Fornaro, R. Lanari, G. Puglisi, E. Sansosti e M. Tesauro (2003). “Coupled magma chamber inflation ad sector collapse slip observed with synthetic radar interferometry on Mt. Etna”, Journal of  Geophysical Research, 108, n. B5, 2247-2262.

  • P. Berardino, M. Costantini, G. Franceschetti, A. Iodice, L. Pietranera, V. Rizzo (2003). “Use of differential SAR interferometry in monitoring and modelling large slope instability at Maratea (Basilicata, Italy)”, Engineering Geology, 68, 31-51.

  • G. Fornaro, F. Serafino, F. Soldovieri (2003). “Three Dimensional Focusing With Multipass SAR Data”, IEEE Trans. Geosci. Remote Sens., vol. 41.

  • R. Lanari, P. Berardino, S. Borgström, C. Del Gaudio, P. De Martino, G. Fornaro, S. Guarino, G. P. Ricciardi, E. Sansosti and P. Lundgren (2003). “The use of IFSAR and classical geodetic techniques for caldera unrest episodes: Application to the Campi Flegrei uplift event of 2000”, Journal of Vulcanology and Geothermal Research.

  • Berardino, P., Fornaro, G., Lanari, R., Sansosti, E. (2002). A new Algorithm for Surface Deformation Monitoring based on Small Baseline Differential SAR Interferograms. IEEE Transactions on Geoscience and Remote Sensing, 40, 11, pp. 2375-2383.

 

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