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C.Tolomei , S. Atzori, J. P.Merryman, G. Pezzo, S. Salvi (1)

Investigating the seismic cycle in Italy by multitemporal analysis of ALOS, COSMO-SkyMed and ERS/Envisat DInSAR data sets. C.Tolomei , S. Atzori, J. P.Merryman, G. Pezzo, S. Salvi (1) (1) Istituto Nazionale di Geofisica e Vulcanologia - Rome, italy. Outline.

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C.Tolomei , S. Atzori, J. P.Merryman, G. Pezzo, S. Salvi (1)

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  1. Investigating the seismic cycle in Italy by multitemporal analysis ofALOS, COSMO-SkyMed and ERS/Envisat DInSAR data sets C.Tolomei, S. Atzori, J. P.Merryman, G. Pezzo, S. Salvi (1) (1) Istituto Nazionale di Geofisica e Vulcanologia - Rome, italy

  2. Outline • The SIGRIS Project (funded by Italian Space Agency):exploiting Earth Observation data for seismic risk management • SAR data processed and DInSAR techniquesused • The Straits of Messina and the L’Aquila cases • Conclusions Further information: www.sigris.it

  3. Two operations mode The SIGRIS Project Specific objectives • To generate EO-based, value-added products for the operational use by the National Civil Protection Service in two risk management phases: • Knowledge & Prevention, i.e. support to the Seismic Hazard assessment • Warning & Crisis, i.e. support to the Emergency management • To identify factors limiting the EO data exploitation • During normal routine operations, the products for the Knowledge & Prevention (i.e. support to Seismic Hazard Assessment), are generated • During a seismic Crisis, activated by the INGV surveillance system (SISMAP) for earthquakes > M5.5, products are generated in near-real time, in incremental versions

  4. What we produce Ground velocity maps at the fault scale The SIGRIS PR1 products are maps showing the small (mm/yr) progressive movements of the Earth’s surface occurred over a period of years. We use them to quantify the crustal deformation associated to the seismic cycle, in particular in the inter-seismic and post-seismic phases. The amount and patterns of crustal deformation are related to the tectonic stress accumulated and then released during the earthquakes.

  5. What data we use • SAR data • Same viewing geometry (interferometric acquisitions) • From ascending and descending passes • Consistent datasets (15-20 images minimum) • Minimum acquisition frequency: 2 months for L-band, 1 month for C-band, 10 days for X-band (note: some images can be discarded during processing) • X-Band: Cosmo-SkyMed (April, 2009 ->), asc-desc • C-Band: ERS1/2 (1992-2001), asc-desc • ENVISAT (2003-2010), asc-desc • L-Band: ALOS (2007->), asc • CGPS data • Site displacement time series for the 3 cartesian components • Minimum 3 stations per SAR coverage for a correct SAR-GPS integration • To estimate and remove possible ramps

  6. DInSAR techniques • We use multitemporalInSAR techniques: • SBAS-Small BAseline Subset (IREA-CNR), SARscape (Sarmap); • Permanent Scatterers (T.R.E.,Milano). • We validate the result using: • CGPS • levellinglines • Geological and seismological data. • Bernardino P. et al., 2002, A new algorithm for surface deformation monitoring based on Small Baseline Differential SAR Interferograms. IEEE Trans on Geosci. and Remote Sensing, 40. • Ferretti, A., C. Prati, and F. Rocca (2001), Permanent scatterers in SAR interferometry, IEEE Trans. Geosci. Remote Sens., 39(1), 8– 20.

  7. SIGRIS Test Sites The SIGRIS Project considers 4 test areas in Italy. We processed over 1100 SAR images from ERS, ENVISAT, ALOS, and COSMO-SkyMed satellites. We generated, validated, and delivered to the Italian Civil Protection over 100 PR1 product items.

  8. The Straits of Messina Inter-seismic phase The largest earthquake of the XX century in Italy Mw = 7.1, in 1908 Debated earthquake source (at least 5 different fault models) To be crossed by a 4-km long suspended bridge From Amoruso et al, 2002, JGR

  9. Ground deformation using time-series DInSAR SAR Data: ERS (1992-2001) 71 images (D), 37 (A) ENVISAT (2003-2008) 34 images (A) ALOS (2007-2010) 22 images (A) COSMO-Skymed (2009-2010) 17 images (D)

  10. Mean Ground Velocity Maps (LoS) ERS+ENVISAT Descending orbit Ascending Orbit

  11. Time Series examples

  12. Up & East Velocity Maps • We constrained the SAR North component based on the CGPS one. • look angle = variable along the swath East Component Up Component

  13. -0.5 mm/yr _ -2 mm/yr 1.5 mm/yr + 0 mm/yr 3 mm/yr 2 mm/yr Up Component Legend Up Velocity (mm/yr)

  14. -9 mm/yr East Component -5 mm/yr -4 mm/yr 0 mm/yr -1 mm/yr 4 mm/yr Legend East Velocity (mm/yr)

  15. ALOS Mean Ground Velocity Map (LoS) Processed with SARscape 22 images Temporal span: 10/01/07- 05/06/10

  16. What ALOS can detect 2007-2010 1992-2010 1 2 N W S E S 1 2

  17. COSMO-SkyMed Ground Velocity map (LoS) 2 2 Ascending orbit 1 1 1 2 Area 11st of October, 2009: Mud landslide, 30 casualties

  18. The April 6, 2009 L’Aquila earthquake Co-seismic &post-seismic phase

  19. Co-seismic deformation maps: first clear SAR interferogram (ENVISAT desc) -27 cm LoS displacement

  20. Co-seismic deformation maps: second clear SAR interferogram (COSMO asc) -25 cm LoS displacement

  21. Co-seismic deformation maps: vertical ground displacement

  22. Co-seismic deformation maps: East ground displacement

  23. The L’Aquila case • Ascending Orbit • 34 images (Envisat) • From September, 2003 to June, 2010 • 91 interferograms • Descending Orbit • 52 images (Envisat) • From February,2003 to July, 2010 • 135 interferograms

  24. ASAR Mean Velocity Map (LoS) earthquake Ascending Pass Descending Pass 26/02/2003- 14/07/2010 02/09/2003- 22/06/2010

  25. ALOS Mean Velocity Map (LoS) Track 639 Frame 830 Temporal span: 15/01/2007-26/07/2010 16 images Processed with SARscape

  26. COSMO-SkyMed Mean GroundVelocity Map (LoS) Temporal span: 29/04/2009-13/10/2009 23 slc used Ascending Orbit earthquake earthquake Processed with SARscape

  27. COSMO-SkyMed Displacement Map (LoS)

  28. Conclusions • Multitemporal InSAR techniques are able to measure the ground deformation related to the seismic cycle, down to 1 mm/yr (inter-seismic phase); • In our setting we find that, for the measurements of low-level inter-seismic deformation, the C Band is the best suited, while the X Band is too subject to temporal decorrelation, and the L band lacks sensitivity; • The post-seismic trends are best measured using X band data (higher resolution); • All SAR systems used are well suited for co-seismic deformation mapping, although shorter revisit intervals (2-3 days) are needed for fully operational applications; • Continuity of data acquisition and archival is needed to effectively measure the long-term deformation associated to the seismic cycle; • Using images from different sensors (C, L, X band) in a synergistic way, allows cross-validation and more significant results. Acknowledgements: Dr. Paolo Riccardi, Dr. Alessio Cantone (SARMAP); Dr. Simona Zoffoli, Italian Space Agency.

  29. Thankyoufor yourattention!

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