A new era of geodetic big data - challenges and opportunities Tim Wright (COMET, University of Leeds) S @NERC_COMET N
A New Era of Geodetic Big Data?
GEM Strain Rate Model 17,491 GNSS sites included in v2 of GEM Strain Rate Model (2013); [cf. 4,281 in v1.2 (2004)] Data from University of Reno: GSRM, Corné Kreemer
Radar Missions RISAT COSMO-4 COSMO-3 COSMO-2 COSMO-1 DesDYNI TerraSAR-L RCM ALOS-2 Sentinel-1B Sentinel-1A JERS-1 Radarsat-1 ERS-2 ERS-1 Envisat ALOS-1 TanDEM-X TerraSAR-X Radarsat-2 1990 1995 2000 2005 2010 2015
Radar Missions RISAT COSMO-4 COSMO-3 COSMO-2 COSMO-1 DesDYNI TerraSAR-L RCM ALOS-2 Sentinel-1B Sentinel-1A JERS-1 Radarsat-1 ERS-2 ERS-1 Envisat ALOS-1 TanDEM-X TerraSAR-X Radarsat-2 1990 1995 2000 2005 2010 2015
Sentinel-1 Constellation Envisat Stand-alone mission not specifically designed for InSAR Haphazard acquisition strategy (multiple modes) Archive typically has ~30 images over 7 years Loss of signal due to long time gaps or large orbital separations Sentinel-1 20 year operational program, designed for InSAR Systematic acquisitions over deformation belts 12 day revisit 30 images per satellite per year 6 day revisit (with two satellites), small orbital separation
10 km km Digital Topography (LiDAR) SRTM 90 m SPOT5 6 m LiDAR <1 m
Challenges
Challenges Data Access / Cost GNSS data available for free via UNAVCO (and eventually EPOS) Sentinel-1 data available for free from EU Copernicus, but data from other missions can be very expensive Data volumes Sentinel-1A 0.5 TB/day. LiDAR DEM for 600 km 2 of Afar same size as SRTM for USA+Russia Processing Processing requires specialist knowledge Global GNSS processing available from University of Reno Global InSAR processing will be available from COMET/LiCS Data Information
Opportunities
Tectonic Strain & Seismic Hazard Figure from Corné Kreemer/Ross Stein/GEM
Accuracy Requirements and Earthquake Hazard Cumulative percentage of earthquake deaths Magnitude of tectonic strain (x10-9 /yr) 96% of all earthquake deaths are in regions with strain rates greater than 1mm/yr over 100 km (10-8 /yr) 77% of fatalities occur where deformation rates are 5 mm/yr over 100 km.
Achieving 1 mm/yr accuracy Accurate Orbital Models mm/yr 5 0 Atmospheric Corrections -5 Wang, Wright et al, 2008
Achieving 1 mm/yr accuracy Length scale of observation (km) 0.1 1 mm/yr rates over 100 km can be achieved with 5 years of acquisitions (12 day revisit) 1 2 3 4 5 Duration of time series (years) mm/yr 5 0-5 Wang, Wright et al, 2008
Example: Strain mapping in E. Turkey Turkey Iran
Mapping tectonic strain with InSAR E = e xy 2 e xx e yy Walters et al. (JGR In revision 2014) Methods: Wang and Wright (GRL 2012)
How much better than existing missions? Envisat Data, 70 Day Repeat, 7 years data 40% of areas straining above 10-8 yr -1 Sentinel-1A Data, 12 Day Repeat, 5 years data 80% of areas straining above 10-8 yr -1 [90 % with two satellites] Wright et al., Fringe 2011
Yamasaki, Wright and Houseman (JGR 2014) Modelling time-varying phenomena Weak τ 0 = 0.01 Strong τ 0 = 1 Geodesist s view of a fault zone
Modelling time-varying phenomena Post-intrusion deformation in Afar requires magma movement plus viscoelastic deformation. Hamling et al. (GJI 2014)
How do faults link and grow? Vertical movement in Afar between October 2009 and November 2012. Barbara Hofmann PhD thesis (2014)
Earthquake Early Warning with GPS Wright et al., GRL 2012
Monitoring volcanic crises (e.g. Santorini) Parks et al., Nature Geoscience 2012
Integrating different disciplines e.g. The Afar Rift Consortium http://www.see.leeds.ac.uk/afar Dabbahu segment Hararo segment
Data Precise Orbits for Sentinel-1 Water Vapour measurements LiCS: Looking inside the continents from space (NERC Large grant 2014-2019) High-resolution deformation measurements from Sentinel-1 Fault Map for Alpine- Himalayan Belt Derived products Earthquake source models Regional Strain Maps Models Earthquake Cycle Deformation Models 3D Models of Continental Tectonics Information Earthquake Hazard
Sub-Commission 3.5: Tectonics and Earthquake Geodesy WEGENER 2014 (1-4 September 2014, Leeds, UK): Measuring and Modelling our Dynamic Planet 17 th General Assembly of WEGENER on earth deformation and the study of earthquakes using geodesy and geodynamics http://see.leeds.ac.uk/wegener wegener2014@leeds.ac.uk
Geographical coverage Global Tectonics: 55 Mkm 2 Ice: 5 Mkm 2 Europe: 10 Mkm 2 Total: 70 Mkm 2 Data throughput = 0.5 TB/day [~1PetaByte over 5 years]
Processing strategy Continuous, near-global processing T=0 ~1 yr (?) +12 days +24 days +36 days Orbit Models (real time + precise) Atmospheric Models (real time + reanalysis) Initial time series Initial linear rates Updated time series Updated linear rates
Data throughput schematic CEMS-academic CEMS-catapult COMET workspace COMET processing facility 10Gb/s link S1-cache Catapult processing facility Catapult Archive BT link S1-PAC COMET archive Catapult services Farnborough Processed results from CEMSacademic will be available free of charge for all users Science users Non-academic users
Savage and Burford, 1973 y = (s/π) arctan (x/d) NAF EAF s = 20 +-3 mm/yr d = 16+-10 km s = 10+-3 mm/yr d = 16+-5 km
Velocity field method VELMAP: Wang and Wright, 2012