Data base of Italian velocities and strain rates at permanent GNSS sites. A. Caporali, M. Bertocco, J. Zurutuza, University of Padova

Transcription

1 Data base of Italian velocities and strain rates at permanent GNSS sites A. Caporali, M. Bertocco, J. Zurutuza, University of Padova

2 Outlook Part 1: GNSS data reduction and organization Italian permanent network: 485 sites, unique Domes and 4 char id, IGS/EPN logsheet; daily processing with IGS/EUREF standards; Cumulative solution from wk1632 (April 2011) present: consistency of orbits,reference frame, antenna models(similar to relocating hypocenters/computing CMT s using unique processing standards and velocity model); rigorous alignment to ETRF2000 (Inspire standard) STA file links to Time Series web page; solution numbers Part 2: interfacing geodetic data to structural data Velocity-to-strain rate Matlab program generates Geostructures, KML/SHP files Overlay to DISS of INGV (surface deformation vs. structural faults/seismogenic areas) How to integrate Geodetic data with statistical seismicity (ZS9, CPTIxx), Catalogue of seismogenic areas (DISS 3.2.0): Static stress drop associated to a seismic province Coulomb stress transfer from regional tectonics to individual faults

3 Weekly Processing at the UPA Local Analysis Center of the EPN Get RINEX files from servers(485 sites at this time): IGMI-RDN (Rete Dinamica Nazionale) TPOS (Provincia Autonoma di Trento) STPOS (Provincia Autonoma di Bolzano) ITALPOS (Rete GNSS nazionale Leica Geosystems) NETGEO (Rete GNSS nazionale Topcon) Rete GNSS Regione Piemonte Rete GNSS Regione Umbria Rete GNSS Regione Abruzzo Rete GNSS Regione Puglia Rete GNSS Regione Friuli Venezia Giulia INGV (Istituto Nazionale di Geofisica e Vulcanologia) Rete GNSS NOA (Grecia) Process with BSW5.2, EPN processing standards, IGS rapid orbits/clocks Publish and disseminate via a weekly Bernese Bullettin with the ETRF2000 coordinates, repeatibilities and related information Report anomalies to station managers.

4 Make data and results visible for maximum transparency and traceability Repository is patterned after EUREF ftp://igs.bkg.bund.de/euref/ Weekly bullettins, plots and numerical results Files RINEX (485 sites and how can they be traced back to ther origin ftp server) Files SINEX, minimum constraints (network, troposphere, discontinuities) Log files (standard EUREF/IGS logsheet) Repository

5 Weekly/ multiyear processing according to EPN guidelinestime series maintenance, dynamic link to STA file

6 Horizontal velocities (numerical values in GE Balloons)

7 Vertical velocities (numerical values in GE Balloons: red=up; blue= down)

8 Results: all the information is stored in a structured variable/site

9 From velocities to strain rate Igb08 velocities from MC cumulative solution (weekly update, published on web site ETRF2000 velocities using 14 params memo v8 xform Convert horizontal velocities to 2D strain rate eigenvectors using weighted least squares collocation (== optimal autoregressive algorithm)

10 Geodetic Strain rate and DISS (numerical values in GE Balloons: red=compression; blue=extension)

11 Emilia

12 Umbria Marche - Abruzzo

13 Irpinia

14 Sicilia

15 Some ideas on combining DISS data Strain rate tensor from GPS geodesy (2D) Convert to elastic stress rate (deviatoric plane stress) Normal and shear stress (rates) can be computed by projecting the total stress rate onto the normal and slip directions of the ISS CFF f (,, Strike, Dip, Rake) with geodetic strain rate data n Plane stress rate from GPS geodesy ISS data from DISS Sources where the CF increases (clamping) can be discriminated from Sources of decreasing CF (unclamping) The location of diffuse seismicity can be expected to correlate with zones of increasing CF (in analogy with aftershocks) Optimally oriented faults can be predicted by searching those angles which maximize the CF A Coulomb Recurrence Time may be defined as the ratio of the Static Stress Drop to the Coulomb Failure rate: how does it compare with the recurrence time from DISS or regional GR?

16 Preliminary map of loading/unloading rates of the ISSs (1/2) (assume =0.4)

17 Preliminary map of loading/unloading rates of the ISSs (2/2)

18 Conclusions So far 485 permanent GNSS sites: IGS style logsheet, daily metadata checking in the Rinex files, unique 4 char id and DOMES from IGN; velocities available for 415 sites Regularly updated database using Matlab script Geostruct with position, velocity, strain rate, stress drop and related information + hyperlinks overlays to DISS as.shp or.kml Can be used to sample geodetic information along structural lines Using the Coulomb Function approach we can discriminate ISS s with increasing or decreasing state of stress on the fault plane