1. Velocities in ITRF – not appropriate for interpretation

2. Velocities in NUVEL-1A – better, but SNARF will be even better!

3. The SCEC 3.0 velocity field

4. Elastic Rebound
Earthquake!
Earthquake!

5. Elastic Rebound
Earthquake!
Earthquake!

6. Elastic Rebound Earthquake! SF 1906 Guatemala 1976 Kobe 1995
Earthquake!
Kobe 1995

7. The SCEC 3.0 velocity field

8. The SCEC 3.0 velocity field

9. Vertical Velocities: Not dominated by tectonics! GIA is the issue.

10. GIA Predicted Velocities: Very sensitive to model parameters

11. The SCEC 3.0 velocity field

12. GPS Data Analysis GIPSY-OASIS 2.5 [Zumberge et al. 1997]
JPL Precise Orbits
ITRF-97
Atmospheric & ionospheric models
Error Analysis [Mao et al. 1999]
Position Uncertainties (mean) 3, 6 & 12 mm
Rate Uncertainties (mean) – 1.0, 1.3 & 2.5 mm/a
Coseismic Offset
Eruption

13. Co-Seismic Offsets (Model from InSAR & local GPS)
Co-Seismic offsets from June 17 & 21, 2000 earthquakes [Pedersen et al., 2003]
[Pedersen et al., 2003]

14. Co-Seismic Corrected June 17 & 21, 2000 SISZ earthquakes
Distributed slip model [Pedersen et al., 2003]
Correct positions for offsets, recalculate time series
Residual = Feb. 28 – March 6, 2000 Hekla eruption

15. Hekla Deformation

16. Co-Seismic Corrected June 17 & 21, 2000 SISZ earthquakes
Distributed slip model [Pedersen et al., 2003]
Correct positions for offsets, recalculate time series
Residual = Feb. 28 – March 6, 2000 Hekla eruption

17. Co-Seismic Corrected Velocity field corrected for co-seismic offsets
Residual equals deformation from volcanic eruptions and inflation events

18. Velocity Field Relative to Stable North America
Overall plate motion parallel velocity field
June 17 & 21, 2000 earthquakes
Hengill effects

19. The SCEC 3.0 velocity field

20. Normalized observed velocity field (in the PoD spherical coordinate system)
The velocity transformation allows us to examine the velocity field by a single quantity - the magnitude of the longitudinal velocity (Vf). Vertical lines mark the orientation of small circles about the PoD. Horizontal lines mark the boundaries between 10 segments of similar velocity transition Velocities are normalized by 0.64°/Myr.

21. Velocity and velocity gradient of all segments

22. Maximum horizontal shear

23. Relation between seismicity and interseismic deformation

25. Earthquake Cycle
Thatcher 1986

28. Rate on a fault: How much displacement is accomodated
On that feature for a given time.
Geologic rate: Distance between offset feature/Time
Geodetic rate: The amount of deformation imposed in the
Model to fit the geodetic data

29. Example of
Geologic rate

30. Seismicity Up to now we have assumed linear behavior of the movement
of the observed point
Lecture 6 May 24th 2005