1. Vertical Land Movements in the Canary Island using Continuous GPS Time Series Analysis: First Results García-Cañada, Laura(1), Teferle, F. Norman(2), Bingley, Richard M.(2) and Sevilla, Miguel J.(1) (1) Instituto de Astronomía y Geodesia (CSIC-UCM), Madrid, Spain. (2) IESSG, University of Nottingham, United Kingdom.

2. Volcanism in the Canary Islands
Last Eruptions (Global Volcanism Program):
La Palma: 1949, 1971
Tenerife: 1909
Gran Canaria: 20 BC ± 75 years
Lanzarote: 1824
Neumann van Padang et al. (1967)
Photo by Alexander Belousov (Institute of Volcanology, Kliuchi)

3. Sea Level data in the Canary Island from Permanent Service for Mean Sea Level (PSMSL)
Sea Level recorded by tide gauges is rising but not at the same rate everywhere.

4. PSMSL Revised Local Reference (RLR) tide gauge records in the Canary Islands

5. New CGPS station LACV on Lanzarote established in 2000
Jameos del
Agua

6. CGPS stations in the Canary Islands
MAS1 (IGS)
LPAL (EPN)
PLUZ (ESEAS)
LACV

7. Regionally reference coordinates time series in ITRF2000
Strategies for the processing of the CGPS data:
1) Regional network solutions based on double-differencing (DD) using Bernese GPS software (BSW) v4.2.
MAS1, MADR and SFER IGS coordinates and velocities are fixed to define reference frame.
Regionally reference coordinates time series in ITRF2000

8. Strategies for the processing of the CGPS data:
2) Precise Point Positioning (PPP) solutions using BSW v5.0 and a Helmert transformation computed from IGb00 stations.
a) 7 parameter Helmert transformation using all IGb00 stations
Globally referenced coordinate time series in ITRF2000
b) 4 parameter Helmert transformation using IGb00 sites in Europe only
Regionally referenced coordinate time series in ITRF2000

9. Velocities estimated for the three different strategies

10. Stochastic Noise
Traditionally, it was assumed that geodetic time series contain only random errors (white noise).
It has been shown that such time series follow more a noise model containing a combination of white and coloured noise (time correlated).
In general, coloured noise is described using different stochastic noise models.
Geophysical phenomena can be described using a power-law (Agnew, 1992).

11. Coordinate time series analysis:
1) Empirical analysis:
Station Motion Model
Using weighted least-squares the parameters are estimated.
Linear, annual and semi-annual terms are fit to data and realistic rate uncertainties, accounting for white and coloured (flicker) noise, are computed afterwards using Zhang et al. (1997) and Williams (2003).

12. Coordinate time series analysis:
2) Maximum Likelihood Estimation (MLE):
C … Co-variance Matrix
I …. Identity Matrix
J … “unit” Co-variance Matrix for a particular type of noise
Amount of noise, linear, annual and semi-annual terms are estimated simultaneously (Williams et al., 2004).
Different noise models can be used:
a) White noise plus flicker noise (WN+FN)
b) White noise plus power law-noise (WN+PLN)

13. Time series analysis results (DD processing)
EMP
WN+FN
WN+PLN

14. Time series analysis results (DD processing)

15. Time series analysis results (PPP regional)
EMP
WN+FN
WN+PLN

16. Time series analysis results (PPP regional)

17. Time series analysis results (PPP global)
EMP
WN+FN
WN+PLN

18. Regional filter Common Mode Analysis
Common periodic variations in the height time series
Common noise characteristic in the height time series
Regional filter
Common Mode Analysis

19. Computation of the common mode bias (weighted stacking method by Wdowinski et al. (1997), Nikolaidis (2002))
1) Postfit residual:
2) Common error:
3) Filtered time series:

20. Comparison of the station velocity estimates for the unfiltered and filtered and the EMP and MLE analysis with white plus flicker noise.
PPP global DD

21. Absolute vertical station velocity estimatesDD
PPPreg
PPPglobal
Unflt
Flt
LACV
0.22
0.40
0.39
0.63
1.81
1.39
LPAL
-0.65
-0.10
-1.34
-0.46
-0.20
MAS1
-1.77
-0.64
0.77
PLUZ
-3.55
-3.01
-1.55
-2.39

22. Relative vertical station velocity estimatesDD
PPPreg
PPPglobal
Unflt
Flt
LACV-LPAL
0.87
0.50
1.73
1.09
2.01
1.00
MAS1-LACV
-2.16
-0.73
-2.45
-0.62
LPAL-MAS1
0.43
-0.36
0.44
-0.38
PLUZ-LACV
-3.94
-3.64
-3.36
-3.78
LPAL-PLUZ 
2.21
2.55
1.35
2.78
MAS1-PLUZ
1.78
2.91
0.91
3.16

23. Conclusions CGPS stations in the Canary Islands have been analized.
Two different processing strategies: BSW-DD and BSW-PPP have been used.
Three different reference frame realizations:2 regional and 1 global.
Regional filter to eliminate common mode in time series has been aplied.
Preliminary vertical station velocities for four CGPS stations have been estimated.