Comunicación presentada en el IAG Symposium celebrado en Jaén, España, entre el 17 y el 19 de marzo de 2005.The Institute of Astronomy and Geodesy
is measuring sea level variations in Lanzarote Island
by two automated tide gauges of precision since
1993. In order to obtain "real" sea level variations a
permanent GPS station has been installed near the
tide gauges. The goal of this GPS station is to
measurement vertical crustal movements in order to
obtain absolute sea level variations removing these
movements from tide gauge data.
A vertical tie with high accuracy between the
reference point of the pillar where the GPS antenna
is installed and the tide gauges bench marks is
absolutely necessary. We have carried out this
altimetric link yearly since year 2000. Methods of
repeated geometric and trigonometric levelling of
very short tracts have been used due to the great
level difference existent.
The control of the local stability of the pillar
where the GPS antenna has been established, is
carried out by a micro-geodetic control network
building around it. This network of 13 benchmarks
has been regularly observed by classic and GPS
geodetic techniques in years 2000, 2001, 2002,
2003 and 2004. The data of these campaigns have
been processed by different types of adjustments in
the same reference system. The precision of the
measurements and the reliability of the networks
have been calculated.
In this work the results obtained, the evaluation
of the altimetric links and levelling campaigns, and
the comparison of the levels of different
measurements are presented.Peer reviewe