Geodynamic network GREVOLCAN is located at two volcanic islands in Greece. It is designed for the monitoring of mass (magma) and fluids movements inside the active volcanic structures in Nisyros (Kos-Nisyros caldera) and Thira in the Aegean Sea. The Greek partner is the National Kapodistrian University of Athens. They perform random campaign of GNSS observations to control the surface displacements.
The monitoring is performed as repeated campaigns of microgravity observations in the networks spread all over the two islands. On the whole, there are 38 sites observed in Thira, and 25 in Nisyros, respectively.The measurements are performed with two gravimeters – LaCoste&Romberg D-188 and Scintrex Autograv CG-6. They provide sufficient accuracy with the measurement error below 5 μGal (1 μGal = 10-8 m.s-2). All network ties are measure four times to achieve maximum accuracy. The observations are tied to a reference station, so that it is possible to compare particular campaigns and define the temporal changes of the gravity field.
With respect to the gravity indication of an extensional displacement in the NE side of Thira, a static gravity survey was performed in this area to contribute to the understanding of tectonic composition of this active fault zone.
The more detailed information on microgravity measurements in Thira (Santorini) are presented in Santorini and West Bohemian Massif and Greece.