Upon its ascent, magma causes vertical or/and horizontal shifting of superimposed rocks and areas. One of the basic precursors to the reactivation of a volcano is coastal depression or rising, which occurs prior to the manifestation of the eruption. To detect such movements, a permanent network has been installed, comprising four telemetry stations that automatically measure and record the sea level, thus any shifting of the coastline.

Stations were designed, constructed and installed by researchers of the Aristotle University. The main signal receiver and logging station is situated at the headquarters of the Volcanology Observatory in Emporeio.

Data obtained from measurements that are performed every hour at the four coastal sites are subject to daily processing and assessment by the local observer. Thereafter, they are relayed by modem to the University of Thessaloniki by the competent scientific group, in order to be finally processed and assessed.

The new comprehensive network of tidal recorders permits continuous recording and real time data transmission to the Volcanology Observatory. The system includes 5 stations, installed at selected sites in the Santorini archipelago. These provide continuous recordings of the sea level and other physical parameters (water temperature, conductivity); the recorded values are relayed to a PC installed at the Observatory by radiolink; there, they are stored and made accessible to the scientific monitoring team over the Internet.

The values currently measured in each of these stations are: sea level variations, water temperature (at a depth of 0.5 meters), and ambient temperature. In fact, the system is much more capable than that and includes measurements of up to 7 different analog values and 2 digital readings per station.