ANOMALIES IN GEOFLUID CIRCULATION AS A PROXY OF THE RELATIONSHIP BETWEEN TECTONIC AND VOLCANIC ACTIVITY IN THE IONIAN - TYRRHENIAN SUBDUCTION MARGIN: RESULTS FROM THE “PNRR MEET” AND “PIANETA DINAMICO WUNDERVUL” INGV PROJECTS
The Ionian - Tyrrhenian subduction margin, in the south Mediterranean, is characterized by the presence of a major regional tectonic lineament, the Aeolian-Tindari-Letojanni Fault System (ATLFS), running from the Aeolian volcanic archipelago to the NW to the Ionian coast of Sicily to the SE. More than two decades of near real time monitoring of hydrothermal aquifers and low temperature (t<100°C) fumaroles at Vulcano island, the southernmost of the Aeolian archipelago and characterized by an intense hydrothermal activity since its last eruption dated 1888-90, have revealed close interplays between tectonic and volcanic activity.
Temperature variations have been recorded here both during changes of the volcanic activity state and in strict time relationship with tectonic seismicity. Sometimes thermal anomalies have preceded tectonic earthquakes with epicenters located not in the close proximity of Vulcano Island, but distributed along the ATLFS area, up to the northern mountain chain of mainland Sicily.
Thermal transients and tectonic seismicity, coupled not following a fixed causality relationship, suggest that both could be considered as crustal transients, driven by changes in the stress field at a regional scale, whose reciprocal timing is determined by the proximity to the stability threshold of the seismogenic fault and of the hydrothermal source.
This conceptual model, linking tectonic and volcanic activity at a regional scale from an holistic point of view, has been elaborated as a result of the “Pianeta Dinamico WUNDERVUL” project. It has been followed in the design of the Strait of Messina hydrogeochemical network, under development within the PNRR “MEET” project: this network will be extended to an area much wider than the simple Strait of Messina, including the whole ATLFS, and related volcanoes.