Rome, March 24, 2017
Investigations continue in the stretch of sea between the islands of Montecristo and Pianosa to understand the phenomenon of outgassing which, as reported on 16 March by some fishermen in the area, caused a column of water to rise a few meters on the surface of the sea near the Ants of Montecristo.
The Civil Protection Department has commissioned the National Institute of Geophysics and Volcanology (INGV) to carry out investigations to understand the extent and characteristics of the phenomenon. The overflights, carried out by the Port Authority with thermal camera surveys, have shown that the gaseous emissions are not associated with localized temperature variations. The chemical analyzes of the sea water, carried out by the geochemical group of the INGV of Naples, have highlighted a significant increase in the concentration of methane. The inspection with remotely controlled submarines, conducted by INGV personnel in Portovenere, did not identify any localized thermal anomalies. From the results it was therefore possible to exclude that the outgassing had a volcanic origin. All the elements allow us to narrow the field of hypotheses, indicating that we are dealing with a phenomenon of the "mud volcano" type in which large quantities of methane come out vigorously.
At the moment the area is affected by only a modest widespread degassing. INGV will continue the research to determine the extent of the affected area and better understand the genesis of the observed phenomenon.
1 - image of the underwater emissions taken by the remote controlled underwater vehicle (ROV) of the INGV of Portovenere
2 - image of the emission area (between the two patrol boats, taken from a helicopter of the Port Authority
3- View of the emission zone, watched over by a lookout from the Port Authority
For information: Gilberto Saccorotti, section director of Pisa-INGV, e-mail
Section of Pisa-INGV: Spina Cianetti, e-mail spina.cianetti@ingv.i