Evidence of a recent input of magmatic gases into the quiescent volcanic edifice of Panarea, Aelian Islands, Italy

Abstract

On 2nd/3rd November 2002, a huge amount of gas, mainly composed of CO2, was suddenly released from the sea bottom off the coast of Panarea, producing a "crater" 20 by 10 meters wide and 7 meters deep. The gas output was estimated to be 109 1/d, two orders of magnitude higher than that measured in the 1980s. The anomalous degassing rate lasted for some weeks, slowly decreasing to an almost constant rate of about 4 × 107 1/d after two months. The geothermo-barometric estimations revealed an increase of both the temperature and pressure in the geothermal system feeding the sampled vents. The 3He/4He ratios were similar to those measured in nearby Stromboli. We have monitored the area for the last two decades, and based on our intensive and extensive geochemical measurements, have ascertained that the geothermal reservoir has lost its steady state. We maintain that a new magmatic input caused these phenomena. Copyright 2004 by the American Geophysical Union.