Radon, pH and temperature monitoring in water wells at Campi Flegrei caldera (southern Italy)

Monitoring of the Campi Flegrei caldera has been undertaken since 1983 by measuring radon content (by track etch method), pH and temperature in three thermal water wells. Collection of data started after the area was affected by a dramatic phase of volcano unrest, with a high rate of uplift and increased seismicity. Results show that the radon content is different from well to well; low in the cold well and at least one order of magnitude greater in the two hot wells. Variations in radon content in the three wells sometimes occurred simultaneously and indicate an influence from the same phenomena and feeding source. Three main events, (i) rain fall, (ii) seismic activity and (iii) volcano unrest have been identified to correlate with variations in the radon content, with pH and temperature changes at the same time.