Dome growth rates, eruption frequency and assessment of volcanic hazard: Insights from new U/Th dating of the Panarea and Basiluzzo dome lavas and pyroclastics, Aeolian Islands, Italy

The chronology of the volcanic events at Panarea suggests that the volcanic activity developed through two main phases. Effusive activity mainly characterized the first phase of the dome growth, while during the second phase explosive activity prevailed. The second phase occurred from 31±7 to 20±2 ka. Assessing the age of the first phase is more difficult. The age of 155±12 ka, which is in the same time span obtained from K/Ar or Ar/Ar methods, is not consistent with field evidence. Furthermore, although the alignment of the points on the isochron is very good, the initial value of the 230Th/232Th ratio is very low and does not have a clear meaning. Our data strongly suggest that the age of 155±12 ka is not realistic. Two alternative scenarios are proposed, implying a revision of the geological and geochronological evolution of the island together with the significance of the marine terraces on Panarea.