Dispersal of Historical Subplinian-Plinian Explosive Eruptions of Hekla Volcano, Iceland

Monday, 15 December 2014: 2:10 PM
Maria H Janebo1, Bruce F Houghton1, Thor Thordarson2 and Gudrun Larsen3, (1)University of Hawaii at Manoa, Honolulu, HI, United States, (2)University of Iceland, Nordic Volcanological Center, Institute of Earth Sciences, Reykjavik, Iceland, (3)University of Iceland, Reykjavik, Iceland
Hekla is one of the most active Icelandic volcanoes, with 18 subplinian-Plinian eruptions since 1104 AD and since 1970, the frequency of such eruptions have increased to once every decade. Hekla is currently inflated to the levels observed prior to the most recent eruptions in 1991 and 2000. Any future eruption is likely to pose a hazard to air traffic between North America and Europe because explosive eruptions of Hekla, independent of size, typically start with a powerful explosive phase that produces a sustained ash plume. We present an overview of 5 of the 18 historical Hekla eruptions (1104, 1158, 1300, 1693, and 1766). These eruptions cover a range of magma composition (andesite to rhyolite), eruptive volume (0.3 to 2 km3) and intensity (VEI 3 to 5), and with contrasting wind fields (dispersal axes NW to NE). New isopach maps have been constructed, which show both greater deposit thicknesses in the proximal region and wider dispersal than previously inferred. This leads to a significant increase in the estimated volume and mass eruption rates for these eruptions.