金曜日セミナー(10月20日) Prof. Freysteinn Sigmundsson (The Nordic Volcanological Centre, Institute of Earth Sciences, University of Iceland)

Struggle of humans against ice and fire has been a key element of life in Iceland since the time of settlement on the island (about 874 A.D.). High volcanic activity relates to interaction of the Mid-Atlantic Ridge crossing Iceland and the underlying Icelandic Mantle Plume. In addition to effusive basaltic fissure eruptions, explosive volcanism as a result of ice-magma interaction at subglacial volcanoes, and due to silicic eruptions at central volcanoes. Volcano monitoring and research is aimed at better understanding and forecasting of eruptions, and an example of recently finished large collaborative project is FUTUREVOLC (http://www.futurevolc.hi.is). Extensive geodetic measurements of ground deformation using GPS and satellite radar interferometry (InSAR) as well as other techniques have revealed clear signals that have been interpreted in terms of subsurface magma movements, e.g. in relation to the Eyjafjallajökull 2010 explosive eruption that closed Europe’s airspace, the 2011 Grímsvötn eruption, and the 2014-2015 activity in the Bárðarbunga volcanic system including the formation of 50 km long lateral dyke, slow caldera collapse of over 60 m, and the largest effusive lava eruption in Iceland since 1783. At present, several of the volcanoes are known to be recharging: Grímsvötn, Bárðarbunga and Hekla. Furthermore, Mt. Katla is estimated to be in such conditions that an eruption can begin with a short warning time. An overview of activity of Icelandic volcanoes can be found at a new online catalogue of Icelandic volcanoes (http://icelandicvolcanoes.is).=