Riesgos volcanicos del eyjafjallajokull y katla

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  • 1. Hazard due to eruptions and floods from Katla and Eyjafjallajökull, south Iceland Magnús T. Guðmundsson1, Jónas Elíasson2, Guðrún Larsen1, Ágúst Gunnar Gylfason3, Páll Einarsson1, Tómas Jóhannesson4, Kristín Martha Hákonardóttir4 and Helgi Torfason5 1: Institute of Earth Sciences University of Iceland 2: Institute of Engineering, University of Iceland 3: Civil Protection Department, National Commissioner of the Icelandic Police 4: Icelandic Meteorological Office 5: Institute of Natural History This presentation is a summary of project funded by the Government of Iceland. The results are found in a special publication available on the web-page of the Civil Protection Department of the National Commissioner of the Icelandic Police – see end of presentation for details
  • 2. Mýrdalsjökull Eyjafjallajökull Katla caldera Eyjafjallajökull Summit caldera 10 km Kortagrunnur utan jökla: Landmælingar Íslands Botn Mýrdalsjökuls: Helgi Björnsson o.fl. 12 Botn Eyjafjallajökuls: Sara M. Strachan 13
  • 3. Eruptions and associated floods caused by ice melting a major hazard - Unrest (seismicity, inflation, geothermal activity) - Catastrophic floods to the east well known - New: floods to west more frequent than previously thought Tasks of hazard assessment for area to the west of the volcanoes: - Estimate eruption frequency for sectors of the volcanoes - Estimate likely flood magnitude - Estimate which areas would be affected by floods
  • 4. Katla caldera – 400-700 m thick ice About two eruptions / century 1918 eruption site
  • 5. Katla - Large phreatomagmatic eruptions Katla eruption 1918
  • 6. Katla eruptions cause catastrophic jökulhlaups - the 1918 event the largest of its kind in the 20th century Peak discharge 100-300·103 m3s-1 • ~1 km3 of sediments transported • 3 km long peninsula formed at coast • Katla jökulhlaups one of the largest volcanological hazards in Iceland From Larsen (2000) Kjartan Guðmundsson 1918
  • 7. Eyjafjallajökull - ice covered stratovolcano Eruptions once every few hundred years 1821-1823 eruption
  • 8. Evidence for hazardous floods towards west ng á Channels of a ri-R pre-historic jökulhlaups E y st Drumbabót: Jökulhlaup sediments ~1200 BP Þverá Sediments indicate repeated large jökulhlaups ll Aff a eruption r Á la site 1822 ót rflj Eyjafjallajökull Katla rka Ma Austur-Landeyjar: sediments from a large jökulhlaup ~1600 BP Pathways of 1822 Minor flooding jökulhlaups 1822 5 km
  • 9. Types of eruptions: a gos undir þykkum jökli a thick ice ís a: Katla 1918, Gjálp 1996 b sprungugos b thin ice í hlíð - flank ís b: Grímsvötn 1998, Eyjafjallajökull ~920 c sprengigos með c pyroclastic gjóskuflóði út á jökul flow ís c: Redoubt 1990, Eyjafjallajökull 1821-23? d d dome gúlagos í jökli ís eruption d: Mount St. Helens 2004 -
  • 10. Ice thickness in Eyjafjallajökull and Mýrdalsjökull Radio-eccho soundings (Helgi Björnsson er al., 2000; Sara Strachan, 2001) Water divides in glaciers 0 100 200 300 400 500 600 700 800 meters Eyjafjallajökull Katla 5 km
  • 11. Recurrence time of eruptions Ny rð ri E < 100 years ms tru 100-1.000 years á 1.000-10.000 years Syð ri E MNV Mýrdalsjökull - northwest part mst Sléttjökull ru á MV Mýrdalsjökull - west flank En MSV Mýrdalsjökull - southwest flank t tu jó jö EN Eyjafjallajökull - north flank rfl k ul ka l ar ES Eyjafjallajökull - south flank M Ljósá MNV Þröngá Markarfljót Jökulsá Stei Krossá Ak nh Krossárjökull st olt Hv að Langanes sá an ná aá MV Hrunar EN Tungna- kvíslajökull ES MSV Írá á la á il sk Fjallg ð l Mi ku l á sá óg il lt jö sár g Ho Sk ma Sv La ug l h ei Jöku að bæ fsá Sól ar á kli li sá lda Ka 5 km
  • 12. Magnitude of jökulhlaups caused by eruptions Ny rðr maximum discharge: iE ms tru 1: < 3.000 m3 /s á 2: 3.000-10.000 m3 /s Sy ð ri E 3 ms Sléttjökull 3: 10.000-30.000 m /s t ru á 3 4: 30.000-100.000 m /s En t tu jó j ök 3 5: > 100.000 m /s rfl u ka ll ar Ljósá M Þröngá Markarfljót S Jökulsá tein Krossá A ho ks lts Hv Krossárjökull ta Langanes á an ða ná á Hrunar Tungna- kvíslajökull Írá á ála il k Fj allg iðs l kul á M óg sá il lt ajö lsárg Ho Sk m Sv L au g a hei Jöku að á b S ól fs æl kli rá isá lda Ka 5 km
  • 13. Catastrophic jökulhlaup (300,000 m3/s) AQUARIVER flood simulation Timing of flood wave from start of eruption
  • 14. Floods due to eruptions hazard areas - travel times of floods No eruption- generated floods Water divides 15-30 min from start of eruption Hazard zone boundaries
  • 15. Floods from Ljósá and Þröngá – path and travel times reccurence time of eruptions 1,000-10,000 years 15-30 min 3 hours Time from source Water divides Path of flood
  • 16. Floods Eyjafjallajökull caldera – path and travel times reccurence time of eruptions 100-1,000 years 1 - 1.5 hours 15-30 min Time from source Water divides Path of flood
  • 17. Results - Hazard assessment • Recurrence time of eruptions varies between areas - from 50 to 10,000 years • Recurrence time of large floods to west 500-800 years • Largest pre-historic floods from Katla caldera ~250,000 m3/s (2 x Amazon River) • Magnitude of floods due to eruptions on flanks of volcanoes mostly 3,000-10,000 m3/s • GIS presentation important to convey information to inhabitants and authorities
  • 18. This presentation is a short summary of: Magnús T. Guðmundsson, Jónas Elíasson, Guðrún Larsen, Ágúst Gunnar Gylfason, Páll Einarsson, Tómas Jóhannesson, Kristín Martha Hákonardóttir og Helgi Torfason. 2005: Yfirlit um hættumat vegna eldgosa og hlaupa frá vesturhluta Mýrdalsjökuls og Eyjafjallajökli. (in Icelandic), (Overview of hazard due to volcanic eruptions and jökulhlaups from the western part of Mýrdalsjökull and Eyjafjallajökull) In: Magnús T. Guðmundsson and Ágúst Gunnar Gylfason (editors): Hættumat vegna eldgosa og hlaupa frá vestanverðum Mýrdalsjökli og Eyjafjallajökli, 11-44. Ríkislögreglustjórinn og Háskólaútgáfan. In addition to the above overview, the publication on hazard assessment has 11 specialized papers on varous aspects of hazard assessment for the area. All the papers are available on the web-page of the Civil Protection Department of the National Commissioner of the Icelandic police (Ríkislögreglustjóri, Almannavarnadeild): http://www.almannavarnir.is/ or http://www.almannavarnir.is/displayer.asp?cat_id=183