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Long-term prediction of Hekla eruptions using geodesy and seismicity

Geological setting of Hekla. Hekla. 1500 m a.s.l. ridge, built up by repeated eruptions during last 7500 yearsOne of the most active volcanoes in IcelandAt least 18 eruptions during last 1100 yearsTypically 1-2 eruptions/centuryNew pattern: most recent in 1970, 1980-81, 1991 and 2000Notorious with lack of precursories.

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Long-term prediction of Hekla eruptions using geodesy and seismicity

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    1. Long-term prediction of Hekla eruptions using geodesy and seismicity Heidi Soosalu1 and Erik Sturkell2 1Bullard Laboratories, University of Cambridge 2Nordic Volcanological Center, University of Iceland

    2. Geological setting of Hekla

    3. Hekla 1500 m a.s.l. ridge, built up by repeated eruptions during last 7500 years One of the most active volcanoes in Iceland At least 18 eruptions during last 1100 years Typically 1-2 eruptions/century New pattern: most recent in 1970, 1980-81, 1991 and 2000 Notorious with lack of precursories

    4. Stations and measuring points around Hekla Yearly measurements of GPS and dry tilt Continuous seismic measurements: digital three-component and analogue vertical component stations Continuous strain measurements

    5. Tilt measurements at MOHN

    6. Tilt measurements at RAUK

    7. Tilt measurements at NAEF Directly west from Hekla East component especially sensitive for deformation under Hekla Similar uplift level as prior to 1991 and 2000 eruptions has now been reached

    8. GPS measurements at HAFU

    9. GPS measurements at NBJA

    10. GPS measurements at MOHN At the root of Hekla Shows now uplift under Hekla During eruptions MOHN is heavily influenced by the dike Interpretation more complicated than at NAEF

    11. Precursory seismicity Eruption-related seismicity observed only 30-80 minutes before onset Swarm of numerous small earthquakes (ML < 3) No help for long-term predicting Strain is another short-term prediction tool

    12. Frequency content of Hekla events

    13. Hekla seismicity between eruptions Not “volcanic” Follows the pattern of the South Iceland seismic zone to the west

    15. Timing of the next Hekla eruption Geodetic measurements show that inflation at Hekla has reached former pre-eruption levels Frequency content of Hekla earthquakes is a weak signal, but indicates that stress is building up again We suggest that the next Hekla eruption is quite likely within next ~2 years

    16. Thanks to

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