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Scientific Aspects of South Iceland Earthquakes - Research Insights from UPStrat MAFA General Meeting

Explore source parameters, ground motion prediction, seismic moment estimation, and duration analysis of recent and historic earthquakes in South Iceland. Learn about the Icelandic Strong Motion Network and the Discrete Time Realization method discussed at the UPStrat MAFA General Meeting in Selfoss.

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Scientific Aspects of South Iceland Earthquakes - Research Insights from UPStrat MAFA General Meeting

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  1. Scientific aspects of South Iceland earthquakes 26 July 2013 SímonÓlafsson, EERC

  2. Outline • Introduction • Icelandic Strong Motion Network • Estimation of source parameters • Ground motion prediction equation (GMPE) • Discrete time realization • Conclusions UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  3. Historicalearthquakesinthe SISZ UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  4. Icelandic Strong Motion Network UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  5. ÁrborgTown Hall: The strong-motion array UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  6. The Árborg Town Hall: Earthquake 29 May 2008, UTM 15:45 UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  7. Internet Site for the European Strong motion Database (ISESD) UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  8. Recent earthquakes in South Iceland • Mw6.0, 25 May 1987 • Mw 6.5, 17 June 2000 • Mw6.5, 21 June 2000 • Mw6.3, 28th May 2008 UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  9. Ground motion model (Stochastic method) UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  10. Selection of S-wave window UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  11. Estimation of parameters Dsstress drop k =R/Qb‘spectral attenuation’ M0 seismic moment Moment magnitude Mw(Hanks-Kanamori): UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  12. Earthquake 28 May 2008 - Parameters ParameterEstimate Units _____________________________________ Mo 3.4×1018 N m Mw 6.26 Fc 0.24Hz r 6.4km k 0.053 s Ds 73.0×104 Pa u 79.4 cm _____________________________________ UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  13. Attenuation of PGA South Iceland June 2000 UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  14. Geometric spreading function d = epicentral distance h = depth parameter D1, D2 and D3are used to set the limits for the different zones of the spreading function UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  15. Derivation of GMPE Parseval theorem: PGA(amax) related to rms-acceleration (arms) with peak factor (p): amax = parms UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  16. Theoretical GMPE UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  17. Attenuation for 29 May 2008 UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  18. Duration estimation • a) Duration based on 90% cumulative energy. The dotted red curve represent mean value +/- one standard deviation (+/-1s). b) The curves represent the duration function of Eqn. 3.10 for different fractions of total cumulative energy (50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% and 90%). UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  19. Ground motion simulation UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  20. Discrete time realizations Time domain equations for sub-filters representing discrete model. UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  21. Conclusions • For the South Iceland earthquakes the near-field attenuation has a high rate of attenuation (R-2) • Ground motion model (GMPE) has to include a geometrical attenuation term to accound for the fast rate of attenuation in the near-field • GMPE based on a physical model can be applied to obtain ground motion parameters and for time series simulation • For realistic simulation of ground motion time sequences a realistic estimate of duration is important. UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  22. UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  23. Introduction • Examine relationship: Modified Mercally Intensity (IMM) vs. g UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  24. UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  25. Estimating parameters • PGA, PGV: Use for example larger og two horizontal component, average of peak values for horizontal UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  26. Intensities map UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

  27. UPStrat MAFA: 3rd General Meeting in Selfoss, July 23-26, 2013

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