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Calibration of the input parameters in pilot test areas D. Galluzzo, F. Bianco, H. Langer, L.Scarfi, G. Tusa & G. Zonno INGV, Catania, Milano, Napoli, Italy A. Carvalho LNEC, Lisboa, Portugal S. Olafsson, R. Rupakhety & R. Sigbjörnsson EERC, Selfoss, Iceland M.Garcia Fernandez, M.J. Jimenez, J. Jenny CSIC, Madrid, Spain M. La Rocca, M. Massa and R. Nappi are aknowledged for their contributions INGV, Napoli, Milano TaskC Task C

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Main Goals of Task C: Calibration of earthquake source, path and site parameters/physical quantities by comparison between observed and synthetic waveforms. The application of the finite fault stochastic approach. Simulation of scenarios for strong and rare earthquakes for which real data may not be available

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Task C - D E L I V E R A B L E S C1.1 Definition of the critical points to calibrate the input parameters of the finite fault stochastic program C2.1 Estimates of input parameters of EXSIM for the pilot study in test area 1 (Mt Etna M L =4.8, Mt Vesuvius M D = 3.6, Campi Flegrei M D =2.2) C2.2 Estimates of input parameters of EXSIM for the pilot study in test area 2 (Azores Islands Mw=6.0, mainland and offshore Portugal) C2.3 Estimates of input parameters of EXSIM for the pilot study in test area 3 (Spain, M L > 4.5) C2.4 Estimates of input parameters of EXSIM for the pilot study in test area 4 (South Iceland M W =6.5) C3.1 Computation of synthetic ground shaking at the pilot test sites C4.1 Computation of synthetic macroseismic fields derived from simulated PGV C5.1 Enriched dataset using observed and synthetic bedrock Mfs.

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Outline Strategy of work: Calibration of ground motion parameters: application of a stochastic approach (EXSIM code, Motazedian and Atkinson, 2005) 1 - Definition of critical points to calibrate physical quantities and parameters 2 - Calibration: examples of applications for the investigated areas 3 - Conclusions and Further developments

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Definition of Critical Points for Calibration Procedure The different data set characteristics have induced the participants to fix the criticalities that could be arise in managing different areas: -the low magnitude data set for some areas; -the application of stochastic approach for small faults; -the variation of input parameters relative to the wide hypocentral distance range and focal depth of earthquakes; -the uncertainties associated to some input parameters (stress drop for low magnitude earthquakes and time duration); - Ground Motion Parmeters to be evaluated: PGA (PGV for small-to-moderate earthquakes), Response Spectra (5%), Housner/Arias Intensity...

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Calibration of input parameters …the most important parameters: Source: Magnitude, Fault dimensions, Stress Drop, Subfault divisions Path: Q(f,R) attenuation parameter Site: High frequency decay “k” parameter, Empirical ”Site Effect” function ..Others: Time duration

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Source parameter: the Magnitude Seismic Moment estimation from low frequency flat part of displacement spectrum (Havskov & Ottemoller, 2010)..a tool for a UNIFORM earthquake size determination … From Catalogue M L =5.3, from Low Frequency Disp. Spectra Mw=5.1 +/ :55:13 South Iceland EQ Mw = 5.1

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:38:16 Mt. Etna EQ Catalogue ML = 3.2 MD = Low Freq. Disp. Spectra Mw = 3.3 +/- 0.2 Mw = 3.3

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Mw = :34 Campi Flegrei EQ Catalogue M D = LFDS Mw = 2.5 +/- 0.2

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M D [-0.3, 2.2], Depth [0.5, 3.0] km b.s.l., 30 seismic events in the period Campi Flegrei (Southern Italy, Area 1) Epicenters of selected earthquakes (red stars) Seismic stations (blu triangles)

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..An example of VT earthquake.. Volcano-Tectonic Seismic Event occurred on ; MD=1.7 Geostructural Map of Campi Flegrei (Di Vito et al., 1999)

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Fault Geometrical ParameterStrike = 300°, Dip = 80° MagnitudeMw=2.7 Fault Dimension0.2 x 0.2 km 2 Depth of the fault2.8 km b.s.l. Stress Drop7 bar Average S-Wave velocity2.0 km/s Density2.5 g/cm 3 Attenuation Q parameterQ=27 f 0.6 Geometrical Spreading1/R Volcano-Tectonic Seismic Event occurred on M D = M W =2.5 +/- 0.2

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Calibration Results: Sensitivity to Stress Drop Sim. 1 bar Sim. 7 bar Sim. 15 bar Obs.E-W Obs. N-S

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Calibration Results: Sensitivity to Stress Drop Sim. 1 bar Sim. 7 bar Sim. 15 bar Obs.E-W Obs. N-S

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Stochastic Simulation vs Empirical Results for VT earthquake occurred on , 07:34 [km]

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Mt. Vesuvius (Southern Italy, Area 1) M D [1.5, 3.6], Depth =[0.0, 4.0] km b.s.l., 50 seismic events in the period

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Fault Geometrical ParameterStrike = 300°, Dip = 80° MagnitudeMw=2.4 Fault Dimension0.2 x 0.2 km 2 Depth of the fault1.7 km b.s.l. Stress Drop12 bar Average S-Wave velocity1.7 km/s Density2.5 g/cm 3 Attenuation Q parameterQ=30 f 0.7 Geometrical Spreading1/R Mt. Vesuvius EQ MD=2.8

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Results of Calibration : Sensitivity to Stress Drop Sim. 1 bar Sim. 5 bar Sim. 12 bar Sim. 20 bar Obs.E-W Obs. N-S

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Sensitivity to Q and high freq k values Q=10 f 0.5 Q=30 f 0.7 Q=50 f 0.8 k=0.015 k=0.04 k=0.06

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Mt. Etna (Southern Italy, Area 1) Epicentres of selected earthquakes and seismic stations of the RSPSO (triangles) for the Etnean zone. M L [3.0, 4.8], Depth =[5.0, 30.0] km b.s.l., more than 120 seismic events in the period

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Empirical and synthetic ground motion prediction for a superficial ML=3.3 earthquake. Empirical and synthetic ground motion prediction for a deeper (z= 10 km) ML=4 earthquake. Results of Calibration procedure: synthetic vs predicted PGA

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Azores Island, Mainland and Offshore of Portugal (Area 2 ) M L [3, 6], Depth =[5.0, 30.0] km b.s.l., 47 seismic events in the period Strong-motion network stations (yellow triangles) in Central Group Azores Archipelago.

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Left:Example of k estimations from the amplitude Fourier spectra of acceleration. Right: Example of a displacement-amplitude spectra of S-waves and lines of ω 2 model K parameter estimation

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Southern Spain (Area 3) Earthquakes (red circles) and strong-motion stations (white triangles) selected for calibration and validation. M L [3.3, 5.2], Epicentral dist. < 100 km, selected well constrained 24 seismic events in the period

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Sensitivity of spectral amplitudes (FAS, PSA, PSV) to different values of the stress parameter (50, 100 and 200 bar). (a) Site 1, (b) Site 2. Results of Calibration : ground motion simulations at two sites (55 km NE, and 5 km SW of the epicenter) were done to evaluate the effect of stress drop parameters

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Results of Calibration procedure: synthetic vs observed FAS and PSA 02/03/2008 M3.5 Vega Baja earthquake. Comparison of recorded and EXSIM- simulated horizontal-component spectral amplitudes (FAS and PSA) at stations TOR, GUA and CTG.

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South Iceland (Iceland, Area 4) South Iceland map. The faults of the largest earthquakes since 1912 are indicated and the stations in the Icelandic Strong Motion Network are shown triangles.

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Observed (black dashed) and simulated (red solid curve) Mw6.5 seismic event accelerograms for 9 stations of Icelandic Strong Motion Network. Calibration and Simulations for the South-Iceland was done earthquake on July 21, 2000 (Mw6.5)

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Acceleration response spectra, with 5% damping, for 9 stations of Icelandic Strong Motion Network. A comparison of the average PSA for the simulations (red curve) and PSA of the measured acceleration records for Mw6.5 earthquake.

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Stress Drop (bar)[7 – 250] bar MagnitudeMw= [2.0 – 6.5] Q=Q 0 f b Q 0 = [27-100] ; b = [ ] k[0.015 – 0.070] Site EffectSoil Classification, H/V, H/Href..A synthetic overview…

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Conclusions and Further Developments The Stochastic Aprroach has revealed a good tool to calibrate source, path and site parameters/physical quantities; The joint use of the different Data Set has allowed to define the limits of applicability, the potentiality of implementation of stochastic procedure and give an interesting general overview of seismological quantities referred to different areas; The next step consists on the application of well-calibrated parameter to genereate large earthquake scenario.

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S I M U L T I O N S I M U A T I O N TASK C A L I B R A T I O N Thank you!

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