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WP 4.3 Estimates of earthquakes source parameters and structure characteristics from massive seismic waveform analysis Task 4 L’Aquila seismic sequence:

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Presentation on theme: "WP 4.3 Estimates of earthquakes source parameters and structure characteristics from massive seismic waveform analysis Task 4 L’Aquila seismic sequence:"— Presentation transcript:

1 WP 4.3 Estimates of earthquakes source parameters and structure characteristics from massive seismic waveform analysis Task 4 L’Aquila seismic sequence: a test site to understand the physical processes in the earthquake generation Project S5 High resolution multi-disciplinary monitoring of active fault test-sites areas in Italy

2 WP 4.3 : Estimates of earthquakes source parameters and structure characteristics from massive seismic waveform analysis STRUCURE CHARACTERISTICS ➲ Automatic P and S wave arrival time picking and P-polarity measurements (  WP 1.1) ➲ Events location in 1D velocity models ➲ Seismic anisotropy (  WP 2.3 ) ➲ Vp/Vs estimation from traveltime data. ➲ Seismic tomography (Vp, Vp/Vs) of the fault system. SOURCE PARAMETERS ➲ Moment tensor solutions (  WP 2.5: Cut and Paste Method) ➲ Source parameters estimations (  WP 3.2) ➲ Preliminary attenuation and site response determination

3 DATA ANALYSIS Automatic P and S wave arrival time picking and P-polarity measurements (  WP 1.1) 2866 aftershocks with Ml>1.9 P obs= 72,829 Weights 0 =30,351 (41.68 %) Weights 1= 27,649 (37.97 %) Weights 2= 9,398 (12.90 %) Weights 3= 5,431 ( 7.45 %) S obs=36,229 Weights 2= 21,060 (58.13 %) Weights 3= (41.87 %)

4 1D P-wave Velocity Model

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9 Vp/Vs analysis from traveltime data. Investigation of the possible role of the fluid migrations in the fault system. Method: linear regression of S-P vs P traveltimes (Wadati diagram). Application to: Foreshocks (manual picks: events from 2009 January 16 to 2009 April 06 (h 00:36) Aftershocks (on MPX dataset: in progress)

10 Vp/Vs (foreshocks)

11 and anisotropy at AQU

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13 Vp/Vs (foreshocks) Observations not explained by the previous scheme: complexity of the fluid diffusion processes.

14 Vp/Vs analysis from traveltime data (aftershocks) Vertical bars = occurrence of M>3.8

15 CAP Each waveform is broken into Pnl and surface wave segments Mw + depth Research Unit S5 –RU4 (University of Messina) Moment tensor solutions of the 2009 L’Aquila seismic sequence schematic flow chart for data processing

16 Selected dataset From 2009/04/01 to 2009/07/31 Ml>=2.7 Total earthquakes = 554

17 SOURCE PARAMETERS ESTIMATIONS (  WP 3.2) Events: Ml>=2.5 (from 2009 March 30 to 2009 April 30) Data: Waveforms from accelerometers (RAN DPC +INGV rete mobile)


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