WP 4.3 Estimates of earthquakes source parameters and
structure characteristics from massive seismic waveform analysis
Task 4L’Aquila seismic sequence:
a test site to understand the physical processes in the earthquake generation
Project S5High resolution multi-disciplinary monitoring of active fault
test-sites areas in Italy
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
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= 72,829Weights 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=36,229Weights 2= 21,060 (58.13 %)Weights 3= 15.169 (41.87 %)
1D P-wave Velocity Model
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)
Vp/Vs (foreshocks)
Vp/Vs (foreshocks)and anisotropy at AQU
Vp/Vs (foreshocks)
Observations not explained by the previous scheme: complexity of the fluid diffusion processes.
Vp/Vs analysis from traveltime data (aftershocks)
Vertical bars = occurrence of M>3.8
CAP
Eachwaveform 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 chartfor data processing
Selected datasetFrom 2009/04/01 to 2009/07/31
Ml>=2.7Total earthquakes = 554
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)