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)