the april 6 2009, l’aquila (italy) earthquake: dinsar...

The April 6th 2009, L’Aquila (Italy) earthquake: DInSAR analysis and seismic source model inversion

Simone Atzori, Christian Bignami, Marco Chini, Christodoulos Kyriakopoulos, Salvatore Stramondo, Cristiano Tolomei, Elisa Trasatti and Stefano Salvi

Istituto Nazionale di Geofisica e Vulcanologia

Advances in the Science and Applications of SAR Interferometry

ESA ESRIN30th November - 4th December 2009Frascati, Italy

2/19Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th Nov - 4th Dec 2009 Frascati, Italy

L’Aquila EQ context


DInSAR pairs

27 ap

r 200

8

11 m

ar 20

09

12 ap

r 200

9

15 ap

r 200

9

04 ap

r 200

9

22 ap

r 200

9

20 ju

l 200

8

Envisat Asc

Envisat Dsc

COSMO SkyMed Asc

ALOS Asc

• Images processed with SARscape®

• Topography subtracted with a 5-m DTM (from Airborne SAR)

• Linear trends removed with GPS (permanent stations)


Envisat ASC (C-band)(11/03/09 -15/04/09)

GPS stations


Envisat DSC (C-band)(27/04/08 - 12/04/09)


ALOS PALSAR (L-band)(20/07/08 - 22/04/09)

70 km

113 km


COSMO SkyMed Asc (X-band)(04/04/09 - 12/04/09)

45 km

“Among its strength points are its flexibility (it can operate in three different modalities, routine, crisis or emergency) and its short revisit time”

from ASI website


GPS stations

* Anzidei et al., Coseismic deformation of the destructive April 6, 2009 L’Aquila earthquake (central Italy) from GPS data, GRL (36), L17307, doi:10.1029/2009GL039145, 2009

Five new stations were added 5 days before the main event*


Modeling• Non-linear inversion (fault geometries) with analytical

homogeneneous elastic model (Okada).• Linear inversion (slip distribution) with analytical

homogeneous elastic model.• Linear inversion with analytical layered elastic

model (Wang).• Linear inversion with Finite Element model• CFF analysis (stress transfer over surrounding

faults).• Non-linear joint inversion of geodetic and

seismological (teleseismic) data


Subsampling


Geodetic Model and seismicity

* from Chiaraluce et al., 2009 [in prep.]

Length 12.164 (km) in [10 - 20]Width 12.455 (km) in [5 - 15]Depth 2.269 (km) in [0 - 8]Strike angle 135.6 (°) in [100 - 150]Dip angle 50.0 (°) fixed Fault east 373.648 (km) in [370.000 - 380.000]Fault north 4690.944 (km) in [4680.000 - 4694.000]Rake angle -103.3 (°) in [-120 - -70]Slip 0.51 (m) in [0 - 15]

Aftershocks relocated with double difference technique (and 1-D velocity model)*.

From non-linear inversion of DInSAR and GPS data:


Numerical fault modelling

We use Finite Element Methods to define a more realistic model of the crustal structure, including:

surface topography medium anisotropyvertical and lateral discontinuities Masterlark 2008

3D seismic tomography by De Gori and Chiarabba [in prep.]


The tomography evidences a lateral and verticalheterogeneous elasticstructure

Vp, Vs velocities transformedinto elastic parameters(rigidity, Poisson coeff.)

Tomography cross sections

Complex geological structure


ResultsMaximum Slip 0.9 mMean Rake -90°Misfit 4.1Mgeod 1.5 1018 Nm Mw = 6.1

Slip (m)

FE heterogeneous model

Method

Slip distribution

Resolution matrix


Shear modulusSlip distribution

• The coseismic slip is distributed along the strike direction, in an area of low seismicity;

• Slip is concentrated between 5-8 km depths;

• Slip is inhibited at greater depths because of the high rigidity values.

Slip distribution and structure on fault


PostseismicEnvisat Asc

Envisat DscCOSMO Asc ALOS

Galvani A. et al, DEFORMAZIONE INTER E POSTSISMICA DA DATI GPS DEL BACINO DELL'AQUILA, 28° Convegno Nazionale GNGTS, sessione 1.2, 16-19 Novembre 2009


COSMO acquisitionsfrom 6/4 to 22/4

Satellite Date & Time Mode Beam Polar. Looking side Satellite Date & Time Mode Beam Polar. Looking sideS 1 6/4/09 17.29 H I 0B VV R D S 3 14/4/09 17.11 HI 15 HH RDS 1 7/4/09 4.24 H I 5 HH L A S 2 14/4/09 17.29 HI 0B VV RDS 3 8/4/09 5.12 H I 14 HH R A s2 15/4/09 4.24 HI 5 HH LAS 3 8/4/09 16.59 H I 24 VV R D S 1 15/4/09 5.12 HI 14 HH RAS 2 8/4/09 17.17 H I 9 HH R D S 1 15/4/09 16.59 HI 24 VV RDS 1 8/4/09 18.05 S 2 15 HH L D S 3 15/4/09 17.29 HI 0B VV RDS 2 9/4/09 4.12 H I 15 HH L A S 3 16/4/09 0.00 S 2 9 HH LAS 1 9/4/09 5.00 S 2 7 HH R A S 1 16/4/09 17.17 HI 9 HH RDS 3 9/4/09 17.17 H I 10 HH R D S 2 16/4/09 18.05 S 2 14 HH LDS 3 10/4/09 4.12 H I 15 HH L A S 1 17/4/09 4.12 HI 15 HH LAS 2 10/4/09 4.30 S 2 0D HH L A S 2 17/4/09 5.00 S 2 7 HH RAS 1 10/4/09 5.18 H I 18 HH R A S 3 17/4/09 18.05 S 2 15 HH LDS 1 10/4/09 17.05 H I 19 VV R D S 2 18/4/09 5.18 HI 18 HH RAS 2 10/4/09 17.53 H I 0B HH L D S 2 18/4/09 17.05 HI 19 VV RDS 1 11/4/09 4.00 H I 23 HH L A S 1 18/4/09 17.52 HI 0B HH LDS 3 11/4/09 4.30 S 2 0D HH L A S 3 19/4/09 0.00 HI 18 HH RAS 1 11/4/09 17.23 H I 5 HH R D S 2 19/4/09 4.00 HI 23 HH LAS 3 11/4/09 17.53 H I 0B HH L D S 3 19/4/09 17.05 HI 19 VV RDS 1 12/4/09 4.18 H I 11 HH L A S 2 19/4/09 17.23 HI 5 VV RDS 2 12/4/09 5.06 H I 9 HH R A S 3 20/4/09 0.00 HI 5 VV RDS 3 12/4/09 18.11 H I 14 HH L D S 2 20/4/09 4.18 HI 11 HH LAS 3 13/4/09 5.06 H I 9 HH R A S 1 20/4/09 5.06 HI 9 HH RAS 2 13/4/09 5.24 S 2 33 HH R A S 3 21/4/09 4.18 HI 11 HH LAS 2 13/4/09 17.11 H I 15 HH R D S 1 21/4/09 17.11 HI 15 HH RDS 1 14/4/09 4.54 H I 0A HH R A S 2 22/4/09 18.17 HI 19 HH LDS 3 14/4/09 5.24 S 2 33 HH R A S 1 22/4/09 17.29 HI 0B VV RD


Conclusions• COSMO SkyMed and Envisat provided useful information for the on-

field survey teams during the emergency, defining the exact location of the active fault. ALOS passed too late but can contain info about post-seismic displacement.

• Two completely independent datasets (from geodesy and seismology) defined with high precision the location and orientation of the Paganica fault.

• The tomography evidences lateral and vertical elastic heterogeneities, with a potential effect on coseismic slip distribution.

• The coseismic slip is distributed along the strike direction, in an area of low seismicity.

• Slip is concentrated between 5-8 km depths and it is inhibited at greater depths because of the high rigidity values.

• Most of the posteismic signal happens in few days after the EQ; COSMO SkyMed shown its high flexibility, unfortunately (apparently) not oriented to DInSAR analysis.

• Precise integration of DInSAR and GPS allows the detection of low frequency displacement components.


Thank you!


Thank you!

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the april 6 2009, l’aquila (italy) earthquake: dinsar...

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