Advances in the Science and Applications of SAR Interferometry … · 2018-05-15 · Deep-seated Gravitational Slope Deformation (DGSD) triggered by the 2009 L’Aquila earthquake

Deep-seated Gravitational Slope Deformation (DGSD) triggered by the 2009 L’Aquila earthquake detected by X-band DInSAR

M. Chini1, M. Moro1, M. Saroli2, S. Stramondo1, C. A. Brunori1 and S. Salvi1

1 Istituto Nazionale di Geofisica e Vulcanologia

Advances in the Science and Applications of SAR Interferometry

ESA ESRIN30th November - 4th December 2009Frascati, Italy

2 University of Cassino

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Outline

• Dataset: COSMO-SkyMed X-Band SAR

• Deep-seated Gravitational Slope Deformation (DGSD): characteristics

• April 6th, 2009, L’ Aquila earthquake

• Results

• Conclusions

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

- COSMO-SkyMed is a constellation of 4 satellites (three already in orbit) developed by the Italian Space Agency.

- COSMO is aimed to provide fast, metric resolution all-weather imagery for disaster management. It hosts a flexible multi-mode X-band Synthetic Aperture Radar (SAR), with right and left-looking imaging capabilities, incidence angle range 20°-60°, and 12 hours minimum revisit time (full constellation).

- The first ever seismological application of COSMO DInSAR is the May 12, 2008, Sichuan (China) earthquake.

COSMO-SkyMed X-Band SAR

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Deep-seated Gravitational Slope Deformation (DGSD): characteristics

• Involved mass volume (of about hundreds m3);

• Width and length extension (few kilometers);

• Thickness (from about 60 m up to hundreds of meters);

• Movement rates (from few millimeters per year up to few centimeters per year);

• The mechanical and dynamic behavior is affected by gravitational creep phenomena.

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

shear contraction zone

• Sackung or rock flow

Sliding planes are not always recognizable

• Lateral spreadIt is due to rocks with a fragile behavior superimposed on a more plastic bedrock

• Block slideSliding planes (preexistent or new) are well defined

DGSD typology

• Sagging of Mountain slopes (Hutchinson, 1988). Comparable to Sackung phenomena by Zischinski.

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Morphological characteristics

• Double ridges

• Linear and bent depressions (natural trenches)

• Scarps and counterscarps

• Bulging lower slopes

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

April 6th, 2009, L’Aquila earthquake

A Mw 6.3 earthquake occurred on April 6th, 2009 (01:32 GMT) few km from L’Aquila city.

The seism hit a densely populated region of the Apennines and was felt all over Central Italy.

The earthquake has been imaged by COSMO-SkyMed that acquired a number of data thanks to the request of the Department of Civil Protection to ASI.

06/4/2009

07/4/2009

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Co-seismic deformation pattern

Colle Clinelle

Colle Campetello

COSMO-SkyMed

dataset acquisition:

04/04/2009

12/04/2009

Geometric resolution: 5m

Perpendicular baseline: 430m

Look angle: 35°

1 color cycle = 1.5 cm LOS

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Colle Campetello sackung

The entire deformation is located in the major trench zonesIt is up to 4-5 cm

Colle Campetello

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Major trench zone

“Colle Campetello” sackung 3D view

A

BA B

B

A

Major trench zone

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Colle Campetello Main trench

OpeningOpeningOpeningOpeningOpeningOpening

trench

trenchOpeningOpeningOpening

OpeningOpeningOpening

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

“Colle Clinelle” sagging

The entire deformation is located in the major trench zonesIt is about 3 cm

A BC

AB

C

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

The B portion of the profile corresponds with the main trench zone and a prevalent vertical movement is expected.

The C portion of the profile is less steep. It is in agreement with the sagging model where part of the DGSD is laterally moving.

A

B

C0

-2

-3

cm

-1

“Colle Clinelle” deformation profile

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

“Colle Clinelle” sagging 3D view

AB

C

Major trench zone

Front of DGSD.Zone of major lateral movement

Zone of major vertical movement

A BC

Major trench zone

Advances in the Science and Applications of SAR Interferometry ESA ESRIN, 30th November - 4th December 2009 Frascati, Italy

Conclusions

The HR SAR of COSMO- SkyMed (and DInSAR outcomes) and photogeological analysis allowed us to verify the seismic triggering of DGSD for the L’Aquila earthquake.

The observed deformations are co-seismic only, since no movements have been detected in the post-seismic interferograms.

The measured deformation varies from 3 up to 5 cm for Colle Clinelle and Colle Campetello, respectively.

The study demonstrate that the Mw 6.3 L’Aquila earthquake induced a ground shaking large enough to trigger pre-existing DGSDs.

Bigger earthquakes may reactivate a larger number of DGSD, it seems to be a reliable hypothesis, leading to increase the likelihood of a catastrophic collapse.