Task 2. Test site “Messina Strait”

WP2.5 G. Neri, Univ. Messina

Meccanismi dei terremoti e regimi di stress tettonico nell’area dello Stretto di Messina

Focal mechanisms – CAP methodFocal mechanisms – CAP method

• We computed the moment tensor solutions using the “Cut And Paste” (CAP) method originally proposed by Zhao and Helmerger (1994) and later modified by Zhu and Helmerger (1996).

•The focal mechanisms and source depth are determined using a grid search technique. Each waveform is broken into Pnl and surface-wave segments.

• CAP has proven to be effective for analyzing earthquakes even with magnitudes between 2.5 and 4.0

Department of Earth & Atmospheric Sciences

Università di Messina

• 23 eqks (M>=3; focal depths less than 25 km; period 2004-2008)

• broadband stations of INGV & MedNet

from Barberi et al., 2004

(km)

trav

el t

ime

(sec

)1. si definisce un set di eventi e stazioni

2. si calcolano i TT teorici relativi nel modello 3D

3. si costruisce il

grafico TT vs

4. dai fits con la teoria delle

dromocrone si

ricostruisce il

modello 1D

“equivalente”

valori Vp da tomografia

RESULTS

TESTS

from Barberi et al., 2004 from Barberi et al., 2004 for the present

dataset

from Neri et al., 2009

TESTS

RESULTS

RESULTS

Black and white in the polar plot correspond to P

and T axes, respectively.

Black and white in the polar plots correspond to P and T axes, respectively.

Normal faulting resulted to be dominant in sector A, more favourably positioned with respect to the southeast-ward retreat of subduction hinge, while strike-slip components become evident in sector B located across the transfer zone between the extensional and compressional domains.

3<=M<3.5M>=3.5

EARTHQUAKES

97 eqks

M>=3.0

Period 2004-2008

DATA

STATIONS

CAT/SCAN Project funded by

National Science Fundation

- Lamont Observatory NY

- Dipartimento di Fisica Università

della Calabria

- Istituto Nazionale di Geofisica e Vulcanologia

Eventi in studio con i dati delle stazioni temporanee“Messina 1908-2008”

45 earthquakes

01/11/2007 - 23/05/2009

Ml>2.5

Next steps…

• FM computations with the additional contribution by the INGV experiment data

• Comparison and integration with other data available (RCMT, TDMT, EMMA, literature, … )

• Computations of stress fields