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 method
Università di
Messina
Department of Earth &
Atmospheric Sciences
• 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
• 23 eqks (M>=3; focal
depths less than 25
km; period 2004-2008)
• broadband stations
of INGV & MedNet
from Barberi et al., 2004
1. si definisce un
set di eventi e
stazioni
valori Vp da tomografia
travel time (sec)
2. si calcolano i
TT teorici relativi
nel modello 3D
3. si costruisce il
grafico TT vs 
 (km)
4. dai fits con
la teoria delle
dromocrone si
ricostruisce il
modello 1D
“equivalente”
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.
DATA
EARTHQUAKES
97 eqks
M>=3.0
Period 2004-2008
3<=M<3.5
M>=3.5
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