2009/06/25 23:31:54 43.256 13.085 7.6 3.20 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/25 23:31:54:0 43.26 13.09 7.6 3.2 Italy
Stations used:
IV.AOI IV.ARVD IV.ASQU IV.CESX IV.CING IV.CSNT IV.FDMO
IV.GUMA IV.OFFI IV.PARC IV.PESA
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 6.24e+20 dyne-cm
Mw = 3.13
Z = 6 km
Plane Strike Dip Rake
NP1 175 55 -65
NP2 316 42 -121
Principal Axes:
Axis Value Plunge Azimuth
T 6.24e+20 7 247
N 0.00e+00 20 340
P -6.24e+20 69 140
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.15e+19
Mxy 2.59e+20
Mxz 1.34e+20
Myy 4.90e+20
Myz -2.06e+20
Mzz -5.31e+20
----##########
------################
---#####-###################
########--------##############
##########-----------#############
##########---------------###########
###########-----------------##########
###########-------------------##########
###########---------------------########
############----------------------########
############-----------------------#######
############-----------------------#######
############----------- ----------######
############---------- P ----------#####
# ########---------- -----------####
T #########-----------------------###
#########-----------------------##
###########---------------------##
##########--------------------
##########------------------
#########-------------
#######-------
Global CMT Convention Moment Tensor:
R T P
-5.31e+20 1.34e+20 2.06e+20
1.34e+20 4.15e+19 -2.59e+20
2.06e+20 -2.59e+20 4.90e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090625233154/index.html
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STK = 175
DIP = 55
RAKE = -65
MW = 3.13
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/25 23:31:54:0 43.26 13.09 7.6 3.2 Italy
Stations used:
IV.AOI IV.ARVD IV.ASQU IV.CESX IV.CING IV.CSNT IV.FDMO
IV.GUMA IV.OFFI IV.PARC IV.PESA
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 6.24e+20 dyne-cm
Mw = 3.13
Z = 6 km
Plane Strike Dip Rake
NP1 175 55 -65
NP2 316 42 -121
Principal Axes:
Axis Value Plunge Azimuth
T 6.24e+20 7 247
N 0.00e+00 20 340
P -6.24e+20 69 140
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.15e+19
Mxy 2.59e+20
Mxz 1.34e+20
Myy 4.90e+20
Myz -2.06e+20
Mzz -5.31e+20
----##########
------################
---#####-###################
########--------##############
##########-----------#############
##########---------------###########
###########-----------------##########
###########-------------------##########
###########---------------------########
############----------------------########
############-----------------------#######
############-----------------------#######
############----------- ----------######
############---------- P ----------#####
# ########---------- -----------####
T #########-----------------------###
#########-----------------------##
###########---------------------##
##########--------------------
##########------------------
#########-------------
#######-------
Global CMT Convention Moment Tensor:
R T P
-5.31e+20 1.34e+20 2.06e+20
1.34e+20 4.15e+19 -2.59e+20
2.06e+20 -2.59e+20 4.90e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090625233154/index.html
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The focal mechanism was determined using broadband seismic waveforms. The location of the event and the and stations used for the waveform inversion are shown in the next figure.
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The program wvfgrd96 was used with good traces observed at short distance to determine the focal mechanism, depth and seismic moment. This technique requires a high quality signal and well determined velocity model for the Green functions. To the extent that these are the quality data, this type of mechanism should be preferred over the radiation pattern technique which requires the separate step of defining the pressure and tension quadrants and the correct strike.
The observed and predicted traces are filtered using the following gsac commands:
hp c 0.02 n 3 lp c 0.10 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 0.5 170 65 -80 2.93 0.2174
WVFGRD96 1.0 170 60 -75 2.92 0.2176
WVFGRD96 2.0 175 60 -65 2.98 0.2395
WVFGRD96 3.0 185 75 -65 3.01 0.2551
WVFGRD96 4.0 175 55 -65 3.05 0.2764
WVFGRD96 5.0 175 55 -70 3.12 0.2865
WVFGRD96 6.0 175 55 -65 3.13 0.2962
WVFGRD96 7.0 175 55 -65 3.13 0.2918
WVFGRD96 8.0 180 60 -55 3.10 0.2766
WVFGRD96 9.0 195 90 -25 3.07 0.2641
WVFGRD96 10.0 210 60 25 3.09 0.2575
WVFGRD96 11.0 210 60 25 3.10 0.2564
WVFGRD96 12.0 210 60 25 3.12 0.2540
WVFGRD96 13.0 210 60 25 3.13 0.2508
WVFGRD96 14.0 215 60 25 3.14 0.2466
WVFGRD96 15.0 215 55 25 3.16 0.2384
WVFGRD96 16.0 215 55 25 3.17 0.2331
WVFGRD96 17.0 210 55 20 3.18 0.2276
WVFGRD96 18.0 325 55 25 3.15 0.2235
WVFGRD96 19.0 325 55 25 3.16 0.2208
WVFGRD96 20.0 325 55 25 3.17 0.2190
WVFGRD96 21.0 325 55 30 3.18 0.2178
WVFGRD96 22.0 325 50 30 3.20 0.2179
WVFGRD96 23.0 325 50 30 3.21 0.2184
WVFGRD96 24.0 325 50 35 3.22 0.2187
WVFGRD96 25.0 325 45 35 3.23 0.2188
WVFGRD96 26.0 325 45 40 3.25 0.2205
WVFGRD96 27.0 325 45 40 3.26 0.2214
WVFGRD96 28.0 330 45 45 3.27 0.2210
WVFGRD96 29.0 330 45 50 3.29 0.2214
The best solution is
WVFGRD96 6.0 175 55 -65 3.13 0.2962
The mechanism correspond to the best fit is
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The best fit as a function of depth is given in the following figure:
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The comparison of the observed and predicted waveforms is given in the next figure. The red traces are the observed and the blue are the predicted. Each observed-predicted component is plotted to the same scale and peak amplitudes are indicated by the numbers to the left of each trace. The number in black at the rightr of each predicted traces it the time shift required for maximum correlation between the observed and predicted traces. This time shift is required because the synthetics are not computed at exactly the same distance as the observed and because the velocity model used in the predictions may not be perfect. A positive time shift indicates that the prediction is too fast and should be delayed to match the observed trace (shift to the right in this figure). A negative value indicates that the prediction is too slow. The bandpass filter used in the processing and for the display was
hp c 0.02 n 3 lp c 0.10 n 3
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| Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to thewavefroms. Each solution is plotted as a vector at a given value of strike and dip with the angle of the vector representing the rake angle, measured, with respect to the upward vertical (N) in the figure. |
The nnCIA used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01
C.It. A. Di Luzio et al Earth Plan Lettrs 280 (2009) 1-12 Fig 5. 7-8 MODEL/SURF3
ISOTROPIC
KGS
FLAT EARTH
1-D
CONSTANT VELOCITY
LINE08
LINE09
LINE10
LINE11
H(KM) VP(KM/S) VS(KM/S) RHO(GM/CC) QP QS ETAP ETAS FREFP FREFS
1.5000 3.7497 2.1436 2.2753 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 4.9399 2.8210 2.4858 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
3.0000 6.0129 3.4336 2.7058 0.500E-02 0.100E-01 0.00 0.00 1.00 1.00
7.0000 5.5516 3.1475 2.6093 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
15.0000 5.8805 3.3583 2.6770 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
6.0000 7.1059 4.0081 3.0002 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
8.0000 7.1000 3.9864 3.0120 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
0.0000 7.9000 4.4036 3.2760 0.167E-02 0.333E-02 0.00 0.00 1.00 1.00
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Thu Jun 25 21:29:58 CDT 2009