2009/09/14 20:04:31 44.012 11.284 3.5 4.2 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/09/14 20:04:31:0 44.01 11.28 3.5 4.2 Italy
Stations used:
IG.SC2M IV.ARCI IV.ARVD IV.CAFI IV.CASP IV.CESI IV.CING
IV.CRE IV.FNVD IV.MAON IV.MSSA IV.MURB IV.PARC IV.PESA
IV.PIEI IV.SACS MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.91e+22 dyne-cm
Mw = 4.12
Z = 6 km
Plane Strike Dip Rake
NP1 145 50 -65
NP2 289 46 -117
Principal Axes:
Axis Value Plunge Azimuth
T 1.91e+22 2 218
N 0.00e+00 19 308
P -1.91e+22 71 122
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.14e+22
Mxy 1.01e+22
Mxz 2.52e+21
Myy 5.62e+21
Myz -5.43e+21
Mzz -1.70e+22
##############
######################
--##########################
--############################
----##############################
----#-----------------##############
-#####---------------------###########
#######------------------------#########
#######--------------------------#######
#########---------------------------######
#########-----------------------------####
##########-------------- ------------###
###########------------- P -------------##
###########------------ -------------#
############----------------------------
#############-------------------------
##############----------------------
###############-------------------
# ###########---------------
T ###############----------
######################
##############
Global CMT Convention Moment Tensor:
R T P
-1.70e+22 2.52e+21 5.43e+21
2.52e+21 1.14e+22 -1.01e+22
5.43e+21 -1.01e+22 5.62e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090914200431/index.html
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STK = 145
DIP = 50
RAKE = -65
MW = 4.12
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/09/14 20:04:31:0 44.01 11.28 3.5 4.2 Italy
Stations used:
IG.SC2M IV.ARCI IV.ARVD IV.CAFI IV.CASP IV.CESI IV.CING
IV.CRE IV.FNVD IV.MAON IV.MSSA IV.MURB IV.PARC IV.PESA
IV.PIEI IV.SACS MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.91e+22 dyne-cm
Mw = 4.12
Z = 6 km
Plane Strike Dip Rake
NP1 145 50 -65
NP2 289 46 -117
Principal Axes:
Axis Value Plunge Azimuth
T 1.91e+22 2 218
N 0.00e+00 19 308
P -1.91e+22 71 122
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.14e+22
Mxy 1.01e+22
Mxz 2.52e+21
Myy 5.62e+21
Myz -5.43e+21
Mzz -1.70e+22
##############
######################
--##########################
--############################
----##############################
----#-----------------##############
-#####---------------------###########
#######------------------------#########
#######--------------------------#######
#########---------------------------######
#########-----------------------------####
##########-------------- ------------###
###########------------- P -------------##
###########------------ -------------#
############----------------------------
#############-------------------------
##############----------------------
###############-------------------
# ###########---------------
T ###############----------
######################
##############
Global CMT Convention Moment Tensor:
R T P
-1.70e+22 2.52e+21 5.43e+21
2.52e+21 1.14e+22 -1.01e+22
5.43e+21 -1.01e+22 5.62e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090914200431/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 1.0 165 60 -20 3.83 0.3343
WVFGRD96 2.0 160 45 -30 3.95 0.3803
WVFGRD96 3.0 160 50 -35 3.96 0.4376
WVFGRD96 4.0 160 55 -35 3.97 0.4692
WVFGRD96 5.0 150 45 -50 4.09 0.5117
WVFGRD96 6.0 145 50 -65 4.12 0.5284
WVFGRD96 7.0 150 50 -55 4.10 0.5260
WVFGRD96 8.0 160 60 -35 4.03 0.5000
WVFGRD96 9.0 -5 75 20 4.06 0.4944
WVFGRD96 10.0 -5 75 20 4.07 0.4895
WVFGRD96 11.0 -5 80 20 4.08 0.4819
WVFGRD96 12.0 -5 80 20 4.09 0.4713
WVFGRD96 13.0 170 75 -5 4.11 0.4587
WVFGRD96 14.0 170 75 -5 4.12 0.4467
WVFGRD96 15.0 170 70 0 4.14 0.4341
WVFGRD96 16.0 170 70 0 4.15 0.4193
WVFGRD96 17.0 170 70 0 4.16 0.4032
WVFGRD96 18.0 170 70 -5 4.17 0.3879
WVFGRD96 19.0 170 70 -5 4.18 0.3721
WVFGRD96 20.0 170 65 -5 4.18 0.3568
WVFGRD96 21.0 170 65 -5 4.19 0.3429
WVFGRD96 22.0 170 65 -5 4.20 0.3288
WVFGRD96 23.0 170 65 -5 4.21 0.3159
WVFGRD96 24.0 170 65 -5 4.21 0.3044
WVFGRD96 25.0 170 60 -5 4.22 0.2956
WVFGRD96 26.0 170 65 -5 4.23 0.2899
WVFGRD96 27.0 170 65 0 4.25 0.2833
WVFGRD96 28.0 170 65 -5 4.26 0.2813
WVFGRD96 29.0 170 70 -5 4.28 0.2790
The best solution is
WVFGRD96 6.0 145 50 -65 4.12 0.5284
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=Mon Sep 14 18:53:03 CDT 2009