2009/07/03 09:43:53 42.328 13.361 10.1 3.60 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/07/03 09:43:53:0 42.33 13.36 10.1 3.6 Italy
Stations used:
IV.ARCI IV.ARVD IV.ASSB IV.CAFI IV.CERT IV.CESI IV.CESX
IV.CING IV.FDMO IV.FIAM IV.GUAR IV.GUMA IV.INTR IV.LATE
IV.LPEL IV.MAON IV.MNS IV.MTCE IV.NRCA IV.OFFI IV.PIEI
IV.RMP IV.TERO IV.TRTR MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.76e+21 dyne-cm
Mw = 3.43
Z = 10 km
Plane Strike Dip Rake
NP1 139 54 -110
NP2 350 40 -65
Principal Axes:
Axis Value Plunge Azimuth
T 1.76e+21 7 242
N 0.00e+00 16 150
P -1.76e+21 72 357
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.11e+20
Mxy 7.17e+20
Mxz -6.09e+20
Myy 1.36e+21
Myz -1.74e+20
Mzz -1.57e+21
-------#######
--------------########
-------------------#########
#---------------------########
###----------------------#########
####-----------------------#########
#####------------------------#########
######------------ ----------#########
#######----------- P -----------########
#########---------- -----------#########
##########-----------------------#########
###########-----------------------########
############----------------------########
############---------------------#######
# ##########------------------########
T ############----------------#######
##############-------------#######
#################-----------######
###################------#####
#######################-----
##################----
############--
Global CMT Convention Moment Tensor:
R T P
-1.57e+21 -6.09e+20 1.74e+20
-6.09e+20 2.11e+20 -7.17e+20
1.74e+20 -7.17e+20 1.36e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090703094353/index.html
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STK = 350
DIP = 40
RAKE = -65
MW = 3.43
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/07/03 09:43:53:0 42.33 13.36 10.1 3.6 Italy
Stations used:
IV.ARCI IV.ARVD IV.ASSB IV.CAFI IV.CERT IV.CESI IV.CESX
IV.CING IV.FDMO IV.FIAM IV.GUAR IV.GUMA IV.INTR IV.LATE
IV.LPEL IV.MAON IV.MNS IV.MTCE IV.NRCA IV.OFFI IV.PIEI
IV.RMP IV.TERO IV.TRTR MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.76e+21 dyne-cm
Mw = 3.43
Z = 10 km
Plane Strike Dip Rake
NP1 139 54 -110
NP2 350 40 -65
Principal Axes:
Axis Value Plunge Azimuth
T 1.76e+21 7 242
N 0.00e+00 16 150
P -1.76e+21 72 357
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.11e+20
Mxy 7.17e+20
Mxz -6.09e+20
Myy 1.36e+21
Myz -1.74e+20
Mzz -1.57e+21
-------#######
--------------########
-------------------#########
#---------------------########
###----------------------#########
####-----------------------#########
#####------------------------#########
######------------ ----------#########
#######----------- P -----------########
#########---------- -----------#########
##########-----------------------#########
###########-----------------------########
############----------------------########
############---------------------#######
# ##########------------------########
T ############----------------#######
##############-------------#######
#################-----------######
###################------#####
#######################-----
##################----
############--
Global CMT Convention Moment Tensor:
R T P
-1.57e+21 -6.09e+20 1.74e+20
-6.09e+20 2.11e+20 -7.17e+20
1.74e+20 -7.17e+20 1.36e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090703094353/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 80 30 80 3.14 0.2425
WVFGRD96 1.0 160 20 -75 3.24 0.2349
WVFGRD96 2.0 180 30 -50 3.27 0.2676
WVFGRD96 3.0 215 40 25 3.25 0.3080
WVFGRD96 4.0 225 45 30 3.28 0.3609
WVFGRD96 5.0 225 35 20 3.36 0.3937
WVFGRD96 6.0 230 30 20 3.37 0.4230
WVFGRD96 7.0 345 35 -75 3.45 0.4552
WVFGRD96 8.0 345 40 -70 3.42 0.4819
WVFGRD96 9.0 345 40 -70 3.42 0.4923
WVFGRD96 10.0 350 40 -65 3.43 0.4932
WVFGRD96 11.0 350 40 -65 3.44 0.4866
WVFGRD96 12.0 350 40 -65 3.45 0.4751
WVFGRD96 13.0 345 45 -70 3.45 0.4602
WVFGRD96 14.0 340 45 -80 3.46 0.4461
WVFGRD96 15.0 340 45 -80 3.49 0.4406
WVFGRD96 16.0 155 40 -85 3.50 0.4305
WVFGRD96 17.0 155 40 -85 3.51 0.4201
WVFGRD96 18.0 155 40 -85 3.52 0.4100
WVFGRD96 19.0 175 40 -60 3.52 0.4033
WVFGRD96 20.0 175 40 -60 3.53 0.3956
WVFGRD96 21.0 170 40 -65 3.54 0.3883
WVFGRD96 22.0 170 40 -65 3.55 0.3812
WVFGRD96 23.0 170 40 -65 3.56 0.3743
WVFGRD96 24.0 170 40 -65 3.56 0.3652
WVFGRD96 25.0 355 50 -55 3.58 0.3606
WVFGRD96 26.0 -5 50 -55 3.59 0.3501
WVFGRD96 27.0 355 50 -55 3.59 0.3363
WVFGRD96 28.0 355 50 -55 3.60 0.3207
WVFGRD96 29.0 185 35 -50 3.59 0.3090
The best solution is
WVFGRD96 10.0 350 40 -65 3.43 0.4932
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=Fri Jul 3 06:23:41 CDT 2009