2009/07/03 01:14:07 42.320 13.378 11.6 3.40 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/07/03 01:14:07:0 42.32 13.38 11.6 3.4 Italy
Stations used:
IV.AOI IV.ARCI IV.ARVD IV.ASSB IV.BSSO IV.CAFI IV.CERA
IV.CERT IV.CESX IV.CING IV.FDMO IV.FIAM IV.GUAR IV.GUMA
IV.INTR IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.OFFI IV.PIEI
IV.RDP IV.RMP IV.ROM9 IV.SACS IV.TERO IV.VAGA MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.09e+21 dyne-cm
Mw = 3.48
Z = 8 km
Plane Strike Dip Rake
NP1 150 53 -106
NP2 355 40 -70
Principal Axes:
Axis Value Plunge Azimuth
T 2.09e+21 7 251
N 0.00e+00 13 159
P -2.09e+21 76 8
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.44e+19
Mxy 6.20e+20
Mxz -5.75e+20
Myy 1.84e+21
Myz -2.92e+20
Mzz -1.93e+21
--------######
---------------#######
###-----------------########
###--------------------#######
#####---------------------########
######----------------------########
#######-----------------------########
########----------- ---------#########
########----------- P ----------########
##########---------- ----------#########
##########-----------------------#########
###########----------------------#########
############---------------------#########
#########--------------------########
T ##########-------------------########
###########-----------------########
##############---------------#######
###############------------#######
###############---------######
#################-----######
#################--###
###########---
Global CMT Convention Moment Tensor:
R T P
-1.93e+21 -5.75e+20 2.92e+20
-5.75e+20 9.44e+19 -6.20e+20
2.92e+20 -6.20e+20 1.84e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090703011407/index.html
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STK = 355
DIP = 40
RAKE = -70
MW = 3.48
HS = 8.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/07/03 01:14:07:0 42.32 13.38 11.6 3.4 Italy
Stations used:
IV.AOI IV.ARCI IV.ARVD IV.ASSB IV.BSSO IV.CAFI IV.CERA
IV.CERT IV.CESX IV.CING IV.FDMO IV.FIAM IV.GUAR IV.GUMA
IV.INTR IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.OFFI IV.PIEI
IV.RDP IV.RMP IV.ROM9 IV.SACS IV.TERO IV.VAGA MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.09e+21 dyne-cm
Mw = 3.48
Z = 8 km
Plane Strike Dip Rake
NP1 150 53 -106
NP2 355 40 -70
Principal Axes:
Axis Value Plunge Azimuth
T 2.09e+21 7 251
N 0.00e+00 13 159
P -2.09e+21 76 8
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.44e+19
Mxy 6.20e+20
Mxz -5.75e+20
Myy 1.84e+21
Myz -2.92e+20
Mzz -1.93e+21
--------######
---------------#######
###-----------------########
###--------------------#######
#####---------------------########
######----------------------########
#######-----------------------########
########----------- ---------#########
########----------- P ----------########
##########---------- ----------#########
##########-----------------------#########
###########----------------------#########
############---------------------#########
#########--------------------########
T ##########-------------------########
###########-----------------########
##############---------------#######
###############------------#######
###############---------######
#################-----######
#################--###
###########---
Global CMT Convention Moment Tensor:
R T P
-1.93e+21 -5.75e+20 2.92e+20
-5.75e+20 9.44e+19 -6.20e+20
2.92e+20 -6.20e+20 1.84e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090703011407/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 0.5 335 60 85 3.22 0.3185
WVFGRD96 1.0 185 30 -50 3.25 0.3065
WVFGRD96 2.0 180 35 -55 3.32 0.3574
WVFGRD96 3.0 215 50 30 3.30 0.3930
WVFGRD96 4.0 220 50 30 3.34 0.4353
WVFGRD96 5.0 220 40 20 3.40 0.4544
WVFGRD96 6.0 350 40 -80 3.50 0.4758
WVFGRD96 7.0 350 40 -75 3.51 0.5173
WVFGRD96 8.0 355 40 -70 3.48 0.5255
WVFGRD96 9.0 355 40 -70 3.49 0.5241
WVFGRD96 10.0 360 45 -60 3.49 0.5182
WVFGRD96 11.0 0 45 -60 3.50 0.5076
WVFGRD96 12.0 0 45 -60 3.51 0.4933
WVFGRD96 13.0 5 50 -55 3.51 0.4760
WVFGRD96 14.0 195 50 -35 3.51 0.4630
WVFGRD96 15.0 190 45 -45 3.54 0.4603
WVFGRD96 16.0 195 45 -40 3.55 0.4497
WVFGRD96 17.0 195 45 -40 3.56 0.4388
WVFGRD96 18.0 195 45 -35 3.57 0.4278
WVFGRD96 19.0 195 45 -35 3.58 0.4162
WVFGRD96 20.0 195 45 -35 3.59 0.4053
WVFGRD96 21.0 195 45 -35 3.60 0.3952
WVFGRD96 22.0 195 45 -35 3.60 0.3856
WVFGRD96 23.0 195 45 -35 3.61 0.3759
WVFGRD96 24.0 195 45 -35 3.62 0.3668
WVFGRD96 25.0 195 45 -35 3.62 0.3579
WVFGRD96 26.0 195 45 -35 3.63 0.3478
WVFGRD96 27.0 200 45 -30 3.63 0.3380
WVFGRD96 28.0 200 45 -30 3.64 0.3310
WVFGRD96 29.0 200 45 -30 3.65 0.3264
The best solution is
WVFGRD96 8.0 355 40 -70 3.48 0.5255
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 Jul 2 21:12:58 CDT 2009