2009/04/06 06:21:05 42.317 13.416 10.6 3.3 ITALY
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/04/06 06:21:05:0 42.32 13.42 10.6 3.3 ITALY
Stations used:
IV.GUAR IV.INTR IV.MNS IV.MTCE IV.NRCA IV.OFFI IV.POFI
IV.RMP IV.TRTR
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.57e+21 dyne-cm
Mw = 3.54
Z = 12 km
Plane Strike Dip Rake
NP1 128 61 -96
NP2 320 30 -80
Principal Axes:
Axis Value Plunge Azimuth
T 2.57e+21 15 223
N 0.00e+00 5 131
P -2.57e+21 74 24
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.13e+21
Mxy 1.12e+21
Mxz -1.11e+21
Myy 1.07e+21
Myz -7.21e+20
Mzz -2.19e+21
##############
######################
-----------------###########
---------------------#########
#-------------------------########
##---------------------------#######
####---------------------------#######
#####----------------------------#######
######-------------- -----------######
########------------- P ------------######
##########----------- -------------#####
###########--------------------------#####
#############------------------------#####
##############-----------------------###
################---------------------###
##################-----------------###
####################--------------##
#### #################--------##
## T #########################
# #######################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-2.19e+21 -1.11e+21 7.21e+20
-1.11e+21 1.13e+21 -1.12e+21
7.21e+20 -1.12e+21 1.07e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090406062105/index.html
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STK = 320
DIP = 30
RAKE = -80
MW = 3.54
HS = 12.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/04/06 06:21:05:0 42.32 13.42 10.6 3.3 ITALY
Stations used:
IV.GUAR IV.INTR IV.MNS IV.MTCE IV.NRCA IV.OFFI IV.POFI
IV.RMP IV.TRTR
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.57e+21 dyne-cm
Mw = 3.54
Z = 12 km
Plane Strike Dip Rake
NP1 128 61 -96
NP2 320 30 -80
Principal Axes:
Axis Value Plunge Azimuth
T 2.57e+21 15 223
N 0.00e+00 5 131
P -2.57e+21 74 24
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.13e+21
Mxy 1.12e+21
Mxz -1.11e+21
Myy 1.07e+21
Myz -7.21e+20
Mzz -2.19e+21
##############
######################
-----------------###########
---------------------#########
#-------------------------########
##---------------------------#######
####---------------------------#######
#####----------------------------#######
######-------------- -----------######
########------------- P ------------######
##########----------- -------------#####
###########--------------------------#####
#############------------------------#####
##############-----------------------###
################---------------------###
##################-----------------###
####################--------------##
#### #################--------##
## T #########################
# #######################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-2.19e+21 -1.11e+21 7.21e+20
-1.11e+21 1.13e+21 -1.12e+21
7.21e+20 -1.12e+21 1.07e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090406062105/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 0.5 305 40 90 3.29 0.4450
WVFGRD96 1.0 120 55 90 3.35 0.4122
WVFGRD96 2.0 280 25 65 3.43 0.3564
WVFGRD96 3.0 270 20 50 3.41 0.3524
WVFGRD96 4.0 255 25 35 3.39 0.3755
WVFGRD96 5.0 290 15 70 3.48 0.4089
WVFGRD96 6.0 20 30 -30 3.50 0.4260
WVFGRD96 7.0 15 35 -40 3.54 0.4791
WVFGRD96 8.0 320 25 -80 3.48 0.5222
WVFGRD96 9.0 320 25 -80 3.49 0.5527
WVFGRD96 10.0 320 30 -80 3.51 0.5742
WVFGRD96 11.0 320 30 -80 3.52 0.5870
WVFGRD96 12.0 320 30 -80 3.54 0.5924
WVFGRD96 13.0 320 30 -80 3.55 0.5919
WVFGRD96 14.0 320 30 -80 3.56 0.5866
WVFGRD96 15.0 320 30 -85 3.61 0.5838
WVFGRD96 16.0 320 30 -85 3.62 0.5749
WVFGRD96 17.0 135 55 -90 3.63 0.5628
WVFGRD96 18.0 320 35 -85 3.64 0.5489
WVFGRD96 19.0 315 35 -90 3.65 0.5322
WVFGRD96 20.0 330 40 -75 3.66 0.5138
WVFGRD96 21.0 330 40 -75 3.67 0.4948
WVFGRD96 22.0 330 40 -75 3.68 0.4722
WVFGRD96 23.0 340 35 -60 3.68 0.4467
WVFGRD96 24.0 100 20 60 3.67 0.4265
WVFGRD96 25.0 105 20 65 3.67 0.4088
WVFGRD96 26.0 110 20 70 3.67 0.3891
WVFGRD96 27.0 110 20 70 3.67 0.3706
WVFGRD96 28.0 105 20 70 3.67 0.3551
WVFGRD96 29.0 105 20 65 3.67 0.3405
The best solution is
WVFGRD96 12.0 320 30 -80 3.54 0.5924
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=Wed Sep 2 08:15:47 CDT 2009