2009/06/11 07:04:49 42.335 13.438 10.6 3.40 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/11 07:04:49:0 42.33 13.44 10.6 3.4 Italy
Stations used:
IV.ARVD IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.GUMA IV.INTR IV.LNSS IV.MIDA
IV.MODR IV.MTCE IV.OFFI IV.RDP IV.SGG IV.TERO IV.VAGA
IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.12e+21 dyne-cm
Mw = 3.30
Z = 6 km
Plane Strike Dip Rake
NP1 124 72 -99
NP2 330 20 -65
Principal Axes:
Axis Value Plunge Azimuth
T 1.12e+21 26 220
N 0.00e+00 8 126
P -1.12e+21 62 20
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.04e+20
Mxy 3.64e+20
Mxz -7.75e+20
Myy 3.50e+20
Myz -4.52e+20
Mzz -6.54e+20
##############
---------------#######
----------------------######
-------------------------#####
-----------------------------#####
#------------------------------#####
###----------------- -----------####
######--------------- P ------------####
#######-------------- ------------####
##########----------------------------####
############--------------------------####
##############------------------------####
#################---------------------####
###################------------------###
######################---------------###
########################------------##
####### ##################------##
###### T #######################--
#### ######################-
###########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-6.54e+20 -7.75e+20 4.52e+20
-7.75e+20 3.04e+20 -3.64e+20
4.52e+20 -3.64e+20 3.50e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090611070449/index.html
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STK = 330
DIP = 20
RAKE = -65
MW = 3.30
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/11 07:04:49:0 42.33 13.44 10.6 3.4 Italy
Stations used:
IV.ARVD IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.GUMA IV.INTR IV.LNSS IV.MIDA
IV.MODR IV.MTCE IV.OFFI IV.RDP IV.SGG IV.TERO IV.VAGA
IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.12e+21 dyne-cm
Mw = 3.30
Z = 6 km
Plane Strike Dip Rake
NP1 124 72 -99
NP2 330 20 -65
Principal Axes:
Axis Value Plunge Azimuth
T 1.12e+21 26 220
N 0.00e+00 8 126
P -1.12e+21 62 20
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.04e+20
Mxy 3.64e+20
Mxz -7.75e+20
Myy 3.50e+20
Myz -4.52e+20
Mzz -6.54e+20
##############
---------------#######
----------------------######
-------------------------#####
-----------------------------#####
#------------------------------#####
###----------------- -----------####
######--------------- P ------------####
#######-------------- ------------####
##########----------------------------####
############--------------------------####
##############------------------------####
#################---------------------####
###################------------------###
######################---------------###
########################------------##
####### ##################------##
###### T #######################--
#### ######################-
###########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-6.54e+20 -7.75e+20 4.52e+20
-7.75e+20 3.04e+20 -3.64e+20
4.52e+20 -3.64e+20 3.50e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090611070449/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 0.5 295 45 -90 3.00 0.3351
WVFGRD96 1.0 305 35 -75 3.05 0.2890
WVFGRD96 2.0 115 85 -80 3.23 0.3786
WVFGRD96 3.0 115 80 -80 3.19 0.4589
WVFGRD96 4.0 305 15 -80 3.18 0.5000
WVFGRD96 5.0 315 15 -75 3.29 0.5309
WVFGRD96 6.0 330 20 -65 3.30 0.5502
WVFGRD96 7.0 330 20 -65 3.30 0.5477
WVFGRD96 8.0 335 25 -60 3.26 0.5316
WVFGRD96 9.0 340 25 -55 3.26 0.5151
WVFGRD96 10.0 345 25 -50 3.26 0.4969
WVFGRD96 11.0 345 25 -50 3.26 0.4770
WVFGRD96 12.0 -10 25 -40 3.26 0.4564
WVFGRD96 13.0 20 25 -10 3.27 0.4377
WVFGRD96 14.0 30 25 5 3.27 0.4252
WVFGRD96 15.0 35 20 10 3.31 0.4128
WVFGRD96 16.0 35 20 10 3.32 0.3993
WVFGRD96 17.0 35 20 10 3.33 0.3854
WVFGRD96 18.0 35 25 10 3.34 0.3716
WVFGRD96 19.0 35 25 15 3.35 0.3581
WVFGRD96 20.0 40 25 20 3.35 0.3455
WVFGRD96 21.0 295 65 80 3.34 0.3387
WVFGRD96 22.0 295 65 80 3.35 0.3323
WVFGRD96 23.0 135 30 110 3.36 0.3260
WVFGRD96 24.0 300 60 85 3.37 0.3187
WVFGRD96 25.0 125 25 95 3.37 0.3144
WVFGRD96 26.0 305 65 100 3.39 0.3121
WVFGRD96 27.0 130 40 95 3.40 0.3104
WVFGRD96 28.0 305 50 90 3.41 0.3105
WVFGRD96 29.0 125 40 90 3.43 0.3053
The best solution is
WVFGRD96 6.0 330 20 -65 3.30 0.5502
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 11 08:15:06 CDT 2009