2009/06/19 19:47:09 42.302 13.383 9.9 3.30 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/19 19:47:09:0 42.30 13.38 9.9 3.3 Italy
Stations used:
IV.ASSB IV.CAMP IV.CERT IV.CESX IV.FAGN IV.FDMO IV.FIAM
IV.GUAR IV.INTR IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.RMP
IV.RNI2 IV.SACS MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 6.68e+20 dyne-cm
Mw = 3.15
Z = 10 km
Plane Strike Dip Rake
NP1 327 51 -98
NP2 160 40 -80
Principal Axes:
Axis Value Plunge Azimuth
T 6.68e+20 5 63
N 0.00e+00 6 332
P -6.68e+20 82 193
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.24e+20
Mxy 2.65e+20
Mxz 1.23e+20
Myy 5.24e+20
Myz 7.70e+19
Mzz -6.48e+20
##############
--####################
####-------#################
####-----------###############
#####--------------###############
#####-----------------############
######-------------------########## T
#######---------------------######## #
#######----------------------###########
########-----------------------###########
########------------------------##########
########----------- ----------##########
#########---------- P -----------#########
########---------- -----------########
#########------------------------#######
#########-----------------------######
#########----------------------#####
##########--------------------####
##########------------------##
###########---------------##
###########-----------
#############-
Global CMT Convention Moment Tensor:
R T P
-6.48e+20 1.23e+20 -7.70e+19
1.23e+20 1.24e+20 -2.65e+20
-7.70e+19 -2.65e+20 5.24e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090619194709/index.html
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STK = 160
DIP = 40
RAKE = -80
MW = 3.15
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/19 19:47:09:0 42.30 13.38 9.9 3.3 Italy
Stations used:
IV.ASSB IV.CAMP IV.CERT IV.CESX IV.FAGN IV.FDMO IV.FIAM
IV.GUAR IV.INTR IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.RMP
IV.RNI2 IV.SACS MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 6.68e+20 dyne-cm
Mw = 3.15
Z = 10 km
Plane Strike Dip Rake
NP1 327 51 -98
NP2 160 40 -80
Principal Axes:
Axis Value Plunge Azimuth
T 6.68e+20 5 63
N 0.00e+00 6 332
P -6.68e+20 82 193
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.24e+20
Mxy 2.65e+20
Mxz 1.23e+20
Myy 5.24e+20
Myz 7.70e+19
Mzz -6.48e+20
##############
--####################
####-------#################
####-----------###############
#####--------------###############
#####-----------------############
######-------------------########## T
#######---------------------######## #
#######----------------------###########
########-----------------------###########
########------------------------##########
########----------- ----------##########
#########---------- P -----------#########
########---------- -----------########
#########------------------------#######
#########-----------------------######
#########----------------------#####
##########--------------------####
##########------------------##
###########---------------##
###########-----------
#############-
Global CMT Convention Moment Tensor:
R T P
-6.48e+20 1.23e+20 -7.70e+19
1.23e+20 1.24e+20 -2.65e+20
-7.70e+19 -2.65e+20 5.24e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090619194709/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 0.5 155 50 90 2.90 0.3872
WVFGRD96 1.0 155 50 90 2.93 0.3483
WVFGRD96 2.0 150 80 80 3.04 0.3500
WVFGRD96 3.0 150 85 75 3.03 0.4315
WVFGRD96 4.0 330 90 -75 3.00 0.4785
WVFGRD96 5.0 145 90 75 3.12 0.5049
WVFGRD96 6.0 170 20 -65 3.09 0.5328
WVFGRD96 7.0 165 30 -75 3.12 0.5664
WVFGRD96 8.0 165 40 -75 3.12 0.5960
WVFGRD96 9.0 160 40 -80 3.14 0.6117
WVFGRD96 10.0 160 40 -80 3.15 0.6193
WVFGRD96 11.0 160 40 -80 3.16 0.6190
WVFGRD96 12.0 160 40 -80 3.17 0.6122
WVFGRD96 13.0 160 40 -80 3.18 0.6006
WVFGRD96 14.0 160 40 -80 3.20 0.5843
WVFGRD96 15.0 160 35 -80 3.23 0.5745
WVFGRD96 16.0 160 35 -80 3.23 0.5588
WVFGRD96 17.0 160 35 -80 3.24 0.5410
WVFGRD96 18.0 160 35 -80 3.25 0.5219
WVFGRD96 19.0 165 35 -75 3.26 0.5029
WVFGRD96 20.0 160 35 -80 3.26 0.4846
WVFGRD96 21.0 165 35 -75 3.27 0.4679
WVFGRD96 22.0 165 35 -75 3.27 0.4529
WVFGRD96 23.0 160 35 -80 3.28 0.4402
WVFGRD96 24.0 165 35 -75 3.29 0.4274
WVFGRD96 25.0 165 35 -75 3.29 0.4132
WVFGRD96 26.0 170 35 -70 3.29 0.3963
WVFGRD96 27.0 180 25 -60 3.30 0.3857
WVFGRD96 28.0 185 25 -55 3.31 0.3774
WVFGRD96 29.0 195 30 -45 3.32 0.3726
The best solution is
WVFGRD96 10.0 160 40 -80 3.15 0.6193
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 Jun 19 21:46:32 CDT 2009