2009/06/04 12:40:31 42.244 13.540 9.4 3.20 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/04 12:40:31:0 42.24 13.54 9.4 3.2 Italy
Stations used:
IV.CAMP IV.CERT IV.CESI IV.CESX IV.FIAM IV.GUAR IV.MNS
IV.MTCE IV.OFFI IV.TERO IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 7.94e+20 dyne-cm
Mw = 3.20
Z = 5 km
Plane Strike Dip Rake
NP1 141 65 -85
NP2 310 25 -100
Principal Axes:
Axis Value Plunge Azimuth
T 7.94e+20 20 228
N 0.00e+00 4 319
P -7.94e+20 69 60
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.94e+20
Mxy 3.05e+20
Mxz -3.05e+20
Myy 3.05e+20
Myz -4.19e+20
Mzz -5.99e+20
##############
######################
-#----------------##########
##---------------------#######
####-----------------------#######
######------------------------######
#######--------------------------#####
#########--------------------------#####
##########------------- ----------####
############------------ P -----------####
#############----------- -----------####
##############-------------------------###
###############------------------------###
################----------------------##
#################---------------------##
##################-------------------#
#### ############----------------#
### T ###############-------------
# ##################--------
#########################---
######################
##############
Global CMT Convention Moment Tensor:
R T P
-5.99e+20 -3.05e+20 4.19e+20
-3.05e+20 2.94e+20 -3.05e+20
4.19e+20 -3.05e+20 3.05e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090604124031/index.html
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STK = 310
DIP = 25
RAKE = -100
MW = 3.20
HS = 5.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/04 12:40:31:0 42.24 13.54 9.4 3.2 Italy
Stations used:
IV.CAMP IV.CERT IV.CESI IV.CESX IV.FIAM IV.GUAR IV.MNS
IV.MTCE IV.OFFI IV.TERO IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 7.94e+20 dyne-cm
Mw = 3.20
Z = 5 km
Plane Strike Dip Rake
NP1 141 65 -85
NP2 310 25 -100
Principal Axes:
Axis Value Plunge Azimuth
T 7.94e+20 20 228
N 0.00e+00 4 319
P -7.94e+20 69 60
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.94e+20
Mxy 3.05e+20
Mxz -3.05e+20
Myy 3.05e+20
Myz -4.19e+20
Mzz -5.99e+20
##############
######################
-#----------------##########
##---------------------#######
####-----------------------#######
######------------------------######
#######--------------------------#####
#########--------------------------#####
##########------------- ----------####
############------------ P -----------####
#############----------- -----------####
##############-------------------------###
###############------------------------###
################----------------------##
#################---------------------##
##################-------------------#
#### ############----------------#
### T ###############-------------
# ##################--------
#########################---
######################
##############
Global CMT Convention Moment Tensor:
R T P
-5.99e+20 -3.05e+20 4.19e+20
-3.05e+20 2.94e+20 -3.05e+20
4.19e+20 -3.05e+20 3.05e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090604124031/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 0.5 340 40 -55 2.96 0.3545
WVFGRD96 1.0 345 45 -55 2.98 0.3430
WVFGRD96 2.0 350 40 -50 3.05 0.3350
WVFGRD96 3.0 145 75 -80 3.10 0.3807
WVFGRD96 4.0 145 70 -80 3.10 0.4065
WVFGRD96 5.0 310 25 -100 3.20 0.4306
WVFGRD96 6.0 320 25 -90 3.20 0.4271
WVFGRD96 7.0 340 30 -75 3.20 0.4118
WVFGRD96 8.0 340 30 -75 3.16 0.3822
WVFGRD96 9.0 345 35 -70 3.16 0.3629
WVFGRD96 10.0 350 35 -65 3.16 0.3433
WVFGRD96 11.0 -5 40 -55 3.16 0.3241
WVFGRD96 12.0 0 40 -50 3.16 0.3057
WVFGRD96 13.0 25 55 20 3.16 0.2934
WVFGRD96 14.0 30 55 25 3.17 0.2927
WVFGRD96 15.0 95 25 40 3.20 0.2896
WVFGRD96 16.0 95 30 40 3.22 0.2883
WVFGRD96 17.0 95 30 40 3.23 0.2863
WVFGRD96 18.0 90 30 35 3.24 0.2820
WVFGRD96 19.0 95 30 40 3.25 0.2766
WVFGRD96 20.0 180 75 45 3.25 0.2709
WVFGRD96 21.0 180 75 45 3.26 0.2731
WVFGRD96 22.0 180 75 45 3.27 0.2742
WVFGRD96 23.0 180 75 45 3.28 0.2747
WVFGRD96 24.0 180 75 45 3.29 0.2734
WVFGRD96 25.0 180 75 45 3.29 0.2714
WVFGRD96 26.0 175 75 45 3.30 0.2696
WVFGRD96 27.0 175 75 45 3.31 0.2688
WVFGRD96 28.0 180 70 45 3.31 0.2675
WVFGRD96 29.0 180 70 40 3.32 0.2679
The best solution is
WVFGRD96 5.0 310 25 -100 3.20 0.4306
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 4 16:00:05 CDT 2009