2009/06/21 16:31:11 42.567 13.195 9.9 3.40 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/21 16:31:11:0 42.57 13.19 9.9 3.4 Italy
Stations used:
IV.CAMP IV.CERT IV.CESI IV.CING IV.FDMO IV.GUMA IV.MNS
IV.MTCE IV.SACS IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 7.67e+20 dyne-cm
Mw = 3.19
Z = 3 km
Plane Strike Dip Rake
NP1 132 51 -98
NP2 325 40 -80
Principal Axes:
Axis Value Plunge Azimuth
T 7.67e+20 5 228
N 0.00e+00 6 137
P -7.67e+20 82 358
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.25e+20
Mxy 3.79e+20
Mxz -1.59e+20
Myy 4.19e+20
Myz -4.89e+19
Mzz -7.44e+20
##############
######################
--------------##############
------------------############
#----------------------###########
##------------------------##########
###-------------------------##########
#####--------------------------#########
#####------------- -----------########
#######------------ P ------------########
########----------- ------------########
#########--------------------------#######
##########-------------------------#######
###########------------------------#####
############-----------------------#####
##############--------------------####
###############-----------------####
# #############--------------###
T ##################--------##
##########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-7.44e+20 -1.59e+20 4.89e+19
-1.59e+20 3.25e+20 -3.79e+20
4.89e+19 -3.79e+20 4.19e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090621163111/index.html
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STK = 325
DIP = 40
RAKE = -80
MW = 3.19
HS = 3.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/21 16:31:11:0 42.57 13.19 9.9 3.4 Italy
Stations used:
IV.CAMP IV.CERT IV.CESI IV.CING IV.FDMO IV.GUMA IV.MNS
IV.MTCE IV.SACS IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 7.67e+20 dyne-cm
Mw = 3.19
Z = 3 km
Plane Strike Dip Rake
NP1 132 51 -98
NP2 325 40 -80
Principal Axes:
Axis Value Plunge Azimuth
T 7.67e+20 5 228
N 0.00e+00 6 137
P -7.67e+20 82 358
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.25e+20
Mxy 3.79e+20
Mxz -1.59e+20
Myy 4.19e+20
Myz -4.89e+19
Mzz -7.44e+20
##############
######################
--------------##############
------------------############
#----------------------###########
##------------------------##########
###-------------------------##########
#####--------------------------#########
#####------------- -----------########
#######------------ P ------------########
########----------- ------------########
#########--------------------------#######
##########-------------------------#######
###########------------------------#####
############-----------------------#####
##############--------------------####
###############-----------------####
# #############--------------###
T ##################--------##
##########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-7.44e+20 -1.59e+20 4.89e+19
-1.59e+20 3.25e+20 -3.79e+20
4.89e+19 -3.79e+20 4.19e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090621163111/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 0.5 345 30 -35 3.06 0.3430
WVFGRD96 1.0 345 35 -40 3.05 0.3631
WVFGRD96 2.0 340 35 -50 3.13 0.4290
WVFGRD96 3.0 325 40 -80 3.19 0.4976
WVFGRD96 4.0 320 40 -85 3.22 0.4946
WVFGRD96 5.0 135 50 -95 3.28 0.4770
WVFGRD96 6.0 330 40 -75 3.25 0.4014
WVFGRD96 7.0 190 60 -15 3.17 0.3407
WVFGRD96 8.0 195 65 -10 3.17 0.3299
WVFGRD96 9.0 195 65 -10 3.18 0.3193
WVFGRD96 10.0 200 65 -5 3.19 0.3111
WVFGRD96 11.0 200 65 -5 3.21 0.3033
WVFGRD96 12.0 195 65 -5 3.21 0.2950
WVFGRD96 13.0 195 65 -5 3.22 0.2858
WVFGRD96 14.0 200 65 -5 3.24 0.2775
WVFGRD96 15.0 205 65 0 3.27 0.2703
WVFGRD96 16.0 205 65 0 3.28 0.2640
WVFGRD96 17.0 205 65 0 3.29 0.2584
WVFGRD96 18.0 205 65 5 3.30 0.2543
WVFGRD96 19.0 205 65 5 3.31 0.2516
WVFGRD96 20.0 205 65 5 3.32 0.2497
WVFGRD96 21.0 210 65 10 3.34 0.2488
WVFGRD96 22.0 205 55 40 3.34 0.2496
WVFGRD96 23.0 205 55 40 3.35 0.2501
WVFGRD96 24.0 210 55 45 3.36 0.2492
WVFGRD96 25.0 205 55 35 3.37 0.2495
WVFGRD96 26.0 205 60 30 3.38 0.2500
WVFGRD96 27.0 205 60 30 3.39 0.2500
WVFGRD96 28.0 200 60 20 3.39 0.2497
WVFGRD96 29.0 200 55 20 3.40 0.2511
The best solution is
WVFGRD96 3.0 325 40 -80 3.19 0.4976
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=Sun Jun 21 15:52:57 CDT 2009