2009/03/30 19:05:28 42.316 13.373 9.7 3.1 ITALY
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/03/30 19:05:28:0 42.32 13.37 9.7 3.1 ITALY
Stations used:
IV.CERT IV.FAGN IV.FDMO IV.LPEL IV.MTCE IV.OFFI IV.RMP
IV.TERO
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.08e+21 dyne-cm
Mw = 3.29
Z = 11 km
Plane Strike Dip Rake
NP1 292 71 -137
NP2 185 50 -25
Principal Axes:
Axis Value Plunge Azimuth
T 1.08e+21 13 54
N 0.00e+00 44 311
P -1.08e+21 43 156
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.27e+20
Mxy 7.02e+20
Mxz 6.36e+20
Myy 5.78e+20
Myz -2.42e+19
Mzz -4.51e+20
-------#######
--------##############
----------##################
---------#####################
----------#################### #
----------##################### T ##
-----------##################### ###
###########-----########################
###########----------###################
###########----------------###############
###########-------------------############
###########----------------------#########
###########-------------------------######
##########---------------------------###
##########----------------------------##
##########------------ -------------
#########------------ P ------------
#########----------- -----------
########----------------------
########--------------------
######----------------
####----------
Global CMT Convention Moment Tensor:
R T P
-4.51e+20 6.36e+20 2.42e+19
6.36e+20 -1.27e+20 -7.02e+20
2.42e+19 -7.02e+20 5.78e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090330190528/index.html
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STK = 185
DIP = 50
RAKE = -25
MW = 3.29
HS = 11.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/03/30 19:05:28:0 42.32 13.37 9.7 3.1 ITALY
Stations used:
IV.CERT IV.FAGN IV.FDMO IV.LPEL IV.MTCE IV.OFFI IV.RMP
IV.TERO
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.08e+21 dyne-cm
Mw = 3.29
Z = 11 km
Plane Strike Dip Rake
NP1 292 71 -137
NP2 185 50 -25
Principal Axes:
Axis Value Plunge Azimuth
T 1.08e+21 13 54
N 0.00e+00 44 311
P -1.08e+21 43 156
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.27e+20
Mxy 7.02e+20
Mxz 6.36e+20
Myy 5.78e+20
Myz -2.42e+19
Mzz -4.51e+20
-------#######
--------##############
----------##################
---------#####################
----------#################### #
----------##################### T ##
-----------##################### ###
###########-----########################
###########----------###################
###########----------------###############
###########-------------------############
###########----------------------#########
###########-------------------------######
##########---------------------------###
##########----------------------------##
##########------------ -------------
#########------------ P ------------
#########----------- -----------
########----------------------
########--------------------
######----------------
####----------
Global CMT Convention Moment Tensor:
R T P
-4.51e+20 6.36e+20 2.42e+19
6.36e+20 -1.27e+20 -7.02e+20
2.42e+19 -7.02e+20 5.78e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090330190528/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 0.5 270 50 90 3.03 0.3341
WVFGRD96 1.0 335 45 -90 3.01 0.3124
WVFGRD96 2.0 230 30 15 3.13 0.3339
WVFGRD96 3.0 225 30 10 3.15 0.4067
WVFGRD96 4.0 225 35 25 3.16 0.4596
WVFGRD96 5.0 215 30 30 3.26 0.5020
WVFGRD96 6.0 210 35 30 3.27 0.5354
WVFGRD96 7.0 215 35 30 3.28 0.5557
WVFGRD96 8.0 185 45 -30 3.25 0.5737
WVFGRD96 9.0 185 45 -30 3.26 0.5852
WVFGRD96 10.0 185 50 -25 3.28 0.5926
WVFGRD96 11.0 185 50 -25 3.29 0.5953
WVFGRD96 12.0 185 55 -25 3.31 0.5932
WVFGRD96 13.0 185 55 -25 3.32 0.5891
WVFGRD96 14.0 185 55 -20 3.34 0.5805
WVFGRD96 15.0 180 55 -25 3.37 0.5745
WVFGRD96 16.0 185 55 -25 3.36 0.5646
WVFGRD96 17.0 185 55 -25 3.37 0.5535
WVFGRD96 18.0 185 55 -20 3.38 0.5413
WVFGRD96 19.0 185 65 0 3.41 0.5336
WVFGRD96 20.0 185 65 0 3.42 0.5234
WVFGRD96 21.0 185 65 0 3.42 0.5130
WVFGRD96 22.0 185 70 5 3.43 0.5027
WVFGRD96 23.0 185 70 5 3.44 0.4930
WVFGRD96 24.0 185 70 5 3.44 0.4837
WVFGRD96 25.0 190 40 -25 3.43 0.4750
WVFGRD96 26.0 190 40 -25 3.44 0.4687
WVFGRD96 27.0 190 40 -25 3.44 0.4626
WVFGRD96 28.0 190 80 20 3.47 0.4565
WVFGRD96 29.0 190 80 20 3.49 0.4557
The best solution is
WVFGRD96 11.0 185 50 -25 3.29 0.5953
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 10:51:00 CDT 2009