2010/02/02 19:42:43 43.101 13.389 9.7 3.5 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2010/02/02 19:42:43:0 43.10 13.39 9.7 3.5 Italy
Stations used:
IV.AOI IV.ARVD IV.CESX IV.CSNT IV.FAGN IV.FDMO IV.INTR
IV.MNS IV.MTCE IV.PARC IV.PESA IV.PIEI IV.TERO
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.58e+21 dyne-cm
Mw = 3.40
Z = 19 km
Plane Strike Dip Rake
NP1 270 75 60
NP2 156 33 152
Principal Axes:
Axis Value Plunge Azimuth
T 1.58e+21 51 146
N 0.00e+00 29 278
P -1.58e+21 24 23
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.86e+20
Mxy -7.65e+20
Mxz -1.19e+21
Myy -1.83e+13
Myz 2.05e+20
Mzz 6.86e+20
--------------
#--------------- ---
###---------------- P ------
###----------------- -------
####------------------------------
####--------------------------------
#####---------------------------------
#####-----------------------------------
#####-----------------------------------
######---########################---------
##----##################################--
-------###################################
-------###################################
-------#################################
--------################ #############
--------############### T ############
--------############## ###########
--------##########################
--------######################
----------##################
----------############
--------------
Global CMT Convention Moment Tensor:
R T P
6.86e+20 -1.19e+21 -2.05e+20
-1.19e+21 -6.86e+20 7.65e+20
-2.05e+20 7.65e+20 -1.83e+13
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100202194243/index.html
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STK = 270
DIP = 75
RAKE = 60
MW = 3.40
HS = 19.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2010/02/02 19:42:43:0 43.10 13.39 9.7 3.5 Italy
Stations used:
IV.AOI IV.ARVD IV.CESX IV.CSNT IV.FAGN IV.FDMO IV.INTR
IV.MNS IV.MTCE IV.PARC IV.PESA IV.PIEI IV.TERO
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.58e+21 dyne-cm
Mw = 3.40
Z = 19 km
Plane Strike Dip Rake
NP1 270 75 60
NP2 156 33 152
Principal Axes:
Axis Value Plunge Azimuth
T 1.58e+21 51 146
N 0.00e+00 29 278
P -1.58e+21 24 23
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.86e+20
Mxy -7.65e+20
Mxz -1.19e+21
Myy -1.83e+13
Myz 2.05e+20
Mzz 6.86e+20
--------------
#--------------- ---
###---------------- P ------
###----------------- -------
####------------------------------
####--------------------------------
#####---------------------------------
#####-----------------------------------
#####-----------------------------------
######---########################---------
##----##################################--
-------###################################
-------###################################
-------#################################
--------################ #############
--------############### T ############
--------############## ###########
--------##########################
--------######################
----------##################
----------############
--------------
Global CMT Convention Moment Tensor:
R T P
6.86e+20 -1.19e+21 -2.05e+20
-1.19e+21 -6.86e+20 7.65e+20
-2.05e+20 7.65e+20 -1.83e+13
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100202194243/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 1.0 275 40 90 3.04 0.3191
WVFGRD96 2.0 275 35 90 3.13 0.3132
WVFGRD96 3.0 265 90 45 3.12 0.2752
WVFGRD96 4.0 75 80 -40 3.14 0.3087
WVFGRD96 5.0 270 85 55 3.21 0.3390
WVFGRD96 6.0 270 85 55 3.22 0.3743
WVFGRD96 7.0 270 85 55 3.23 0.4100
WVFGRD96 8.0 275 80 55 3.21 0.4400
WVFGRD96 9.0 275 80 55 3.23 0.4649
WVFGRD96 10.0 275 80 55 3.24 0.4857
WVFGRD96 11.0 275 80 55 3.26 0.5032
WVFGRD96 12.0 275 75 55 3.28 0.5179
WVFGRD96 13.0 275 75 55 3.29 0.5303
WVFGRD96 14.0 270 75 55 3.30 0.5397
WVFGRD96 15.0 270 75 60 3.35 0.5484
WVFGRD96 16.0 270 75 60 3.36 0.5549
WVFGRD96 17.0 270 75 60 3.37 0.5590
WVFGRD96 18.0 270 75 60 3.39 0.5613
WVFGRD96 19.0 270 75 60 3.40 0.5618
WVFGRD96 20.0 270 70 60 3.41 0.5605
WVFGRD96 21.0 270 70 60 3.42 0.5600
WVFGRD96 22.0 270 70 60 3.43 0.5570
WVFGRD96 23.0 270 70 60 3.44 0.5530
WVFGRD96 24.0 270 70 60 3.45 0.5465
WVFGRD96 25.0 270 70 60 3.46 0.5384
WVFGRD96 26.0 270 70 60 3.47 0.5267
WVFGRD96 27.0 270 70 60 3.47 0.5124
WVFGRD96 28.0 270 70 60 3.48 0.4966
WVFGRD96 29.0 270 70 60 3.48 0.4796
The best solution is
WVFGRD96 19.0 270 75 60 3.40 0.5618
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=Tue Feb 2 17:05:31 CST 2010