2010/02/03 11:16:45 43.129 13.431 22.0 3.2 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2010/02/03 11:16:45:0 43.13 13.43 22.0 3.2 Italy
Stations used:
IV.AOI IV.CESI IV.CESX IV.FDMO IV.MNS IV.NRCA IV.SACS
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 = 14 km
Plane Strike Dip Rake
NP1 350 73 -148
NP2 250 60 -20
Principal Axes:
Axis Value Plunge Azimuth
T 7.94e+20 8 118
N 0.00e+00 54 16
P -7.94e+20 34 214
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.08e+20
Mxy -5.71e+20
Mxz 2.55e+20
Myy 4.43e+20
Myz 3.04e+20
Mzz -2.35e+20
####----------
##########------------
##############--------------
################--------------
##################----------------
####################----------------
####################--##############--
################-------#################
############------------################
##########---------------#################
#######------------------#################
######--------------------################
####----------------------################
##-----------------------###############
#------------------------########### #
------------------------########### T
--------- -----------###########
-------- P -----------############
------ -----------##########
-------------------#########
---------------#######
-----------###
Global CMT Convention Moment Tensor:
R T P
-2.35e+20 2.55e+20 -3.04e+20
2.55e+20 -2.08e+20 5.71e+20
-3.04e+20 5.71e+20 4.43e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100203111645/index.html
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STK = 250
DIP = 60
RAKE = -20
MW = 3.20
HS = 14.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2010/02/03 11:16:45:0 43.13 13.43 22.0 3.2 Italy
Stations used:
IV.AOI IV.CESI IV.CESX IV.FDMO IV.MNS IV.NRCA IV.SACS
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 = 14 km
Plane Strike Dip Rake
NP1 350 73 -148
NP2 250 60 -20
Principal Axes:
Axis Value Plunge Azimuth
T 7.94e+20 8 118
N 0.00e+00 54 16
P -7.94e+20 34 214
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.08e+20
Mxy -5.71e+20
Mxz 2.55e+20
Myy 4.43e+20
Myz 3.04e+20
Mzz -2.35e+20
####----------
##########------------
##############--------------
################--------------
##################----------------
####################----------------
####################--##############--
################-------#################
############------------################
##########---------------#################
#######------------------#################
######--------------------################
####----------------------################
##-----------------------###############
#------------------------########### #
------------------------########### T
--------- -----------###########
-------- P -----------############
------ -----------##########
-------------------#########
---------------#######
-----------###
Global CMT Convention Moment Tensor:
R T P
-2.35e+20 2.55e+20 -3.04e+20
2.55e+20 -2.08e+20 5.71e+20
-3.04e+20 5.71e+20 4.43e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100203111645/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 1.0 310 40 -75 2.89 0.3608
WVFGRD96 2.0 330 40 -45 2.98 0.3431
WVFGRD96 3.0 350 90 25 2.98 0.3177
WVFGRD96 4.0 350 85 20 3.02 0.3308
WVFGRD96 5.0 250 50 -30 3.08 0.3555
WVFGRD96 6.0 175 70 45 3.09 0.4016
WVFGRD96 7.0 180 60 45 3.14 0.4403
WVFGRD96 8.0 175 60 35 3.13 0.4697
WVFGRD96 9.0 175 60 40 3.13 0.4873
WVFGRD96 10.0 180 55 40 3.16 0.4980
WVFGRD96 11.0 175 60 40 3.16 0.5034
WVFGRD96 12.0 175 60 35 3.18 0.5053
WVFGRD96 13.0 250 60 -25 3.19 0.5067
WVFGRD96 14.0 250 60 -20 3.20 0.5096
WVFGRD96 15.0 250 55 -20 3.22 0.5088
WVFGRD96 16.0 250 55 -20 3.24 0.5065
WVFGRD96 17.0 250 55 -20 3.25 0.5029
WVFGRD96 18.0 250 55 -20 3.26 0.4976
WVFGRD96 19.0 250 55 -15 3.27 0.4911
WVFGRD96 20.0 255 55 -5 3.27 0.4834
WVFGRD96 21.0 255 55 0 3.27 0.4750
WVFGRD96 22.0 255 55 0 3.28 0.4657
WVFGRD96 23.0 255 55 0 3.29 0.4549
WVFGRD96 24.0 255 55 5 3.29 0.4435
WVFGRD96 25.0 255 55 5 3.29 0.4302
WVFGRD96 26.0 255 55 5 3.30 0.4161
WVFGRD96 27.0 255 55 10 3.29 0.4018
WVFGRD96 28.0 255 55 10 3.30 0.3867
WVFGRD96 29.0 255 60 10 3.32 0.3717
The best solution is
WVFGRD96 14.0 250 60 -20 3.20 0.5096
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 Feb 3 12:26:10 CST 2010