2009/04/14 19:28:02 42.536 13.307 11.0 3.40 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/04/14 19:28:02:0 42.54 13.31 11.0 3.4 Italy
Stations used:
IV.CERT IV.CESX IV.FAGN IV.FDMO IV.FIAM IV.MNS IV.MTCE
IV.MURB IV.NRCA IV.OFFI IV.TERO IV.TRTR MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.33e+21 dyne-cm
Mw = 3.35
Z = 7 km
Plane Strike Dip Rake
NP1 345 50 -70
NP2 135 44 -112
Principal Axes:
Axis Value Plunge Azimuth
T 1.33e+21 3 61
N 0.00e+00 15 152
P -1.33e+21 74 320
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.57e+20
Mxy 6.11e+20
Mxz -2.27e+20
Myy 9.77e+20
Myz 2.86e+20
Mzz -1.23e+21
---###########
-----------###########
----------------############
-------------------###########
##--------------------###########
##-----------------------######### T
###------------------------########
#####-----------------------############
#####----------- ----------###########
######----------- P -----------###########
#######---------- -----------###########
########-----------------------###########
#########-----------------------##########
#########----------------------#########
##########---------------------#########
###########-------------------########
############----------------########
##############-------------#######
###############---------######
#######################-----
##################----
#############-
Global CMT Convention Moment Tensor:
R T P
-1.23e+21 -2.27e+20 -2.86e+20
-2.27e+20 2.57e+20 -6.11e+20
-2.86e+20 -6.11e+20 9.77e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090414192802/index.html
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STK = 345
DIP = 50
RAKE = -70
MW = 3.35
HS = 7.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/04/14 19:28:02:0 42.54 13.31 11.0 3.4 Italy
Stations used:
IV.CERT IV.CESX IV.FAGN IV.FDMO IV.FIAM IV.MNS IV.MTCE
IV.MURB IV.NRCA IV.OFFI IV.TERO IV.TRTR MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.33e+21 dyne-cm
Mw = 3.35
Z = 7 km
Plane Strike Dip Rake
NP1 345 50 -70
NP2 135 44 -112
Principal Axes:
Axis Value Plunge Azimuth
T 1.33e+21 3 61
N 0.00e+00 15 152
P -1.33e+21 74 320
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.57e+20
Mxy 6.11e+20
Mxz -2.27e+20
Myy 9.77e+20
Myz 2.86e+20
Mzz -1.23e+21
---###########
-----------###########
----------------############
-------------------###########
##--------------------###########
##-----------------------######### T
###------------------------########
#####-----------------------############
#####----------- ----------###########
######----------- P -----------###########
#######---------- -----------###########
########-----------------------###########
#########-----------------------##########
#########----------------------#########
##########---------------------#########
###########-------------------########
############----------------########
##############-------------#######
###############---------######
#######################-----
##################----
#############-
Global CMT Convention Moment Tensor:
R T P
-1.23e+21 -2.27e+20 -2.86e+20
-2.27e+20 2.57e+20 -6.11e+20
-2.86e+20 -6.11e+20 9.77e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090414192802/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 5 60 -40 3.02 0.2670
WVFGRD96 1.0 5 55 -40 3.05 0.2618
WVFGRD96 2.0 205 35 -5 3.18 0.3141
WVFGRD96 3.0 210 40 0 3.18 0.3649
WVFGRD96 4.0 205 55 15 3.20 0.3992
WVFGRD96 5.0 340 50 -80 3.34 0.4328
WVFGRD96 6.0 340 50 -75 3.36 0.5013
WVFGRD96 7.0 345 50 -70 3.35 0.5098
WVFGRD96 8.0 345 50 -70 3.31 0.4799
WVFGRD96 9.0 350 50 -60 3.31 0.4595
WVFGRD96 10.0 5 60 -35 3.31 0.4408
WVFGRD96 11.0 5 65 -35 3.32 0.4229
WVFGRD96 12.0 180 55 -40 3.31 0.4015
WVFGRD96 13.0 185 60 -35 3.32 0.3846
WVFGRD96 14.0 185 60 -35 3.33 0.3656
WVFGRD96 15.0 185 60 -35 3.36 0.3568
WVFGRD96 16.0 185 65 -35 3.36 0.3408
WVFGRD96 17.0 20 55 0 3.36 0.3334
WVFGRD96 18.0 20 55 0 3.36 0.3279
WVFGRD96 19.0 30 55 -5 3.37 0.3233
WVFGRD96 20.0 30 55 -5 3.38 0.3191
WVFGRD96 21.0 35 55 0 3.39 0.3156
WVFGRD96 22.0 35 55 0 3.40 0.3127
WVFGRD96 23.0 35 55 0 3.40 0.3104
WVFGRD96 24.0 35 55 5 3.41 0.3096
WVFGRD96 25.0 35 55 5 3.42 0.3080
WVFGRD96 26.0 35 55 5 3.43 0.3061
WVFGRD96 27.0 35 60 5 3.45 0.3038
WVFGRD96 28.0 35 60 5 3.46 0.3033
WVFGRD96 29.0 35 60 5 3.48 0.3034
The best solution is
WVFGRD96 7.0 345 50 -70 3.35 0.5098
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=Mon Apr 20 12:03:37 CDT 2009