2009/05/14 06:30:22 42.501 13.406 7.9 3.80 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/05/14 06:30:22:0 42.50 13.41 7.9 3.8 Italy
Stations used:
IV.CAFI IV.CAFR IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.FRES IV.GUAR IV.GUMA IV.INTR
IV.LATE IV.LNSS IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.MURB
IV.PIEI IV.POFI IV.RDP IV.RMP IV.SACS IV.TERO IV.TOLF
IV.VAGA IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.24e+21 dyne-cm
Mw = 3.50
Z = 6 km
Plane Strike Dip Rake
NP1 155 55 -85
NP2 326 35 -97
Principal Axes:
Axis Value Plunge Azimuth
T 2.24e+21 10 241
N 0.00e+00 4 332
P -2.24e+21 79 84
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.97e+20
Mxy 9.05e+20
Mxz -2.21e+20
Myy 1.60e+21
Myz -7.39e+20
Mzz -2.10e+21
##############
-#-----###############
####------------############
####----------------##########
######------------------##########
#######--------------------#########
########----------------------########
#########-----------------------########
#########------------------------#######
###########------------ ---------#######
###########------------ P ---------#######
############----------- ----------######
#############-----------------------######
############-----------------------#####
## ########----------------------#####
# T ##########--------------------####
###########-------------------###
##############-----------------###
##############---------------#
################-----------#
################------
##############
Global CMT Convention Moment Tensor:
R T P
-2.10e+21 -2.21e+20 7.39e+20
-2.21e+20 4.97e+20 -9.05e+20
7.39e+20 -9.05e+20 1.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090514063022/index.html
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STK = 155
DIP = 55
RAKE = -85
MW = 3.50
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/05/14 06:30:22:0 42.50 13.41 7.9 3.8 Italy
Stations used:
IV.CAFI IV.CAFR IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.FRES IV.GUAR IV.GUMA IV.INTR
IV.LATE IV.LNSS IV.LPEL IV.MIDA IV.MNS IV.MTCE IV.MURB
IV.PIEI IV.POFI IV.RDP IV.RMP IV.SACS IV.TERO IV.TOLF
IV.VAGA IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.24e+21 dyne-cm
Mw = 3.50
Z = 6 km
Plane Strike Dip Rake
NP1 155 55 -85
NP2 326 35 -97
Principal Axes:
Axis Value Plunge Azimuth
T 2.24e+21 10 241
N 0.00e+00 4 332
P -2.24e+21 79 84
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.97e+20
Mxy 9.05e+20
Mxz -2.21e+20
Myy 1.60e+21
Myz -7.39e+20
Mzz -2.10e+21
##############
-#-----###############
####------------############
####----------------##########
######------------------##########
#######--------------------#########
########----------------------########
#########-----------------------########
#########------------------------#######
###########------------ ---------#######
###########------------ P ---------#######
############----------- ----------######
#############-----------------------######
############-----------------------#####
## ########----------------------#####
# T ##########--------------------####
###########-------------------###
##############-----------------###
##############---------------#
################-----------#
################------
##############
Global CMT Convention Moment Tensor:
R T P
-2.10e+21 -2.21e+20 7.39e+20
-2.21e+20 4.97e+20 -9.05e+20
7.39e+20 -9.05e+20 1.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090514063022/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 0.5 170 60 -65 3.20 0.2916
WVFGRD96 1.0 175 60 -55 3.21 0.2918
WVFGRD96 2.0 180 80 -65 3.33 0.3162
WVFGRD96 3.0 165 70 -75 3.35 0.3692
WVFGRD96 4.0 155 60 -85 3.39 0.4331
WVFGRD96 5.0 320 30 -105 3.49 0.4924
WVFGRD96 6.0 155 55 -85 3.50 0.5194
WVFGRD96 7.0 155 55 -80 3.48 0.5078
WVFGRD96 8.0 160 55 -75 3.44 0.4634
WVFGRD96 9.0 170 60 -60 3.42 0.4349
WVFGRD96 10.0 180 65 -45 3.42 0.4118
WVFGRD96 11.0 185 75 -30 3.43 0.3965
WVFGRD96 12.0 190 85 -25 3.44 0.3813
WVFGRD96 13.0 190 85 -25 3.45 0.3668
WVFGRD96 14.0 190 85 -25 3.45 0.3509
WVFGRD96 15.0 185 70 -30 3.47 0.3385
WVFGRD96 16.0 185 70 -30 3.47 0.3242
WVFGRD96 17.0 190 75 -25 3.48 0.3104
WVFGRD96 18.0 190 70 -25 3.48 0.2974
WVFGRD96 19.0 190 70 -20 3.48 0.2862
WVFGRD96 20.0 190 65 -25 3.48 0.2757
WVFGRD96 21.0 190 70 -25 3.49 0.2667
WVFGRD96 22.0 190 70 -25 3.50 0.2599
WVFGRD96 23.0 185 60 -30 3.50 0.2546
WVFGRD96 24.0 190 65 -25 3.51 0.2523
WVFGRD96 25.0 190 65 -25 3.52 0.2497
WVFGRD96 26.0 190 65 -25 3.53 0.2486
WVFGRD96 27.0 190 65 -25 3.54 0.2472
WVFGRD96 28.0 190 70 -20 3.56 0.2463
WVFGRD96 29.0 190 70 -20 3.57 0.2458
The best solution is
WVFGRD96 6.0 155 55 -85 3.50 0.5194
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=Thu May 14 06:42:41 CDT 2009