2009/08/12 14:51:33 42.347 13.312 10.8 3.92 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/08/12 14:51:33:0 42.35 13.31 10.8 3.9 Italy
Stations used:
IV.ARVD IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.FRES IV.GIUL IV.GUMA IV.LATE
IV.LAV9 IV.MNS IV.MTCE IV.MURB IV.OFFI IV.PIEI IV.POFI
IV.RDP IV.RMP IV.RNI2 IV.SACS IV.TOLF IV.VAGA IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.43e+21 dyne-cm
Mw = 3.37
Z = 7 km
Plane Strike Dip Rake
NP1 308 80 -107
NP2 190 20 -30
Principal Axes:
Axis Value Plunge Azimuth
T 1.43e+21 33 53
N 0.00e+00 17 312
P -1.43e+21 52 198
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.31e+20
Mxy 3.19e+20
Mxz 1.05e+21
Myy 5.90e+20
Myz 7.41e+20
Mzz -4.59e+20
----##########
----##################
-----#######################
----##########################
###-##############################
####----#################### #####
####--------################# T ######
####-----------############### #######
####--------------######################
####------------------####################
####--------------------##################
####----------------------################
####------------------------##############
###--------------------------###########
####---------------------------#########
###----------- ---------------######
###---------- P ----------------####
###--------- ------------------#
##----------------------------
###-------------------------
##--------------------
#-------------
Global CMT Convention Moment Tensor:
R T P
-4.59e+20 1.05e+21 -7.41e+20
1.05e+21 -1.31e+20 -3.19e+20
-7.41e+20 -3.19e+20 5.90e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090812145133/index.html
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STK = 190
DIP = 20
RAKE = -30
MW = 3.37
HS = 7.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/08/12 14:51:33:0 42.35 13.31 10.8 3.9 Italy
Stations used:
IV.ARVD IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.CING
IV.FAGN IV.FDMO IV.FIAM IV.FRES IV.GIUL IV.GUMA IV.LATE
IV.LAV9 IV.MNS IV.MTCE IV.MURB IV.OFFI IV.PIEI IV.POFI
IV.RDP IV.RMP IV.RNI2 IV.SACS IV.TOLF IV.VAGA IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.43e+21 dyne-cm
Mw = 3.37
Z = 7 km
Plane Strike Dip Rake
NP1 308 80 -107
NP2 190 20 -30
Principal Axes:
Axis Value Plunge Azimuth
T 1.43e+21 33 53
N 0.00e+00 17 312
P -1.43e+21 52 198
Moment Tensor: (dyne-cm)
Component Value
Mxx -1.31e+20
Mxy 3.19e+20
Mxz 1.05e+21
Myy 5.90e+20
Myz 7.41e+20
Mzz -4.59e+20
----##########
----##################
-----#######################
----##########################
###-##############################
####----#################### #####
####--------################# T ######
####-----------############### #######
####--------------######################
####------------------####################
####--------------------##################
####----------------------################
####------------------------##############
###--------------------------###########
####---------------------------#########
###----------- ---------------######
###---------- P ----------------####
###--------- ------------------#
##----------------------------
###-------------------------
##--------------------
#-------------
Global CMT Convention Moment Tensor:
R T P
-4.59e+20 1.05e+21 -7.41e+20
1.05e+21 -1.31e+20 -3.19e+20
-7.41e+20 -3.19e+20 5.90e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090812145133/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 0.5 320 55 -85 3.16 0.4269
WVFGRD96 1.0 320 50 -80 3.19 0.3797
WVFGRD96 2.0 175 15 -45 3.31 0.3984
WVFGRD96 3.0 185 15 -35 3.29 0.4997
WVFGRD96 4.0 185 20 -40 3.27 0.5542
WVFGRD96 5.0 175 15 -50 3.38 0.5958
WVFGRD96 6.0 185 20 -35 3.36 0.6159
WVFGRD96 7.0 190 20 -30 3.37 0.6233
WVFGRD96 8.0 190 20 -30 3.32 0.6168
WVFGRD96 9.0 185 20 -35 3.33 0.6093
WVFGRD96 10.0 190 20 -30 3.34 0.5985
WVFGRD96 11.0 190 20 -30 3.34 0.5858
WVFGRD96 12.0 185 20 -35 3.35 0.5708
WVFGRD96 13.0 180 20 -40 3.36 0.5566
WVFGRD96 14.0 190 25 -30 3.37 0.5415
WVFGRD96 15.0 185 20 -35 3.42 0.5292
WVFGRD96 16.0 175 20 -50 3.43 0.5126
WVFGRD96 17.0 170 20 -55 3.44 0.4963
WVFGRD96 18.0 165 20 -60 3.45 0.4814
WVFGRD96 19.0 320 80 -65 3.49 0.4651
WVFGRD96 20.0 320 80 -65 3.50 0.4513
WVFGRD96 21.0 320 80 -65 3.51 0.4357
WVFGRD96 22.0 320 80 -65 3.52 0.4193
WVFGRD96 23.0 320 80 -65 3.52 0.4011
WVFGRD96 24.0 325 75 -85 3.51 0.3853
WVFGRD96 25.0 265 30 45 3.52 0.3743
WVFGRD96 26.0 260 35 40 3.53 0.3718
WVFGRD96 27.0 260 35 40 3.53 0.3659
WVFGRD96 28.0 260 35 45 3.54 0.3574
WVFGRD96 29.0 265 35 50 3.54 0.3466
The best solution is
WVFGRD96 7.0 190 20 -30 3.37 0.6233
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 Aug 12 13:28:22 CDT 2009