2009/04/10 04:33:04 42.458 13.350 10.5 3.30 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/04/10 04:33:04:0 42.46 13.35 10.5 3.3 Italy
Stations used:
IV.AOI IV.CAFR IV.CERT IV.CESX IV.FIAM IV.LPEL IV.MNS
IV.MTCE IV.NRCA IV.OFFI IV.POFI IV.RMP IV.SACS IV.TERO
IV.TOLF MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 10 km
Plane Strike Dip Rake
NP1 304 81 -102
NP2 180 15 -35
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 35 45
N 0.00e+00 12 306
P -1.29e+21 52 200
Moment Tensor: (dyne-cm)
Component Value
Mxx -4.78e+13
Mxy 2.73e+20
Mxz 1.02e+21
Myy 3.69e+20
Myz 6.40e+20
Mzz -3.69e+20
--############
--####################
---#########################
--############################
---###################### ######
###--##################### T #######
###------################## ########
###-----------##########################
###--------------#######################
###------------------#####################
###---------------------##################
###-----------------------################
###--------------------------#############
###---------------------------##########
###------------ --------------########
###----------- P ----------------#####
###---------- ------------------##
###-------------------------------
##----------------------------
###-------------------------
##--------------------
##------------
Global CMT Convention Moment Tensor:
R T P
-3.69e+20 1.02e+21 -6.40e+20
1.02e+21 -4.78e+13 -2.73e+20
-6.40e+20 -2.73e+20 3.69e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090410043304/index.html
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STK = 180
DIP = 15
RAKE = -35
MW = 3.34
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/04/10 04:33:04:0 42.46 13.35 10.5 3.3 Italy
Stations used:
IV.AOI IV.CAFR IV.CERT IV.CESX IV.FIAM IV.LPEL IV.MNS
IV.MTCE IV.NRCA IV.OFFI IV.POFI IV.RMP IV.SACS IV.TERO
IV.TOLF MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 10 km
Plane Strike Dip Rake
NP1 304 81 -102
NP2 180 15 -35
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 35 45
N 0.00e+00 12 306
P -1.29e+21 52 200
Moment Tensor: (dyne-cm)
Component Value
Mxx -4.78e+13
Mxy 2.73e+20
Mxz 1.02e+21
Myy 3.69e+20
Myz 6.40e+20
Mzz -3.69e+20
--############
--####################
---#########################
--############################
---###################### ######
###--##################### T #######
###------################## ########
###-----------##########################
###--------------#######################
###------------------#####################
###---------------------##################
###-----------------------################
###--------------------------#############
###---------------------------##########
###------------ --------------########
###----------- P ----------------#####
###---------- ------------------##
###-------------------------------
##----------------------------
###-------------------------
##--------------------
##------------
Global CMT Convention Moment Tensor:
R T P
-3.69e+20 1.02e+21 -6.40e+20
1.02e+21 -4.78e+13 -2.73e+20
-6.40e+20 -2.73e+20 3.69e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090410043304/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 0.5 305 40 -90 3.13 0.4141
WVFGRD96 1.0 130 55 -90 3.18 0.3637
WVFGRD96 2.0 155 10 -65 3.28 0.3168
WVFGRD96 3.0 175 10 -45 3.26 0.4232
WVFGRD96 4.0 180 15 -40 3.24 0.4848
WVFGRD96 5.0 165 10 -55 3.35 0.5341
WVFGRD96 6.0 180 15 -35 3.35 0.5739
WVFGRD96 7.0 175 15 -40 3.36 0.5988
WVFGRD96 8.0 180 20 -35 3.33 0.6120
WVFGRD96 9.0 175 15 -40 3.33 0.6173
WVFGRD96 10.0 180 15 -35 3.34 0.6175
WVFGRD96 11.0 180 15 -35 3.35 0.6125
WVFGRD96 12.0 180 15 -35 3.36 0.6040
WVFGRD96 13.0 185 15 -30 3.37 0.5934
WVFGRD96 14.0 195 15 -20 3.37 0.5814
WVFGRD96 15.0 195 15 -20 3.42 0.5672
WVFGRD96 16.0 200 15 -15 3.43 0.5497
WVFGRD96 17.0 205 15 -10 3.44 0.5318
WVFGRD96 18.0 210 15 -5 3.45 0.5126
WVFGRD96 19.0 210 15 -5 3.46 0.4935
WVFGRD96 20.0 205 15 -5 3.47 0.4752
WVFGRD96 21.0 205 15 -5 3.48 0.4568
WVFGRD96 22.0 205 15 -5 3.49 0.4398
WVFGRD96 23.0 195 15 -15 3.49 0.4228
WVFGRD96 24.0 160 20 -50 3.50 0.4128
WVFGRD96 25.0 150 20 -55 3.51 0.4060
WVFGRD96 26.0 160 20 -50 3.51 0.3977
WVFGRD96 27.0 275 15 70 3.51 0.3883
WVFGRD96 28.0 115 75 90 3.52 0.3856
WVFGRD96 29.0 120 75 70 3.52 0.3836
The best solution is
WVFGRD96 10.0 180 15 -35 3.34 0.6175
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 27 14:17:10 CDT 2009