2009/07/06 07:02:18 42.451 13.314 13.8 3.00 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/07/06 07:02:18:0 42.45 13.31 13.8 3.0 Italy
Stations used:
IV.ARVD IV.CERT IV.CING IV.FDMO IV.GUAR IV.GUMA IV.MNS
IV.MTCE IV.NRCA IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.27e+20 dyne-cm
Mw = 3.02
Z = 10 km
Plane Strike Dip Rake
NP1 145 80 50
NP2 43 41 165
Principal Axes:
Axis Value Plunge Azimuth
T 4.27e+20 41 18
N 0.00e+00 39 153
P -4.27e+20 24 265
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.17e+20
Mxy 3.98e+19
Mxz 2.15e+20
Myy -3.29e+20
Myz 2.24e+20
Mzz 1.12e+20
##############
######################
--##########################
----############# ##########
-------############ T ##########--
---------########### ###########--
-----------########################---
-------------#######################----
--------------#####################-----
----------------####################------
---- ----------##################-------
---- P ------------################-------
---- -------------##############--------
--------------------############--------
----------------------########----------
----------------------######----------
-----------------------##-----------
----------------------#-----------
----------------#######-------
##--------##############----
######################
##############
Global CMT Convention Moment Tensor:
R T P
1.12e+20 2.15e+20 -2.24e+20
2.15e+20 2.17e+20 -3.98e+19
-2.24e+20 -3.98e+19 -3.29e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090706070218/index.html
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STK = 145
DIP = 80
RAKE = 50
MW = 3.02
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/07/06 07:02:18:0 42.45 13.31 13.8 3.0 Italy
Stations used:
IV.ARVD IV.CERT IV.CING IV.FDMO IV.GUAR IV.GUMA IV.MNS
IV.MTCE IV.NRCA IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.27e+20 dyne-cm
Mw = 3.02
Z = 10 km
Plane Strike Dip Rake
NP1 145 80 50
NP2 43 41 165
Principal Axes:
Axis Value Plunge Azimuth
T 4.27e+20 41 18
N 0.00e+00 39 153
P -4.27e+20 24 265
Moment Tensor: (dyne-cm)
Component Value
Mxx 2.17e+20
Mxy 3.98e+19
Mxz 2.15e+20
Myy -3.29e+20
Myz 2.24e+20
Mzz 1.12e+20
##############
######################
--##########################
----############# ##########
-------############ T ##########--
---------########### ###########--
-----------########################---
-------------#######################----
--------------#####################-----
----------------####################------
---- ----------##################-------
---- P ------------################-------
---- -------------##############--------
--------------------############--------
----------------------########----------
----------------------######----------
-----------------------##-----------
----------------------#-----------
----------------#######-------
##--------##############----
######################
##############
Global CMT Convention Moment Tensor:
R T P
1.12e+20 2.15e+20 -2.24e+20
2.15e+20 2.17e+20 -3.98e+19
-2.24e+20 -3.98e+19 -3.29e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090706070218/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 0.5 135 50 -80 2.76 0.4040
WVFGRD96 1.0 125 50 -70 2.79 0.3756
WVFGRD96 2.0 125 60 -65 2.87 0.3602
WVFGRD96 3.0 135 90 60 2.89 0.4188
WVFGRD96 4.0 315 85 -55 2.89 0.4724
WVFGRD96 5.0 140 85 60 2.99 0.5136
WVFGRD96 6.0 140 90 55 3.01 0.5514
WVFGRD96 7.0 140 85 55 3.02 0.5787
WVFGRD96 8.0 320 90 -50 3.00 0.5925
WVFGRD96 9.0 140 85 50 3.01 0.6019
WVFGRD96 10.0 145 80 50 3.02 0.6042
WVFGRD96 11.0 320 90 -50 3.03 0.6003
WVFGRD96 12.0 140 85 50 3.04 0.5984
WVFGRD96 13.0 320 90 -45 3.06 0.5903
WVFGRD96 14.0 140 85 50 3.06 0.5834
WVFGRD96 15.0 320 90 -50 3.10 0.5735
WVFGRD96 16.0 320 90 -50 3.11 0.5623
WVFGRD96 17.0 320 90 -50 3.12 0.5510
WVFGRD96 18.0 315 85 -50 3.12 0.5405
WVFGRD96 19.0 315 85 -50 3.13 0.5308
WVFGRD96 20.0 140 90 50 3.14 0.5174
WVFGRD96 21.0 315 80 -50 3.14 0.5112
WVFGRD96 22.0 315 80 -50 3.15 0.5062
WVFGRD96 23.0 315 80 -50 3.16 0.4999
WVFGRD96 24.0 315 75 -50 3.16 0.4967
WVFGRD96 25.0 315 75 -50 3.17 0.4923
WVFGRD96 26.0 315 75 -50 3.18 0.4879
WVFGRD96 27.0 310 75 -55 3.18 0.4831
WVFGRD96 28.0 310 75 -55 3.18 0.4813
WVFGRD96 29.0 310 75 -55 3.19 0.4816
The best solution is
WVFGRD96 10.0 145 80 50 3.02 0.6042
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 Jul 6 09:40:37 CDT 2009