2010/09/05 07:07:23 44.107 12.170 30.0 3.7 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2010/09/05 07:07:23:0 44.11 12.17 30.0 3.7 Italy
Stations used:
GU.MAIM GU.SC2M IV.ARVD IV.ASQU IV.ATFO IV.ATPC IV.ATVO
IV.BDI IV.CASP IV.CESI IV.CING IV.CRE IV.CRMI IV.CSNT
IV.FIAM IV.FNVD IV.FSSB IV.GUMA IV.LATE IV.LNSS IV.MCIV
IV.MGAB IV.MNS IV.MSSA IV.MTCE IV.MURB IV.PARC IV.ROVR
IV.RSM IV.SACS IV.SASS IV.SNTG IV.TOLF IV.ZCCA MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.95e+21 dyne-cm
Mw = 3.73
Z = 17 km
Plane Strike Dip Rake
NP1 318 62 101
NP2 115 30 70
Principal Axes:
Axis Value Plunge Azimuth
T 4.95e+21 71 252
N 0.00e+00 10 132
P -4.95e+21 16 40
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.66e+21
Mxy -2.09e+21
Mxz -1.49e+21
Myy -1.37e+21
Myz -2.31e+21
Mzz 4.03e+21
--------------
----------------------
------------------------ -
########----------------- P --
##############------------- ----
#################-------------------
#####################-----------------
-#######################----------------
-########################---------------
--##########################--------------
---############ ###########-------------
---############ T #############-----------
----########### ##############----------
----############################--------
-----###########################--------
------##########################------
-------#########################---#
--------#######################-##
----------#################--#
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
4.03e+21 -1.49e+21 2.31e+21
-1.49e+21 -2.66e+21 2.09e+21
2.31e+21 2.09e+21 -1.37e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100905070723/index.html
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STK = 115
DIP = 30
RAKE = 70
MW = 3.73
HS = 17.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2010/09/05 07:07:23:0 44.11 12.17 30.0 3.7 Italy
Stations used:
GU.MAIM GU.SC2M IV.ARVD IV.ASQU IV.ATFO IV.ATPC IV.ATVO
IV.BDI IV.CASP IV.CESI IV.CING IV.CRE IV.CRMI IV.CSNT
IV.FIAM IV.FNVD IV.FSSB IV.GUMA IV.LATE IV.LNSS IV.MCIV
IV.MGAB IV.MNS IV.MSSA IV.MTCE IV.MURB IV.PARC IV.ROVR
IV.RSM IV.SACS IV.SASS IV.SNTG IV.TOLF IV.ZCCA MN.VLC
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.95e+21 dyne-cm
Mw = 3.73
Z = 17 km
Plane Strike Dip Rake
NP1 318 62 101
NP2 115 30 70
Principal Axes:
Axis Value Plunge Azimuth
T 4.95e+21 71 252
N 0.00e+00 10 132
P -4.95e+21 16 40
Moment Tensor: (dyne-cm)
Component Value
Mxx -2.66e+21
Mxy -2.09e+21
Mxz -1.49e+21
Myy -1.37e+21
Myz -2.31e+21
Mzz 4.03e+21
--------------
----------------------
------------------------ -
########----------------- P --
##############------------- ----
#################-------------------
#####################-----------------
-#######################----------------
-########################---------------
--##########################--------------
---############ ###########-------------
---############ T #############-----------
----########### ##############----------
----############################--------
-----###########################--------
------##########################------
-------#########################---#
--------#######################-##
----------#################--#
----------------------------
----------------------
--------------
Global CMT Convention Moment Tensor:
R T P
4.03e+21 -1.49e+21 2.31e+21
-1.49e+21 -2.66e+21 2.09e+21
2.31e+21 2.09e+21 -1.37e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100905070723/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 1.0 325 45 -90 3.41 0.2506
WVFGRD96 2.0 145 40 -85 3.45 0.2120
WVFGRD96 3.0 350 20 -45 3.43 0.1784
WVFGRD96 4.0 120 80 80 3.40 0.2030
WVFGRD96 5.0 160 -10 -50 3.52 0.2375
WVFGRD96 6.0 305 10 90 3.55 0.2804
WVFGRD96 7.0 305 15 90 3.57 0.3218
WVFGRD96 8.0 125 70 90 3.55 0.3612
WVFGRD96 9.0 130 65 80 3.58 0.3916
WVFGRD96 10.0 115 30 75 3.60 0.4199
WVFGRD96 11.0 115 30 70 3.62 0.4443
WVFGRD96 12.0 115 30 70 3.63 0.4632
WVFGRD96 13.0 115 30 70 3.65 0.4779
WVFGRD96 14.0 115 35 70 3.66 0.4901
WVFGRD96 15.0 115 30 70 3.71 0.5004
WVFGRD96 16.0 115 30 70 3.72 0.5073
WVFGRD96 17.0 115 30 70 3.73 0.5105
WVFGRD96 18.0 115 30 70 3.74 0.5104
WVFGRD96 19.0 115 30 70 3.75 0.5069
WVFGRD96 20.0 115 30 70 3.76 0.4997
WVFGRD96 21.0 115 30 70 3.77 0.4890
WVFGRD96 22.0 115 30 70 3.78 0.4752
WVFGRD96 23.0 125 25 75 3.79 0.4591
WVFGRD96 24.0 120 25 70 3.80 0.4414
WVFGRD96 25.0 115 25 65 3.80 0.4199
WVFGRD96 26.0 110 25 60 3.80 0.3961
WVFGRD96 27.0 110 25 60 3.80 0.3741
WVFGRD96 28.0 105 25 55 3.80 0.3523
WVFGRD96 29.0 100 25 50 3.80 0.3324
The best solution is
WVFGRD96 17.0 115 30 70 3.73 0.5105
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=Sun Sep 5 06:58:13 CDT 2010