2009/06/22 22:49:20 42.441 13.333 13.8 3.1 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/22 22:49:20:2 42.44 13.33 13.8 3.1 Italy
Stations used:
IV.CAMP IV.FDMO IV.GUMA IV.MNS IV.MTCE IV.RMP IV.TERO
MN.AQU
Filtering commands used:
hp c 0.04 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.82e+20 dyne-cm
Mw = 2.90
Z = 10 km
Plane Strike Dip Rake
NP1 140 85 65
NP2 39 25 168
Principal Axes:
Axis Value Plunge Azimuth
T 2.82e+20 44 25
N 0.00e+00 25 142
P -2.82e+20 35 251
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.85e+19
Mxy -1.24e+18
Mxz 1.70e+20
Myy -1.43e+20
Myz 1.86e+20
Mzz 4.44e+19
##############
######################
-##########################-
---###########################
------############## ##########-
--------############# T ##########--
-----------########### ###########--
-------------########################---
---------------######################---
-----------------#####################----
-------------------###################----
--------------------##################----
------- ------------###############-----
------ P -------------#############-----
------ ---------------##########------
-------------------------#######------
-------------------------#####------
--------------------------#-------
-----------------------###----
-------------------########-
##---------###########
##############
Global CMT Convention Moment Tensor:
R T P
4.44e+19 1.70e+20 -1.86e+20
1.70e+20 9.85e+19 1.24e+18
-1.86e+20 1.24e+18 -1.43e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090622224920/index.html
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STK = 140
DIP = 85
RAKE = 65
MW = 2.90
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/22 22:49:20:2 42.44 13.33 13.8 3.1 Italy
Stations used:
IV.CAMP IV.FDMO IV.GUMA IV.MNS IV.MTCE IV.RMP IV.TERO
MN.AQU
Filtering commands used:
hp c 0.04 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.82e+20 dyne-cm
Mw = 2.90
Z = 10 km
Plane Strike Dip Rake
NP1 140 85 65
NP2 39 25 168
Principal Axes:
Axis Value Plunge Azimuth
T 2.82e+20 44 25
N 0.00e+00 25 142
P -2.82e+20 35 251
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.85e+19
Mxy -1.24e+18
Mxz 1.70e+20
Myy -1.43e+20
Myz 1.86e+20
Mzz 4.44e+19
##############
######################
-##########################-
---###########################
------############## ##########-
--------############# T ##########--
-----------########### ###########--
-------------########################---
---------------######################---
-----------------#####################----
-------------------###################----
--------------------##################----
------- ------------###############-----
------ P -------------#############-----
------ ---------------##########------
-------------------------#######------
-------------------------#####------
--------------------------#-------
-----------------------###----
-------------------########-
##---------###########
##############
Global CMT Convention Moment Tensor:
R T P
4.44e+19 1.70e+20 -1.86e+20
1.70e+20 9.85e+19 1.24e+18
-1.86e+20 1.24e+18 -1.43e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090622224920/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 0.04 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 1.0 125 50 70 2.71 0.3866
WVFGRD96 2.0 310 90 -80 2.83 0.3615
WVFGRD96 3.0 140 85 75 2.81 0.4745
WVFGRD96 4.0 140 85 70 2.79 0.5385
WVFGRD96 5.0 140 85 70 2.90 0.5819
WVFGRD96 6.0 145 80 70 2.91 0.6241
WVFGRD96 7.0 140 85 70 2.91 0.6521
WVFGRD96 8.0 140 85 65 2.88 0.6692
WVFGRD96 9.0 140 85 65 2.89 0.6773
WVFGRD96 10.0 140 85 65 2.90 0.6804
WVFGRD96 11.0 140 85 65 2.92 0.6768
WVFGRD96 12.0 135 90 65 2.92 0.6715
WVFGRD96 13.0 135 90 65 2.93 0.6642
WVFGRD96 14.0 315 90 -65 2.94 0.6542
WVFGRD96 15.0 130 90 65 2.99 0.6422
WVFGRD96 16.0 130 90 65 3.00 0.6253
WVFGRD96 17.0 305 85 -65 3.01 0.6083
WVFGRD96 18.0 305 80 -65 3.02 0.5914
WVFGRD96 19.0 305 80 -65 3.03 0.5750
WVFGRD96 20.0 300 75 -70 3.03 0.5577
WVFGRD96 21.0 310 70 -70 3.04 0.5487
WVFGRD96 22.0 315 70 -70 3.06 0.5407
WVFGRD96 23.0 315 70 -70 3.06 0.5313
WVFGRD96 24.0 315 70 -70 3.07 0.5195
WVFGRD96 25.0 320 70 -70 3.08 0.5048
WVFGRD96 26.0 315 65 -70 3.08 0.4907
WVFGRD96 27.0 320 65 -65 3.09 0.4743
WVFGRD96 28.0 315 60 -65 3.10 0.4688
WVFGRD96 29.0 320 60 -65 3.12 0.4634
The best solution is
WVFGRD96 10.0 140 85 65 2.90 0.6804
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 0.04 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 May 17 14:37:17 CDT 2010