2009/06/22 20:58:40 42.446 13.356 14.2 4.50 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/22 20:58:40:0 42.45 13.36 14.2 4.5 Italy
Stations used:
IV.AOI IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.FDMO
IV.FIAM IV.FSSB IV.GIUL IV.GUAR IV.GUMA IV.LNSS IV.MIDA
IV.MNS IV.MTCE IV.MURB IV.NRCA IV.OFFI IV.PIEI IV.RDP
IV.RMP IV.SACS IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.84e+22 dyne-cm
Mw = 4.39
Z = 10 km
Plane Strike Dip Rake
NP1 320 90 -75
NP2 50 15 -180
Principal Axes:
Axis Value Plunge Azimuth
T 4.84e+22 43 35
N 0.00e+00 15 140
P -4.84e+22 43 245
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.23e+22
Mxy 2.18e+21
Mxz 3.01e+22
Myy -1.23e+22
Myz 3.58e+22
Mzz 4.09e+15
##############
######################
-###########################
---###########################
-------############### #########
---------############## T ##########
------------############ ##########-
---------------########################-
----------------#######################-
-------------------#####################--
--------------------####################--
----------------------##################--
--------- -----------################---
-------- P -------------##############--
-------- --------------############---
--------------------------#########---
---------------------------######---
---------------------------###----
--------------------------#---
#----------------------####-
##--------------######
##############
Global CMT Convention Moment Tensor:
R T P
4.09e+15 3.01e+22 -3.58e+22
3.01e+22 1.23e+22 -2.18e+21
-3.58e+22 -2.18e+21 -1.23e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090622205840/index.html
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STK = 320
DIP = 90
RAKE = -75
MW = 4.39
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 20:58:40:0 42.45 13.36 14.2 4.5 Italy
Stations used:
IV.AOI IV.CAMP IV.CERA IV.CERT IV.CESI IV.CESX IV.FDMO
IV.FIAM IV.FSSB IV.GIUL IV.GUAR IV.GUMA IV.LNSS IV.MIDA
IV.MNS IV.MTCE IV.MURB IV.NRCA IV.OFFI IV.PIEI IV.RDP
IV.RMP IV.SACS IV.TERO MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 4.84e+22 dyne-cm
Mw = 4.39
Z = 10 km
Plane Strike Dip Rake
NP1 320 90 -75
NP2 50 15 -180
Principal Axes:
Axis Value Plunge Azimuth
T 4.84e+22 43 35
N 0.00e+00 15 140
P -4.84e+22 43 245
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.23e+22
Mxy 2.18e+21
Mxz 3.01e+22
Myy -1.23e+22
Myz 3.58e+22
Mzz 4.09e+15
##############
######################
-###########################
---###########################
-------############### #########
---------############## T ##########
------------############ ##########-
---------------########################-
----------------#######################-
-------------------#####################--
--------------------####################--
----------------------##################--
--------- -----------################---
-------- P -------------##############--
-------- --------------############---
--------------------------#########---
---------------------------######---
---------------------------###----
--------------------------#---
#----------------------####-
##--------------######
##############
Global CMT Convention Moment Tensor:
R T P
4.09e+15 3.01e+22 -3.58e+22
3.01e+22 1.23e+22 -2.18e+21
-3.58e+22 -2.18e+21 -1.23e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090622205840/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 40 -90 4.15 0.4311
WVFGRD96 1.0 310 45 -95 4.17 0.3645
WVFGRD96 2.0 175 10 -40 4.31 0.3569
WVFGRD96 3.0 175 10 -45 4.29 0.4840
WVFGRD96 4.0 315 85 -80 4.27 0.5572
WVFGRD96 5.0 140 90 80 4.39 0.6128
WVFGRD96 6.0 315 85 -80 4.39 0.6672
WVFGRD96 7.0 315 85 -80 4.40 0.7024
WVFGRD96 8.0 140 90 75 4.37 0.7230
WVFGRD96 9.0 140 90 75 4.38 0.7326
WVFGRD96 10.0 320 90 -75 4.39 0.7357
WVFGRD96 11.0 140 90 75 4.40 0.7329
WVFGRD96 12.0 135 90 75 4.40 0.7259
WVFGRD96 13.0 135 90 80 4.41 0.7163
WVFGRD96 14.0 135 90 80 4.42 0.7045
WVFGRD96 15.0 315 90 -80 4.47 0.6900
WVFGRD96 16.0 315 90 -80 4.49 0.6710
WVFGRD96 17.0 135 90 80 4.50 0.6499
WVFGRD96 18.0 315 90 -80 4.51 0.6281
WVFGRD96 19.0 315 90 -80 4.52 0.6069
WVFGRD96 20.0 315 90 -80 4.53 0.5853
WVFGRD96 21.0 135 90 80 4.54 0.5645
WVFGRD96 22.0 135 90 80 4.54 0.5442
WVFGRD96 23.0 135 90 80 4.55 0.5258
WVFGRD96 24.0 150 20 -80 4.55 0.5107
WVFGRD96 25.0 150 20 -80 4.56 0.4987
WVFGRD96 26.0 130 80 80 4.57 0.4874
WVFGRD96 27.0 130 80 80 4.57 0.4795
WVFGRD96 28.0 130 80 80 4.57 0.4711
WVFGRD96 29.0 130 80 75 4.57 0.4626
The best solution is
WVFGRD96 10.0 320 90 -75 4.39 0.7357
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 Jun 22 18:37:26 CDT 2009