2009/06/30 00:38:10 42.569 13.198 10.5 3.40 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/30 00:38:10:0 42.57 13.20 10.5 3.4 Italy
Stations used:
IV.ARCI IV.ASSB IV.CAMP IV.CERT IV.CESI IV.CESX IV.CING
IV.FDMO IV.FIAM IV.GUMA IV.LNSS IV.LPEL IV.MNS IV.MTCE
IV.OFFI 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 = 1.82e+21 dyne-cm
Mw = 3.44
Z = 4 km
Plane Strike Dip Rake
NP1 135 50 -95
NP2 323 40 -84
Principal Axes:
Axis Value Plunge Azimuth
T 1.82e+21 5 229
N 0.00e+00 4 138
P -1.82e+21 84 10
Moment Tensor: (dyne-cm)
Component Value
Mxx 7.71e+20
Mxy 8.93e+20
Mxz -2.95e+20
Myy 1.01e+21
Myz -1.51e+20
Mzz -1.79e+21
##############
######################
-------------###############
------------------############
##--------------------############
###----------------------###########
####------------------------##########
#####--------------------------#########
######------------- ----------########
#######------------- P -----------########
########------------ -----------########
#########--------------------------#######
##########--------------------------######
###########------------------------#####
############-----------------------#####
#############---------------------####
##############-------------------###
# ############---------------###
T ################-----------#
##########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-1.79e+21 -2.95e+20 1.51e+20
-2.95e+20 7.71e+20 -8.93e+20
1.51e+20 -8.93e+20 1.01e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090630003810/index.html
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STK = 135
DIP = 50
RAKE = -95
MW = 3.44
HS = 4.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/30 00:38:10:0 42.57 13.20 10.5 3.4 Italy
Stations used:
IV.ARCI IV.ASSB IV.CAMP IV.CERT IV.CESI IV.CESX IV.CING
IV.FDMO IV.FIAM IV.GUMA IV.LNSS IV.LPEL IV.MNS IV.MTCE
IV.OFFI 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 = 1.82e+21 dyne-cm
Mw = 3.44
Z = 4 km
Plane Strike Dip Rake
NP1 135 50 -95
NP2 323 40 -84
Principal Axes:
Axis Value Plunge Azimuth
T 1.82e+21 5 229
N 0.00e+00 4 138
P -1.82e+21 84 10
Moment Tensor: (dyne-cm)
Component Value
Mxx 7.71e+20
Mxy 8.93e+20
Mxz -2.95e+20
Myy 1.01e+21
Myz -1.51e+20
Mzz -1.79e+21
##############
######################
-------------###############
------------------############
##--------------------############
###----------------------###########
####------------------------##########
#####--------------------------#########
######------------- ----------########
#######------------- P -----------########
########------------ -----------########
#########--------------------------#######
##########--------------------------######
###########------------------------#####
############-----------------------#####
#############---------------------####
##############-------------------###
# ############---------------###
T ################-----------#
##########################-
######################
##############
Global CMT Convention Moment Tensor:
R T P
-1.79e+21 -2.95e+20 1.51e+20
-2.95e+20 7.71e+20 -8.93e+20
1.51e+20 -8.93e+20 1.01e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090630003810/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 0.5 350 25 -35 3.31 0.3579
WVFGRD96 1.0 345 35 -40 3.26 0.3711
WVFGRD96 2.0 340 35 -50 3.35 0.4324
WVFGRD96 3.0 320 40 -85 3.41 0.5155
WVFGRD96 4.0 135 50 -95 3.44 0.5275
WVFGRD96 5.0 320 40 -85 3.50 0.5184
WVFGRD96 6.0 315 40 -95 3.48 0.4394
WVFGRD96 7.0 -5 55 -30 3.39 0.3712
WVFGRD96 8.0 5 65 -10 3.36 0.3484
WVFGRD96 9.0 190 65 15 3.38 0.3358
WVFGRD96 10.0 190 65 15 3.39 0.3246
WVFGRD96 11.0 190 65 15 3.39 0.3136
WVFGRD96 12.0 190 65 15 3.40 0.3031
WVFGRD96 13.0 190 65 15 3.41 0.2931
WVFGRD96 14.0 190 65 15 3.42 0.2835
WVFGRD96 15.0 190 65 15 3.44 0.2728
WVFGRD96 16.0 190 65 20 3.45 0.2653
WVFGRD96 17.0 15 65 20 3.44 0.2601
WVFGRD96 18.0 10 65 15 3.45 0.2560
WVFGRD96 19.0 10 65 15 3.46 0.2528
WVFGRD96 20.0 10 65 15 3.47 0.2500
WVFGRD96 21.0 10 65 15 3.47 0.2473
WVFGRD96 22.0 10 65 15 3.48 0.2450
WVFGRD96 23.0 190 65 25 3.50 0.2446
WVFGRD96 24.0 -5 80 15 3.51 0.2425
WVFGRD96 25.0 195 65 25 3.52 0.2430
WVFGRD96 26.0 195 65 25 3.53 0.2424
WVFGRD96 27.0 195 65 25 3.54 0.2418
WVFGRD96 28.0 195 65 25 3.56 0.2412
WVFGRD96 29.0 190 70 20 3.57 0.2419
The best solution is
WVFGRD96 4.0 135 50 -95 3.44 0.5275
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 29 20:26:11 CDT 2009