Location
2010/08/28 07:08:03 42.845 12.661 8.0 4.0 Italy
Arrival Times (from USGS)
Arrival time list
Felt Map
USGS Felt map for this earthquake
USGS Felt reports page for
Focal Mechanism
USGS/SLU Moment Tensor Solution
ENS 2010/08/28 07:08:03:0 42.85 12.66 8.0 4.0 Italy
Stations used:
IV.ARVD IV.ATFO IV.ATVO IV.CAFI IV.CAMP IV.CASP IV.CERA
IV.CERT IV.CESI IV.CING IV.CRE IV.CRMI IV.CSNT IV.FAGN
IV.FIAM IV.FRES IV.FSSB IV.GIUL IV.GUAR IV.GUMA IV.LATE
IV.MAON IV.MCIV IV.MGAB IV.MIDA IV.MNS IV.MTCE IV.PARC
IV.POFI IV.RDP IV.RMP IV.RSM IV.SACS IV.SNTG IV.TERO
IV.TOLF IV.TRTR IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+22 dyne-cm
Mw = 4.08
Z = 6 km
Plane Strike Dip Rake
NP1 340 75 -90
NP2 160 15 -90
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+22 30 70
N 0.00e+00 -0 160
P -1.66e+22 60 250
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.71e+20
Mxy 2.67e+21
Mxz 4.92e+21
Myy 7.33e+21
Myz 1.35e+22
Mzz -8.30e+21
##############
#-----################
##--------##################
#------------#################
##--------------##################
##----------------##################
##------------------##################
###-------------------########## #####
##--------------------########## T #####
###---------------------######### ######
###----------------------#################
###--------- ----------#################
###--------- P -----------################
###-------- -----------###############
###-----------------------##############
###----------------------#############
###----------------------###########
###---------------------##########
###-------------------########
####-----------------#######
####--------------####
#####---------
Global CMT Convention Moment Tensor:
R T P
-8.30e+21 4.92e+21 -1.35e+22
4.92e+21 9.71e+20 -2.67e+21
-1.35e+22 -2.67e+21 7.33e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100828070803/index.html
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Preferred Solution
The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is
STK = 340
DIP = 75
RAKE = -90
MW = 4.08
HS = 6.0
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
INGV |
USGS/SLU Moment Tensor Solution
ENS 2010/08/28 07:08:03:0 42.85 12.66 8.0 4.0 Italy
Stations used:
IV.ARVD IV.ATFO IV.ATVO IV.CAFI IV.CAMP IV.CASP IV.CERA
IV.CERT IV.CESI IV.CING IV.CRE IV.CRMI IV.CSNT IV.FAGN
IV.FIAM IV.FRES IV.FSSB IV.GIUL IV.GUAR IV.GUMA IV.LATE
IV.MAON IV.MCIV IV.MGAB IV.MIDA IV.MNS IV.MTCE IV.PARC
IV.POFI IV.RDP IV.RMP IV.RSM IV.SACS IV.SNTG IV.TERO
IV.TOLF IV.TRTR IV.VVLD
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.66e+22 dyne-cm
Mw = 4.08
Z = 6 km
Plane Strike Dip Rake
NP1 340 75 -90
NP2 160 15 -90
Principal Axes:
Axis Value Plunge Azimuth
T 1.66e+22 30 70
N 0.00e+00 -0 160
P -1.66e+22 60 250
Moment Tensor: (dyne-cm)
Component Value
Mxx 9.71e+20
Mxy 2.67e+21
Mxz 4.92e+21
Myy 7.33e+21
Myz 1.35e+22
Mzz -8.30e+21
##############
#-----################
##--------##################
#------------#################
##--------------##################
##----------------##################
##------------------##################
###-------------------########## #####
##--------------------########## T #####
###---------------------######### ######
###----------------------#################
###--------- ----------#################
###--------- P -----------################
###-------- -----------###############
###-----------------------##############
###----------------------#############
###----------------------###########
###---------------------##########
###-------------------########
####-----------------#######
####--------------####
#####---------
Global CMT Convention Moment Tensor:
R T P
-8.30e+21 4.92e+21 -1.35e+22
4.92e+21 9.71e+20 -2.67e+21
-1.35e+22 -2.67e+21 7.33e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100828070803/index.html
|
INGV -Time Domain Moment Tensor
http://earthquake.rm.ingv.it/tdmt.php
|
Quick Regional Centroid Moment Tensor
http://earthquake.rm.ingv.it/qrcmt.php
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Waveform Inversion
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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Location of broadband stations used for waveform inversion
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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 3
The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT
WVFGRD96 1.0 345 30 -90 3.87 0.3549
WVFGRD96 2.0 340 80 -90 4.01 0.4258
WVFGRD96 3.0 155 10 -95 3.99 0.5362
WVFGRD96 4.0 155 15 -95 3.97 0.5886
WVFGRD96 5.0 150 15 -100 4.08 0.6187
WVFGRD96 6.0 340 75 -90 4.08 0.6239
WVFGRD96 7.0 150 15 -100 4.07 0.6069
WVFGRD96 8.0 340 75 -80 4.02 0.5778
WVFGRD96 9.0 340 75 -80 4.02 0.5543
WVFGRD96 10.0 345 80 -80 4.02 0.5287
WVFGRD96 11.0 345 80 -80 4.03 0.5049
WVFGRD96 12.0 345 80 -80 4.03 0.4802
WVFGRD96 13.0 345 80 -80 4.03 0.4551
WVFGRD96 14.0 345 85 -80 4.04 0.4317
WVFGRD96 15.0 345 85 -80 4.08 0.4106
WVFGRD96 16.0 165 90 80 4.09 0.3847
WVFGRD96 17.0 165 85 75 4.10 0.3621
WVFGRD96 18.0 300 15 45 4.10 0.3412
WVFGRD96 19.0 310 15 55 4.11 0.3216
WVFGRD96 20.0 305 20 50 4.11 0.3031
WVFGRD96 21.0 310 20 55 4.11 0.2871
WVFGRD96 22.0 315 20 60 4.12 0.2722
WVFGRD96 23.0 310 25 55 4.12 0.2597
WVFGRD96 24.0 320 25 65 4.12 0.2497
WVFGRD96 25.0 330 30 75 4.12 0.2432
WVFGRD96 26.0 335 30 80 4.13 0.2393
WVFGRD96 27.0 325 30 70 4.13 0.2353
WVFGRD96 28.0 320 35 70 4.14 0.2300
WVFGRD96 29.0 165 70 -70 4.14 0.2246
The best solution is
WVFGRD96 6.0 340 75 -90 4.08 0.6239
The mechanism correspond to the best fit is
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Figure 1. Waveform inversion focal mechanism
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The best fit as a function of depth is given in the following figure:
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Figure 2. Depth sensitivity for waveform mechanism
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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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Figure 3. Waveform comparison for selected depth
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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.
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Discussion
Velocity Model
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
Quality Control
Here we tabulate the reasons for not using certain digital data sets
The following stations did not have a valid response files:
DATE=Sat Aug 28 07:48:21 CDT 2010
Last Changed 2010/08/28