2009/06/29 05:54:33 42.463 13.366 13.5 3.10 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/06/29 05:54:33:0 42.46 13.37 13.5 3.1 Italy
Stations used:
IV.ASSB IV.CERT IV.CESI IV.CESX IV.CING IV.FDMO IV.FIAM
IV.GIUL IV.GUMA IV.INTR IV.LNSS IV.MTCE IV.NRCA IV.OFFI
IV.RNI2 IV.SACS IV.TERO IV.TOLF MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.22e+20 dyne-cm
Mw = 3.21
Z = 10 km
Plane Strike Dip Rake
NP1 335 65 -60
NP2 101 38 -137
Principal Axes:
Axis Value Plunge Azimuth
T 8.22e+20 15 44
N 0.00e+00 27 141
P -8.22e+20 59 288
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.83e+20
Mxy 4.48e+20
Mxz 3.60e+19
Myy 1.63e+20
Myz 4.88e+20
Mzz -5.45e+20
##############
-----#################
----------############## #
-------------############ T ##
-----------------########## ####
-------------------#################
----------------------################
------------------------################
----------- -----------###############
#----------- P ------------###############
#----------- -------------##############
##--------------------------##############
###--------------------------#############
####------------------------############
#####------------------------#########--
#######---------------------########--
#########------------------#####----
############--------------#-------
#########################-----
#######################-----
####################--
##############
Global CMT Convention Moment Tensor:
R T P
-5.45e+20 3.60e+19 -4.88e+20
3.60e+19 3.83e+20 -4.48e+20
-4.88e+20 -4.48e+20 1.63e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090629055433/index.html
|
STK = 335
DIP = 65
RAKE = -60
MW = 3.21
HS = 10.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/06/29 05:54:33:0 42.46 13.37 13.5 3.1 Italy
Stations used:
IV.ASSB IV.CERT IV.CESI IV.CESX IV.CING IV.FDMO IV.FIAM
IV.GIUL IV.GUMA IV.INTR IV.LNSS IV.MTCE IV.NRCA IV.OFFI
IV.RNI2 IV.SACS IV.TERO IV.TOLF MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 8.22e+20 dyne-cm
Mw = 3.21
Z = 10 km
Plane Strike Dip Rake
NP1 335 65 -60
NP2 101 38 -137
Principal Axes:
Axis Value Plunge Azimuth
T 8.22e+20 15 44
N 0.00e+00 27 141
P -8.22e+20 59 288
Moment Tensor: (dyne-cm)
Component Value
Mxx 3.83e+20
Mxy 4.48e+20
Mxz 3.60e+19
Myy 1.63e+20
Myz 4.88e+20
Mzz -5.45e+20
##############
-----#################
----------############## #
-------------############ T ##
-----------------########## ####
-------------------#################
----------------------################
------------------------################
----------- -----------###############
#----------- P ------------###############
#----------- -------------##############
##--------------------------##############
###--------------------------#############
####------------------------############
#####------------------------#########--
#######---------------------########--
#########------------------#####----
############--------------#-------
#########################-----
#######################-----
####################--
##############
Global CMT Convention Moment Tensor:
R T P
-5.45e+20 3.60e+19 -4.88e+20
3.60e+19 3.83e+20 -4.48e+20
-4.88e+20 -4.48e+20 1.63e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090629055433/index.html
|
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.
|
|
|
|
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 0.5 315 40 -85 2.94 0.2934
WVFGRD96 1.0 345 45 -40 2.96 0.2706
WVFGRD96 2.0 345 35 -35 3.04 0.2873
WVFGRD96 3.0 350 80 -65 3.08 0.3233
WVFGRD96 4.0 345 75 -65 3.09 0.3738
WVFGRD96 5.0 340 70 -70 3.20 0.4222
WVFGRD96 6.0 335 65 -70 3.22 0.4791
WVFGRD96 7.0 335 65 -65 3.22 0.5173
WVFGRD96 8.0 335 65 -60 3.20 0.5302
WVFGRD96 9.0 335 65 -60 3.20 0.5378
WVFGRD96 10.0 335 65 -60 3.21 0.5393
WVFGRD96 11.0 335 65 -60 3.22 0.5340
WVFGRD96 12.0 335 65 -65 3.23 0.5235
WVFGRD96 13.0 335 70 -65 3.23 0.5144
WVFGRD96 14.0 335 70 -65 3.24 0.5020
WVFGRD96 15.0 335 70 -65 3.28 0.4922
WVFGRD96 16.0 340 70 -65 3.29 0.4770
WVFGRD96 17.0 340 70 -65 3.30 0.4609
WVFGRD96 18.0 345 75 -60 3.30 0.4465
WVFGRD96 19.0 345 75 -60 3.31 0.4326
WVFGRD96 20.0 345 75 -60 3.32 0.4202
WVFGRD96 21.0 345 75 -60 3.33 0.4089
WVFGRD96 22.0 345 75 -60 3.34 0.4005
WVFGRD96 23.0 345 75 -60 3.34 0.3941
WVFGRD96 24.0 345 75 -60 3.35 0.3869
WVFGRD96 25.0 345 75 -60 3.36 0.3782
WVFGRD96 26.0 345 75 -60 3.36 0.3684
WVFGRD96 27.0 345 75 -55 3.37 0.3572
WVFGRD96 28.0 345 75 -55 3.37 0.3456
WVFGRD96 29.0 345 75 -55 3.38 0.3344
The best solution is
WVFGRD96 10.0 335 65 -60 3.21 0.5393
The mechanism correspond to the best fit is
|
|
|
The best fit as a function of depth is given in the following figure:
|
|
|
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
|
|
|
|
| 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 08:11:46 CDT 2009