2009/05/14 06:32:33 42.481 13.410 10.0 3.50 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2009/05/14 06:32:33:0 42.48 13.41 10.0 3.5 Italy
Stations used:
IV.AOI IV.CAFR IV.CERA IV.CERT IV.CING IV.FIAM IV.FRES
IV.GIUL IV.LATE IV.LPEL IV.NRCA IV.SACS IV.TOLF IV.VAGA
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.76e+21 dyne-cm
Mw = 3.43
Z = 6 km
Plane Strike Dip Rake
NP1 151 55 -87
NP2 325 35 -95
Principal Axes:
Axis Value Plunge Azimuth
T 1.76e+21 10 239
N 0.00e+00 3 329
P -1.76e+21 80 75
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.59e+20
Mxy 7.43e+20
Mxz -2.41e+20
Myy 1.19e+21
Myz -5.63e+20
Mzz -1.65e+21
##############
-#----################
###-------------############
####----------------##########
#####-------------------##########
######---------------------#########
#######-----------------------########
#########-----------------------########
#########------------------------#######
##########------------- ---------#######
###########------------ P ---------#######
############----------- ----------######
#############-----------------------######
#############----------------------#####
##############---------------------#####
# ##########--------------------####
T ###########-------------------###
#############----------------###
###############--------------#
#################----------#
##################----
##############
Global CMT Convention Moment Tensor:
R T P
-1.65e+21 -2.41e+20 5.63e+20
-2.41e+20 4.59e+20 -7.43e+20
5.63e+20 -7.43e+20 1.19e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090514063233/index.html
|
STK = 325
DIP = 35
RAKE = -95
MW = 3.43
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2009/05/14 06:32:33:0 42.48 13.41 10.0 3.5 Italy
Stations used:
IV.AOI IV.CAFR IV.CERA IV.CERT IV.CING IV.FIAM IV.FRES
IV.GIUL IV.LATE IV.LPEL IV.NRCA IV.SACS IV.TOLF IV.VAGA
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.76e+21 dyne-cm
Mw = 3.43
Z = 6 km
Plane Strike Dip Rake
NP1 151 55 -87
NP2 325 35 -95
Principal Axes:
Axis Value Plunge Azimuth
T 1.76e+21 10 239
N 0.00e+00 3 329
P -1.76e+21 80 75
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.59e+20
Mxy 7.43e+20
Mxz -2.41e+20
Myy 1.19e+21
Myz -5.63e+20
Mzz -1.65e+21
##############
-#----################
###-------------############
####----------------##########
#####-------------------##########
######---------------------#########
#######-----------------------########
#########-----------------------########
#########------------------------#######
##########------------- ---------#######
###########------------ P ---------#######
############----------- ----------######
#############-----------------------######
#############----------------------#####
##############---------------------#####
# ##########--------------------####
T ###########-------------------###
#############----------------###
###############--------------#
#################----------#
##################----
##############
Global CMT Convention Moment Tensor:
R T P
-1.65e+21 -2.41e+20 5.63e+20
-2.41e+20 4.59e+20 -7.43e+20
5.63e+20 -7.43e+20 1.19e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20090514063233/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 0 40 -40 3.15 0.3233
WVFGRD96 1.0 0 40 -40 3.17 0.3254
WVFGRD96 2.0 0 35 -40 3.25 0.3603
WVFGRD96 3.0 5 40 -30 3.25 0.3952
WVFGRD96 4.0 155 55 -85 3.34 0.4490
WVFGRD96 5.0 325 35 -95 3.43 0.5086
WVFGRD96 6.0 325 35 -95 3.43 0.5324
WVFGRD96 7.0 315 40 -110 3.41 0.5147
WVFGRD96 8.0 10 65 -15 3.34 0.4655
WVFGRD96 9.0 10 70 -15 3.36 0.4584
WVFGRD96 10.0 10 70 -15 3.37 0.4484
WVFGRD96 11.0 190 80 -20 3.38 0.4344
WVFGRD96 12.0 190 80 -20 3.39 0.4215
WVFGRD96 13.0 190 75 -20 3.40 0.4092
WVFGRD96 14.0 190 75 -20 3.41 0.3938
WVFGRD96 15.0 190 75 -20 3.43 0.3829
WVFGRD96 16.0 190 75 -20 3.44 0.3677
WVFGRD96 17.0 190 70 -20 3.44 0.3518
WVFGRD96 18.0 190 70 -20 3.45 0.3349
WVFGRD96 19.0 190 70 -20 3.45 0.3175
WVFGRD96 20.0 190 70 -20 3.46 0.3007
WVFGRD96 21.0 190 70 -20 3.46 0.2865
WVFGRD96 22.0 190 70 -20 3.47 0.2773
WVFGRD96 23.0 195 70 -20 3.47 0.2719
WVFGRD96 24.0 100 70 15 3.49 0.2742
WVFGRD96 25.0 100 70 15 3.50 0.2791
WVFGRD96 26.0 280 70 15 3.53 0.2829
WVFGRD96 27.0 280 70 15 3.55 0.2852
WVFGRD96 28.0 280 70 15 3.56 0.2851
WVFGRD96 29.0 280 75 10 3.58 0.2842
The best solution is
WVFGRD96 6.0 325 35 -95 3.43 0.5324
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=Thu May 14 11:17:02 CDT 2009