Location
2010/04/15 01:47:36 43.477 12.425 9.1 3.7 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 2010/04/15 01:47:36:0 43.48 12.43 9.1 3.7 Italy
Stations used:
IV.ARVD IV.ASQU IV.CAFI IV.CASP IV.CESX IV.CING IV.CRE
IV.CSNT IV.FDMO IV.FSSB IV.GUMA IV.LATE IV.MGAB IV.NRCA
IV.OFFI IV.PARC IV.PESA IV.SACS MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 5.13e+21 dyne-cm
Mw = 3.74
Z = 5 km
Plane Strike Dip Rake
NP1 315 60 -95
NP2 145 30 -81
Principal Axes:
Axis Value Plunge Azimuth
T 5.13e+21 15 49
N 0.00e+00 4 317
P -5.13e+21 74 212
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.83e+21
Mxy 2.21e+21
Mxz 1.96e+21
Myy 2.60e+21
Myz 1.65e+21
Mzz -4.42e+21
##############
######################
-###########################
#------####################
##-----------################ T ##
###---------------############ ###
###------------------#################
####--------------------################
####----------------------##############
#####------------------------#############
#####-------------------------############
######------------ ----------###########
######------------ P ------------#########
######----------- -------------#######
#######--------------------------#######
#######--------------------------#####
#######-------------------------####
########------------------------##
########----------------------
##########------------------
#############--------#
##############
Global CMT Convention Moment Tensor:
R T P
-4.42e+21 1.96e+21 -1.65e+21
1.96e+21 1.83e+21 -2.21e+21
-1.65e+21 -2.21e+21 2.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100415014736/index.html
|
Preferred Solution
The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is
STK = 315
DIP = 60
RAKE = -95
MW = 3.74
HS = 5.0
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
TDMT |
RCMT |
USGS/SLU Moment Tensor Solution
ENS 2010/04/15 01:47:36:0 43.48 12.43 9.1 3.7 Italy
Stations used:
IV.ARVD IV.ASQU IV.CAFI IV.CASP IV.CESX IV.CING IV.CRE
IV.CSNT IV.FDMO IV.FSSB IV.GUMA IV.LATE IV.MGAB IV.NRCA
IV.OFFI IV.PARC IV.PESA IV.SACS MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 5.13e+21 dyne-cm
Mw = 3.74
Z = 5 km
Plane Strike Dip Rake
NP1 315 60 -95
NP2 145 30 -81
Principal Axes:
Axis Value Plunge Azimuth
T 5.13e+21 15 49
N 0.00e+00 4 317
P -5.13e+21 74 212
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.83e+21
Mxy 2.21e+21
Mxz 1.96e+21
Myy 2.60e+21
Myz 1.65e+21
Mzz -4.42e+21
##############
######################
-###########################
#------####################
##-----------################ T ##
###---------------############ ###
###------------------#################
####--------------------################
####----------------------##############
#####------------------------#############
#####-------------------------############
######------------ ----------###########
######------------ P ------------#########
######----------- -------------#######
#######--------------------------#######
#######--------------------------#####
#######-------------------------####
########------------------------##
########----------------------
##########------------------
#############--------#
##############
Global CMT Convention Moment Tensor:
R T P
-4.42e+21 1.96e+21 -1.65e+21
1.96e+21 1.83e+21 -2.21e+21
-1.65e+21 -2.21e+21 2.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100415014736/index.html
|
|
RCMT from ing Bologna
http://cnt.rm.ingv.it/data_id/2211882670/qrcmt.gif
|
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 1.0 160 30 -55 3.53 0.4183
WVFGRD96 2.0 330 70 -80 3.64 0.4789
WVFGRD96 3.0 320 60 -90 3.65 0.5321
WVFGRD96 4.0 315 60 -95 3.65 0.5427
WVFGRD96 5.0 315 60 -95 3.74 0.5756
WVFGRD96 6.0 145 30 -85 3.72 0.5088
WVFGRD96 7.0 170 35 -50 3.67 0.4448
WVFGRD96 8.0 185 70 20 3.64 0.4143
WVFGRD96 9.0 185 70 20 3.64 0.3988
WVFGRD96 10.0 190 70 20 3.64 0.3822
WVFGRD96 11.0 190 70 20 3.65 0.3688
WVFGRD96 12.0 190 70 20 3.65 0.3566
WVFGRD96 13.0 190 70 20 3.66 0.3464
WVFGRD96 14.0 190 65 20 3.67 0.3369
WVFGRD96 15.0 190 65 20 3.69 0.3227
WVFGRD96 16.0 190 65 20 3.70 0.3131
WVFGRD96 17.0 5 45 -20 3.71 0.3061
WVFGRD96 18.0 5 45 -20 3.72 0.3034
WVFGRD96 19.0 0 50 -20 3.74 0.3012
WVFGRD96 20.0 0 50 -20 3.75 0.3000
WVFGRD96 21.0 0 50 -25 3.76 0.2989
WVFGRD96 22.0 0 50 -25 3.77 0.2977
WVFGRD96 23.0 0 50 -25 3.78 0.2956
WVFGRD96 24.0 -5 50 -30 3.79 0.2929
WVFGRD96 25.0 125 55 70 3.79 0.2955
WVFGRD96 26.0 130 60 60 3.80 0.2989
WVFGRD96 27.0 130 60 60 3.81 0.3015
WVFGRD96 28.0 125 60 55 3.83 0.3013
WVFGRD96 29.0 125 60 55 3.84 0.3004
The best solution is
WVFGRD96 5.0 315 60 -95 3.74 0.5756
The mechanism correspond to the best fit is
|
|
Figure 1. Waveform inversion focal mechanism
|
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
|
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
|
|
|
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.
|
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=Mon May 17 08:32:36 CDT 2010
Last Changed 2010/04/15
