Location
2013/06/30 14:40:08 44.171 10.205 9.8 4.4 Italy
Arrival Times (from USGS)
Arrival time list
Felt Map
USGS Felt map for this earthquake
USGS Felt reports page for
Focal Mechanism
SLU Moment Tensor Solution
ENS 2013/06/30 14:40:08:0 44.17 10.20 9.8 4.4 Italy
Stations used:
CH.FUSIO CH.VDL FR.CALF FR.EILF FR.ISO FR.SAOF FR.SMPL
GU.ENR GU.FINB GU.GORR GU.MAIM GU.NEGI GU.PCP GU.POPM
IV.AOI IV.ARCI IV.ARVD IV.ASQU IV.BDI IV.BOB IV.CAFI
IV.CESI IV.CESX IV.CING IV.CRE IV.CRMI IV.CSNT IV.DOI
IV.FDMO IV.FSSB IV.GROG IV.LNSS IV.MAON IV.MSSA IV.PARC
IV.PESA IV.QLNO IV.ROVR IV.SACS IV.TEOL IV.TOLF IV.ZCCA
MN.TUE MN.VLC
Filtering commands used:
cut a -30 a 120
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.05 n 3
Best Fitting Double Couple
Mo = 5.96e+22 dyne-cm
Mw = 4.45
Z = 3 km
Plane Strike Dip Rake
NP1 251 52 -117
NP2 110 45 -60
Principal Axes:
Axis Value Plunge Azimuth
T 5.96e+22 4 359
N 0.00e+00 21 268
P -5.96e+22 69 99
Moment Tensor: (dyne-cm)
Component Value
Mxx 5.91e+22
Mxy 4.47e+20
Mxz 7.20e+21
Myy -7.50e+21
Myz -1.98e+22
Mzz -5.16e+22
##### T ######
######### ##########
############################
##############################
##################################
###################-----------######
##############----------------------##
-##########-----------------------------
-########-------------------------------
---####-----------------------------------
---###------------------- --------------
------------------------- P --------------
---###------------------- --------------
-######---------------------------------
#########-------------------------------
##########---------------------------#
#############--------------------###
###################-------########
##############################
############################
######################
##############
Global CMT Convention Moment Tensor:
R T P
-5.16e+22 7.20e+21 1.98e+22
7.20e+21 5.91e+22 -4.47e+20
1.98e+22 -4.47e+20 -7.50e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130630144008/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 = 110
DIP = 45
RAKE = -60
MW = 4.45
HS = 3.0
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
INGVTDMT |
SLU Moment Tensor Solution
ENS 2013/06/30 14:40:08:0 44.17 10.20 9.8 4.4 Italy
Stations used:
CH.FUSIO CH.VDL FR.CALF FR.EILF FR.ISO FR.SAOF FR.SMPL
GU.ENR GU.FINB GU.GORR GU.MAIM GU.NEGI GU.PCP GU.POPM
IV.AOI IV.ARCI IV.ARVD IV.ASQU IV.BDI IV.BOB IV.CAFI
IV.CESI IV.CESX IV.CING IV.CRE IV.CRMI IV.CSNT IV.DOI
IV.FDMO IV.FSSB IV.GROG IV.LNSS IV.MAON IV.MSSA IV.PARC
IV.PESA IV.QLNO IV.ROVR IV.SACS IV.TEOL IV.TOLF IV.ZCCA
MN.TUE MN.VLC
Filtering commands used:
cut a -30 a 120
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.05 n 3
Best Fitting Double Couple
Mo = 5.96e+22 dyne-cm
Mw = 4.45
Z = 3 km
Plane Strike Dip Rake
NP1 251 52 -117
NP2 110 45 -60
Principal Axes:
Axis Value Plunge Azimuth
T 5.96e+22 4 359
N 0.00e+00 21 268
P -5.96e+22 69 99
Moment Tensor: (dyne-cm)
Component Value
Mxx 5.91e+22
Mxy 4.47e+20
Mxz 7.20e+21
Myy -7.50e+21
Myz -1.98e+22
Mzz -5.16e+22
##### T ######
######### ##########
############################
##############################
##################################
###################-----------######
##############----------------------##
-##########-----------------------------
-########-------------------------------
---####-----------------------------------
---###------------------- --------------
------------------------- P --------------
---###------------------- --------------
-######---------------------------------
#########-------------------------------
##########---------------------------#
#############--------------------###
###################-------########
##############################
############################
######################
##############
Global CMT Convention Moment Tensor:
R T P
-5.16e+22 7.20e+21 1.98e+22
7.20e+21 5.91e+22 -4.47e+20
1.98e+22 -4.47e+20 -7.50e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130630144008/index.html
|
|
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:
cut a -30 a 120
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.05 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 1.0 115 45 -50 4.36 0.5507
WVFGRD96 2.0 115 40 -50 4.42 0.5933
WVFGRD96 3.0 110 45 -60 4.45 0.6090
WVFGRD96 4.0 100 40 -75 4.48 0.5859
WVFGRD96 5.0 105 40 -70 4.52 0.5937
WVFGRD96 6.0 105 40 -65 4.49 0.5261
WVFGRD96 7.0 120 50 -40 4.42 0.4655
WVFGRD96 8.0 130 55 -5 4.34 0.4384
WVFGRD96 9.0 130 60 5 4.34 0.4449
WVFGRD96 10.0 135 60 10 4.36 0.4523
WVFGRD96 11.0 135 60 15 4.37 0.4600
WVFGRD96 12.0 135 60 15 4.38 0.4649
WVFGRD96 13.0 135 65 15 4.39 0.4698
WVFGRD96 14.0 135 65 20 4.40 0.4737
WVFGRD96 15.0 135 65 15 4.41 0.4693
WVFGRD96 16.0 135 65 15 4.42 0.4691
WVFGRD96 17.0 135 65 15 4.43 0.4674
WVFGRD96 18.0 135 65 15 4.43 0.4650
WVFGRD96 19.0 135 65 20 4.44 0.4621
WVFGRD96 20.0 135 65 15 4.44 0.4590
WVFGRD96 21.0 135 65 20 4.45 0.4557
WVFGRD96 22.0 135 65 20 4.46 0.4524
WVFGRD96 23.0 135 70 20 4.47 0.4495
WVFGRD96 24.0 135 70 20 4.48 0.4474
WVFGRD96 25.0 135 70 20 4.49 0.4451
WVFGRD96 26.0 135 70 20 4.50 0.4433
WVFGRD96 27.0 135 70 20 4.51 0.4418
WVFGRD96 28.0 135 70 20 4.52 0.4416
WVFGRD96 29.0 135 70 20 4.54 0.4416
The best solution is
WVFGRD96 3.0 110 45 -60 4.45 0.6090
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. A pair of numbers is given in black at the right of each predicted traces. The upper number 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 lower number gives the percentage of variance reduction to characterize the individual goodness of fit (100% indicates a perfect fit).
The bandpass filter used in the processing and for the display was
cut a -30 a 120
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.05 n 3
|
|
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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A check on the assumed source location is possible by looking at the time shifts between the observed and predicted traces. The time shifts for waveform matching arise for several reasons:
- The origin time and epicentral distance are incorrect
- The velocity model used for the inversion is incorrect
- The velocity model used to define the P-arrival time is not the
same as the velocity model used for the waveform inversion
(assuming that the initial trace alignment is based on the
P arrival time)
Assuming only a mislocation, the time shifts are fit to a functional form:
Time_shift = A + B cos Azimuth + C Sin Azimuth
The time shifts for this inversion lead to the next figure:
The derived shift in origin time and epicentral coordinates are given at the bottom of 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=Sun Jun 30 14:16:46 CDT 2013
Last Changed 2013/06/30
