Location
2013/06/21 10:33:57 44.15 10.14 5.1 5.2 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 2013/06/21 10:33:57:0 44.15 10.14 5.1 5.2 Italy
Stations used:
FR.ESCA FR.MON FR.SAOF GU.BHB GU.ENR GU.FINB GU.GORR
GU.MAIM GU.NEGI GU.POPM GU.PZZ GU.ROTM GU.TRAV IV.ARCI
IV.ARVD IV.ASQU IV.BOB IV.CAFI IV.CASP IV.CRMI IV.CSNT
IV.DOI IV.FNVD IV.FSSB IV.IMI IV.MAON IV.MSSA IV.MURB
IV.PARC IV.PESA IV.PIEI IV.QLNO IV.SACS IV.SNTG IV.SSFR
MN.VLC
Filtering commands used:
cut a -30 a 150
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 4.90e+23 dyne-cm
Mw = 5.06
Z = 5 km
Plane Strike Dip Rake
NP1 115 50 -60
NP2 253 48 -121
Principal Axes:
Axis Value Plunge Azimuth
T 4.90e+23 1 184
N 0.00e+00 23 275
P -4.90e+23 67 92
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.87e+23
Mxy 3.94e+22
Mxz -2.29e+20
Myy -6.91e+22
Myz -1.74e+23
Mzz -4.18e+23
##############
######################
############################
##############################
##################################
################---------------#####
############------------------------##
--#######------------------------------#
--#####---------------------------------
----##------------------------------------
----#-------------------- --------------
---###------------------- P --------------
--######----------------- --------------
-########-------------------------------
###########-----------------------------
#############-------------------------
################------------------##
##################################
##############################
############################
######## ###########
#### T #######
Global CMT Convention Moment Tensor:
R T P
-4.18e+23 -2.29e+20 1.74e+23
-2.29e+20 4.87e+23 -3.94e+22
1.74e+23 -3.94e+22 -6.91e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130621103357/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 = 115
DIP = 50
RAKE = -60
MW = 5.06
HS = 5.0
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
INGVTDMT |
SLU Moment Tensor Solution
ENS 2013/06/21 10:33:57:0 44.15 10.14 5.1 5.2 Italy
Stations used:
FR.ESCA FR.MON FR.SAOF GU.BHB GU.ENR GU.FINB GU.GORR
GU.MAIM GU.NEGI GU.POPM GU.PZZ GU.ROTM GU.TRAV IV.ARCI
IV.ARVD IV.ASQU IV.BOB IV.CAFI IV.CASP IV.CRMI IV.CSNT
IV.DOI IV.FNVD IV.FSSB IV.IMI IV.MAON IV.MSSA IV.MURB
IV.PARC IV.PESA IV.PIEI IV.QLNO IV.SACS IV.SNTG IV.SSFR
MN.VLC
Filtering commands used:
cut a -30 a 150
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 n 3
Best Fitting Double Couple
Mo = 4.90e+23 dyne-cm
Mw = 5.06
Z = 5 km
Plane Strike Dip Rake
NP1 115 50 -60
NP2 253 48 -121
Principal Axes:
Axis Value Plunge Azimuth
T 4.90e+23 1 184
N 0.00e+00 23 275
P -4.90e+23 67 92
Moment Tensor: (dyne-cm)
Component Value
Mxx 4.87e+23
Mxy 3.94e+22
Mxz -2.29e+20
Myy -6.91e+22
Myz -1.74e+23
Mzz -4.18e+23
##############
######################
############################
##############################
##################################
################---------------#####
############------------------------##
--#######------------------------------#
--#####---------------------------------
----##------------------------------------
----#-------------------- --------------
---###------------------- P --------------
--######----------------- --------------
-########-------------------------------
###########-----------------------------
#############-------------------------
################------------------##
##################################
##############################
############################
######## ###########
#### T #######
Global CMT Convention Moment Tensor:
R T P
-4.18e+23 -2.29e+20 1.74e+23
-2.29e+20 4.87e+23 -3.94e+22
1.74e+23 -3.94e+22 -6.91e+22
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130621103357/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 150
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 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 1.0 125 50 -40 4.90 0.4724
WVFGRD96 2.0 120 45 -45 4.95 0.5280
WVFGRD96 3.0 120 50 -50 4.98 0.5728
WVFGRD96 4.0 110 50 -65 5.02 0.5932
WVFGRD96 5.0 115 50 -60 5.06 0.6259
WVFGRD96 6.0 115 55 -60 5.06 0.6129
WVFGRD96 7.0 120 60 -50 5.02 0.5831
WVFGRD96 8.0 130 70 -25 4.95 0.5560
WVFGRD96 9.0 130 70 -20 4.95 0.5520
WVFGRD96 10.0 135 70 -10 4.95 0.5503
WVFGRD96 11.0 320 75 10 4.97 0.5481
WVFGRD96 12.0 320 75 10 4.98 0.5450
WVFGRD96 13.0 320 75 10 4.99 0.5425
WVFGRD96 14.0 320 75 10 5.00 0.5385
WVFGRD96 15.0 135 70 -5 5.00 0.5367
WVFGRD96 16.0 135 70 -5 5.01 0.5321
WVFGRD96 17.0 135 70 -5 5.01 0.5265
WVFGRD96 18.0 135 70 0 5.02 0.5207
WVFGRD96 19.0 135 70 0 5.02 0.5147
WVFGRD96 20.0 135 70 0 5.03 0.5084
WVFGRD96 21.0 135 75 0 5.04 0.5024
WVFGRD96 22.0 135 75 0 5.05 0.4963
WVFGRD96 23.0 135 75 0 5.06 0.4901
WVFGRD96 24.0 135 75 0 5.07 0.4843
WVFGRD96 25.0 135 75 5 5.08 0.4789
WVFGRD96 26.0 135 75 5 5.09 0.4747
WVFGRD96 27.0 135 75 5 5.10 0.4706
WVFGRD96 28.0 135 75 5 5.12 0.4670
WVFGRD96 29.0 135 75 10 5.14 0.4644
The best solution is
WVFGRD96 5.0 115 50 -60 5.06 0.6259
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 150
rtr
taper w 0.1
hp c 0.02 n 3
lp c 0.06 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=Fri Jun 21 12:17:26 CDT 2013
Last Changed 2013/06/21
