Location
2010/07/13 03:36:18 40.581 15.452 10.4 3.4 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 2010/07/13 03:36:18:0 40.58 15.45 10.4 3.4 Italy
Stations used:
IV.BULG IV.CDRU IV.CMPR IV.MCEL IV.MCRV IV.MODR IV.MRVN
IV.MSAG IV.PAOL IV.PSB1 IV.SGRT IV.SIRI MN.TIP
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.75e+21 dyne-cm
Mw = 3.56
Z = 7 km
Plane Strike Dip Rake
NP1 340 70 -92
NP2 165 20 -85
Principal Axes:
Axis Value Plunge Azimuth
T 2.75e+21 25 71
N 0.00e+00 2 340
P -2.75e+21 65 247
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.59e+20
Mxy 5.12e+20
Mxz 7.62e+20
Myy 1.60e+21
Myz 1.97e+21
Mzz -1.76e+21
##############
##----################
###--------#################
##-----------#################
###--------------#################
###----------------#################
###------------------#################
####-------------------########## ####
###---------------------######### T ####
####---------------------######### #####
####----------------------################
####--------- -----------###############
####--------- P -----------###############
####-------- ------------#############
####-----------------------#############
####----------------------############
####----------------------##########
#####--------------------#########
####-------------------#######
#####-----------------######
#####--------------###
######--------
Global CMT Convention Moment Tensor:
R T P
-1.76e+21 7.62e+20 -1.97e+21
7.62e+20 1.59e+20 -5.12e+20
-1.97e+21 -5.12e+20 1.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100713033618/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 = 165
DIP = 20
RAKE = -85
MW = 3.56
HS = 7.0
The waveform inversion is preferred.
Moment Tensor Comparison
The following compares this source inversion to others
| SLU |
SLU |
USGS/SLU Moment Tensor Solution
ENS 2010/07/13 03:36:18:0 40.58 15.45 10.4 3.4 Italy
Stations used:
IV.BULG IV.CDRU IV.CMPR IV.MCEL IV.MCRV IV.MODR IV.MRVN
IV.MSAG IV.PAOL IV.PSB1 IV.SGRT IV.SIRI MN.TIP
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 2.75e+21 dyne-cm
Mw = 3.56
Z = 7 km
Plane Strike Dip Rake
NP1 340 70 -92
NP2 165 20 -85
Principal Axes:
Axis Value Plunge Azimuth
T 2.75e+21 25 71
N 0.00e+00 2 340
P -2.75e+21 65 247
Moment Tensor: (dyne-cm)
Component Value
Mxx 1.59e+20
Mxy 5.12e+20
Mxz 7.62e+20
Myy 1.60e+21
Myz 1.97e+21
Mzz -1.76e+21
##############
##----################
###--------#################
##-----------#################
###--------------#################
###----------------#################
###------------------#################
####-------------------########## ####
###---------------------######### T ####
####---------------------######### #####
####----------------------################
####--------- -----------###############
####--------- P -----------###############
####-------- ------------#############
####-----------------------#############
####----------------------############
####----------------------##########
#####--------------------#########
####-------------------#######
#####-----------------######
#####--------------###
######--------
Global CMT Convention Moment Tensor:
R T P
-1.76e+21 7.62e+20 -1.97e+21
7.62e+20 1.59e+20 -5.12e+20
-1.97e+21 -5.12e+20 1.60e+21
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100713033618/index.html
|
SLU location using elocate is elocate.txt
|
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 1.0 170 50 -15 3.32 0.3595
WVFGRD96 2.0 170 40 -15 3.41 0.4084
WVFGRD96 3.0 175 40 -5 3.42 0.4628
WVFGRD96 4.0 335 70 -85 3.44 0.5048
WVFGRD96 5.0 335 70 -90 3.54 0.5475
WVFGRD96 6.0 340 70 -90 3.55 0.5791
WVFGRD96 7.0 165 20 -85 3.56 0.5947
WVFGRD96 8.0 175 25 -75 3.53 0.5910
WVFGRD96 9.0 175 25 -75 3.54 0.5837
WVFGRD96 10.0 180 25 -70 3.55 0.5751
WVFGRD96 11.0 170 20 -80 3.55 0.5643
WVFGRD96 12.0 175 20 -75 3.56 0.5510
WVFGRD96 13.0 195 30 -45 3.57 0.5319
WVFGRD96 14.0 195 30 -45 3.58 0.5172
WVFGRD96 15.0 195 25 -50 3.63 0.5047
WVFGRD96 16.0 215 55 40 3.59 0.4933
WVFGRD96 17.0 215 55 40 3.60 0.4871
WVFGRD96 18.0 215 55 40 3.61 0.4779
WVFGRD96 19.0 220 50 40 3.62 0.4687
WVFGRD96 20.0 215 55 40 3.63 0.4591
WVFGRD96 21.0 220 50 40 3.63 0.4504
WVFGRD96 22.0 215 50 35 3.64 0.4443
WVFGRD96 23.0 220 50 45 3.65 0.4399
WVFGRD96 24.0 220 50 40 3.66 0.4365
WVFGRD96 25.0 220 50 40 3.67 0.4333
WVFGRD96 26.0 225 50 50 3.68 0.4295
WVFGRD96 27.0 225 50 45 3.69 0.4246
WVFGRD96 28.0 230 50 55 3.70 0.4192
WVFGRD96 29.0 230 50 50 3.71 0.4153
The best solution is
WVFGRD96 7.0 165 20 -85 3.56 0.5947
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
|
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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.
|
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=Tue Jul 13 09:26:46 CDT 2010
Last Changed 2010/07/13