2010/08/29 10:11:17 42.837 12.664 5.7 3.1 Italy
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution
ENS 2010/08/29 10:11:17:0 42.84 12.66 5.7 3.1 Italy
Stations used:
IV.AOI IV.ARVD IV.CAFI IV.CAMP IV.CERT IV.CESI IV.CING
IV.CRE IV.FAGN IV.FDMO IV.FIAM IV.GUMA IV.LATE IV.MCIV
IV.MGAB IV.MTCE IV.MURB IV.POFI IV.SACS IV.SNTG IV.T0104
IV.TERO IV.TOLF IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 6 km
Plane Strike Dip Rake
NP1 355 80 -93
NP2 190 10 -75
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 35 87
N 0.00e+00 3 355
P -1.29e+21 55 262
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.97e+18
Mxy -1.84e+19
Mxz 1.20e+20
Myy 4.33e+20
Myz 1.21e+21
Mzz -4.26e+20
##----########
##--------############
###-----------##############
##-------------###############
##----------------################
##-----------------#################
##------------------##################
##--------------------##################
##--------------------##################
##---------------------########## ######
##--------- ---------########## T ######
##--------- P ----------######### ######
##--------- ----------##################
##---------------------#################
##---------------------#################
##--------------------################
##-------------------###############
##------------------##############
#-----------------############
##---------------###########
#------------#########
---------#####
Global CMT Convention Moment Tensor:
R T P
-4.26e+20 1.20e+20 -1.21e+21
1.20e+20 -6.97e+18 1.84e+19
-1.21e+21 1.84e+19 4.33e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100829101117/index.html
|
STK = 190
DIP = 10
RAKE = -75
MW = 3.34
HS = 6.0
The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution
ENS 2010/08/29 10:11:17:0 42.84 12.66 5.7 3.1 Italy
Stations used:
IV.AOI IV.ARVD IV.CAFI IV.CAMP IV.CERT IV.CESI IV.CING
IV.CRE IV.FAGN IV.FDMO IV.FIAM IV.GUMA IV.LATE IV.MCIV
IV.MGAB IV.MTCE IV.MURB IV.POFI IV.SACS IV.SNTG IV.T0104
IV.TERO IV.TOLF IV.VVLD MN.AQU
Filtering commands used:
hp c 0.02 n 3
lp c 0.10 n 3
Best Fitting Double Couple
Mo = 1.29e+21 dyne-cm
Mw = 3.34
Z = 6 km
Plane Strike Dip Rake
NP1 355 80 -93
NP2 190 10 -75
Principal Axes:
Axis Value Plunge Azimuth
T 1.29e+21 35 87
N 0.00e+00 3 355
P -1.29e+21 55 262
Moment Tensor: (dyne-cm)
Component Value
Mxx -6.97e+18
Mxy -1.84e+19
Mxz 1.20e+20
Myy 4.33e+20
Myz 1.21e+21
Mzz -4.26e+20
##----########
##--------############
###-----------##############
##-------------###############
##----------------################
##-----------------#################
##------------------##################
##--------------------##################
##--------------------##################
##---------------------########## ######
##--------- ---------########## T ######
##--------- P ----------######### ######
##--------- ----------##################
##---------------------#################
##---------------------#################
##--------------------################
##-------------------###############
##------------------##############
#-----------------############
##---------------###########
#------------#########
---------#####
Global CMT Convention Moment Tensor:
R T P
-4.26e+20 1.20e+20 -1.21e+21
1.20e+20 -6.97e+18 1.84e+19
-1.21e+21 1.84e+19 4.33e+20
Details of the solution is found at
http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20100829101117/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 1.0 10 35 -85 3.12 0.3252
WVFGRD96 2.0 210 5 -60 3.30 0.3987
WVFGRD96 3.0 210 5 -60 3.26 0.5070
WVFGRD96 4.0 200 10 -65 3.24 0.5534
WVFGRD96 5.0 195 10 -70 3.35 0.5747
WVFGRD96 6.0 190 10 -75 3.34 0.5781
WVFGRD96 7.0 200 15 -65 3.34 0.5671
WVFGRD96 8.0 205 20 -60 3.30 0.5465
WVFGRD96 9.0 210 20 -55 3.30 0.5256
WVFGRD96 10.0 215 20 -50 3.30 0.5025
WVFGRD96 11.0 225 25 -45 3.30 0.4789
WVFGRD96 12.0 225 25 -45 3.30 0.4553
WVFGRD96 13.0 225 25 -45 3.31 0.4326
WVFGRD96 14.0 220 25 -50 3.31 0.4110
WVFGRD96 15.0 200 20 -70 3.35 0.3915
WVFGRD96 16.0 200 20 -70 3.35 0.3704
WVFGRD96 17.0 190 20 -80 3.36 0.3498
WVFGRD96 18.0 195 20 -75 3.36 0.3295
WVFGRD96 19.0 195 20 -75 3.37 0.3085
WVFGRD96 20.0 195 25 -75 3.37 0.2880
WVFGRD96 21.0 185 25 -90 3.37 0.2681
WVFGRD96 22.0 180 65 70 3.38 0.2518
WVFGRD96 23.0 180 60 70 3.39 0.2456
WVFGRD96 24.0 175 60 65 3.40 0.2455
WVFGRD96 25.0 180 55 70 3.41 0.2513
WVFGRD96 26.0 180 55 70 3.42 0.2557
WVFGRD96 27.0 185 55 75 3.43 0.2563
WVFGRD96 28.0 -5 45 65 3.43 0.2531
WVFGRD96 29.0 355 45 65 3.45 0.2508
The best solution is
WVFGRD96 6.0 190 10 -75 3.34 0.5781
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=Sun Aug 29 06:28:49 CDT 2010