2013/03/04 03:53:15 44.037 11.566 9.1 3.4 Italy
USGS Felt map for this earthquake
SLU Moment Tensor Solution ENS 2013/03/04 03:53:15:0 44.04 11.57 9.1 3.4 Italy Stations used: FR.SAOF GU.ENR GU.GORR GU.MAIM IV.ARCI IV.ARVD IV.ASQU IV.ASSB IV.BDI IV.CAFI IV.CASP IV.CRMI IV.CSNT IV.FDMO IV.FNVD IV.GUMA IV.MAON IV.MGAB IV.MSSA IV.MTRZ IV.PIEI IV.PLMA IV.SACS IV.SNTG IV.SSFR IV.ZCCA MN.AQU MN.VLC Filtering commands used: hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 3.63e+21 dyne-cm Mw = 3.64 Z = 5 km Plane Strike Dip Rake NP1 288 61 -99 NP2 125 30 -75 Principal Axes: Axis Value Plunge Azimuth T 3.63e+21 16 24 N 0.00e+00 7 292 P -3.63e+21 73 177 Moment Tensor: (dyne-cm) Component Value Mxx 2.48e+21 Mxy 1.27e+21 Mxz 1.90e+21 Myy 5.58e+20 Myz 3.39e+20 Mzz -3.04e+21 ############## ################# ## #################### T ##### ##################### ###### ################################## #################################### -####-----------###################### ##----------------------################ ##--------------------------############ ###-----------------------------########## ####-------------------------------####### ####---------------------------------##### #####--------------- ----------------### #####-------------- P -----------------# ######------------- ------------------ ######-------------------------------- #######----------------------------- #########------------------------- ##########-------------------# ##############---------##### ###################### ############## Global CMT Convention Moment Tensor: R T P -3.04e+21 1.90e+21 -3.39e+20 1.90e+21 2.48e+21 -1.27e+21 -3.39e+20 -1.27e+21 5.58e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130304035315/index.html |
STK = 125 DIP = 30 RAKE = -75 MW = 3.64 HS = 5.0
The waveform inversion is preferred.
The following compares this source inversion to others
SLU Moment Tensor Solution ENS 2013/03/04 03:53:15:0 44.04 11.57 9.1 3.4 Italy Stations used: FR.SAOF GU.ENR GU.GORR GU.MAIM IV.ARCI IV.ARVD IV.ASQU IV.ASSB IV.BDI IV.CAFI IV.CASP IV.CRMI IV.CSNT IV.FDMO IV.FNVD IV.GUMA IV.MAON IV.MGAB IV.MSSA IV.MTRZ IV.PIEI IV.PLMA IV.SACS IV.SNTG IV.SSFR IV.ZCCA MN.AQU MN.VLC Filtering commands used: hp c 0.03 n 3 lp c 0.08 n 3 Best Fitting Double Couple Mo = 3.63e+21 dyne-cm Mw = 3.64 Z = 5 km Plane Strike Dip Rake NP1 288 61 -99 NP2 125 30 -75 Principal Axes: Axis Value Plunge Azimuth T 3.63e+21 16 24 N 0.00e+00 7 292 P -3.63e+21 73 177 Moment Tensor: (dyne-cm) Component Value Mxx 2.48e+21 Mxy 1.27e+21 Mxz 1.90e+21 Myy 5.58e+20 Myz 3.39e+20 Mzz -3.04e+21 ############## ################# ## #################### T ##### ##################### ###### ################################## #################################### -####-----------###################### ##----------------------################ ##--------------------------############ ###-----------------------------########## ####-------------------------------####### ####---------------------------------##### #####--------------- ----------------### #####-------------- P -----------------# ######------------- ------------------ ######-------------------------------- #######----------------------------- #########------------------------- ##########-------------------# ##############---------##### ###################### ############## Global CMT Convention Moment Tensor: R T P -3.04e+21 1.90e+21 -3.39e+20 1.90e+21 2.48e+21 -1.27e+21 -3.39e+20 -1.27e+21 5.58e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130304035315/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.
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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 0.03 n 3 lp c 0.08 n 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 130 40 -60 3.44 0.4066 WVFGRD96 2.0 135 35 -50 3.51 0.4283 WVFGRD96 3.0 140 35 -45 3.52 0.4396 WVFGRD96 4.0 125 30 -75 3.56 0.4538 WVFGRD96 5.0 125 30 -75 3.64 0.4919 WVFGRD96 6.0 125 30 -75 3.63 0.4728 WVFGRD96 7.0 150 45 -30 3.56 0.4514 WVFGRD96 8.0 160 60 5 3.53 0.4418 WVFGRD96 9.0 160 60 5 3.54 0.4391 WVFGRD96 10.0 165 60 15 3.55 0.4339 WVFGRD96 11.0 165 60 15 3.55 0.4285 WVFGRD96 12.0 160 60 5 3.56 0.4217 WVFGRD96 13.0 160 60 5 3.57 0.4143 WVFGRD96 14.0 160 60 5 3.57 0.4059 WVFGRD96 15.0 160 60 0 3.60 0.3978 WVFGRD96 16.0 160 60 0 3.60 0.3874 WVFGRD96 17.0 160 60 0 3.61 0.3780 WVFGRD96 18.0 160 60 0 3.61 0.3698 WVFGRD96 19.0 160 60 0 3.62 0.3611 WVFGRD96 20.0 160 60 -5 3.63 0.3530 WVFGRD96 21.0 160 60 -5 3.63 0.3458 WVFGRD96 22.0 340 65 10 3.64 0.3393 WVFGRD96 23.0 340 65 10 3.65 0.3358 WVFGRD96 24.0 340 65 10 3.66 0.3314 WVFGRD96 25.0 345 65 15 3.67 0.3281 WVFGRD96 26.0 345 65 15 3.68 0.3251 WVFGRD96 27.0 345 65 15 3.70 0.3234 WVFGRD96 28.0 345 70 20 3.71 0.3240 WVFGRD96 29.0 345 70 20 3.73 0.3269
The best solution is
WVFGRD96 5.0 125 30 -75 3.64 0.4919
The mechanism correspond to the best fit is
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The best fit as a function of depth is given in the following figure:
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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
hp c 0.03 n 3 lp c 0.08 n 3
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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. |
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:
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.
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=Mon Mar 4 20:58:50 CST 2013