2013/09/20 02:06:33 47.94 16.51 5.0 4.2 Austria
USGS Felt map for this earthquake
SLU Moment Tensor Solution ENS 2013/09/20 02:06:33:0 47.94 16.51 5.0 4.2 Austria Stations used: CZ.KHC CZ.KRUC CZ.PRU CZ.TREC CZ.VRAC GR.GEC2 GR.WET HU.BUD HU.MORH HU.SOP IV.PTCC OE.ARSA OE.CONA OE.CSNA OE.KBA OE.MOA OE.MYKA OE.OBKA OE.SOKA SL.BOJS SL.CADS SL.CEY SL.CRES SL.CRNS SL.GBAS SL.GCIS SL.GORS SL.JAVS SL.KOGS SL.LJU SL.MOZS SL.PERS SL.ROBS SL.VISS SL.VOJS Filtering commands used: cut a -10 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 4.47e+21 dyne-cm Mw = 3.70 Z = 17 km Plane Strike Dip Rake NP1 134 85 170 NP2 225 80 5 Principal Axes: Axis Value Plunge Azimuth T 4.47e+21 11 89 N 0.00e+00 79 288 P -4.47e+21 4 180 Moment Tensor: (dyne-cm) Component Value Mxx -4.45e+21 Mxy 6.66e+19 Mxz 2.88e+20 Myy 4.32e+21 Myz 8.05e+20 Mzz 1.33e+20 -------------- ---------------------- ---------------------------- #---------------------------## ####-----------------------####### #######-------------------########## #########---------------############## ############-----------################# ##############-------################### ################----################## # ###################################### T # #################---################## # ###############-------#################### ############-----------################# ###########--------------############### ########------------------############ ######---------------------######### ####-------------------------##### #----------------------------# ---------------------------- ---------- --------- ------ P ----- Global CMT Convention Moment Tensor: R T P 1.33e+20 2.88e+20 -8.05e+20 2.88e+20 -4.45e+21 -6.66e+19 -8.05e+20 -6.66e+19 4.32e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130920020633/index.html |
STK = 225 DIP = 80 RAKE = 5 MW = 3.70 HS = 17.0
The NDK file is 20130920020633.ndk The waveform inversion is preferred.
The following compares this source inversion to others
SLU Moment Tensor Solution ENS 2013/09/20 02:06:33:0 47.94 16.51 5.0 4.2 Austria Stations used: CZ.KHC CZ.KRUC CZ.PRU CZ.TREC CZ.VRAC GR.GEC2 GR.WET HU.BUD HU.MORH HU.SOP IV.PTCC OE.ARSA OE.CONA OE.CSNA OE.KBA OE.MOA OE.MYKA OE.OBKA OE.SOKA SL.BOJS SL.CADS SL.CEY SL.CRES SL.CRNS SL.GBAS SL.GCIS SL.GORS SL.JAVS SL.KOGS SL.LJU SL.MOZS SL.PERS SL.ROBS SL.VISS SL.VOJS Filtering commands used: cut a -10 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 4.47e+21 dyne-cm Mw = 3.70 Z = 17 km Plane Strike Dip Rake NP1 134 85 170 NP2 225 80 5 Principal Axes: Axis Value Plunge Azimuth T 4.47e+21 11 89 N 0.00e+00 79 288 P -4.47e+21 4 180 Moment Tensor: (dyne-cm) Component Value Mxx -4.45e+21 Mxy 6.66e+19 Mxz 2.88e+20 Myy 4.32e+21 Myz 8.05e+20 Mzz 1.33e+20 -------------- ---------------------- ---------------------------- #---------------------------## ####-----------------------####### #######-------------------########## #########---------------############## ############-----------################# ##############-------################### ################----################## # ###################################### T # #################---################## # ###############-------#################### ############-----------################# ###########--------------############### ########------------------############ ######---------------------######### ####-------------------------##### #----------------------------# ---------------------------- ---------- --------- ------ P ----- Global CMT Convention Moment Tensor: R T P 1.33e+20 2.88e+20 -8.05e+20 2.88e+20 -4.45e+21 -6.66e+19 -8.05e+20 -6.66e+19 4.32e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.IT/20130920020633/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:
cut a -10 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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 40 70 -10 3.29 0.2733 WVFGRD96 2.0 35 65 -15 3.40 0.3489 WVFGRD96 3.0 230 70 35 3.47 0.3939 WVFGRD96 4.0 230 70 30 3.50 0.4460 WVFGRD96 5.0 225 75 25 3.51 0.4910 WVFGRD96 6.0 225 80 20 3.53 0.5347 WVFGRD96 7.0 225 80 15 3.56 0.5721 WVFGRD96 8.0 225 75 10 3.59 0.6062 WVFGRD96 9.0 225 75 5 3.61 0.6357 WVFGRD96 10.0 225 80 5 3.63 0.6586 WVFGRD96 11.0 225 80 5 3.64 0.6763 WVFGRD96 12.0 225 80 5 3.65 0.6882 WVFGRD96 13.0 225 80 0 3.67 0.6959 WVFGRD96 14.0 225 80 0 3.68 0.7006 WVFGRD96 15.0 225 85 5 3.68 0.7026 WVFGRD96 16.0 225 80 5 3.69 0.7041 WVFGRD96 17.0 225 80 5 3.70 0.7047 WVFGRD96 18.0 225 80 5 3.71 0.7034 WVFGRD96 19.0 225 80 10 3.71 0.7009 WVFGRD96 20.0 225 85 10 3.72 0.6979 WVFGRD96 21.0 225 85 10 3.73 0.6940 WVFGRD96 22.0 225 85 10 3.74 0.6885 WVFGRD96 23.0 225 85 10 3.74 0.6813 WVFGRD96 24.0 45 90 -10 3.75 0.6682 WVFGRD96 25.0 45 90 -10 3.76 0.6600 WVFGRD96 26.0 225 85 10 3.77 0.6551 WVFGRD96 27.0 40 90 -15 3.77 0.6419 WVFGRD96 28.0 40 90 -15 3.78 0.6315 WVFGRD96 29.0 40 90 -15 3.78 0.6208
The best solution is
WVFGRD96 17.0 225 80 5 3.70 0.7047
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
cut a -10 a 140 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 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 WUS used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:
MODEL.01 Model after 8 iterations 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 1.9000 3.4065 2.0089 2.2150 0.302E-02 0.679E-02 0.00 0.00 1.00 1.00 6.1000 5.5445 3.2953 2.6089 0.349E-02 0.784E-02 0.00 0.00 1.00 1.00 13.0000 6.2708 3.7396 2.7812 0.212E-02 0.476E-02 0.00 0.00 1.00 1.00 19.0000 6.4075 3.7680 2.8223 0.111E-02 0.249E-02 0.00 0.00 1.00 1.00 0.0000 7.9000 4.6200 3.2760 0.164E-10 0.370E-10 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=Fri Sep 20 09:24:58 CDT 2013