USGS/SLU Moment Tensor Solution ENS 2023/04/17 13:28:57:0 42.96 0.34 4.7 4.3 Spain Stations used: CA.ARBS CA.CAVN CA.CBEU CA.CBRU CA.CBUD CA.CEST CA.CFAR CA.CFON CA.CGAR CA.CLLI CA.CMAS CA.CORG CA.CORI CA.CTRE CA.POBL EB.EROQ FR.ABJF FR.AGO FR.ARBF FR.ATE FR.BANN FR.BORF FR.BRGF FR.BSCF FR.CARF FR.CFF FR.CHIF FR.CLMF FR.CMPS FR.COLF FR.CRAS FR.DUNF FR.FILF FR.FNEB FR.FRNF FR.GARF FR.GENF FR.GNEF FR.GZNF FR.HRSF FR.IRAF FR.LABF FR.LATF FR.LEUC FR.LGIF FR.LRVF FR.MELF FR.MLS FR.MLZA FR.MONQ FR.OGCB FR.OGDF FR.ORDF FR.OSSF FR.PAND FR.PLDF FR.PYHE FR.PYLO FR.RESF FR.REST FR.REYF FR.RUFF FR.SALF FR.SGSF FR.SLVF FR.TERF FR.URDF FR.VALC FR.VERF FR.VIEF G.SSB RD.MTLF XP.FR21A XP.FR26A Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.04 n 3 lp c 0.08 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 2.02e+21 dyne-cm Mw = 3.47 Z = 16 km Plane Strike Dip Rake NP1 302 69 -103 NP2 155 25 -60 Principal Axes: Axis Value Plunge Azimuth T 2.02e+21 22 42 N 0.00e+00 12 307 P -2.02e+21 64 191 Moment Tensor: (dyne-cm) Component Value Mxx 5.66e+20 Mxy 7.87e+20 Mxz 1.30e+21 Myy 7.73e+20 Myz 6.32e+20 Mzz -1.34e+21 ############## -##################### --########################## --####################### ## ---######################## T #### ###------################### ##### ###------------####################### ####----------------#################### ####-------------------################# #####----------------------############### #####------------------------############# #####--------------------------########### #####----------------------------######### #####------------ --------------###### ######----------- P ---------------##### ######---------- ----------------### ######-----------------------------# ######---------------------------- ######------------------------ #######--------------------- ########-------------- ############## Global CMT Convention Moment Tensor: R T P -1.34e+21 1.30e+21 -6.32e+20 1.30e+21 5.66e+20 -7.87e+20 -6.32e+20 -7.87e+20 7.73e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20230417132857/index.html |
STK = 155 DIP = 25 RAKE = -60 MW = 3.47 HS = 16.0
The NDK file is 20230417132857.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2023/04/17 13:28:57:0 42.96 0.34 4.7 4.3 Spain Stations used: CA.ARBS CA.CAVN CA.CBEU CA.CBRU CA.CBUD CA.CEST CA.CFAR CA.CFON CA.CGAR CA.CLLI CA.CMAS CA.CORG CA.CORI CA.CTRE CA.POBL EB.EROQ FR.ABJF FR.AGO FR.ARBF FR.ATE FR.BANN FR.BORF FR.BRGF FR.BSCF FR.CARF FR.CFF FR.CHIF FR.CLMF FR.CMPS FR.COLF FR.CRAS FR.DUNF FR.FILF FR.FNEB FR.FRNF FR.GARF FR.GENF FR.GNEF FR.GZNF FR.HRSF FR.IRAF FR.LABF FR.LATF FR.LEUC FR.LGIF FR.LRVF FR.MELF FR.MLS FR.MLZA FR.MONQ FR.OGCB FR.OGDF FR.ORDF FR.OSSF FR.PAND FR.PLDF FR.PYHE FR.PYLO FR.RESF FR.REST FR.REYF FR.RUFF FR.SALF FR.SGSF FR.SLVF FR.TERF FR.URDF FR.VALC FR.VERF FR.VIEF G.SSB RD.MTLF XP.FR21A XP.FR26A Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.04 n 3 lp c 0.08 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 2.02e+21 dyne-cm Mw = 3.47 Z = 16 km Plane Strike Dip Rake NP1 302 69 -103 NP2 155 25 -60 Principal Axes: Axis Value Plunge Azimuth T 2.02e+21 22 42 N 0.00e+00 12 307 P -2.02e+21 64 191 Moment Tensor: (dyne-cm) Component Value Mxx 5.66e+20 Mxy 7.87e+20 Mxz 1.30e+21 Myy 7.73e+20 Myz 6.32e+20 Mzz -1.34e+21 ############## -##################### --########################## --####################### ## ---######################## T #### ###------################### ##### ###------------####################### ####----------------#################### ####-------------------################# #####----------------------############### #####------------------------############# #####--------------------------########### #####----------------------------######### #####------------ --------------###### ######----------- P ---------------##### ######---------- ----------------### ######-----------------------------# ######---------------------------- ######------------------------ #######--------------------- ########-------------- ############## Global CMT Convention Moment Tensor: R T P -1.34e+21 1.30e+21 -6.32e+20 1.30e+21 5.66e+20 -7.87e+20 -6.32e+20 -7.87e+20 7.73e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20230417132857/index.html |
(a) ML computed using the IASPEI formula for Horizontal components; (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
(a) ML computed using the IASPEI formula for Vertical components (research); (b) ML residuals computed using a modified IASPEI formula that accounts for path specific attenuation; the values used for the trimmed mean are indicated. The ML relation used for each figure is given at the bottom of each plot.
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 o DIST/3.3 -30 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.04 n 3 lp c 0.08 n 3 br c 0.12 0.25 n 4 p 2The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 140 85 -5 3.06 0.2737 WVFGRD96 2.0 120 45 -90 3.27 0.3975 WVFGRD96 3.0 140 80 -35 3.26 0.3344 WVFGRD96 4.0 170 15 -50 3.37 0.3605 WVFGRD96 5.0 175 15 -45 3.38 0.4255 WVFGRD96 6.0 165 15 -55 3.37 0.4681 WVFGRD96 7.0 155 15 -65 3.36 0.4928 WVFGRD96 8.0 150 15 -70 3.43 0.5072 WVFGRD96 9.0 145 20 -75 3.43 0.5254 WVFGRD96 10.0 145 20 -70 3.43 0.5415 WVFGRD96 11.0 145 25 -70 3.44 0.5545 WVFGRD96 12.0 145 25 -70 3.45 0.5655 WVFGRD96 13.0 150 25 -65 3.45 0.5728 WVFGRD96 14.0 150 25 -65 3.45 0.5774 WVFGRD96 15.0 155 25 -60 3.46 0.5801 WVFGRD96 16.0 155 25 -60 3.47 0.5811 WVFGRD96 17.0 160 25 -55 3.47 0.5809 WVFGRD96 18.0 160 25 -55 3.48 0.5795 WVFGRD96 19.0 150 20 -60 3.50 0.5782 WVFGRD96 20.0 155 20 -55 3.50 0.5760 WVFGRD96 21.0 155 20 -55 3.52 0.5741 WVFGRD96 22.0 155 20 -55 3.53 0.5699 WVFGRD96 23.0 155 20 -55 3.54 0.5645 WVFGRD96 24.0 150 15 -60 3.55 0.5578 WVFGRD96 25.0 145 15 -65 3.56 0.5520 WVFGRD96 26.0 150 15 -60 3.57 0.5447 WVFGRD96 27.0 150 15 -60 3.58 0.5361 WVFGRD96 28.0 150 15 -60 3.59 0.5255 WVFGRD96 29.0 140 15 -75 3.59 0.5135
The best solution is
WVFGRD96 16.0 155 25 -60 3.47 0.5811
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 o DIST/3.3 -30 o DIST/3.3 +60 rtr taper w 0.1 hp c 0.04 n 3 lp c 0.08 n 3 br c 0.12 0.25 n 4 p 2
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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.
Thanks also to the many seismic network operators whose dedication make this effort possible: University of Nevada Reno, University of Alaska, University of Washington, Oregon State University, University of Utah, Montana Bureas of Mines, UC Berkely, Caltech, UC San Diego, Saint Louis University, University of Memphis, Lamont Doherty Earth Observatory, the Iris stations and the Transportable Array of EarthScope.
The WUS.model 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: