USGS/SLU Moment Tensor Solution ENS 2017/07/17 09:27:04:0 36.73 -115.91 7.7 4.2 Nevada Stations used: AE.U15A AE.W13A CI.ARV CI.BC3 CI.BEL CI.BFS CI.CHF CI.DAN CI.DEC CI.DJJ CI.EDW2 CI.FUR CI.GLA CI.GMR CI.GRA CI.HEC CI.IRM CI.ISA CI.MWC CI.NEE2 CI.OSI CI.PASC CI.PDM CI.SLA CI.TIN CI.TUQ CI.VES CI.VOG IM.NV31 LB.BMN LB.TPH NN.CMK6 NN.DSP NN.GMN NN.GWY NN.LHV NN.MOHS NN.PIO NN.PRN NN.Q09A NN.Q12A NN.QSM NN.S11A NN.SHP NN.SPR3 NN.UNVG NN.V12A NN.WLDB PY.BPH02 SN.HEL TA.R11B US.WUAZ UU.CCUT UU.FOR1 UU.FOR4 UU.KNB UU.PSUT UU.SWUT UU.SZCU UU.TCRU Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 6.53e+21 dyne-cm Mw = 3.81 Z = 10 km Plane Strike Dip Rake NP1 155 90 -155 NP2 65 65 0 Principal Axes: Axis Value Plunge Azimuth T 6.53e+21 17 287 N 0.00e+00 65 155 P -6.53e+21 17 23 Moment Tensor: (dyne-cm) Component Value Mxx -4.53e+21 Mxy -3.80e+21 Mxz -1.17e+21 Myy 4.53e+21 Myz -2.50e+21 Mzz 0.00e+00 -------------- ###------------- --- #######------------ P ------ #########----------- ------- ###########----------------------- #############----------------------- ###############----------------------- ## ############---------------------## ## T #############------------------#### ### ##############----------------###### #####################-------------######## #####################-----------########## ######################-------############# ######################---############### #####################--################# ###############--------############### -----------------------############# -----------------------########### ---------------------######### ---------------------####### -------------------### -------------- Global CMT Convention Moment Tensor: R T P 0.00e+00 -1.17e+21 2.50e+21 -1.17e+21 -4.53e+21 3.80e+21 2.50e+21 3.80e+21 4.53e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20170717092704/index.html |
STK = 65 DIP = 65 RAKE = 0 MW = 3.81 HS = 10.0
The NDK file is 20170717092704.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2017/07/17 09:27:04:0 36.73 -115.91 7.7 4.2 Nevada Stations used: AE.U15A AE.W13A CI.ARV CI.BC3 CI.BEL CI.BFS CI.CHF CI.DAN CI.DEC CI.DJJ CI.EDW2 CI.FUR CI.GLA CI.GMR CI.GRA CI.HEC CI.IRM CI.ISA CI.MWC CI.NEE2 CI.OSI CI.PASC CI.PDM CI.SLA CI.TIN CI.TUQ CI.VES CI.VOG IM.NV31 LB.BMN LB.TPH NN.CMK6 NN.DSP NN.GMN NN.GWY NN.LHV NN.MOHS NN.PIO NN.PRN NN.Q09A NN.Q12A NN.QSM NN.S11A NN.SHP NN.SPR3 NN.UNVG NN.V12A NN.WLDB PY.BPH02 SN.HEL TA.R11B US.WUAZ UU.CCUT UU.FOR1 UU.FOR4 UU.KNB UU.PSUT UU.SWUT UU.SZCU UU.TCRU Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 n 3 Best Fitting Double Couple Mo = 6.53e+21 dyne-cm Mw = 3.81 Z = 10 km Plane Strike Dip Rake NP1 155 90 -155 NP2 65 65 0 Principal Axes: Axis Value Plunge Azimuth T 6.53e+21 17 287 N 0.00e+00 65 155 P -6.53e+21 17 23 Moment Tensor: (dyne-cm) Component Value Mxx -4.53e+21 Mxy -3.80e+21 Mxz -1.17e+21 Myy 4.53e+21 Myz -2.50e+21 Mzz 0.00e+00 -------------- ###------------- --- #######------------ P ------ #########----------- ------- ###########----------------------- #############----------------------- ###############----------------------- ## ############---------------------## ## T #############------------------#### ### ##############----------------###### #####################-------------######## #####################-----------########## ######################-------############# ######################---############### #####################--################# ###############--------############### -----------------------############# -----------------------########### ---------------------######### ---------------------####### -------------------### -------------- Global CMT Convention Moment Tensor: R T P 0.00e+00 -1.17e+21 2.50e+21 -1.17e+21 -4.53e+21 3.80e+21 2.50e+21 3.80e+21 4.53e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20170717092704/index.html |
REVIEWED BY NSL STAFF Event ID:596256 Origin ID:1592846 Algorithm: Ichinose (2003) Long Period, Regional-Distance Waves Seismic Moment Tensor Solution 2017/07/17 (198) 09:27:05.00 36.7304 -115.9092 1592846 Depth = 12.0 (km) Mw = 3.86 Mo = 7.72x10^21 (dyne x cm) Percent Double Couple = 97 % Percent CLVD = 3 % no ISO calculated Epsilon=-0.02 Percent Variance Reduction = 65.81 % Total Fit = 15.35 Major Double Couple strike dip rake Nodal Plane 1: 63 74 6 Nodal Plane 2: 332 84 164 DEVIATORIC MOMENT TENSOR Moment Tensor Elements: Spherical Coordinates Mrr= 0.32 Mtt= -6.20 Mff= 5.88 Mrt= -0.28 Mrf= 2.23 Mtf= 4.25 EXP=21 Moment Tensor Elements: Cartesian Coordinates -6.20 -4.25 -0.28 -4.25 5.88 -2.23 -0.28 -2.23 0.32 Eigenvalues: T-axis eigenvalue= 7.79 N-axis eigenvalue= -0.13 P-axis eigenvalue= -7.66 Eigenvalues and eigenvectors of the Major Double Couple: T-axis ev= 7.79 trend=287 plunge=15 N-axis ev= 0.00 trend=132 plunge=73 P-axis ev=-7.79 trend=19 plunge=7 Maximum Azmuithal Gap=89 Distance to Nearest Station= 90.7 (km) Number of Stations (D=Displacement/V=Velocity) Used=11 (defining only) GWY.NN.D HEL.SN.D UNVG.NN.D S11A.NN.D PRN.NN.D QSM.NN.D V12A.NN.D PIO.NN.D TPH.LB.D GMR.CI.D W13A.AE.D ------------ P -- ####------------ ------ #######---------------------- ##########----------------------- ############----------------------- ##############----------------------- -#################---------------------## ###################-------------------### T ####################----------------###### #####################-------------######## #######################----------########### ########################------############## #########################--################# ############################################ ########################-################## ####################------################# ###############-----------############### #######-------------------############## --------------------------############# -------------------------########### -------------------------######## ------------------------##### ----------------------### ----------------- All Stations defining and nondefining: Station.Net Def Distance Azi Bazi lo-f hi-f vmodel (km) (deg) (deg) (Hz) (Hz) GWY.NN (D) Y 90.7 229 48 0.020 0.080 GWY.NN.wus.glib HEL.SN (D) Y 95.4 270 89 0.020 0.080 HEL.SN.wus.glib UNVG.NN (D) Y 97.4 135 315 0.020 0.080 UNVG.NN.wus.glib S11A.NN (D) Y 102.0 8 188 0.020 0.080 S11A.NN.wus.glib PRN.NN (D) Y 107.3 45 226 0.020 0.080 PRN.NN.wus.glib QSM.NN (D) Y 120.5 226 45 0.020 0.080 QSM.NN.wus.glib V12A.NN (D) Y 146.2 139 320 0.020 0.080 V12A.NN.wus.glib PIO.NN (D) Y 184.6 42 223 0.020 0.080 PIO.NN.wus.glib TPH.LB (D) Y 189.4 323 142 0.020 0.080 TPH.LB.wus.glib GMR.CI (D) Y 217.9 174 354 0.020 0.080 GMR.CI.wus.glib W13A.AE (D) Y 256.6 134 316 0.020 0.080 W13A.AE.wus.glib (V)-velocity (D)-Displacement Author: www-data Date: 2017/07/17 13:30:56 mtinv Version 2.1_DEVEL OCT2008 |
(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 +70 rtr taper w 0.1 hp c 0.03 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 1.0 335 90 -10 3.37 0.3082 WVFGRD96 2.0 65 75 0 3.50 0.3807 WVFGRD96 3.0 65 55 0 3.59 0.4219 WVFGRD96 4.0 65 55 0 3.63 0.4597 WVFGRD96 5.0 65 60 0 3.66 0.4888 WVFGRD96 6.0 65 60 0 3.69 0.5106 WVFGRD96 7.0 65 65 0 3.72 0.5286 WVFGRD96 8.0 65 60 0 3.77 0.5413 WVFGRD96 9.0 65 65 0 3.79 0.5464 WVFGRD96 10.0 65 65 0 3.81 0.5471 WVFGRD96 11.0 65 65 0 3.83 0.5428 WVFGRD96 12.0 65 70 0 3.85 0.5357 WVFGRD96 13.0 65 70 0 3.86 0.5260 WVFGRD96 14.0 65 70 0 3.87 0.5135 WVFGRD96 15.0 65 70 0 3.88 0.4992 WVFGRD96 16.0 65 70 0 3.89 0.4833 WVFGRD96 17.0 65 70 5 3.90 0.4661 WVFGRD96 18.0 65 70 5 3.91 0.4493 WVFGRD96 19.0 65 70 5 3.92 0.4318 WVFGRD96 20.0 65 70 5 3.92 0.4143 WVFGRD96 21.0 65 65 5 3.93 0.3978 WVFGRD96 22.0 65 70 5 3.93 0.3825 WVFGRD96 23.0 65 70 10 3.94 0.3688 WVFGRD96 24.0 70 70 15 3.94 0.3586 WVFGRD96 25.0 70 75 15 3.95 0.3500 WVFGRD96 26.0 70 75 15 3.95 0.3423 WVFGRD96 27.0 70 75 15 3.96 0.3350 WVFGRD96 28.0 155 90 20 3.96 0.3386 WVFGRD96 29.0 335 90 -20 3.97 0.3474
The best solution is
WVFGRD96 10.0 65 65 0 3.81 0.5471
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 +70 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.10 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.
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: