USGS Felt map for this earthquake
Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA//index.html Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA//index.html Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA//index.html Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA//index.html |
STK = 30 DIP = 70 RAKE = -75 MW = 3.87 HS = 9.0
The NDK file is .ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 0000/00/00 00:00:00:0 0.00 0.00 0.0 0.0 Stations used: BK.WDC IM.NV31 IU.COR IW.MFID IW.PLID LB.TPH NC.AFD NC.KBO NC.KCPB NC.KEB NC.KHMB NC.KMR NC.KRMB NC.MDPB NN.BEK NN.KVN NN.LHV NN.OMMB NN.PAH NN.PNT NN.REDF NN.RUB NN.RYN NN.VCN NN.WAK NN.WDEM TA.R11A UO.PINE US.BMO US.ELK US.HAWA US.HLID UU.BGU UW.BLOW UW.BRAN UW.CCRK UW.DDRF UW.IRON UW.IZEE UW.LON UW.PHIN UW.TUCA UW.UMAT UW.YACT 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 0.07 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 8.04e+21 dyne-cm Mw = 3.87 Z = 9 km Plane Strike Dip Rake NP1 30 70 -75 NP2 172 25 -125 Principal Axes: Axis Value Plunge Azimuth T 8.04e+21 24 108 N 0.00e+00 14 205 P -8.04e+21 62 323 Moment Tensor: (dyne-cm) Component Value Mxx -4.45e+20 Mxy -1.18e+21 Mxz -3.59e+21 Myy 5.43e+21 Myz 4.79e+21 Mzz -4.99e+21 ##------------ ###------------------# ####--------------------#### ###----------------------##### ####-----------------------####### ####------------------------######## ####------------------------########## #####---------- -----------########### ####----------- P ----------############ #####----------- ---------############## #####----------------------############### #####---------------------################ #####--------------------########## #### #####------------------########### T ### #####-----------------############ ### #####---------------################## #####------------################### #####---------#################### #####------################### ######-##################### #----################# -----######### Global CMT Convention Moment Tensor: R T P -4.99e+21 -3.59e+21 -4.79e+21 -3.59e+21 -4.45e+20 1.18e+21 -4.79e+21 1.18e+21 5.43e+21 USGS/SLU Moment Tensor Solution ENS 2014/11/06 01:17:10:0 41.87 -119.64 0.0 3.5 Nevada Stations used: BK.WDC IM.NV31 IU.COR IW.MFID IW.PLID LB.TPH NC.AFD NC.KBO NC.KCPB NC.KEB NC.KHMB NC.KMR NC.KRMB NC.MDPB NN.BEK NN.KVN NN.LHV NN.OMMB NN.PAH NN.PNT NN.REDF NN.RUB NN.RYN NN.VCN NN.WAK NN.WDEM TA.R11A UO.PINE US.BMO US.ELK US.HAWA US.HLID UU.BGU UW.BLOW UW.BRAN UW.CCRK UW.DDRF UW.IRON UW.IZEE UW.LON UW.PHIN UW.TUCA UW.UMAT UW.YACT 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 0.07 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 8.04e+21 dyne-cm Mw = 3.87 Z = 9 km Plane Strike Dip Rake NP1 30 70 -75 NP2 172 25 -125 Principal Axes: Axis Value Plunge Azimuth T 8.04e+21 24 108 N 0.00e+00 14 205 P -8.04e+21 62 323 Moment Tensor: (dyne-cm) Component Value Mxx -4.45e+20 Mxy -1.18e+21 Mxz -3.59e+21 Myy 5.43e+21 Myz 4.79e+21 Mzz -4.99e+21 ##------------ ###------------------# ####--------------------#### ###----------------------##### ####-----------------------####### ####------------------------######## ####------------------------########## #####---------- -----------########### ####----------- P ----------############ #####----------- ---------############## #####----------------------############### #####---------------------################ #####--------------------########## #### #####------------------########### T ### #####-----------------############ ### #####---------------################## #####------------################### #####---------#################### #####------################### ######-##################### #----################# -----######### Global CMT Convention Moment Tensor: R T P -4.99e+21 -3.59e+21 -4.79e+21 -3.59e+21 -4.45e+20 1.18e+21 -4.79e+21 1.18e+21 5.43e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20141106011710/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 +70 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.07 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 35 40 -90 3.66 0.5697 WVFGRD96 2.0 215 55 -90 3.72 0.5961 WVFGRD96 3.0 45 85 -70 3.87 0.6035 WVFGRD96 4.0 40 80 -75 3.88 0.6824 WVFGRD96 5.0 35 75 -75 3.86 0.7167 WVFGRD96 6.0 35 75 -75 3.83 0.7336 WVFGRD96 7.0 30 70 -75 3.83 0.7397 WVFGRD96 8.0 35 75 -75 3.87 0.7437 WVFGRD96 9.0 30 70 -75 3.87 0.7446 WVFGRD96 10.0 30 70 -75 3.86 0.7380 WVFGRD96 11.0 30 70 -70 3.85 0.7281 WVFGRD96 12.0 30 70 -70 3.85 0.7162 WVFGRD96 13.0 35 70 -65 3.83 0.7044 WVFGRD96 14.0 35 70 -65 3.83 0.6928 WVFGRD96 15.0 50 90 -45 3.82 0.6843 WVFGRD96 16.0 50 90 -45 3.83 0.6760 WVFGRD96 17.0 45 85 -45 3.84 0.6665 WVFGRD96 18.0 45 85 -45 3.84 0.6567 WVFGRD96 19.0 230 90 40 3.85 0.6452 WVFGRD96 20.0 230 90 40 3.86 0.6338 WVFGRD96 21.0 45 85 -45 3.87 0.6234 WVFGRD96 22.0 230 90 40 3.87 0.6087 WVFGRD96 23.0 230 90 40 3.88 0.5952 WVFGRD96 24.0 230 90 40 3.89 0.5811 WVFGRD96 25.0 45 85 -45 3.89 0.5692 WVFGRD96 26.0 45 80 -45 3.90 0.5545 WVFGRD96 27.0 45 80 -45 3.91 0.5394 WVFGRD96 28.0 45 80 -45 3.91 0.5238 WVFGRD96 29.0 45 85 -45 3.92 0.5080
The best solution is
WVFGRD96 9.0 30 70 -75 3.87 0.7446
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 0.07 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: