The ANSS event ID is nn00432876 and the event page is at https://earthquake.usgs.gov/earthquakes/eventpage/nn00432876/executive.
2014/01/02 12:04:50 39.057 -118.108 6.4 3.9 Nevada
USGS/SLU Moment Tensor Solution ENS 2014/01/02 12:04:50:0 39.06 -118.11 6.4 3.9 Nevada Stations used: BK.CMB CI.CWC CI.GRA CI.MLAC CI.MPM CI.SHO CI.SLA CI.TIN CI.TUQ IM.NV31 LB.DAC NN.BEK NN.OMMB NN.PNT NN.RUB NN.RYN NN.SHP NN.VCN NN.WAK NN.YER TA.O03E TA.R11A US.DUG US.ELK US.TPNV US.WVOR UU.PSUT Filtering commands used: cut a -30 a 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 1.88e+21 dyne-cm Mw = 3.45 Z = 10 km Plane Strike Dip Rake NP1 80 80 45 NP2 340 46 166 Principal Axes: Axis Value Plunge Azimuth T 1.88e+21 38 311 N 0.00e+00 44 90 P -1.88e+21 22 203 Moment Tensor: (dyne-cm) Component Value Mxx -8.90e+20 Mxy -1.15e+21 Mxz 1.19e+21 Myy 4.35e+20 Myz -4.45e+20 Mzz 4.56e+20 #------------- ##########------------ ################------------ ###################----------- #######################----------- ####### ###############----------- ######## T ################----------- ######### #################----------- ##############################---------- ################################--------## ################################---####### #############################----######### ####################-------------######### --------------------------------######## --------------------------------######## -------------------------------####### ------------------------------###### ----------------------------###### ------- ----------------#### ------ P ---------------#### --- --------------## -------------- Global CMT Convention Moment Tensor: R T P 4.56e+20 1.19e+21 4.45e+20 1.19e+21 -8.90e+20 1.15e+21 4.45e+20 1.15e+21 4.35e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140102120450/index.html |
STK = 80 DIP = 80 RAKE = 45 MW = 3.45 HS = 10.0
The NDK file is 20140102120450.ndk The waveform inversion is preferred.
The following compares this source inversion to those provided by others. The purpose is to look for major differences and also to note slight differences that might be inherent to the processing procedure. For completeness the USGS/SLU solution is repeated from above.
USGS/SLU Moment Tensor Solution ENS 2014/01/02 12:04:50:0 39.06 -118.11 6.4 3.9 Nevada Stations used: BK.CMB CI.CWC CI.GRA CI.MLAC CI.MPM CI.SHO CI.SLA CI.TIN CI.TUQ IM.NV31 LB.DAC NN.BEK NN.OMMB NN.PNT NN.RUB NN.RYN NN.SHP NN.VCN NN.WAK NN.YER TA.O03E TA.R11A US.DUG US.ELK US.TPNV US.WVOR UU.PSUT Filtering commands used: cut a -30 a 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 1.88e+21 dyne-cm Mw = 3.45 Z = 10 km Plane Strike Dip Rake NP1 80 80 45 NP2 340 46 166 Principal Axes: Axis Value Plunge Azimuth T 1.88e+21 38 311 N 0.00e+00 44 90 P -1.88e+21 22 203 Moment Tensor: (dyne-cm) Component Value Mxx -8.90e+20 Mxy -1.15e+21 Mxz 1.19e+21 Myy 4.35e+20 Myz -4.45e+20 Mzz 4.56e+20 #------------- ##########------------ ################------------ ###################----------- #######################----------- ####### ###############----------- ######## T ################----------- ######### #################----------- ##############################---------- ################################--------## ################################---####### #############################----######### ####################-------------######### --------------------------------######## --------------------------------######## -------------------------------####### ------------------------------###### ----------------------------###### ------- ----------------#### ------ P ---------------#### --- --------------## -------------- Global CMT Convention Moment Tensor: R T P 4.56e+20 1.19e+21 4.45e+20 1.19e+21 -8.90e+20 1.15e+21 4.45e+20 1.15e+21 4.35e+20 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20140102120450/index.html |
REVIEWED BY NSL STAFF Event ID:432876 Origin ID:1074894 Algorithm: Ichinose (2003) Long Period, Regional-Distance Waves Seismic Moment Tensor Solution 2014/01/02 (002) 12:04:52.00 39.0570 -118.1082 1074894 Depth = 8.0 (km) Mw = 3.44 Mo = 1.78x10^21 (dyne x cm) Percent Double Couple = 99 % Percent CLVD = 1 % no ISO calculated Epsilon=-0.00 Percent Variance Reduction = 58.44 % Total Fit = 31.02 Major Double Couple strike dip rake Nodal Plane 1: 346 43 -173 Nodal Plane 2: 251 85 -47 DEVIATORIC MOMENT TENSOR Moment Tensor Elements: Spherical Coordinates Mrr= -0.23 Mtt= -0.55 Mff= 0.77 Mrt= 1.25 Mrf= 0.33 Mtf= 1.02 EXP=21 Moment Tensor Elements: Cartesian Coordinates -0.55 -1.02 1.25 -1.02 0.77 -0.33 1.25 -0.33 -0.23 Eigenvalues: T-axis eigenvalue= 1.79 N-axis eigenvalue= -0.01 P-axis eigenvalue= -1.78 Eigenvalues and eigenvectors of the Major Double Couple: T-axis ev= 1.79 trend=308 plunge=27 N-axis ev= 0.00 trend=66 plunge=43 P-axis ev=-1.79 trend=197 plunge=35 Maximum Azmuithal Gap=240 Distance to Nearest Station= 59.3 (km) Number of Stations (D=Displacement/V=Velocity) Used=9 (defining only) RYN.NN.D NV31.IM.D YER.NN.D PNT.NN.D WAK.NN.D PAH.NN.D VCN.NN.D RUB.NN.D OMMB.NN.D #######---------- ###############---------- ###################---------- #######################---------- #######################---------- T ########################---------- -# #########################----------- ###############################---------- #################################--######## ########################################### #############################----########### #######################----------########### ##################----------------########## #############---------------------########## ########--------------------------######### ####------------------------------######### --------------------------------######### -------------------------------######### ------------------------------######### ----------------------------######## --------- --------------####### ------- P ------------####### ----- -----------###### -------------##### All Stations defining and nondefining: Station.Net Def Distance Azi Bazi lo-f hi-f vmodel (km) (deg) (deg) (Hz) (Hz) RYN.NN (D) Y 59.3 217 37 0.020 0.080 RYN.NN.wus.glib NV31.IM (D) Y 69.8 184 4 0.020 0.080 NV31.IM.wus.glib YER.NN (D) Y 98.0 266 85 0.020 0.080 YER.NN.wus.glib PNT.NN (D) Y 128.7 272 91 0.020 0.080 PNT.NN.wus.glib WAK.NN (D) Y 130.9 242 61 0.020 0.080 WAK.NN.wus.glib PAH.NN (D) Y 131.8 304 123 0.020 0.080 PAH.NN.wus.glib VCN.NN (D) Y 135.5 282 101 0.020 0.080 VCN.NN.wus.glib RUB.NN (D) Y 176.2 270 89 0.020 0.080 RUB.NN.wus.glib OMMB.NN (D) Y 178.6 206 26 0.020 0.080 OMMB.NN.wus.glib (V)-velocity (D)-Displacement Author: www-data Date: 2014/01/02 13:23:51 mtinv Version 2.1_DEVEL OCT2008 |
![]() |
![]() |
|
Given the availability of digital waveforms for determination of the moment tensor, this section documents the added processing leading to mLg, if appropriate to the region, and ML by application of the respective IASPEI formulae. As a research study, the linear distance term of the IASPEI formula for ML is adjusted to remove a linear distance trend in residuals to give a regionally defined ML. The defined ML uses horizontal component recordings, but the same procedure is applied to the vertical components since there may be some interest in vertical component ground motions. Residual plots versus distance may indicate interesting features of ground motion scaling in some distance ranges. A residual plot of the regionalized magnitude is given as a function of distance and azimuth, since data sets may transcend different wave propagation provinces.
Left: ML computed using the IASPEI formula for Horizontal components. Center: 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.
Right: Residuals from new relation as a function of distance and azimuth.
Left: ML computed using the IASPEI formula for Vertical components (research). Center: 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.
Right: Residuals from new relation as a function of distance and azimuth.
![]() |
The focal mechanism was determined using broadband seismic waveforms. The location of the event (star) and the stations used for (red) the waveform inversion are shown in the next figure.
![]() |
|
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's 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 -30 a 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3The results of this grid search are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 0.5 250 70 15 3.09 0.2530 WVFGRD96 1.0 65 90 5 3.12 0.2705 WVFGRD96 2.0 70 80 10 3.20 0.3360 WVFGRD96 3.0 250 90 -20 3.25 0.3509 WVFGRD96 4.0 250 85 -45 3.33 0.3729 WVFGRD96 5.0 250 85 -45 3.35 0.3953 WVFGRD96 6.0 250 85 -40 3.36 0.4139 WVFGRD96 7.0 250 85 -40 3.38 0.4271 WVFGRD96 8.0 75 85 45 3.43 0.4377 WVFGRD96 9.0 75 85 45 3.44 0.4444 WVFGRD96 10.0 80 80 45 3.45 0.4480 WVFGRD96 11.0 75 85 40 3.45 0.4472 WVFGRD96 12.0 80 80 40 3.45 0.4460 WVFGRD96 13.0 80 80 40 3.46 0.4407 WVFGRD96 14.0 75 85 35 3.47 0.4364 WVFGRD96 15.0 75 85 35 3.48 0.4310 WVFGRD96 16.0 75 85 35 3.48 0.4243 WVFGRD96 17.0 255 90 -35 3.48 0.4167 WVFGRD96 18.0 255 90 -35 3.49 0.4099 WVFGRD96 19.0 255 90 -35 3.49 0.4028 WVFGRD96 20.0 255 90 -30 3.50 0.3956 WVFGRD96 21.0 255 90 -35 3.51 0.3879 WVFGRD96 22.0 255 90 -35 3.51 0.3800 WVFGRD96 23.0 255 90 -30 3.52 0.3721 WVFGRD96 24.0 255 90 -30 3.52 0.3645 WVFGRD96 25.0 255 90 -30 3.52 0.3569 WVFGRD96 26.0 250 85 -30 3.54 0.3493 WVFGRD96 27.0 250 85 -30 3.55 0.3417 WVFGRD96 28.0 250 80 -30 3.55 0.3337 WVFGRD96 29.0 250 80 -30 3.55 0.3262
The best solution is
WVFGRD96 10.0 80 80 45 3.45 0.4480
The mechanism corresponding to the best fit is
![]() |
|
The best fit as a function of depth is given in the following figure:
![]() |
|
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, the velocity model used in the predictions may not be perfect and the epicentral parameters may be be off. 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 -30 a 180 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.06 n 3
![]() |
Figure 3. Waveform comparison for selected depth. Red: observed; Blue - predicted. The time shift with respect to the model prediction is indicated. The percent of fit is also indicated. The time scale is relative to the first trace sample. |
![]() |
Focal mechanism sensitivity at the preferred depth. The red color indicates a very good fit to the waveforms. 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.model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows (The format is in the model96 format of Computer Programs in Seismology).
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