The ANSS event ID is nn00402688 and the event page is at https://earthquake.usgs.gov/earthquakes/eventpage/nn00402688/executive.
2013/02/13 00:10:13 38.022 -118.055 7.5 5.1 Nevada
USGS/SLU Moment Tensor Solution ENS 2013/02/13 00:10:13:0 38.02 -118.06 7.5 5.1 Nevada Stations used: BK.ORV BK.WDC CI.GSC CI.ISA CI.LDF CI.MWC CI.OSI CI.PASC CI.SNCC II.PFO TA.109C TA.R11A TA.Y12C US.DUG US.ELK US.TPNV US.WVOR UU.BGU UU.CCUT UU.KNB UU.LCMT UU.MPU UU.MTPU UU.NLU UU.PKCU UU.PSUT UU.SZCU UU.TCRU UW.IRON Filtering commands used: hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 5.82e+23 dyne-cm Mw = 5.11 Z = 14 km Plane Strike Dip Rake NP1 356 85 -165 NP2 265 75 -5 Principal Axes: Axis Value Plunge Azimuth T 5.82e+23 7 130 N 0.00e+00 74 14 P -5.82e+23 14 222 Moment Tensor: (dyne-cm) Component Value Mxx -7.21e+22 Mxy -5.54e+23 Mxz 5.69e+22 Myy 9.75e+22 Myz 1.46e+23 Mzz -2.54e+22 ######-------- ##########------------ ##############-------------- ###############--------------- #################----------------- ##################------------------ ####################------------------ #####################------------------- #####################------------------- #############---------#################--- ######----------------#################### ##--------------------#################### ----------------------#################### ---------------------################### ----------------------################## ---------------------################# --------------------############ # ---- ------------############ T -- P ------------############ - ------------############ -------------######### --------###### Global CMT Convention Moment Tensor: R T P -2.54e+22 5.69e+22 -1.46e+23 5.69e+22 -7.21e+22 5.54e+23 -1.46e+23 5.54e+23 9.75e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20130213001013/index.html |
STK = 265 DIP = 75 RAKE = -5 MW = 5.11 HS = 14.0
The NDK file is 20130213001013.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 2013/02/13 00:10:13:0 38.02 -118.06 7.5 5.1 Nevada Stations used: BK.ORV BK.WDC CI.GSC CI.ISA CI.LDF CI.MWC CI.OSI CI.PASC CI.SNCC II.PFO TA.109C TA.R11A TA.Y12C US.DUG US.ELK US.TPNV US.WVOR UU.BGU UU.CCUT UU.KNB UU.LCMT UU.MPU UU.MTPU UU.NLU UU.PKCU UU.PSUT UU.SZCU UU.TCRU UW.IRON Filtering commands used: hp c 0.02 n 3 lp c 0.06 n 3 Best Fitting Double Couple Mo = 5.82e+23 dyne-cm Mw = 5.11 Z = 14 km Plane Strike Dip Rake NP1 356 85 -165 NP2 265 75 -5 Principal Axes: Axis Value Plunge Azimuth T 5.82e+23 7 130 N 0.00e+00 74 14 P -5.82e+23 14 222 Moment Tensor: (dyne-cm) Component Value Mxx -7.21e+22 Mxy -5.54e+23 Mxz 5.69e+22 Myy 9.75e+22 Myz 1.46e+23 Mzz -2.54e+22 ######-------- ##########------------ ##############-------------- ###############--------------- #################----------------- ##################------------------ ####################------------------ #####################------------------- #####################------------------- #############---------#################--- ######----------------#################### ##--------------------#################### ----------------------#################### ---------------------################### ----------------------################## ---------------------################# --------------------############ # ---- ------------############ T -- P ------------############ - ------------############ -------------######### --------###### Global CMT Convention Moment Tensor: R T P -2.54e+22 5.69e+22 -1.46e+23 5.69e+22 -7.21e+22 5.54e+23 -1.46e+23 5.54e+23 9.75e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20130213001013/index.html |
REVIEWED BY NSL STAFF Event ID:402688 Origin ID:991992 Algorithm: Ichinose (2003) Long Period, Regional-Distance Waves Seismic Moment Tensor Solution 2013/02/13 (044) 00:10:16.00 38.0446 -118.0232 991992 Depth = 8.0 (km) Mw = 5.09 Mo = 5.38x10^23 (dyne x cm) Percent Double Couple = 95 % Percent CLVD = 5 % no ISO calculated Epsilon=0.02 Percent Variance Reduction = 87.30 % Total Fit = 14.71 Major Double Couple strike dip rake Nodal Plane 1: 261 70 -11 Nodal Plane 2: 355 80 -159 DEVIATORIC MOMENT TENSOR Moment Tensor Elements: Spherical Coordinates Mrr= -0.54 Mtt= -0.95 Mff= 1.48 Mrt= 1.09 Mrf= -1.73 Mtf= 4.80 EXP=23 Moment Tensor Elements: Cartesian Coordinates -0.95 -4.80 1.09 -4.80 1.48 1.73 1.09 1.73 -0.54 Eigenvalues: T-axis eigenvalue= 5.31 N-axis eigenvalue= 0.13 P-axis eigenvalue= -5.45 Eigenvalues and eigenvectors of the Major Double Couple: T-axis ev= 5.31 trend=127 plunge=7 N-axis ev= 0.00 trend=19 plunge=67 P-axis ev=-5.31 trend=219 plunge=22 Maximum Azmuithal Gap=131 Distance to Nearest Station= 78.1 (km) Number of Stations (D=Displacement/V=Velocity) Used=12 (defining only) RYN.NN.D MLAC.CI.D OMMB.NN.D KVN.NN.D TIN.CI.D GRA.CI.D WAK.NN.D YER.NN.D CWC.CI.D PNT.NN.D TPNV.US.D VCN.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 78.1 327 146 0.020 0.080 RYN.NN.wus.glib MLAC.CI (D) Y 85.2 238 57 0.020 0.080 MLAC.CI.wus.glib OMMB.NN (D) Y 98.4 241 60 0.020 0.080 OMMB.NN.wus.glib KVN.NN (D) Y 111.9 357 177 0.020 0.080 KVN.NN.wus.glib TIN.CI (D) Y 112.0 189 9 0.020 0.080 TIN.CI.wus.glib GRA.CI (D) Y 129.6 153 334 0.020 0.080 GRA.CI.wus.glib WAK.NN (D) Y 133.5 293 112 0.020 0.080 WAK.NN.wus.glib YER.NN (D) Y 149.1 315 134 0.020 0.080 YER.NN.wus.glib CWC.CI (D) Y 178.4 182 2 0.020 0.080 CWC.CI.wus.glib PNT.NN (D) Y 179.6 311 130 0.020 0.080 PNT.NN.wus.glib TPNV.US (D) Y 198.0 127 308 0.020 0.080 TPNV.US.wus.glib VCN.NN (D) Y 198.4 315 134 0.020 0.080 VCN.NN.wus.glib (V)-velocity (D)-Displacement Author: www-data Date: 2013/02/13 00:33:22 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:
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 90 75 20 4.78 0.4078 WVFGRD96 1.0 90 75 15 4.80 0.4334 WVFGRD96 2.0 90 75 20 4.88 0.5184 WVFGRD96 3.0 265 90 5 4.90 0.5593 WVFGRD96 4.0 265 70 0 4.94 0.5924 WVFGRD96 5.0 265 70 0 4.96 0.6210 WVFGRD96 6.0 265 70 0 4.99 0.6475 WVFGRD96 7.0 265 70 -5 5.01 0.6730 WVFGRD96 8.0 265 65 -5 5.04 0.6981 WVFGRD96 9.0 265 70 -5 5.05 0.7166 WVFGRD96 10.0 265 70 -10 5.07 0.7315 WVFGRD96 11.0 265 70 -10 5.08 0.7415 WVFGRD96 12.0 265 70 -5 5.09 0.7468 WVFGRD96 13.0 265 75 -5 5.10 0.7503 WVFGRD96 14.0 265 75 -5 5.11 0.7507 WVFGRD96 15.0 265 75 -5 5.12 0.7482 WVFGRD96 16.0 265 75 -5 5.13 0.7434 WVFGRD96 17.0 265 75 -5 5.14 0.7368 WVFGRD96 18.0 265 75 -5 5.15 0.7291 WVFGRD96 19.0 265 75 -5 5.15 0.7204 WVFGRD96 20.0 265 75 -5 5.16 0.7106 WVFGRD96 21.0 90 80 10 5.17 0.6935 WVFGRD96 22.0 90 80 10 5.17 0.6843 WVFGRD96 23.0 90 80 10 5.18 0.6736 WVFGRD96 24.0 90 80 10 5.19 0.6634 WVFGRD96 25.0 90 80 10 5.19 0.6515 WVFGRD96 26.0 90 80 10 5.20 0.6401 WVFGRD96 27.0 90 80 10 5.21 0.6268 WVFGRD96 28.0 90 80 10 5.21 0.6126 WVFGRD96 29.0 90 80 10 5.22 0.5992
The best solution is
WVFGRD96 14.0 265 75 -5 5.11 0.7507
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
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