USGS/SLU Moment Tensor Solution ENS 2015/07/27 01:05:33:0 41.88 -119.62 9.1 4.6 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.KRMB NC.MDPB NN.KVN NN.LHV NN.PAH NN.PNT NN.REDF NN.RUB NN.RYN NN.VCN NN.WAK NN.YER TA.R11A UO.BUCK UO.PINE US.BMO US.ELK US.HAWA US.HLID US.WVOR UW.BLOW UW.BRAN UW.CCRK UW.DDRF UW.IRON UW.IZEE UW.PHIN UW.TREE UW.TUCA UW.UMAT Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.10 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 1.04e+23 dyne-cm Mw = 4.61 Z = 9 km Plane Strike Dip Rake NP1 20 70 -75 NP2 162 25 -125 Principal Axes: Axis Value Plunge Azimuth T 1.04e+23 24 98 N 0.00e+00 14 195 P -1.04e+23 62 313 Moment Tensor: (dyne-cm) Component Value Mxx -8.66e+21 Mxy -1.37e+21 Mxz -3.48e+22 Myy 7.29e+22 Myz 6.88e+22 Mzz -6.43e+22 -------------- ##-----------------### ###-------------------###### ##---------------------####### ###----------------------######### ###-----------------------########## ####----------------------############ ####--------- -----------############# ####--------- P -----------############# #####--------- ----------############### #####----------------------############### #####---------------------######### #### #####--------------------########## T #### #####-------------------########## ### ######-----------------################# #####----------------################# #####--------------################# ######-----------################# ######-------################# #######----################# ######-############### --------###### Global CMT Convention Moment Tensor: R T P -6.43e+22 -3.48e+22 -6.88e+22 -3.48e+22 -8.66e+21 1.37e+21 -6.88e+22 1.37e+21 7.29e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20150727010533/index.html |
STK = 20 DIP = 70 RAKE = -75 MW = 4.61 HS = 9.0
The NDK file is 20150727010533.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2015/07/27 01:05:33:0 41.88 -119.62 9.1 4.6 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.KRMB NC.MDPB NN.KVN NN.LHV NN.PAH NN.PNT NN.REDF NN.RUB NN.RYN NN.VCN NN.WAK NN.YER TA.R11A UO.BUCK UO.PINE US.BMO US.ELK US.HAWA US.HLID US.WVOR UW.BLOW UW.BRAN UW.CCRK UW.DDRF UW.IRON UW.IZEE UW.PHIN UW.TREE UW.TUCA UW.UMAT Filtering commands used: cut o DIST/3.3 -30 o DIST/3.3 +70 rtr taper w 0.1 hp c 0.02 n 3 lp c 0.10 n 3 br c 0.12 0.25 n 4 p 2 Best Fitting Double Couple Mo = 1.04e+23 dyne-cm Mw = 4.61 Z = 9 km Plane Strike Dip Rake NP1 20 70 -75 NP2 162 25 -125 Principal Axes: Axis Value Plunge Azimuth T 1.04e+23 24 98 N 0.00e+00 14 195 P -1.04e+23 62 313 Moment Tensor: (dyne-cm) Component Value Mxx -8.66e+21 Mxy -1.37e+21 Mxz -3.48e+22 Myy 7.29e+22 Myz 6.88e+22 Mzz -6.43e+22 -------------- ##-----------------### ###-------------------###### ##---------------------####### ###----------------------######### ###-----------------------########## ####----------------------############ ####--------- -----------############# ####--------- P -----------############# #####--------- ----------############### #####----------------------############### #####---------------------######### #### #####--------------------########## T #### #####-------------------########## ### ######-----------------################# #####----------------################# #####--------------################# ######-----------################# ######-------################# #######----################# ######-############### --------###### Global CMT Convention Moment Tensor: R T P -6.43e+22 -3.48e+22 -6.88e+22 -3.48e+22 -8.66e+21 1.37e+21 -6.88e+22 1.37e+21 7.29e+22 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20150727010533/index.html |
TMTS Moment 9.310e+15 N-m Magnitude 4.58 Depth 3.5 km Percent DC 50% Half Duration – Catalog NC (nc72495151) Data Source NC2 Contributor NC2 Nodal Planes Plane Strike Dip Rake NP1 19 78 -77 NP2 151 18 -137 Principal Axes Axis Value Plunge Azimuth T 10.333 32 98 N -2.599 13 196 P -7.734 55 306 |
(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 0.02 n 3 lp c 0.10 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 25 45 -85 4.28 0.4090 WVFGRD96 2.0 15 45 -95 4.44 0.5980 WVFGRD96 3.0 35 85 -55 4.45 0.5384 WVFGRD96 4.0 35 85 -65 4.53 0.6406 WVFGRD96 5.0 30 80 -70 4.55 0.7230 WVFGRD96 6.0 25 75 -75 4.55 0.7689 WVFGRD96 7.0 20 70 -75 4.55 0.7935 WVFGRD96 8.0 20 70 -75 4.61 0.8154 WVFGRD96 9.0 20 70 -75 4.61 0.8227 WVFGRD96 10.0 25 70 -70 4.60 0.8196 WVFGRD96 11.0 25 70 -65 4.59 0.8137 WVFGRD96 12.0 25 70 -65 4.59 0.8062 WVFGRD96 13.0 25 70 -60 4.60 0.7979 WVFGRD96 14.0 25 75 -55 4.60 0.7898 WVFGRD96 15.0 30 80 -50 4.61 0.7805 WVFGRD96 16.0 30 80 -50 4.61 0.7713 WVFGRD96 17.0 30 80 -50 4.62 0.7606 WVFGRD96 18.0 30 80 -50 4.63 0.7487 WVFGRD96 19.0 30 80 -45 4.64 0.7368 WVFGRD96 20.0 30 80 -45 4.65 0.7239 WVFGRD96 21.0 30 80 -45 4.67 0.7110 WVFGRD96 22.0 30 85 -45 4.68 0.6970 WVFGRD96 23.0 30 85 -45 4.69 0.6830 WVFGRD96 24.0 30 85 -45 4.70 0.6686 WVFGRD96 25.0 30 85 -50 4.70 0.6543 WVFGRD96 26.0 30 85 -50 4.71 0.6390 WVFGRD96 27.0 30 85 -50 4.72 0.6229 WVFGRD96 28.0 30 85 -50 4.73 0.6059 WVFGRD96 29.0 30 85 -50 4.73 0.5893
The best solution is
WVFGRD96 9.0 20 70 -75 4.61 0.8227
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 0.02 n 3 lp c 0.10 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: