USGS/SLU Moment Tensor Solution ENS 2016/09/22 06:42:18:0 36.43 96.92 2.5 3.2 Oklahoma Stations used: GS.OK025 GS.OK029 GS.OK030 GS.OK033 GS.OK034 GS.OK038 GS.OK044 GS.OK047 GS.OK049 GS.OK051 N4.T35B OK.CROK OK.U32A Filtering commands used: cut o DIST/3.3 20 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.15 n 3 Best Fitting Double Couple Mo = 2.63e+20 dynecm Mw = 2.88 Z = 3 km Plane Strike Dip Rake NP1 100 90 5 NP2 10 85 180 Principal Axes: Axis Value Plunge Azimuth T 2.63e+20 4 325 N 0.00e+00 85 100 P 2.63e+20 4 235 Moment Tensor: (dynecm) Component Value Mxx 8.96e+19 Mxy 2.46e+20 Mxz 2.26e+19 Myy 8.96e+19 Myz 3.98e+18 Mzz 2.00e+12 ########### ############### T ############## # ############## #################### ##################### ###################### ###################### ###################### ################## ###### #### ############### #################### #################### ################### ################### P ################## ################# ################ ############## ########## Global CMT Convention Moment Tensor: R T P 2.00e+12 2.26e+19 3.98e+18 2.26e+19 8.96e+19 2.46e+20 3.98e+18 2.46e+20 8.96e+19 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20160922064218/index.html 
STK = 100 DIP = 90 RAKE = 5 MW = 2.88 HS = 3.0
The NDK file is 20160922064218.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2016/09/22 06:42:18:0 36.43 96.92 2.5 3.2 Oklahoma Stations used: GS.OK025 GS.OK029 GS.OK030 GS.OK033 GS.OK034 GS.OK038 GS.OK044 GS.OK047 GS.OK049 GS.OK051 N4.T35B OK.CROK OK.U32A Filtering commands used: cut o DIST/3.3 20 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.15 n 3 Best Fitting Double Couple Mo = 2.63e+20 dynecm Mw = 2.88 Z = 3 km Plane Strike Dip Rake NP1 100 90 5 NP2 10 85 180 Principal Axes: Axis Value Plunge Azimuth T 2.63e+20 4 325 N 0.00e+00 85 100 P 2.63e+20 4 235 Moment Tensor: (dynecm) Component Value Mxx 8.96e+19 Mxy 2.46e+20 Mxz 2.26e+19 Myy 8.96e+19 Myz 3.98e+18 Mzz 2.00e+12 ########### ############### T ############## # ############## #################### ##################### ###################### ###################### ###################### ################## ###### #### ############### #################### #################### ################### ################### P ################## ################# ################ ############## ########## Global CMT Convention Moment Tensor: R T P 2.00e+12 2.26e+19 3.98e+18 2.26e+19 8.96e+19 2.46e+20 3.98e+18 2.46e+20 8.96e+19 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20160922064218/index.html 

(a) mLg computed using the IASPEI formula; (b) mLg residuals ; the values used for the trimmed mean are indicated.
(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.

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 20 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.15 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 10 90 15 2.67 0.3890 WVFGRD96 2.0 190 80 10 2.83 0.4547 WVFGRD96 3.0 100 90 5 2.88 0.4627 WVFGRD96 4.0 105 75 20 2.95 0.4584 WVFGRD96 5.0 100 85 5 2.97 0.4470 WVFGRD96 6.0 280 90 5 3.01 0.4292 WVFGRD96 7.0 280 90 5 3.05 0.4043 WVFGRD96 8.0 280 90 10 3.08 0.3738 WVFGRD96 9.0 280 90 10 3.11 0.3500 WVFGRD96 10.0 280 90 15 3.13 0.3308 WVFGRD96 11.0 105 85 20 3.16 0.3116 WVFGRD96 12.0 105 85 20 3.17 0.2926 WVFGRD96 13.0 275 70 10 3.18 0.2793 WVFGRD96 14.0 275 70 15 3.19 0.2679 WVFGRD96 15.0 185 35 5 3.33 0.2579 WVFGRD96 16.0 190 30 5 3.35 0.2544 WVFGRD96 17.0 190 30 5 3.35 0.2502 WVFGRD96 18.0 190 35 0 3.35 0.2452 WVFGRD96 19.0 180 35 25 3.33 0.2435 WVFGRD96 20.0 175 35 25 3.34 0.2463 WVFGRD96 21.0 175 35 25 3.36 0.2536 WVFGRD96 22.0 170 35 30 3.37 0.2604 WVFGRD96 23.0 170 35 30 3.38 0.2698 WVFGRD96 24.0 175 40 30 3.38 0.2769 WVFGRD96 25.0 180 40 25 3.39 0.2863 WVFGRD96 26.0 180 40 30 3.40 0.2935 WVFGRD96 27.0 180 40 30 3.41 0.2995 WVFGRD96 28.0 180 40 30 3.41 0.3030 WVFGRD96 29.0 180 40 30 3.42 0.3050
The best solution is
WVFGRD96 3.0 100 90 5 2.88 0.4627
The mechanism correspond 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 observedpredicted 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 20 o DIST/3.3 +40 rtr taper w 0.1 hp c 0.03 n 3 lp c 0.15 n 3

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 1D 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 0.302E02 0.679E02 0.00 0.00 1.00 1.00 6.1000 5.5445 3.2953 2.6089 0.349E02 0.784E02 0.00 0.00 1.00 1.00 13.0000 6.2708 3.7396 2.7812 0.212E02 0.476E02 0.00 0.00 1.00 1.00 19.0000 6.4075 3.7680 2.8223 0.111E02 0.249E02 0.00 0.00 1.00 1.00 0.0000 7.9000 4.6200 3.2760 0.164E10 0.370E10 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: