2015/01/09 06:44:16 35.829 -97.431 5.0 4.0 Oklahoma
USGS Felt map for this earthquake
USGS/SLU Moment Tensor Solution ENS 2015/01/09 06:44:16:0 35.83 -97.43 5.0 4.0 Oklahoma Stations used: GS.KAN10 GS.KAN14 GS.OK025 GS.OK031 N4.R32B N4.T35B N4.Z38B OK.CROK OK.FNO OK.U32A OK.X37A TA.TUL1 US.MIAR US.WMOK 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 Best Fitting Double Couple Mo = 2.48e+21 dyne-cm Mw = 3.53 Z = 4 km Plane Strike Dip Rake NP1 57 62 -139 NP2 305 55 -35 Principal Axes: Axis Value Plunge Azimuth T 2.48e+21 4 179 N 0.00e+00 42 86 P -2.48e+21 48 274 Moment Tensor: (dyne-cm) Component Value Mxx 2.46e+21 Mxy 5.90e+19 Mxz -2.70e+20 Myy -1.13e+21 Myz 1.24e+21 Mzz -1.34e+21 ############## ###################### ############################ ############################## ------------###################### ------------------#################- ----------------------##############-- --------------------------##########---- ----------------------------#######----- --------- -------------------###-------- --------- P ------------------------------ --------- -------------------###-------- -----------------------------######------- --------------------------#########----- -----------------------#############---- -------------------#################-- -------------######################- ################################## ############################## ############################ ########## ######### ###### T ##### Global CMT Convention Moment Tensor: R T P -1.34e+21 -2.70e+20 -1.24e+21 -2.70e+20 2.46e+21 -5.90e+19 -1.24e+21 -5.90e+19 -1.13e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20150109064416/index.html |
STK = 305 DIP = 55 RAKE = -35 MW = 3.53 HS = 4.0
The NDK file is 20150109064416.ndk The waveform inversion is preferred.
The following compares this source inversion to others
USGS/SLU Moment Tensor Solution ENS 2015/01/09 06:44:16:0 35.83 -97.43 5.0 4.0 Oklahoma Stations used: GS.KAN10 GS.KAN14 GS.OK025 GS.OK031 N4.R32B N4.T35B N4.Z38B OK.CROK OK.FNO OK.U32A OK.X37A TA.TUL1 US.MIAR US.WMOK 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 Best Fitting Double Couple Mo = 2.48e+21 dyne-cm Mw = 3.53 Z = 4 km Plane Strike Dip Rake NP1 57 62 -139 NP2 305 55 -35 Principal Axes: Axis Value Plunge Azimuth T 2.48e+21 4 179 N 0.00e+00 42 86 P -2.48e+21 48 274 Moment Tensor: (dyne-cm) Component Value Mxx 2.46e+21 Mxy 5.90e+19 Mxz -2.70e+20 Myy -1.13e+21 Myz 1.24e+21 Mzz -1.34e+21 ############## ###################### ############################ ############################## ------------###################### ------------------#################- ----------------------##############-- --------------------------##########---- ----------------------------#######----- --------- -------------------###-------- --------- P ------------------------------ --------- -------------------###-------- -----------------------------######------- --------------------------#########----- -----------------------#############---- -------------------#################-- -------------######################- ################################## ############################## ############################ ########## ######### ###### T ##### Global CMT Convention Moment Tensor: R T P -1.34e+21 -2.70e+20 -1.24e+21 -2.70e+20 2.46e+21 -5.90e+19 -1.24e+21 -5.90e+19 -1.13e+21 Details of the solution is found at http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20150109064416/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.
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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 3The results of this grid search from 0.5 to 19 km depth are as follow:
DEPTH STK DIP RAKE MW FIT WVFGRD96 1.0 310 65 -15 3.29 0.3811 WVFGRD96 2.0 310 55 -20 3.43 0.4579 WVFGRD96 3.0 305 50 -30 3.50 0.5055 WVFGRD96 4.0 305 55 -35 3.53 0.5219 WVFGRD96 5.0 310 60 -25 3.53 0.5106 WVFGRD96 6.0 310 65 -15 3.54 0.4979 WVFGRD96 7.0 310 65 -15 3.55 0.4865 WVFGRD96 8.0 310 60 -15 3.59 0.4809 WVFGRD96 9.0 315 65 -5 3.60 0.4648 WVFGRD96 10.0 320 80 30 3.63 0.4503 WVFGRD96 11.0 320 80 30 3.64 0.4486 WVFGRD96 12.0 320 75 30 3.65 0.4491 WVFGRD96 13.0 320 75 30 3.67 0.4475 WVFGRD96 14.0 320 75 30 3.68 0.4439 WVFGRD96 15.0 325 70 25 3.69 0.4417 WVFGRD96 16.0 325 70 25 3.70 0.4388 WVFGRD96 17.0 325 70 25 3.71 0.4342 WVFGRD96 18.0 325 65 20 3.71 0.4296 WVFGRD96 19.0 325 65 20 3.72 0.4233 WVFGRD96 20.0 325 65 15 3.73 0.4170 WVFGRD96 21.0 325 65 15 3.74 0.4084 WVFGRD96 22.0 325 65 15 3.75 0.3995 WVFGRD96 23.0 325 60 10 3.74 0.3897 WVFGRD96 24.0 325 60 10 3.75 0.3803 WVFGRD96 25.0 200 65 15 3.76 0.3795 WVFGRD96 26.0 200 65 15 3.77 0.3841 WVFGRD96 27.0 200 65 15 3.78 0.3874 WVFGRD96 28.0 200 65 15 3.78 0.3893 WVFGRD96 29.0 200 65 10 3.80 0.3901
The best solution is
WVFGRD96 4.0 305 55 -35 3.53 0.5219
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
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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: