Location

Location ANSS

2016/05/08 00:09:31 36.786 -97.624 4.2 3.5 Oklahoma

Focal Mechanism

 USGS/SLU Moment Tensor Solution
 ENS  2016/05/08 00:09:31:0  36.79  -97.62   4.2 3.5 Oklahoma
 
 Stations used:
   GS.KAN01 GS.KAN13 GS.KAN17 GS.OK025 GS.OK033 GS.OK040 
   GS.OK043 N4.T35B OK.CROK OK.FNO OK.U32A TA.TUL1 
 
 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 0.12 n 3 
 
 Best Fitting Double Couple
  Mo = 5.62e+20 dyne-cm
  Mw = 3.10 
  Z  = 2 km
  Plane   Strike  Dip  Rake
   NP1      320    90    -5
   NP2       50    85   -180
  Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   5.62e+20      4       5
    N   0.00e+00     85     140
    P  -5.62e+20      4     275

 Moment Tensor: (dyne-cm)
    Component   Value
       Mxx     5.52e+20
       Mxy     9.73e+19
       Mxz     3.15e+19
       Myy    -5.52e+20
       Myz     3.75e+19
       Mzz     4.28e+12
                                                     
                                                     
                                                     
                                                     
                     ####### T ####                  
                 ###########   ########              
              -###########################           
             ---###########################          
           -------#########################--        
          ---------######################-----       
         ------------##################--------      
        ---------------##############-----------     
        ----------------###########-------------     
         -----------------#######----------------    
       P ------------------####------------------    
         ----------------------------------------    
       --------------------###-------------------    
        ----------------########----------------     
        --------------###########---------------     
         -----------###############------------      
          -------####################---------       
           ---########################-------        
             ###########################---          
              ###########################-           
                 ######################              
                     ##############                  
                                                     
                                                     
                                                     
 Global CMT Convention Moment Tensor:
      R          T          P
  4.28e+12   3.15e+19  -3.75e+19 
  3.15e+19   5.52e+20  -9.73e+19 
 -3.75e+19  -9.73e+19  -5.52e+20 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20160508000931/index.html
        

Preferred Solution

The preferred solution from an analysis of the surface-wave spectral amplitude radiation pattern, waveform inversion and first motion observations is

      STK = 320
      DIP = 90
     RAKE = -5
       MW = 3.10
       HS = 2.0

The NDK file is 20160508000931.ndk The waveform inversion is preferred.

Moment Tensor Comparison

The following compares this source inversion to others
SLU
 USGS/SLU Moment Tensor Solution
 ENS  2016/05/08 00:09:31:0  36.79  -97.62   4.2 3.5 Oklahoma
 
 Stations used:
   GS.KAN01 GS.KAN13 GS.KAN17 GS.OK025 GS.OK033 GS.OK040 
   GS.OK043 N4.T35B OK.CROK OK.FNO OK.U32A TA.TUL1 
 
 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 0.12 n 3 
 
 Best Fitting Double Couple
  Mo = 5.62e+20 dyne-cm
  Mw = 3.10 
  Z  = 2 km
  Plane   Strike  Dip  Rake
   NP1      320    90    -5
   NP2       50    85   -180
  Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   5.62e+20      4       5
    N   0.00e+00     85     140
    P  -5.62e+20      4     275

 Moment Tensor: (dyne-cm)
    Component   Value
       Mxx     5.52e+20
       Mxy     9.73e+19
       Mxz     3.15e+19
       Myy    -5.52e+20
       Myz     3.75e+19
       Mzz     4.28e+12
                                                     
                                                     
                                                     
                                                     
                     ####### T ####                  
                 ###########   ########              
              -###########################           
             ---###########################          
           -------#########################--        
          ---------######################-----       
         ------------##################--------      
        ---------------##############-----------     
        ----------------###########-------------     
         -----------------#######----------------    
       P ------------------####------------------    
         ----------------------------------------    
       --------------------###-------------------    
        ----------------########----------------     
        --------------###########---------------     
         -----------###############------------      
          -------####################---------       
           ---########################-------        
             ###########################---          
              ###########################-           
                 ######################              
                     ##############                  
                                                     
                                                     
                                                     
 Global CMT Convention Moment Tensor:
      R          T          P
  4.28e+12   3.15e+19  -3.75e+19 
  3.15e+19   5.52e+20  -9.73e+19 
 -3.75e+19  -9.73e+19  -5.52e+20 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20160508000931/index.html
	

Magnitudes

mLg Magnitude


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

ML Magnitude


(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.

Context

The next figure presents the focal mechanism for this earthquake (red) in the context of other events (blue) in the SLU Moment Tensor Catalog which are within ± 0.5 degrees of the new event. This comparison is shown in the left panel of the figure. The right panel shows the inferred direction of maximum compressive stress and the type of faulting (green is strike-slip, red is normal, blue is thrust; oblique is shown by a combination of colors).

Discussion

Acknowledgements

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.

Velocity Model

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    

Quality Control

Here we tabulate the reasons for not using certain digital data sets

The following stations did not have a valid response files:

Last Changed Sat May 7 20:11:35 CDT 2016