Location

Location ANSS

2021/08/13 11:57:35 35.877 -84.898 0.0 3.0 Tennessee

Focal Mechanism

 USGS/SLU Moment Tensor Solution
 ENS  2021/08/13 11:57:35:0  35.88  -84.90   0.0 3.0 Tennessee
 
 Stations used:
   CO.CASEE CO.HODGE CO.PAULI ET.CPCT IM.TKL IU.WCI IU.WVT 
   N4.R49A N4.R50A N4.S51A N4.T47A N4.T50A N4.U49A N4.V48A 
   N4.V53A N4.V55A N4.W50A N4.W52A N4.X48A N4.X51A N4.Y52A 
   NM.BLO NM.USIN US.GOGA US.LRAL US.TZTN 
 
 Filtering commands used:
   cut o DIST/3.3 -20 o DIST/3.3 +50
   rtr
   taper w 0.1
   hp c 0.03 n 3 
   lp c 0.10 n 3 
 
 Best Fitting Double Couple
  Mo = 8.04e+21 dyne-cm
  Mw = 3.87 
  Z  = 4 km
  Plane   Strike  Dip  Rake
   NP1      245    80    93
   NP2       50    10    75
  Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   8.04e+21     55     158
    N   0.00e+00      3      65
    P  -8.04e+21     35     333

 Moment Tensor: (dyne-cm)
    Component   Value
       Mxx    -1.91e+21
       Mxy     1.24e+21
       Mxz    -6.90e+21
       Myy    -7.41e+20
       Myz     3.12e+21
       Mzz     2.65e+21
                                                     
                                                     
                                                     
                                                     
                     --------------                  
                 ----------------------              
              ----------------------------           
             -------   --------------------          
           --------- P ----------------------        
          ----------   -----------------------       
         -----------------------------------##-      
        ------------------------------#########-     
        ------------------------###############-     
       ---------------------####################-    
       -----------------########################-    
       --------------##########################--    
       ----------##############################--    
        ------#################################-     
        ----##################   #############--     
         -#################### T ############--      
          ####################   ###########--       
           ################################--        
             ############################--          
              -#######################----           
                 -#################----              
                     --------------                  
                                                     
                                                     
                                                     
 Global CMT Convention Moment Tensor:
      R          T          P
  2.65e+21  -6.90e+21  -3.12e+21 
 -6.90e+21  -1.91e+21  -1.24e+21 
 -3.12e+21  -1.24e+21  -7.41e+20 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20210813115735/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 = 50
      DIP = 10
     RAKE = 75
       MW = 3.87
       HS = 4.0

The NDK file is 20210813115735.ndk The waveform inversion is preferred.

Sections

Moment tensor comparison
Local magnitudes
Spatial context
Double couple grid search (wvfgrd96)
Deviatoric moment tensor linear inversion (wvfmtd96)
Full moment tensor linear inversion (wvfmt96)
Grid search for full moment tensor (wvfmtgrd96)
Grid search for double couple (wvfmtgrd96 -DC)
Grid search for deviatoric moment tensor (wvfmtgrd96 -DEV)

Moment Tensor Comparison

The following compares this source inversion to others
SLU
MTGRDDC
MTGRDDEV
MTGRD
WVFMTD
WVFMT
 USGS/SLU Moment Tensor Solution
 ENS  2021/08/13 11:57:35:0  35.88  -84.90   0.0 3.0 Tennessee
 
 Stations used:
   CO.CASEE CO.HODGE CO.PAULI ET.CPCT IM.TKL IU.WCI IU.WVT 
   N4.R49A N4.R50A N4.S51A N4.T47A N4.T50A N4.U49A N4.V48A 
   N4.V53A N4.V55A N4.W50A N4.W52A N4.X48A N4.X51A N4.Y52A 
   NM.BLO NM.USIN US.GOGA US.LRAL US.TZTN 
 
 Filtering commands used:
   cut o DIST/3.3 -20 o DIST/3.3 +50
   rtr
   taper w 0.1
   hp c 0.03 n 3 
   lp c 0.10 n 3 
 
 Best Fitting Double Couple
  Mo = 8.04e+21 dyne-cm
  Mw = 3.87 
  Z  = 4 km
  Plane   Strike  Dip  Rake
   NP1      245    80    93
   NP2       50    10    75
  Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   8.04e+21     55     158
    N   0.00e+00      3      65
    P  -8.04e+21     35     333

 Moment Tensor: (dyne-cm)
    Component   Value
       Mxx    -1.91e+21
       Mxy     1.24e+21
       Mxz    -6.90e+21
       Myy    -7.41e+20
       Myz     3.12e+21
       Mzz     2.65e+21
                                                     
                                                     
                                                     
                                                     
                     --------------                  
                 ----------------------              
              ----------------------------           
             -------   --------------------          
           --------- P ----------------------        
          ----------   -----------------------       
         -----------------------------------##-      
        ------------------------------#########-     
        ------------------------###############-     
       ---------------------####################-    
       -----------------########################-    
       --------------##########################--    
       ----------##############################--    
        ------#################################-     
        ----##################   #############--     
         -#################### T ############--      
          ####################   ###########--       
           ################################--        
             ############################--          
              -#######################----           
                 -#################----              
                     --------------                  
                                                     
                                                     
                                                     
 Global CMT Convention Moment Tensor:
      R          T          P
  2.65e+21  -6.90e+21  -3.12e+21 
 -6.90e+21  -1.91e+21  -1.24e+21 
 -3.12e+21  -1.24e+21  -7.41e+20 


Details of the solution is found at

http://www.eas.slu.edu/eqc/eqc_mt/MECH.NA/20210813115735/index.html
	
 Moment (dyne-cm)   8.03E+21   dyne-cm
 Magnitude (Mw)    3.87
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   8.03E+21     55.    158.
    N  -1.64E+18      3.     65.
    P  -8.03E+21     35.    333.
 Moment Tensor: (dyne-cm) Aki-Richards
    Component   Value
       Mxx   -1.91E+21
       Mxy    1.24E+21
       Mxz   -6.90E+21
       Myy   -7.40E+20
       Myz    3.12E+21
       Mzz    2.65E+21
 Global CMT Convention Moment Tensor: (dyne-cm)
         R         T         F
  R  2.65E+21 -6.90E+21 -3.12E+21
  T -6.90E+21 -1.91E+21 -1.24E+21
  F -3.12E+21 -1.24E+21 -7.40E+20
 Moment (dyne-cm)   8.03E+21   dyne-cm
 Magnitude (Mw)    3.87
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   8.03E+21     55.    158.
    N  -1.64E+18      3.     65.
    P  -8.03E+21     35.    333.
 Moment Tensor: (dyne-cm) Aki-Richards               Lune parameters
    Component   Value
       Mxx   -1.91E+21                                beta:   90.00
       Mxy    1.24E+21                                gamma:  -0.01
       Mxy    1.24E+21
       Mxz   -6.90E+21
       Myy   -7.40E+20
       Myz    3.12E+21
       Mzz    2.65E+21
 
 
 
                    --------------                         :
                ----------------------                   :---:
             ----------------------------              ::. ..::
            -------   --------------------            :--------:
          --------- P ----------------------         :: .  . .  :
         ----------   -----------------------        :  .  .  .  :
        -----------------------------------##-      :------------::
       ------------------------------#########-    ::  .   .  .   :
       -------------------------##############-    :   .   .   .  :
      ---------------------####################-   :---------------:
      -----------------########################-   :   .   .   .   :
      --------------##########################--   :=======#=======:
      ----------##############################--   :   .   .   .   :
       ------#################################-    :   .   .   .   :
       ----##################   #############--    :---------------:
        -#################### T ############--     :   .   .   .  :
         ####################   ###########--      ::  .   .  .   :
          ################################--        :------------::
            ############################--           :  .  .  .  :
             -#######################----            :: .  . .  :
                -#################----                :--------:
                    --------------                     ::. ..::
                                                         :---:
                                                           :
 
 
        
 Moment (dyne-cm)   1.05E+22   dyne-cm
 Magnitude (Mw)    3.95
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   6.79E+21      3.    229.
    N   5.31E+21     10.    139.
    P  -1.21E+22     79.    335.
 Moment Tensor: (dyne-cm) Aki-Richards
    Component   Value
       Mxx    5.47E+21
       Mxy    9.56E+20
       Mxz   -2.87E+21
       Myy    6.05E+21
       Myz    1.27E+21
       Mzz   -1.15E+22
 Global CMT Convention Moment Tensor: (dyne-cm)
         R         T         F
  R -1.15E+22 -2.87E+21 -1.27E+21
  T -2.87E+21  5.47E+21 -9.56E+20
  F -1.27E+21 -9.56E+20  6.05E+21
 Moment (dyne-cm)   1.05E+22   dyne-cm
 Magnitude (Mw)    3.95
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   6.79E+21      3.    229.
    N   5.31E+21     10.    139.
    P  -1.21E+22     79.    335.
 Moment Tensor: (dyne-cm) Aki-Richards               Lune parameters
    Component   Value
       Mxx    5.47E+21                                beta:   89.96
       Mxy    9.56E+20                                gamma:  25.94
       Mxy    9.56E+20
       Mxz   -2.87E+21
       Myy    6.05E+21
       Myz    1.27E+21
       Mzz   -1.15E+22
 
 
 
                    ##############                         :
                ######################                   :---:
             ############################              ::. ..::
            #######-------------##########            :--------:
          ######-------------------#########         :: .  . .  :
         ######---------------------#########        :  .  .  .  :
        ######------------------------########      :------------::
       ######--------------------------########    ::  .   .  .   :
       ######-----------   ------------########    :   .   .   .  :
      ######------------ P ------------#########   :---------------:
      #######-----------   ------------#########   :   .   .   .   :
      #######--------------------------#########   :==============#:
      ########-------------------------#########   :   .   .   .   :
       ########-----------------------#########    :   .   .   .   :
       #########---------------------##########    :---------------:
        ##########-----------------###########     :   .   .   .  :
         ############-----------#############      ::  .   .  .   :
          #   ##############################        :------------::
            T ############################           :  .  .  .  :
              ###########################            :: .  . .  :
                ######################                :--------:
                    ##############                     ::. ..::
                                                         :---:
                                                           :
 
 
        
 Moment (dyne-cm)   1.46E+22   dyne-cm
 Magnitude (Mw)    4.04
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T  -3.73E+21     10.    123.
    N  -5.65E+21      8.    214.
    P  -1.95E+22     77.    344.
 Moment Tensor: (dyne-cm) Aki-Richards
    Component   Value
       Mxx   -5.71E+21
       Mxy   -6.84E+20
       Mxz   -3.01E+21
       Myy   -4.38E+21
       Myz    1.06E+21
       Mzz   -1.88E+22
 Global CMT Convention Moment Tensor: (dyne-cm)
         R         T         F
  R -1.88E+22 -3.01E+21 -1.06E+21
  T -3.01E+21 -5.71E+21  6.84E+20
  F -1.06E+21  6.84E+20 -4.38E+21
 Moment (dyne-cm)   1.46E+22   dyne-cm
 Magnitude (Mw)    4.04
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T  -3.73E+21     10.    123.
    N  -5.65E+21      8.    214.
    P  -1.95E+22     77.    344.
 Moment Tensor: (dyne-cm) Aki-Richards               Lune parameters
    Component   Value
       Mxx   -5.71E+21                                beta:  143.86
       Mxy   -6.84E+20                                gamma:  23.57
       Mxy   -6.84E+20
       Mxz   -3.01E+21
       Myy   -4.38E+21
       Myz    1.06E+21
       Mzz   -1.88E+22
 
 
 
                    --------------                         :
                ----------------------                   :---:
             ----------------------------              ::. ..::
            ------------------------------            :--------:
          ----------------------------------         :: .  . .  :
         ------------------------------------        :  .  .  .  :
        --------------------------------------      :------------::
       ----------------------------------------    ::  .   .  .   :
       ------------------   -------------------    :   .   .   .  :
      ------------------- P --------------------   :---------------:
      -------------------   --------------------   :   .   .   .   :
      ------------------------------------------   :===============:
      ------------------------------------------   :   .   .   .   :
       ----------------------------------------    :   .   .   .   :
       ----------------------------------------    :---------------:
        ---------------------------------   --     :   .   .   .  :
         -------------------------------- T -      ::  .   .  .   :
          -------------------------------           :------------::
            ------------------------------           :  .  .  .  :
             ----------------------------            :: .  . . #:
                ----------------------                :--------:
                    --------------                     ::. ..::
                                                         :---:
                                                           :
 
 
        
 Moment (dyne-cm)   1.30E+22   dyne-cm
 Magnitude (Mw)    4.01
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   1.44E+22     53.     22.
    N  -3.49E+21      1.    113.
    P  -1.09E+22     37.    204.
 Moment Tensor: (dyne-cm) Aki-Richards
    Component   Value
       Mxx   -1.93E+21
       Mxy    5.33E+20
       Mxz    1.12E+22
       Myy   -3.32E+21
       Myz    4.72E+21
       Mzz    5.24E+21
 Global CMT Convention Moment Tensor: (dyne-cm)
         R         T         F
  R  5.24E+21  1.12E+22 -4.72E+21
  T  1.12E+22 -1.93E+21 -5.33E+20
  F -4.72E+21 -5.33E+20 -3.32E+21
 Moment (dyne-cm)   1.30E+22   dyne-cm
 Magnitude (Mw)    4.01
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T   1.44E+22     53.     22.
    N  -3.49E+21      1.    113.
    P  -1.09E+22     37.    204.
 Moment Tensor: (dyne-cm) Aki-Richards               Lune parameters
    Component   Value
       Mxx   -1.93E+21                                beta:   90.00
       Mxy    5.33E+20                                gamma: -13.43
       Mxy    5.33E+20
       Mxz    1.12E+22
       Myy   -3.32E+21
       Myz    4.72E+21
       Mzz    5.24E+21
 
 
 
                    ----########--                         :
                ---##################-                   :---:
             ----######################--              ::. ..::
            ---##########################-            :--------:
          ----#############################-         :: .  . .  :
         -----###############   ############-        :  .  .  .  :
        ------############### T ############--      :------------::
       --------##############   #############--    ::  .   .  .   :
       ---------#############################--    :   .   .   .  :
      -----------############################---   :---------------:
      -------------##########################---   :   .   .   .   :
      ----------------######################----   :===#===========:
      --------------------#################-----   :   .   .   .   :
       ------------------------#########-------    :   .   .   .   :
       ----------------------------------------    :---------------:
        --------------------------------------     :   .   .   .  :
         -----------   ----------------------      ::  .   .  .   :
          ---------- P ---------------------        :------------::
            --------   -------------------           :  .  .  .  :
             ----------------------------            :: .  . .  :
                ----------------------                :--------:
                    --------------                     ::. ..::
                                                         :---:
                                                           :
 
 
        
 Moment (dyne-cm)   1.20E+22   dyne-cm
 Magnitude (Mw)    3.99
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T  -4.43E+21     23.     28.
    N  -5.08E+21      0.    118.
    P  -1.55E+22     67.    208.
 Moment Tensor: (dyne-cm) Aki-Richards
    Component   Value
       Mxx   -5.91E+21
       Mxy   -4.52E+20
       Mxz    3.54E+21
       Myy   -5.33E+21
       Myz    1.92E+21
       Mzz   -1.38E+22
 Global CMT Convention Moment Tensor: (dyne-cm)
         R         T         F
  R -1.38E+22  3.54E+21 -1.92E+21
  T  3.54E+21 -5.91E+21  4.52E+20
  F -1.92E+21  4.52E+20 -5.33E+21
 Moment (dyne-cm)   1.20E+22   dyne-cm
 Magnitude (Mw)    3.99
  
 Principal Axes:
   Axis    Value   Plunge  Azimuth
    T  -4.43E+21     23.     28.
    N  -5.08E+21      0.    118.
    P  -1.55E+22     67.    208.
 Moment Tensor: (dyne-cm) Aki-Richards               Lune parameters
    Component   Value
       Mxx   -5.91E+21                                beta:  148.63
       Mxy   -4.52E+20                                gamma:  27.00
       Mxy   -4.52E+20
       Mxz    3.54E+21
       Myy   -5.33E+21
       Myz    1.92E+21
       Mzz   -1.38E+22
 
 
 
                    --------------                         :
                ----------------------                   :---:
             --------------------   -----              ::. ..::
            --------------------- T ------            :--------:
          -----------------------   --------         :: .  . .  :
         ------------------------------------        :  .  .  .  :
        --------------------------------------      :------------::
       ----------------------------------------    ::  .   .  .   :
       ----------------------------------------    :   .   .   .  :
      ------------------------------------------   :---------------:
      ------------------------------------------   :   .   .   .   :
      ------------------------------------------   :===============:
      -----------------   ----------------------   :   .   .   .   :
       ---------------- P ---------------------    :   .   .   .   :
       ----------------   ---------------------    :---------------:
        --------------------------------------     :   .   .   .  :
         ------------------------------------      ::  .   .  .   :
          ----------------------------------        :------------::
            ------------------------------           :  .  .  .  :
             ----------------------------            :: .  . . #:
                ----------------------                :--------:
                    --------------                     ::. ..::
                                                         :---:
                                                           :
 
 
        

Local 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.

(Return to selection section)

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).
(Return to selection section)

Waveform Inversion using wvfgrd96

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.
Location of broadband stations used for waveform inversion

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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search from 0.5 to 19 km depth are as follow:

           DEPTH  STK   DIP  RAKE   MW    FIT
WVFGRD96    1.0   240    85    90   4.10 0.3487
WVFGRD96    2.0    30     5    55   3.96 0.4096
WVFGRD96    3.0    40    10    65   3.90 0.4386
WVFGRD96    4.0    50    10    75   3.87 0.4468
WVFGRD96    5.0    50    10    75   3.85 0.4414
WVFGRD96    6.0    65    10    85   3.84 0.4292
WVFGRD96    7.0   240    15  -100   3.85 0.4207
WVFGRD96    8.0    50    60   -80   3.89 0.4185
WVFGRD96    9.0    45    55   -80   3.91 0.4152
WVFGRD96   10.0    50    60   -80   3.91 0.3944
WVFGRD96   11.0    40    55   -85   3.92 0.3844
WVFGRD96   12.0    40    55   -85   3.92 0.3702
WVFGRD96   13.0    40    55   -85   3.91 0.3537
WVFGRD96   14.0   215    35   -90   3.91 0.3361
WVFGRD96   15.0   215    35   -90   3.91 0.3181
WVFGRD96   16.0   220    40   -80   3.92 0.3013
WVFGRD96   17.0   225    45   -75   3.92 0.2852
WVFGRD96   18.0   225    45   -75   3.92 0.2719
WVFGRD96   19.0   225    45   -75   3.93 0.2588
WVFGRD96   20.0   225    50   -75   3.94 0.2412
WVFGRD96   21.0   225    50   -75   3.95 0.2312
WVFGRD96   22.0    35    65   -90   3.95 0.2230
WVFGRD96   23.0   215    30   -85   3.96 0.2168
WVFGRD96   24.0    35    60   -90   3.96 0.2101
WVFGRD96   25.0    35    60   -90   3.97 0.2029
WVFGRD96   26.0   215    30   -85   3.97 0.1957
WVFGRD96   27.0   215    30   -85   3.98 0.1879
WVFGRD96   28.0   295    20   -85   4.02 0.1879
WVFGRD96   29.0   300    20   -75   4.03 0.1885

The best solution is

WVFGRD96    4.0    50    10    75   3.87 0.4468

The mechanism correspond to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.
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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)


Deviatoric Moment Tensor Inversion using wvfmtd96

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.
Location of broadband stations used for waveform inversion

The program wvfmtd96 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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search over depth are as follow:

MT Program  H(km) Mxx(dyne-cm)   Myy        Mxy        Mxz        Myz        Mzz       Mw      Fit
WVFMT96    0.5  113.   77.   89.   3.99     0.428 0.171E-06     0.442     0.655 0.125E-06  58.8 -0.2980918E+22 -0.3882107E+22  0.2982569E+21  0.9632894E+22  0.3907966E+22  0.6863025E+22
WVFMT96    1.0  110.   76.   89.   4.00     0.408 0.174E-06     0.422     0.639 0.127E-06  65.1 -0.3402779E+22 -0.4586292E+22  0.3235546E+21  0.9962901E+22  0.3507894E+22  0.7989070E+22
WVFMT96    2.0  102.   73.   93.   3.96     0.322 0.187E-06     0.330     0.568 0.138E-06  77.1 -0.3552998E+22 -0.4683210E+22  0.6233890E+21  0.8181899E+22  0.2190273E+22  0.8236208E+22
WVFMT96    3.0  111.   75.   94.   3.94     0.310 0.189E-06     0.325     0.557 0.135E-06  66.6 -0.3174843E+22 -0.3323615E+22  0.7088393E+21  0.7573593E+22  0.3413733E+22  0.6498457E+22
WVFMT96    4.0  304.   73.  -96.   3.86     0.235 0.199E-06     0.247     0.485 0.146E-06  53.0  0.2183667E+22  0.3068718E+22  0.6005593E+21  0.5455640E+22  0.2938517E+22 -0.5252385E+22
WVFMT96    5.0  325.   59. -100.   3.93     0.308 0.189E-06     0.324     0.555 0.138E-06  84.4  0.4252532E+22  0.5838505E+22  0.1670062E+21  0.3947046E+22  0.2470017E+22 -0.1009104E+23
WVFMT96    6.0  349.   54. -102.   3.95     0.377 0.179E-06     0.397     0.614 0.130E-06  88.4  0.4771483E+22  0.6402436E+22 -0.3566412E+21  0.3037754E+22  0.2408470E+22 -0.1117392E+23
WVFMT96    7.0  357.   52. -103.   3.94     0.411 0.174E-06     0.431     0.641 0.127E-06  87.2  0.4663736E+22  0.6338698E+22 -0.5404676E+21  0.2811287E+22  0.2261645E+22 -0.1100243E+23
WVFMT96    8.0  360.   51. -105.   3.93     0.420 0.173E-06     0.438     0.648 0.126E-06  86.5  0.4454107E+22  0.6175325E+22 -0.6258397E+21  0.2850330E+22  0.2102078E+22 -0.1062943E+23
WVFMT96    9.0    4.   51. -106.   3.93     0.419 0.173E-06     0.436     0.648 0.126E-06  84.1  0.4292159E+22  0.6129663E+22 -0.8083560E+21  0.2836526E+22  0.2094064E+22 -0.1042182E+23
WVFMT96   10.0   11.   49. -107.   3.95     0.408 0.174E-06     0.424     0.639 0.127E-06  86.4  0.4952394E+22  0.6474266E+22 -0.9658130E+21  0.3095382E+22  0.2093309E+22 -0.1142666E+23

The best solution is

WVFMT96    4.0  304.   73.  -96.   3.86     0.235 0.199E-06     0.247     0.485 0.146E-06  53.0  0.2183667E+22  0.3068718E+22  0.6005593E+21  0.5455640E+22  0.2938517E+22 -0.5252385E+22

The complete moment tensor decomposition using the program mtdinfo is given in the text file MTDinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.

The P-wave first motion mechanism corresponding to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.

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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)


Full Moment Tensor Inversion using wvfmt96

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.
Location of broadband stations used for waveform inversion

The program wvfmt96 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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search over depth are as follow:

MT Program  H(km) Mxx(dyne-cm)   Myy        Mxy        Mxz        Myz        Mzz       Mw      Fit
WVFMT96    0.5  112.   87.   89.   3.99     0.431 0.171E-06     0.446     0.657 0.124E-06  24.8 -0.5651100E+22 -0.6550450E+22  0.2939653E+21  0.9604919E+22  0.3880261E+22 -0.3554232E+22
WVFMT96    1.0  292.   83.  -89.   4.07     0.431 0.171E-06     0.448     0.657 0.124E-06  14.3 -0.8573793E+22 -0.9611517E+22  0.2913409E+21  0.8952540E+22  0.3732950E+22 -0.1302787E+23
WVFMT96    2.0  289.   73.  -90.   4.08     0.440 0.170E-06     0.456     0.663 0.123E-06  48.6 -0.9120139E+22 -0.9971795E+22  0.2926164E+21  0.5531422E+22  0.1967272E+22 -0.1697616E+23
WVFMT96    3.0  294.   68.  -89.   4.08     0.448 0.168E-06     0.466     0.669 0.122E-06  69.3 -0.8539645E+22 -0.9043900E+22  0.1315286E+21  0.4438938E+22  0.2077270E+22 -0.1829677E+23
WVFMT96    4.0  292.   65.  -87.   4.06     0.455 0.167E-06     0.474     0.674 0.121E-06  86.6 -0.7620610E+22 -0.7658268E+22 -0.2660424E+21  0.3811035E+22  0.2008392E+22 -0.1834035E+23
WVFMT96    5.0  348.   57. -110.   4.04     0.458 0.167E-06     0.476     0.677 0.122E-06  96.8 -0.6718315E+22 -0.5774986E+22 -0.6828674E+21  0.3565491E+22  0.2263350E+22 -0.1732724E+23
WVFMT96    6.0    1.   53. -112.   4.01     0.457 0.167E-06     0.476     0.676 0.122E-06  91.9 -0.5355998E+22 -0.4188419E+22 -0.8072977E+21  0.3346521E+22  0.2219578E+22 -0.1643328E+23
WVFMT96    7.0    6.   51. -112.   3.99     0.452 0.168E-06     0.470     0.673 0.122E-06  87.9 -0.3942296E+22 -0.2647008E+22 -0.9362626E+21  0.3173859E+22  0.2187076E+22 -0.1542404E+23
WVFMT96    8.0    8.   50. -111.   3.96     0.444 0.169E-06     0.461     0.666 0.123E-06  85.6 -0.2539388E+22 -0.1174210E+22 -0.9884313E+21  0.3030280E+22  0.2122756E+22 -0.1445834E+23
WVFMT96    9.0   11.   49. -110.   3.94     0.433 0.171E-06     0.449     0.658 0.125E-06  83.5 -0.1255312E+22  0.1879463E+21 -0.1036037E+22  0.2914626E+22  0.1901911E+22 -0.1369065E+23
WVFMT96   10.0   11.   49. -109.   3.97     0.419 0.173E-06     0.434     0.647 0.126E-06  85.9 -0.7330636E+21  0.6982674E+21 -0.1040060E+22  0.3208249E+22  0.2156021E+22 -0.1492567E+23

The best solution is

WVFMT96   10.0   11.   49. -109.   3.97     0.419 0.173E-06     0.434     0.647 0.126E-06  85.9 -0.7330636E+21  0.6982674E+21 -0.1040060E+22  0.3208249E+22  0.2156021E+22 -0.1492567E+23

The complete moment tensor decomposition using the program mtinfo is given in the text file MTinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.

The P-wave first motion mechanism corresponding to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.

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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)


Grid Search Full Moment Tensor Inversion using wvfmtgrd96

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.
Location of broadband stations used for waveform inversion

The program wvfmtgrd96 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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search over depth are as follow:

MT Program  H(km) Mxx(dyne-cm)   Myy        Mxy        Mxz        Myz        Mzz       Mw      Fit
WVFMTGRD96    1.0 -0.107E+23 -0.115E+23 -0.541E+21 -0.105E+22  0.129E+22 -0.192E+23  4.0977  0.4731
WVFMTGRD96    2.0 -0.100E+23 -0.105E+23 -0.821E+21 -0.240E+22  0.371E+22 -0.199E+23  4.1038  0.4895
WVFMTGRD96    3.0 -0.743E+22 -0.832E+22 -0.771E+21 -0.448E+22  0.258E+22 -0.193E+23  4.0803  0.5066
WVFMTGRD96    4.0 -0.716E+22 -0.759E+22 -0.797E+21 -0.368E+22  0.944E+21 -0.195E+23  4.0713  0.5162
WVFMTGRD96    5.0 -0.571E+22 -0.438E+22 -0.684E+21 -0.301E+22  0.106E+22 -0.188E+23  4.0431  0.5194
WVFMTGRD96    6.0 -0.352E+22 -0.259E+22 -0.698E+21 -0.282E+22  0.140E+22 -0.172E+23  4.0081  0.5174
WVFMTGRD96    7.0 -0.194E+22 -0.101E+22 -0.703E+21 -0.284E+22  0.141E+22 -0.157E+23  3.9778  0.5098
WVFMTGRD96    8.0 -0.799E+21  0.728E+21 -0.875E+21 -0.291E+22  0.207E+21 -0.148E+23  3.9588  0.4987
WVFMTGRD96    9.0  0.492E+21  0.204E+22 -0.890E+21 -0.296E+22  0.210E+21 -0.137E+23  3.9420  0.4837
WVFMTGRD96   10.0  0.541E+21  0.225E+22 -0.978E+21 -0.325E+22  0.231E+21 -0.151E+23  3.9695  0.4634

The best solution is

WVFMTGRD96    5.0 -0.571E+22 -0.438E+22 -0.684E+21 -0.301E+22  0.106E+22 -0.188E+23  4.0431  0.5194

The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.

The P-wave first motion mechanism corresponding to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.

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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)


Grid Search Double Couple Inversion using wvfmtgrd96 -DC

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.
Location of broadband stations used for waveform inversion

The program wvfmtgrd96 -DC 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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search over depth are as follow:

MT Program  H(km) Mxx(dyne-cm)   Myy        Mxy        Mxz        Myz        Mzz       Mw      Fit
WVFMTGRD96    1.0 -0.235E+22 -0.783E+21  0.136E+22 -0.154E+23  0.888E+22  0.313E+22  4.1039  0.3487
WVFMTGRD96    2.0 -0.869E+21 -0.698E+21  0.954E+21 -0.989E+22  0.455E+22  0.157E+22  3.9613  0.4096
WVFMTGRD96    3.0 -0.179E+22 -0.981E+21  0.148E+22 -0.775E+22  0.344E+22  0.277E+22  3.9011  0.4386
WVFMTGRD96    4.0 -0.191E+22 -0.740E+21  0.124E+22 -0.690E+22  0.312E+22  0.265E+22  3.8697  0.4468
WVFMTGRD96    5.0 -0.178E+22 -0.689E+21  0.116E+22 -0.642E+22  0.290E+22  0.247E+22  3.8489  0.4414
WVFMTGRD96    6.0 -0.209E+22 -0.354E+21  0.868E+21 -0.635E+22  0.228E+22  0.245E+22  3.8376  0.4292
WVFMTGRD96    7.0  0.326E+22  0.432E+21 -0.119E+22 -0.601E+22  0.219E+22 -0.369E+22  3.8457  0.4205
WVFMTGRD96    8.0  0.304E+22  0.432E+22 -0.385E+22 -0.373E+22  0.216E+22 -0.736E+22  3.8905  0.4185
WVFMTGRD96    9.0  0.292E+22  0.551E+22 -0.421E+22 -0.281E+22  0.153E+22 -0.842E+22  3.9061  0.4152
WVFMTGRD96   10.0  0.327E+22  0.465E+22 -0.414E+22 -0.402E+22  0.232E+22 -0.792E+22  3.9121  0.3944

The best solution is

WVFMTGRD96    4.0 -0.191E+22 -0.740E+21  0.124E+22 -0.690E+22  0.312E+22  0.265E+22  3.8697  0.4468

The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDDCinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.

The P-wave first motion mechanism corresponding to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.

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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)


Grid Search Deviatoric Moment Tensor Inversion using wvfmtgrd96 -DEV

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.
Location of broadband stations used for waveform inversion

The program wvfmtgrd96 -DEV 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 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 n 3 
The results of this grid search over depth are as follow:

MT Program  H(km) Mxx(dyne-cm)   Myy        Mxy        Mxz        Myz        Mzz       Mw      Fit
WVFMTGRD96    1.0 -0.385E+22 -0.468E+22 -0.591E+21  0.429E+22 -0.674E+22  0.854E+22  3.9587  0.4381
WVFMTGRD96    2.0 -0.218E+22 -0.362E+22 -0.859E+21 -0.942E+22  0.439E+22  0.579E+22  3.9763  0.4356
WVFMTGRD96    3.0 -0.177E+22 -0.304E+22 -0.701E+21 -0.809E+22  0.307E+22  0.481E+22  3.9230  0.4542
WVFMTGRD96    4.0 -0.343E+22 -0.456E+22 -0.362E+21 -0.611E+22  0.346E+22  0.799E+22  3.9299  0.4639
WVFMTGRD96    5.0 -0.465E+22 -0.485E+22 -0.109E+22 -0.429E+22  0.391E+22  0.950E+22  3.9372  0.4665
WVFMTGRD96    6.0  0.457E+22  0.621E+22  0.710E+21 -0.409E+22  0.199E+22 -0.108E+23  3.9458  0.4540
WVFMTGRD96    7.0  0.488E+22  0.686E+22  0.116E+21 -0.307E+22  0.118E+22 -0.117E+23  3.9537  0.4775
WVFMTGRD96    8.0  0.547E+22  0.605E+22  0.956E+21 -0.287E+22  0.127E+22 -0.115E+23  3.9476  0.4829
WVFMTGRD96    9.0  0.526E+22  0.624E+22 -0.109E+22 -0.254E+22  0.288E+21 -0.115E+23  3.9435  0.4766
WVFMTGRD96   10.0  0.548E+22  0.666E+22 -0.765E+21 -0.363E+22 -0.148E+21 -0.121E+23  3.9652  0.4577

The best solution is

WVFMTGRD96    8.0  0.547E+22  0.605E+22  0.956E+21 -0.287E+22  0.127E+22 -0.115E+23  3.9476  0.4829

The complete moment tensor decomposition using the program mtinfo is given in the text file MTGRDDEVinfo.txt. (Jost, M. L., and R. B. Herrmann (1989). A student's guide to and review of moment tensors, Seism. Res. Letters 60, 37-57. SRL_60_2_37-57.pdf.

The P-wave first motion mechanism corresponding to the best fit is
Figure 1. Waveform inversion focal mechanism

The best fit as a function of depth is given in the following figure:

Figure 2. Depth sensitivity for waveform mechanism

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 -20 o DIST/3.3 +50
rtr
taper w 0.1
hp c 0.03 n 3 
lp c 0.10 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.

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:

Assuming only a mislocation, the time shifts are fit to a functional form:

 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.

(Return to selection section)

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 Bureau of Mines, UC Berkely, Caltech, UC San Diego, Saint Louis University, University of Memphis, Lamont Doherty Earth Observatory, the Oklahoma Geological Survey, TexNet, the Iris stations, the Transportable Array of EarthScope and other networks.

Velocity Model

The CUS model used for the waveform synthetic seismograms and for the surface wave eigenfunctions and dispersion is as follows:

MODEL.01
CUS Model with Q from simple gamma values
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
  1.0000  5.0000  2.8900  2.5000 0.172E-02 0.387E-02 0.00  0.00  1.00  1.00 
  9.0000  6.1000  3.5200  2.7300 0.160E-02 0.363E-02 0.00  0.00  1.00  1.00 
 10.0000  6.4000  3.7000  2.8200 0.149E-02 0.336E-02 0.00  0.00  1.00  1.00 
 20.0000  6.7000  3.8700  2.9020 0.000E-04 0.000E-04 0.00  0.00  1.00  1.00 
  0.0000  8.1500  4.7000  3.3640 0.194E-02 0.431E-02 0.00  0.00  1.00  1.00 
Last Changed Sat 18 Sep 2021 05:33:47 PM CDT