The 1994 Wyomissing, PA Earthquakes

Work in Collaboration with

Robert Herrmann of Saint Louis University

Chuck Langston of Penn State

Harley Benz of the US Geological Survey

Map with Major Double-Couple Mechanisms

Mainshock inversion results

------------------------------------------------------------------------
Inversion run on: Tue Feb 14 13:29:55 1995
------------------------------------------------------------------------   
 Information from header of first data file: 
 Reference Time: JAN 16 (016), 1994    01:49:56.959
 Origin time (s) relative to reference:   0.
 Event Lat,Lon:  40.300   -76.000
------------------------------------------------------------------------  
 Depth = 3 km
------------------------------------------------------------------------  
 moment tensor:
  0.208E+01      0.334E+01     -0.276E+01
  0.334E+01      0.648E+01      0.101E+01
 -0.276E+01      0.101E+01     -0.856E+01
 m0 =     1.00000E+22
  
 Isotropic Component:   0.
 Subtracted out the isotropic component.
  
 The Deviatoric Moment Tensor:
  0.208E+01      0.334E+01     -0.276E+01
  0.334E+01      0.648E+01      0.101E+01
 -0.276E+01      0.101E+01     -0.856E+01
 
 eigenvalues of the moment tensor
  0.829E+01      0.115E+01     -0.944E+01
 
 and associated eigenvectors (in the columns)
  0.483E+00      0.835E+00     -0.263E+00
  0.875E+00     -0.470E+00      0.116E+00
 -0.267E-01     -0.286E+00     -0.958E+00
  
 Eigenvector 1:
 Az =     241.098 Plunge =     1.53195
 Eigenvector 2:
 Az =     150.640 Plunge =     16.6329
 Eigenvector 3:
 Az =     336.210 Plunge =     73.2926
  
  
 The Total Scalar Moment (Silver&Jordan;,1982) is 
 0.892E+23
 The Total Moment Magnitude (Kanamori(1979)) is 
  4.6
  
 The Deviatoric Scalar Moment (Silver&Jordan;,1982) is 
 0.892E+23
 The Deviatoric Moment Magnitude (Kanamori(1979)) is 
  4.6
  
 double couple eigenvalues= 0.887E+01     -0.887E+01
 (clvd/dc)*100=    24.291
  
 
 moment tensor for the major dislocation
     0.1642       0.7524       0.4533      -0.2649       0.0877
 
 pole vectors p1 and p2
  0.528E+00      0.537E+00      0.658E+00
 -0.156E+00     -0.701E+00      0.696E+00
 
 azimuth and plunge of pole #1;     az1=  45.49     pl1=  41.17
 azimuth and plunge of pole #2;     az2= 257.48     pl2=  44.12
 
 fault angle parameters
  strike      dip     rake
  135.49     48.83     67.65
  347.48     45.88    113.50
 
------------------------------------------------------------------------
 

Foreshock inversion results

------------------------------------------------------------------------ 
Inversion run on: Fri Feb 24 14:03:51 1995
------------------------------------------------------------------------    
 Information from header of first data file: 
 Reference Time: JAN 16 (016), 1994    00:43:24.085
 Origin time (s) relative to reference:   0.
 Event Lat,Lon:  40.327   -76.007
------------------------------------------------------------------------  
 Depth = 3km
------------------------------------------------------------------------ 
 moment tensor:
  0.329E+00      0.491E+00     -0.619E+00
  0.491E+00      0.631E+00     -0.139E-01
 -0.619E+00     -0.139E-01     -0.960E+00
 m0 =     1.00000E+22
  
 Isotropic Component:   0.
 Subtracted out the isotropic component.
  
 The Deviatoric Moment Tensor:
  0.329E+00      0.491E+00     -0.619E+00
  0.491E+00      0.631E+00     -0.139E-01
 -0.619E+00     -0.139E-01     -0.960E+00
 
 eigenvalues of the moment tensor
  0.107E+01      0.153E+00     -0.123E+01
 
 and associated eigenvectors (in the columns)
  0.652E+00     -0.648E+00      0.395E+00
  0.731E+00      0.676E+00     -0.974E-01
 -0.204E+00      0.352E+00      0.914E+00
  
 Eigenvector 1:
 Az =     228.273 Plunge =     11.7424
 Eigenvector 2:
 Az =     133.792 Plunge =     20.6001
 Eigenvector 3:
 Az =     346.129 Plunge =     66.0173
  
  
 The Total Scalar Moment (Silver&Jordan;,1982) is 
 0.116E+23
 The Total Moment Magnitude (Kananmori(1979)) is 
  4.0
  
 The Deviatoric Scalar Moment (Silver&Jordan;,1982) is 
 0.116E+23
 The Deviatoric Moment Magnitude (Kananmori(1979)) is 
  4.0
  
 double couple eigenvalues= 0.115E+01     -0.115E+01
 error (clvd/dc)*100=    25.019
  
 
 moment tensor for the major dislocation
     0.2689       0.5244       0.5146      -0.4932      -0.0597
 
 pole vectors p1 and p2
 -0.182E+00     -0.586E+00      0.790E+00
  0.740E+00      0.448E+00      0.502E+00
 
 azimuth and plunge of pole #1;     az1= 252.76     pl1=  52.18
 azimuth and plunge of pole #2;     az2=  31.18     pl2=  30.14
 
 fault angle parameters
  strike      dip     rake
  342.76     37.82    125.02
  121.18     59.86     65.99
 
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