This is a preliminary UCB moment tensor report for the swarm located
12 km N of Burney, CA on December 20, 2000. Moment tensor solutions for the
four largest events, Mw3.9, Mw3.7, Mw4.3 and Mw4.4 follow. All events have
northwest striking normal-type mechanisms and have a best fitting source 
depth of 5km.

Best regards,
Douglas Dreger
UCB Seismological Laboratory
 
 
 EVENT1 Date/Time:2000/12/20 14:55:51(PST) 40.986N 121.687W
 Best Fitting Double-Couple:
    Mo = 7.65E+21 Dyne-cm
    Mw = 3.89
    Z  = 5 km
    Plane   Strike   Rake   Dip
     NP1      175     -57    52
     NP2      308    -125    49
 Principal Axes:
    Axis    Value   Plunge   Azimuth
      T     7.650       2      242
      N     0.000      26      333
      P    -7.650      64      149
 Moment Tensor: Scale = 10**21 Dyne-cm
    Component   Value
       Mxx      0.640
       Mxy      3.812
       Mxz      2.460
       Myy      5.565
       Myz     -1.732
       Mzz     -6.206
 
 EVENT2 Date/Time: 2000/12/20 14:59:38(PST) 40.988N 121.689W
 Best Fitting Double-Couple:
    Mo = 4.35E+21 Dyne-cm
    Mw = 3.73
    Z = 5 km
    Plane   Strike   Rake   Dip
     NP1      185     -61    55
     NP2      321    -125    44
 Principal Axes:
    Axis    Value   Plunge   Azimuth
      T     4.350       6      255
      N     0.000      23      348
      P    -4.350      66      151
 Moment Tensor: Scale = 10**21 Dyne-cm
    Component   Value
       Mxx     -0.285
       Mxy      1.381
       Mxz      1.317
       Myy      3.846
       Myz     -1.226
       Mzz     -3.561
 
 EVENT3 Date/Time: 2000/12/20 15:22:54(PST) 40.990N 121.698W
 Best Fitting Double-Couple:
    Mo = 3.72E+22 Dyne-cm
    Mw = 4.35
    Z = 5 km
    Plane   Strike   Rake   Dip
     NP1      178     -65    57
     NP2      318    -123    40
 Principal Axes:
    Axis    Value   Plunge   Azimuth
      T     3.722       9      251
      N     0.000      20      344
      P    -3.722      67      138
 Moment Tensor: Scale = 10**22 Dyne-cm
    Component   Value
       Mxx      0.081
       Mxy      1.392
       Mxz      0.791
       Myy      2.994
       Myz     -1.442
       Mzz     -3.074
 
 Event Date/Time: 2000/12/20 15:39:14(PST) 40.989N 121.697W
 Best Fitting Double-Couple:
    Mo = 4.26E+22 Dyne-cm
    Mw = 4.39
    Z = 5 km
    Plane   Strike   Rake   Dip
     NP1      164     -70    54
     NP2      312    -115    41
 Moment Tensor: Scale = 10**22 Dyne-cm
    Component   Value
       Mxx      0.937
       Mxy      2.025
       Mxz      0.510
       Myy      2.886
       Myz     -1.369
       Mzz     -3.823
 Principal Axes:
    Axis    Value   Plunge   Azimuth
      T     4.260       7      240
      N     0.000      16      331
      P    -4.260      73      128
 

 Focal Mechanism for EVENT4
                                               
                                               
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