USGS WPhase Moment Solution

SOUTHERN ALASKA

12/12/04  1:42:48

Epicenter:  61.230 -150.719
MW 5.8

USGS/WPHASE CENTROID MOMENT TENSOR
12/12/04 01:42:48.00
Centroid:   61.230 -150.719
Depth  50         No. of sta: 36
Moment Tensor;   Scale 10**17 Nm
  Mrr= 2.41       Mtt=-3.82
  Mpp= 1.42       Mrt= 0.22
  Mrp= 3.55       Mtp= 2.38
 Principal axes:
  T  Val=  5.82  Plg=45  Azm=285
  N     = -0.88      42      125
  P     = -4.94      10       26

Best Double Couple:Mo=5.4*10**17
 NP1:Strike= 77 Dip=51 Slip=  29
 NP2:       328     68       137

Moment Tensor Solution
The figure above shows a visual representation of the style of faulting (focal mechanism) derived from the estimated moment tensor. Shaded areas show quadrants of the focal sphere in which the P-wave first-motions are away from the source, and unshaded areas show quadrants in which the P-wave first-motions are toward the source. The dots represent the axis of maximum compressional strain (in black, called the "P-axis") and the axis of maximum extensional strain (in white, called the "T-axis") resulting from the earthquake.

Moment Tensor Solution

Details on the W-phase inversion algorithm.