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
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.
