USGS Body-Wave Moment Tensor Solution
SOUTHERN ALASKA
12/12/04 01:42:48.00 Epicenter: 61.230 -150.719 MW 5.7 USGS MOMENT TENSOR SOLUTION Depth 60 No. of sta: 35 Moment Tensor; Scale 10**17 Nm Mrr= 2.34 Mtt=-4.28 Mpp= 1.95 Mrt= 0.08 Mrp= 3.22 Mtp= 1.86 Principal axes: T Val= 5.55 Plg=45 Azm=281 N -0.65 44 116 P -4.90 7 19 Best Double Couple:Mo=5.3*10**17 NP1:Strike=322 Dip=66 Slip= 140 NP2: 70 54 30
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.
