USGS WPhase Moment Solution
OFF W COAST OF NORTHERN SUMATRA
12/ 4/11 10:43:9.00 Epicenter: 0.773 92.452 MW 8.3 USGS/WPHASE CENTROID MOMENT TENSOR 12/ 4/11 10:43: 9.00 Centroid: 0.773 92.452 Depth 16 No. of sta: 6 Moment Tensor; Scale 10**21 Nm Mrr=-1.18 Mtt= 0.18 Mpp= 1.00 Mrt=-0.92 Mrp=-1.33 Mtp=-3.38 Principal axes: T Val= 4.02 Plg= 4 Azm= 49 N = -0.25 58 146 P = -3.77 31 316 Best Double Couple:Mo=3.9*10**21 NP1:Strike= 98 Dip=65 Slip=-159 NP2: 359 72 -26
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.
