USGS WPhase Moment Solution

OFF W COAST OF NORTHERN SUMATRA

12/ 4/11  8:38:38.00

Epicenter:   2.348   93.072
MW 8.6

USGS/WPHASE CENTROID MOMENT TENSOR
12/ 4/11  8:38:38.00
Centroid:    2.248   92.872
Depth  25         No. of sta:109
Moment Tensor;   Scale 10**21 Nm
  Mrr= 1.25       Mtt=-5.99
  Mpp= 4.74       Mrt= 1.34
  Mrp=-0.63       Mtp=-7.03
 Principal axes:
  T  Val=  8.40  Plg= 9  Azm= 63
  N     =  1.14      79      271
  P     = -9.54       4      154

Best Double Couple:Mo=9.0*10**21
 NP1:Strike=199 Dip=80 Slip=   3
 NP2:       108     87       170

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.