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

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.