USGS WPhase Moment Solution

OFF W. COAST OF N. ISLAND, N.Z.

12/07/03 10:36:16

Epicenter: -39.963  173.704
MW 6.3

USGS/WPHASE CENTROID MOMENT TENSOR
12/07/03 10:36:16.00
Centroid:  -40.063  173.704
Depth 230         No. of sta: 21
Moment Tensor;   Scale 10**18 Nm
  Mrr= 0.29       Mtt= 1.13
  Mpp=-1.42       Mrt= 2.85
  Mrp=-2.12       Mtp= 0.28
 Principal axes:
  T  Val=  3.88  Plg=43  Azm= 19
  N     = -0.18      20      129
  P     = -3.69      39      237

Best Double Couple:Mo=3.8*10**18
 NP1:Strike= 34 Dip=20 Slip= 175
 NP2:       129     88        70

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.