USGS Body-Wave Moment Tensor Solution
OFF W. COAST OF N. ISLAND, N.Z.
12/07/03 10:36:15.97 Epicenter: -39.976 173.693 MW 6.3 USGS MOMENT TENSOR SOLUTION Depth 229 No. of sta: 25 Moment Tensor; Scale 10**18 Nm Mrr= 0.08 Mtt= 0.94 Mpp=-1.02 Mrt= 2.74 Mrp=-2.08 Mtp=-0.55 Principal axes: T Val= 3.95 Plg=41 Azm= 28 N -0.79 15 131 P -3.17 45 236 Best Double Couple:Mo=3.6*10**18 NP1:Strike= 49 Dip=15 Slip=-172 NP2: 311 88 -75
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.