USGS Body-Wave Moment Tensor Solution
NORTHERN MID-ATLANTIC RIDGE
12/10/04 23:14:56.74 Epicenter: 17.456 -46.510 MW 5.4 USGS MOMENT TENSOR SOLUTION Depth 4 No. of sta: 37 Moment Tensor; Scale 10**17 Nm Mrr=-0.74 Mtt=-0.16 Mpp= 0.90 Mrt= 0.49 Mrp= 1.36 Mtp=-0.58 Principal axes: T Val= 1.71 Plg=27 Azm=260 N 0.11 25 4 P -1.82 52 130 Best Double Couple:Mo=1.8*10**17 NP1:Strike=190 Dip=77 Slip= -64 NP2: 306 29 -151
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.