USGS Body-Wave Moment Tensor Solution
12/10/08 01:50:25.81 Epicenter: -21.773 -68.298 MW 5.7 USGS MOMENT TENSOR SOLUTION Depth 120 No. of sta: 53 Moment Tensor; Scale 10**17 Nm Mrr=-3.51 Mtt= 0.26 Mpp= 3.25 Mrt=-1.12 Mrp=-3.47 Mtp=-0.06 Principal axes: T Val= 4.74 Plg=23 Azm= 95 N 0.43 8 189 P -5.18 65 297 Best Double Couple:Mo=5.0*10**17 NP1:Strike=169 Dip=23 Slip=-112 NP2: 12 69 -81
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.