USGS Body-Wave Moment Tensor Solution
12/11/11 18:19:42.59 Epicenter: 23.158 95.971 MW 5.5 USGS MOMENT TENSOR SOLUTION Depth 8 No. of sta: 31 Moment Tensor; Scale 10**17 Nm Mrr=-0.04 Mtt=-0.03 Mpp= 0.07 Mrt= 0.58 Mrp= 0.21 Mtp= 1.81 Principal axes: T Val= 1.99 Plg=16 Azm=315 N -0.15 72 104 P -1.84 9 223 Best Double Couple:Mo=1.9*10**17 NP1:Strike=358 Dip=73 Slip= 175 NP2: 90 85 17
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.