USGS/SLU Regional Moment Solution
12/11/10 21:30:00.93 Epicenter: 37.929 20.851 MW 4.2 USGS/SLU REGIONAL MOMENT TENSOR Depth 17 No. of sta: 21 Moment Tensor; Scale 10**15 Nm Mrr=-0.35 Mtt= 2.45 Mpp=-2.10 Mrt= 0.03 Mrp=-0.92 Mtp=-0.14 Principal axes: T Val= 2.45 Plg= 1 Azm= 2 N 0.04 67 95 P -2.49 23 271 Best Double Couple:Mo=2.5*10**15 NP1:Strike= 49 Dip=73 Slip=-164 NP2: 314 75 -18
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.