USGS/SLU Regional Moment Solution
12/12/09 01:23:06.24 Epicenter: 37.888 22.642 MW 4.0 USGS/SLU REGIONAL MOMENT TENSOR Depth 13 No. of sta: 14 Moment Tensor; Scale 10**15 Nm Mrr=-1.01 Mtt= 1.14 Mpp=-0.13 Mrt=-0.41 Mrp= 0.26 Mtp=-0.17 Principal axes: T Val= 1.25 Plg=11 Azm=189 N -0.12 11 281 P -1.13 74 55 Best Double Couple:Mo=1.2*10**15 NP1:Strike=266 Dip=35 Slip=-109 NP2: 109 57 -77
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.