USGS Body-Wave Moment Tensor Solution
OFF EAST COAST OF HONSHU, JAPAN
12/12/07 08:18:23.82 Epicenter: 37.876 144.052 MW 7.3 USGS MOMENT TENSOR SOLUTION Depth 42 No. of sta:112 Moment Tensor; Scale 10**19 Nm Mrr= 8.53 Mtt= 0.28 Mpp=-8.81 Mrt= 2.33 Mrp=-3.26 Mtp=-1.36 Principal axes: T Val= 9.80 Plg=71 Azm= 36 N -0.31 16 183 P -9.49 9 276 Best Double Couple:Mo=9.7*10**19 NP1:Strike= 24 Dip=38 Slip= 116 NP2: 172 56 71
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.