USGS Body-Wave Moment Tensor Solution
OFF W COAST OF NORTHERN SUMATRA
13/01/09 21:05:01.76 Epicenter: 0.749 92.709 MW 5.2 USGS MOMENT TENSOR SOLUTION Depth 19 No. of sta: 8 Moment Tensor; Scale 10**16 Nm Mrr= 0.85 Mtt=-6.33 Mpp= 5.48 Mrt=-0.94 Mrp= 0.18 Mtp=-5.11 Principal axes: T Val= 7.42 Plg= 4 Azm=249 N 0.89 83 119 P -8.31 5 340 Best Double Couple:Mo=7.9*10**16 NP1:Strike= 25 Dip=83 Slip= -1 NP2: 115 89 -173
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.