USGS Body-Wave Moment Tensor Solution
OFFSHORE EL SALVADOR
13/09/12 13:03:10.91 Epicenter: 13.239 -90.245 MW 5.2 USGS MOMENT TENSOR SOLUTION Depth 23 No. of sta: 27 Moment Tensor; Scale 10**16 Nm Mrr= 6.78 Mtt=-4.61 Mpp=-2.17 Mrt= 2.77 Mrp=-1.40 Mtp= 2.98 Principal axes: T Val= 7.47 Plg=77 Azm= 21 N -0.19 3 123 P -7.28 12 213 Best Double Couple:Mo=7.4*10**16 NP1:Strike=307 Dip=33 Slip= 95 NP2: 121 57 87
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.