USGS WPhase Moment Solution
TONGA
12/ 4/28 10: 8:7.00 Epicenter: -18.643 -174.725 MW 6.6 USGS/WPHASE CENTROID MOMENT TENSOR 12/ 4/28 10: 8: 7.00 Centroid: -18.643 -174.513 Depth 140 No. of sta: 39 Moment Tensor; Scale 10**18 Nm Mrr=-7.18 Mtt= 6.15 Mpp= 1.04 Mrt= 7.07 Mrp= 3.29 Mtp= 2.58 Principal axes: T Val= 10.63 Plg=23 Azm=336 N = -0.03 1 246 P =-10.60 66 153 Best Double Couple:Mo=1.1*10**19 NP1:Strike= 69 Dip=21 Slip= -86 NP2: 246 69 -91
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.
