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Unformatted text preview: o thes e planes . By c onvention the c ompres s ional quadrants are
c olour-filled and the tens ional left white. The two nodal planes inters ec t at the N (neutral)ax is . The P and T ax es are als o often plotted; with the N ax is thes e three direc tions
res pec tively matc h the direc tions of the max imum, minimum and intermediate princ iple
c ompres s ive s tres s es as s oc iated with the earthquak e. The P-ax is is plotted in the c entre of
the white s egment, the T-ax is in the c entre of the c olour-filled s egment.
The fault plane res pons ible for the earthquak e will be parallel to one of the nodal planes , the
en.wikipedia.or g /wiki/Focal_mechanism 2/3 12/8/13 Focal mechanism - Wikipedia, the fr ee encyclopedia other being c alled the aux iliary plane. Unfortunately it is not
pos s ible to determine s olely from a foc al mec hanis m whic h of the
nodal planes is in fac t the fault plane. For this other geologic al or
geophy s ic al evidenc e is needed to remove the ambiguity . The s lip
vec tor, whic h is the direc tion of motion of one s ide of the fault
relative to the other, lies within the fault plane, 90 deg from...
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This document was uploaded on 02/04/2014.
- Spring '14