Structural geology Structure Ductile deformation Brittle deformation Fold

Structural geology Structure Ductile deformation Brittle deformation Fold Foliation Lineation etc. . Joint Tension gash Styloite Fault etc. . Reconstruction of regional stress

Fault surfaces displaying the direction of slip lineation

Stereographic projection of a fault slip data set Slickenside lineation pitch Fault plane Lower hemisphere project

Method of right dihedrons obtaining the orientation of principal stress axes from statistic method

STEREOGRAPHIC NET S’/S = f (inclination) S’/S = const.

Wuff net Schmidt net

Wuff net (equiangular) Schmidt net (equal-area) OPM isosceles triangle ON = OX, OX = (2)1/2 OH ON/OP = tan (p/4 -i/2) OH/OP = sin (p/4 -i/2) ON = R tan (p/4 -i/2) ON = (2)1/2 R sin (p/4 -i/2)

3 D inversion of field data in fault tectonics Eigenvalues and eigenvectors of T give the orientation of principal stress axes (s 1 , s 2 and s 3), as well as the shape ratio F of the stress ellipsoid (F = (s 2 -s 3)/(s 1 -s 3)). (e. g. , Angelier, 1979, 1984, 1989, 1990)

Inversion result Field measured data Computed stress axes Theoretical fault shears (Angelier, 1990)

(Chang C. P. , Unpubl. )

Example from the seismic focal mechanism case 1 F = (s 2 -s 3)/(s 1 -s 3) 0 F 1 case 2 F 0 reverse and strike-slip case 2 (Kao and Jian, 2001) F 1 normal and strike-slip