Brittle deformation Joint Tension gash Styloite Fault etc

Brittle deformation

JointTension gashStyloiteFault etc..

Reconstruction of regional stress

Structural geology

Structure

Ductile deformation

FoldFoliationLineation etc.. Fault

Fault surfaces displaying the direction of slip lineation

Stereographic projection of a fault slip data set

Lower hemisphere project

Fault plane

Slickensidelineation

pitch

Fault plane

pitch

Method of right dihedrons

obtaining the orientationof principal stress axesfrom statistic method

S’/S = f (inclination)

STEREOGRAPHIC NET

S’/S = const.

Wuff net Schmidt net

Wuff net (equiangular)

OPM isosceles triangle

ON/OP = tan (/4-i/2)

ON = R tan (/4-i/2)

Schmidt net (equal-area)

ON = OX, OX = (2)1/2 OH

OH/OP = sin (/4-i/2)

ON = (2)1/2 R sin (/4-i/2)

3D inversion of field data in fault tectonics

Eigenvalues and eigenvectors of T give the orientation of principal stress axes (1 ,

2 and 3), as well as the shape ratio of the stress ellipsoid ( = (2-3)/(1-3)).

(e.g., Angelier, 1979, 1984, 1989, 1990)

Field measured data Computed stress axes Theoretical fault shears

Inversion result

(Angelier, 1990)

(Chang C. P., Unpubl.)

Example from the seismic focal mechanism

= (2-3)/(1-3)

0 reverse and strike-slip

1 normal and strike-slip

0 1

case 1

case 2

case 1

case 2

(Kao and Jian, 2001)