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)
