12. FAULTS
ï FAULTS ARE ONE OF THE STRUCTURAL
FEATURES OF ROCKS
ï WHILE ROCKS AT OR NEAR THE
SURFACE OF THE EARTH ARE COOL &
BRITTLE, ROCKS BELOW THE SURFACE
OF THE EARTH ARE HOT AND TEND TO
MOVE
13. FAULTS
ï A LOT OF EXTERNAL FORCES ACT UPON
THE ROCKS AND CAUSE STRESS ON THEM
ï DUE TO THIS STRESSES, ROCKS EITHER
UNDERGO DUCTILE DEFORMATION OR
BRITTLE DEFORMATION
ï IF THEY UNDERGO DUCTILE
DEFORMATION, ROCKS DEVELOP FOLDS.
IF THEY UNDERGO BRITTLE
DEFORMATION, THEY DEVELOP FAULTS.
14. FAULTS
ï FAULT IS DEFINED AS A SPLIT OR CRACK
OR FRACRTURE IN THE ROCK PRESENT
IN EARTHâS CRUST CHARACTERISED BY
RELATIVE DISPLACEMENT OF ONE SIDE
OVER THE OTHER.
36. ELASTIC REBOUND THEORY
ï The elastic rebound theory is an explanation
for how energy is spread during earthquakes.
As plates on opposite sides of a fault are
subjected to force and shift, they accumulate
energy and slowly deform until their internal
strength is exceeded. At that time, a sudden
movement occurs along the fault, releasing
the accumulated energy, and the rocks snap
back to their original undeformed shape.