geology 3120 - introduction to strike-slip...
TRANSCRIPT
OutlineOutline
• Stick-Slip and Creep
• Andersonian Theory
• Kinematics
• Strike-Slip Faults on Continental Margins
• Strike-Slip Faults on Mid-Ocean Ridges
Elastic Rebound TheoryElastic Rebound Theory
•• Imagine a fence across an active Imagine a fence across an active
faultfault
Elastic Rebound TheoryElastic Rebound Theory
•• Imagine a fence across an active Imagine a fence across an active
faultfault
•• Regional deformation occurs but Regional deformation occurs but
the fault does not break. The the fault does not break. The
fence becomes curved.fence becomes curved.
Elastic Rebound TheoryElastic Rebound Theory
•• Imagine a fence across an active Imagine a fence across an active
faultfault
•• Regional deformation occurs but Regional deformation occurs but
the fault does not break. the fault does not break.
••Once the fault breaks, the fence Once the fault breaks, the fence
is sheared in half and marks offsetis sheared in half and marks offset
••Note that farNote that far--field strain may limit field strain may limit
whether the fault accommodates whether the fault accommodates
all the plate motion at its traceall the plate motion at its trace
Elastic Rebound TheoryElastic Rebound Theory
QuickTime™ and a Cinepak decompressor are needed to see this picture.
Creep (Creep (Aseismic Aseismic Slip)Slip)
•• Imagine a fence across an active Imagine a fence across an active
faultfault
•• Slip occurs slowly on the fault Slip occurs slowly on the fault
continually over time.continually over time.
•• Creeping faults do not store Creeping faults do not store
elastic energy that might be elastic energy that might be
released by a stickreleased by a stick--slip event (an slip event (an
earthquake)earthquake)
Arrow Heads ( Arrow Heads ( ) and Tails ( ) and Tails ( ))
Block moving toward you like an arrowhead Block moving toward you like an arrowhead
heading towards youheading towards you
Block moving away from you like seeing the Block moving away from you like seeing the
feathers of an arrow feathers of an arrow
Arrow Heads ( Arrow Heads ( ) and Tails ( ) and Tails ( ))
RightRight--lateral or leftlateral or left--lateral?lateral?
Arrow Heads ( Arrow Heads ( ) and Tails ( ) and Tails ( ))
Sinistral Sinistral or Dextral?or Dextral?
StrikeStrike--Slip Faulting: Shallow Brittle Slip Faulting: Shallow Brittle vsvs Deep ShearDeep Shear
StrikeStrike--Slip Faulting: Slip Faulting: EQ’sEQ’s = dislocations= dislocations
See http://www.data.scec.org/Module/links/landrupt.html
Landers rupture propagation movies
StrikeStrike--Slip Faults on Continental MarginsSlip Faults on Continental Margins
What is the sense of slip?What is the sense of slip?
N50 m
StrikeStrike--Slip Faults on Continental MarginsSlip Faults on Continental Margins
RightRight--lateral (dextral)lateral (dextral)
N50 m
StrikeStrike--Slip Faults on MidSlip Faults on Mid--Ocean RidgesOcean Ridges
What is the sense of slip?What is the sense of slip?
StrikeStrike--Slip Faults on MidSlip Faults on Mid--Ocean RidgesOcean Ridges
RightRight--lateral (Dextral)lateral (Dextral)