Corinth Rift
Corinth Rift Evo Armijo model
Elastic plate -
upper crust
has long term strength
Viscoelastic - ductile lower crust
no long term
strength ∴ flows
Simulated Xylokastro faulting, applying boundary conditions
Deformation model findings
When deform crust - with elastic upper & ductile lower,
BENDING occurs
Footwall uplifted
Hanging wall bulges & slides down
Sensitivity Analysis
Tested fault response to changes in elastic modulus & thickness
= attempt to constrain crustal behaviour
Young's
Elastic
Modulus
Relates amount of strain resulting from given stress in elastic material
Lower elastic modulus --> easier to deform
--> higher strain response
Greater uplift (displacement & bending) for lower elastic modulus
Plate curvature greater on hanging & footwalls
Effective
Elastic Thickness
= measure of flexural rigidity of lithosphere
i.e. resistance to bending under applied vertical load
Xylokastro Fault
∴ Greater elastic thickness --> lower curvature fault surface as lithosphere = harder to bend
To reconcile obv & model results
Very low elastic modulus or thickness required
(1000x lower than norm)
Xylokastro
Fault Slip
Began: 1 Ma
Increases with terrace age
Max uplift rate ~1.3 mm / yr
Constant slip rate
~ 11 mm/yr for 350 ka
when most of deformation focussed on big fault
Xylokastro
Fault
Properties
Properties which best replicate behaviour in reality
= Reduced modulus of seismogenic layer (1000 times lower)
Reduced thickness --> conducive to bending
Max uplift rate 1-3mm / yr
Backtilting Uplifted terraces
Terrace elevation vs distance to fault
--> matches sealevel change over time
Backtilting effect observed on footwall (tilt to the S)
Hanging Wall Bending
Corinth Gulf model
Large scale (km)
Small scale
(10s metres)
Why does hanging wall bend down & not up ?
will likely bend up near fault due to drag @ fault
bends down due to rheology
Inversion
River Flow
Very asymmetric fault distribution in Corinth Gulf
Footwall uplifted & backtilted
causes inversion of river flow
i.e. rivers flow backwards
Geomorphic evidence backtilting
Rivers flow into internally drained basins
i.e. into depressed areas where there is no exit
Backtilting causes river diversion
Previously - rivers flowed into rift basin
After backtilting - flow = inverted
Rivers not powerful enough to overcome zone of uplift ∴ flow in opposite direction (landwards)