Sediment Gravity Flows
Sediment Gravity Flow Types
Slides and Slumps-mass movement
Debris flows-matrix supported flows
Grain flows-grain interaction
Fluidized flows-fluid escape
Turbidity currents-density currents with high
sediment concentrations
Large Slumps can trigger tsunamies and
cause significant damage to offshore
infrastructure
Slump
GeoMap.App
•
For slumping to occur at a given
slope, the shear strength of the
sediment must be overcome by
shear stress
• S(Shear strength) = c + o tan ø,
where:
c = cohesion
o = effective pressure (N-n)
N = normal load
n = pore water pressure
ø = angle of internal friction
• Triggered by slope increase and/or a change in normal load
(deposition), gradual increase in pore water pressure, or a
catastrophic event such as an earthquake that triggers
movement
Slumps maintain some
amount of stratigraphic
integrity (bedding) during
transport and deposition
slump
Seismic
expression of
slumps
(chaotic seismic facies)
slump
Slumps in
outcrop
Debris Flows-fine grain matrix is
supporting medium
Mechanics of
Debris Flow
Transport
(matrix
supported flows)
Debris flow
offshore Texas
ridges
Massive Seismic Character
Debrites
Sediment Gravity Flow
Transitions