Pore Pressure

Pore pressure is the pressure of the fluid filling the void space between sediment grains, and it controls seafloor stability. The grains carry the difference between the total overburden stress and the pore pressure, a quantity called effective stress; raise the pore pressure and effective stress falls, weakening the sediment. Rapid burial that traps fluids faster than they can escape produces overpressure, the main reason for weak accretionary-prism thrusts and for triggering submarine slope failure. Drilling measures it to plan mud weight and avoid blowouts. In gravity flows and during earthquakes, elevated pore pressure can drive liquefaction and let sediment move on near-flat slopes.