Glossary and notation
Glossary and notation — This section fixes the vocabulary used throughout: Void as a transient pressure-deficit boundary condition (not a literal vacuum), void suction as the resulting pulling component, hydroplaning and hydraulic jacking via effective stress (Terzaghi/Biot), passive margins, the rupture nucleation point, spatiotemporal mapping, and cavitation, together with the symbols and units they use.
Symbol Unit Meaning (as used in this white paper) R m Earth radius Δ R m Representative radius change linked to Pacific-side uplift/expansion (model parameter) E Pa Effective crustal Young's modulus (order-of-magnitude) σₜₑₙₛᵢₒₙ Pa Antipodal tensile stress (order-of-magnitude) σ_fail Pa Tensile failure threshold.
Key terms
- Void: not necessarily a vacuum; a transient state sufficiently lower in pressure/density than its surroundings (a pressure deficit boundary condition).
- Void suction: an attractive (pulling) component acting on plates due to the void pressure deficit.
- Hydroplaning: (i) effective-stress reduction that partially decouples contact, and (ii) residual resistance dominated by viscous shear η v/h rather than solid friction.
- Effective stress: σ'=σₙ-α P_f (Terzaghi/Biot). Coulomb-like friction scales roughly as τ~μ σ'.
- Hydraulic jacking: P_f approaches σₙ, driving σ'→ 0 and mechanically lifting/decoupling the interface.
- Passive margin: margins dominated by extension/subsidence/sedimentation rather than subduction/collision.
- Nucleation point: the hypothesized initiation location of long-range rupture propagation (to be inferred from data).
- Spatiotemporal mapping: a procedure linking a rupture-time model to geographic coordinates along a path parameter s.
- Cavitation: a possible breakdown of continuous lubrication when pressure drops induce vapor/bubble formation.
Symbols and units
Symbol Unit Meaning (as used in this white paper) R m Earth radius Δ R m Representative radius change linked to Pacific-side uplift/expansion (model parameter) E Pa Effective crustal Young's modulus (order-of-magnitude) σₜₑₙₛᵢₒₙ Pa Antipodal tensile stress (order-of-magnitude) σ_fail Pa Tensile failure threshold of crust (order-of-magnitude) Δ P Pa Void pressure deficit (outside minus void) A_cross m² Effective cross-sectional area over which suction acts A_base m² Plate–base contact area σₙ Pa Total normal stress at the interface (lithostatic etc.) P_f Pa Pore-fluid / interfacial fluid pressure σ' Pa Effective normal stress: σ'=σₙ-α P_f α – Biot coefficient (typically ~ 1) D_h m²/s Hydraulic diffusivity: D_h=k/(η_f Sₛ) τ_drain s Drainage timescale: τ_drain~ ²/D_h L_v J/kg Latent heat of vaporization (phase-change energy scale) μ_eff – Effective friction coefficient relative to σₙ μ_dry – Dry (solid–solid) Coulomb friction coefficient τᵣₑₛ Pa Residual resisting shear stress (solid friction + viscous shear) η Pa·s Effective viscosity of lubricating fluid h m Effective lubrication-film thickness v m/s Representative sliding speed Λ – Dimensionless suction-to-friction ratio (static gate) τ s Void maintenance time window (impulse gate) s m Arc-length coordinate along the rupture/opening path v(s) m/s Position-dependent rupture speed A_eff m² Effective area used for work/energy accounting