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💧 Liquefaction Triggering Explorer
Shake loose saturated sand hard enough and pore pressure builds faster than it can drain. Effective stress falls toward zero, and ground that was carrying a building becomes a heavy liquid. This is the assessment that governs foundation design across much of coastal and alluvial Turkey — the 1999 Kocaeli earthquake produced extensive liquefaction damage in Adapazarı and Gölcük.
Earthquake
Soil
Live Result
—
CSR (seismic demand)—
CRR7.5 (soil capacity)—
Magnitude scaling factor MSF—
Factor of safety FS—
Effective vertical stress σ′v—
Powered by the Seed & Idriss simplified procedure
as codified in Youd et al. (2001) (
engine/liquefaction.js).
Verified before publishing: MSF returns 1.000 at the reference magnitude
M=7.5 by construction, CRR matches the published curve's characteristic
values, FS scales exactly inversely with amax (CSR is linear in
it), and every monotonic trend was checked across the full input range. Note
the engine returns null rather than an extrapolated number for
(N₁)60cs ≥ 30 — the CRR equation has a pole at N=34, and
extrapolating past a pole produces confident nonsense.Method
Seed & Idriss (1971)CSR = 0.65·(amax/g)·(σv/σ′v)·rd — the cyclic stress demand.
Youd et al. (2001)NCEER/NSF consensus — CRR7.5 from (N₁)60cs; MSF = 10^2.24/M^2.56.
Liao & Whitman (1986)Stress reduction factor rd piecewise fit.
Scope: triggering only — this does not estimate post-liquefaction settlement, lateral spreading, or residual strength. (N₁)60cs must already include energy, overburden, borehole, rod-length and fines corrections. Kσ is held at the conservative 1.0. Not applicable to clayey soils, which need plasticity-based criteria instead. A teaching tool, not a site investigation.