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What is soil liquefaction?

When soil becomes water.

A visual guide to the ground failure that hides beneath an earthquake.

Follow the phase shift
PHASE SHIFT / 01STATIC FALLBACK INCLUDED
Phase shift from stable soil to liquefied ground Three stages show connected grains at rest, shaking with rising pore pressure, and grains losing contact in a fluid-like layer. 01 / RESTING grain contact 02 / SHAKING pore pressure rises 03 / LIQUEFIED contact is lost

Loose, saturated soil can lose the friction that makes it feel solid.

The mechanism

The phase shift.

Four linked events turn shaking into a loss of bearing capacity.

How engineers compute it

The check is simple. The ground is not.

Two paths meet at one familiar ratio.

FACTOR OF SAFETY / 02DEMAND VS. CAPACITY
Factor of safety computation flowSeismic demand becomes cyclic stress ratio, soil capacity becomes cyclic resistance ratio, and the two converge at factor of safety equal to CRR divided by CSR. SEISMIC DEMANDearthquake input SOIL CAPACITYsite resistance CSR CRR FS= CRR / CSR TRIGGERING CHECKFS < 1.0 → demand exceeds resistance

FS compares cyclic resistance ratio (CRR) with cyclic stress ratio (CSR); below 1.0 suggests triggering.

Why the number lies

A precise-looking number can hide a wide distribution.

The same site can produce FS = 0.92 or FS = 0.88 and still be telling you the same story.

UNCERTAINTY / 03PRIOR → POSTERIOR
Prior distribution compresses into a posterior distributionA broad prior distribution narrows after conditioning on similarity-matched case histories. Factor of safety 0.92 and 0.88 sit inside the same practical noise band. PRIORwide uncertainty POSTERIORmatched histories FS = 0.88FS = 0.92LOWER RESISTANCEHIGHER RESISTANCE

Conditioning on similar case histories compresses the uncertainty — it does not turn an estimate into a fact.

What similarity restores

Context beats a single index.

The Engine gets more useful as it finds the right precedents.

SEQUENTIAL CONVERGENCE / 04MORE MATCHES → LESS NOISE
Sequential convergence of factor-of-safety distributionsFive ridgelines narrow progressively as more similarity-matched case histories are added.DISTRIBUTIONprior+ 1 match+ 3 matches+ 10 matches+ 50 matchesFS ESTIMATE

Each matched precedent adds evidence without hiding the mechanics.

Two ways to read the same site

INDEX ONLYSIMILARITY + INDEX
Signalone thresholdcase-grounded range
Contextabstractedearthquake + soil precedent
Outputpass / failreasoned estimate
8,634verified earthquake case histories available to the GeoLiquefy engine

Consequences

When the ground loses its skeleton.

The failure modes are different. The missing friction is the same.

TILTBEARING CAPACITY ↓

Tilting

Foundations rotate when the supporting layer softens.

DISPLACEMENT →SLIP PLANE

Lateral spreading

Liquefied layers move sideways toward a free face.

PRESSURE VENTWATER + SAND

Sand boils

Pressurized water and sand erupt through a vent.

In brief

The ground, answered.

What is soil liquefaction?

Earthquake shaking raises pore-water pressure in loose, saturated soil until grain-to-grain contact and friction are lost.

Does FS below 1.0 guarantee failure?

No. It is a triggering signal in a simplified check; uncertainty around the estimate still matters.

What does GeoLiquefy add?

Similarity-matched case histories put the mechanics back into context, so an engineer can see a reasoned range instead of one unqualified number.

Prediction is prevention.

Make the hidden ground legible.

Explore the engine built to connect geotechnical mechanics with real earthquake precedent.

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