Year 0Slip deficit 0 mLast event noneRecurrence —City P / S 0 s—FPS 0

Drag to orbit, wheel or pinch to zoom. The dark slab dives under the continent; the red patch of the fault is locked and loads up slip deficit (colour = share of the strength used). When it breaks, blue rings show P waves and orange rings S waves in slow motion. Shifts are exaggerated by the slider; the city is not to scale.

Subduction Megathrust

Plates lock, the slip deficit grows, the fault lets go. Learn the numbers behind one earthquake cycle. Educational model, not a forecast of any real event.

Plate motion and locking

Rupture patch

Time and display

Live readouts

Slip deficit history (m)

Landward shift across the margin (m)

Missions

Mission 3: S minus P time at the city, seconds

Use t = R/v for both waves with v_P = 6.0 and v_S = 3.5 km/s and the straight-line distance R from the hypocentre to the city.

Catalogue (Gutenberg-Richter)

b-value of the background seismicity

Independent numerical checks

Controls

Drag / one finger: orbit; wheel / pinch: zoom; three camera presets.
Time scale is years per real second. The fault breaks when the deficit reaches the strength D_c (random ±20 % each cycle). Release now breaks it early.
Shift exaggeration makes centimetres to metres visible at the scale of 100 km; it does not change the physics.

The science

Slip deficit. The plates converge at V, but the locked patch (coupling χ) cannot slip, so its slip deficit grows as D(t) = χ V t. When the elastic strength is reached (D_c, a model value that varies ±20 %) the patch ruptures and the deficit is released: elastic rebound.

Moment and magnitude. M₀ = μ A D with rigidity μ = 30 GPa [перевірити за джерелом], rupture area A = L × W (strike length times down-dip width) and uniform slip D. M_w = (2/3)(log₁₀M₀ − 9.1) (Hanks and Kanamori form, M₀ in N m); every unit of M_w is a factor of about 32 in released energy [перевірити за джерелом].

Surface shift. The shift felt landward is drawn with an arctan (screw-dislocation, Savage-Burford) analogue: u(x) = D · [½ − (1/π) arctan((x − x_f)/d)], x_f above the down-dip end of the locked patch and d its depth. This is an anti-plane analogue, not the full thrust solution; the vertical response is a qualitative bell only.

Waves. In the crust v_P = 6.0 km/s and v_S = 3.5 km/s (typical values, a layered Earth differs). Arrival times t = R/v; the S minus P time gives the distance R = Δt/(1/v_S − 1/v_P). The rings are drawn in slow motion (10x).

Catalogue. Magnitudes follow a truncated Gutenberg-Richter law log₁₀N = a − bM, here with 2 events per year at M ≥ 5 [illustrative rate].

Simplifications. 2D section, planar slab dipping 20°, uniform slip, no viscoelastic relaxation, no aftershocks, no tsunami, no full wavefield, depths and thicknesses schematic. The model cannot predict when or where a real earthquake will happen. Assets built with Blender; scene by Three.js.