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Seismology operators

12 operators in the seismology category of the live registry. Each is a named formula you can compose inside a state contract or call directly through POST /api/zeq/compute. KO42 is always on; add up to three more per call (total ≤ 4), per the 7-step protocol.

OperatorDescriptionEquation
SZ1Primary (compressional) wave velocity derived from the bulk modulus, shear modulus, and density of the transmitting medium.v_P = \sqrt{\frac{K + 4\mu/3}{\rho}}
SZ10Site fundamental frequency from the quarter-wavelength resonance of shear waves in a soft soil layer overlying bedrock.f_0 = \frac{v_S}{4H}
SZ11Seismic wave attenuation model describing amplitude decay with travel time through the intrinsic quality factor Q of the medium.A(f) = A_0 e^{-\pi f t / Q}
SZ12Fault shear strain relating the stress drop across a fault plane to the shear modulus of the surrounding rock.\tau = \frac{\Delta\sigma}{\mu}
SZ2Secondary (shear) wave velocity depending only on the shear modulus and density, unable to propagate through fluids.v_S = \sqrt{\frac{\mu}{\rho}}
SZ3Rayleigh surface wave velocity approximation as a fraction of the shear wave speed, governing ground roll in seismic records.v_R = 0.92 \sqrt{\frac{\mu}{\rho}} \approx 0.92 v_S
SZ4Local magnitude scale computing earthquake size from the base-10 logarithm of peak seismogram amplitude with empirical distance corrections.M_L = \log_{10}A + 2.56\log_{10}\Delta - 1.67
SZ5Seismic moment quantifying earthquake size as the product of rock rigidity, fault rupture area, and average slip displacement.M_0 = \mu A D
SZ6Moment magnitude scale providing a physically based, non-saturating measure of earthquake size from the logarithm of seismic moment.M_w = \frac{2}{3}(\log_{10}M_0 - 9.1)
SZ7Seismic energy-magnitude relation converting moment magnitude to total radiated seismic energy through a logarithmic scaling law.\log_{10}E = 1.5M_w + 4.8
SZ8Peak ground acceleration representing the maximum horizontal acceleration recorded during an earthquake, used for structural design criteria.PGA = a_{max}
SZ9Empirical relationship converting instrumental peak ground acceleration to macroseismic intensity for damage and felt-report estimation.I = \frac{2}{3}(PGA/g + 1)

Compute with one of these​

curl -sS -X POST https://zeqsdk.com/api/zeq/compute \
  -H "Authorization: Bearer $ZEQ_KEY" \
  -H "Content-Type: application/json" \
  -d '{"operators":["SZ1"],"inputs":{}}'

The response carries the bare physics value, its unit and uncertainty, the generated master equation, and a signed envelope you can verify on any node.

See also​