Geotechnical & Seismic Calculators
Airplane Weight Shift
Δ CG = (W_moved · arm) / W_total
Center-of-gravity change from cargo or passenger relocation in light aircraft load balancing.
Calculate →Earthquake Seismometer
M = log₁₀(A) + correction
Richter scale magnitude, moment magnitude, and seismic energy from seismograph amplitude.
Calculate →Electrodialysis Membrane Design
I = F · N · Q · E₁ / (n · E₂)
Electrodialysis cell current, flow, cell-pair count, and removal/current efficiency.
Calculate →Geotextile
ψ = k_n / t
Permittivity and transmissivity for woven and non-woven geotextile filter fabrics.
Calculate →Oil Recovery Factor
ORF = ERO / EIPO
Oil recovery factor from estimated recovered oil and oil initially in place.
Calculate →Seismic Geophone
z = (x/2) · √((V₂ − V₁) / (V₂ + V₁))
Soil layer thickness from refraction-survey arrival times and surface and lower-layer velocities.
Calculate →Soil Resistivity
ρ = 2π · a · R (Wenner)
Soil resistivity from a four-electrode Wenner test for grounding system design.
Calculate →Geotechnical and seismic calculators: bearing capacity, settlement, soil unit weight, slope stability, seismic hazard parameters.
When to use these calculators
Used in civil engineering coursework, geotechnical investigation summaries, and seismic-zone construction planning.
Frequently Asked Questions
- How does the calculator show its work?
- Each calculator displays the substituted arithmetic step-by-step below the solution, so the user can verify the math by hand if needed. The 'Copy result' button captures the full formula → substitution → answer block.
- Are the formulas cross-verified?
- Every calculator's math has been cross-verified against textbook references and round-trip consistency tests (solve A from B, then solve B from A — the result must match the input). Spot-checks against Wolfram Alpha confirm the precision.
- How do I switch between solving for different variables?
- Most calculators in this category support multiple solve-for modes. Pick the unknown variable from the pill-toggle (or equation-card group) above the input fields, then enter the known values. The calculator auto-computes as you type.