Site-specific seismic hazard assessment from the catalogue to the design spectrum. Decluster and fit the earthquake catalogue, draw the area zones and faults on the map and drag them, build the recurrence and ground-motion models and the logic tree, then get mean and fractile hazard curves, uniform-hazard spectra, a rotatable 3D deaggregation, gradient hazard maps and deterministic scenarios. Carry the hazard to the ground surface with an equivalent-linear site response analysis, play synthetic accelerograms against an oscillating building, compare the design spectra of five codes with the site-specific spectrum, and check liquefaction, slope displacement and seismic earth pressure. Take the A3 drawing set, the Excel workbook and the report.
Scope & limitations
For feasibility, preliminary design and education. The sample region, catalogue and ground-motion model are illustrative. A project-specific hazard study needs a regional catalogue, published ground-motion models in a full logic tree, site investigation and independent peer review.
What the seismic hazard studio does
A complete site-specific probabilistic seismic hazard assessment (PSHA) in the browser. Start from an earthquake catalogue — a seeded synthetic catalogue with aftershock sequences and historical incompleteness, or your own pasted list — decluster it with Gardner–Knopoff windows, set completeness periods (with a Stepp plot) and fit a- and b-values by Weichert's maximum-likelihood method.
Model the sources as area zones and planar faults you can drag on the map: truncated Gutenberg–Richter or Youngs & Coppersmith characteristic recurrence, fault activity by moment balance from the slip rate, Wells & Coppersmith rupture scaling, floating ruptures and true rupture distances. Ground motion uses a stochastic point-source model with random-vibration theory, checked against Boore–Joyner–Fumal and Joyner–Boore, with lognormal scatter and truncation.
A logic tree over stress drop, maximum magnitude and b-value gives mean and fractile hazard curves for PGA and spectral periods, uniform-hazard spectra with a return-period slider, a rotatable 3D M–R–ε deaggregation, gradient hazard maps and deterministic scenarios.
At the site, an equivalent-linear site response analysis (layered SH transfer functions with Darendeli curves, solved by RVT) gives surface spectra and amplification, strain, modulus and damping profiles; synthetic accelerograms play with an oscillating building. Design spectra follow AS 1170.4, ASCE 7-16, AASHTO LRFD, BNBC 2020 and BS EN 1998-1, with liquefaction triggering, Newmark slope displacement and Mononobe–Okabe pressures.
Outputs: an A3 drawing set, an Excel workbook with live formulas (recurrence, BJF97 check, code spectra, liquefaction factors of safety) and a JSON model.