From grimoire
Conducts probabilistic seismic hazard analysis (PSHA), ground motion characterization, site amplification, and communicates hazard for engineering design, land use planning, or risk management.
How this skill is triggered — by the user, by Claude, or both
Slash command
/grimoire:design-seismic-hazard-assessmentThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Conduct a probabilistic seismic hazard analysis (PSHA) by characterizing seismic sources, selecting ground motion prediction equations, computing hazard curves, and translating hazard to design-level ground motions with appropriate site-specific amplification.
Conduct a probabilistic seismic hazard analysis (PSHA) by characterizing seismic sources, selecting ground motion prediction equations, computing hazard curves, and translating hazard to design-level ground motions with appropriate site-specific amplification.
Adopted by: USGS National Seismic Hazard Maps (the basis for US building codes), ASCE 7 seismic design standard, Eurocode 8 (European seismic design), IBC (International Building Code), and nuclear regulatory agencies worldwide (IAEA SSG-9, NRC RG 1.165) use PSHA as the standard methodology. The PEER NGA-West2 and NGA-East ground motion databases represent the global state of practice for ground motion prediction. Impact: Cornell (1968) introduced PSHA as a unified framework for quantifying earthquake hazard — it replaced deterministic maximum credible earthquake (MCE) methods that systematically over- or under-designed structures by ignoring earthquake recurrence. PSHA has since been validated by comparison of predicted vs. observed ground motions in major earthquakes (Northridge 1994, Kobe 1995, Christchurch 2011). Building codes based on PSHA have demonstrably reduced structural collapse rates.
Before any technical work:
Identify all earthquake sources that could affect the site:
For each source:
Use USGS Quaternary Fault and Fold Database and peer-reviewed fault studies.
GMPEs predict ground motion intensity (Sa, PGA) as a function of magnitude, distance, and site conditions:
Selection criteria: match the tectonic environment (active crustal, subduction zone, stable continental), magnitude range, and distance range relevant to the site.
PSHA combines source characterization and GMPEs via numerical integration:
λ(Z > z) = Σᵢ νᵢ ∫∫ P(Z > z | m, r) f_M(m) f_R(r) dm dr
Where:
Software: OpenQuake (free, open-source, global standard); HAZ45; EZ-FRISK.
Output: hazard curve (annual probability of exceedance vs. ground motion level); disaggregation (which magnitude-distance bins dominate the hazard at the target return period).
Site-specific amplification modifies reference rock hazard to site soil conditions:
Apply amplification factors to reference rock spectra to obtain site-specific design spectra.
Translate PSHA output to actionable design parameters:
Report: hazard methodology, source model, GMPEs selected with weights, site parameters, target return periods, resulting spectra with comparison to code values.
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