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Engineering & geotechnicsLive data

Seismic Hazard Explorer

A century of earthquakes around your site, turned into statistics.

Retrieves the instrumental earthquake catalogue around any site, fits the Gutenberg–Richter law, and estimates annual rates, return periods and the probability of exceedance over a design life, with plate boundaries on the map.

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Seismic Hazard Explorer
10⁻³10⁻²10⁻¹10⁰10¹10²45678McGutenberg–Richterb = 1.02T(M≥6) ≈ 38 yrMagnitude MN(≥M) per year

Overview

Choose a site and a search radius. Events from the USGS ComCat catalogue are plotted by depth and magnitude. The magnitude of completeness is estimated by maximum curvature, and the b-value by Aki’s maximum-likelihood method.

Return periods follow from the fitted rates, and the Poisson model gives the chance of at least one event above each magnitude during a 50-year design life.

What you enter · What you get

What you enter

  • Site location
  • Search radius and minimum magnitude
  • Catalogue start year and design life

What you get

  • Epicentre map with plate boundaries
  • Gutenberg–Richter fit (a, b, Mc)
  • Return periods and exceedance probabilities
  • Largest events and depth distribution
  • Nearest plate boundary and its type

How it works in the field

Place the site
Fetch the catalogue
Read rates and probabilities

Method and equations

Gutenberg–Richter law

Cumulative annual number of events with magnitude M or larger.

log10 N(M) = a − b M

Maximum-likelihood b-value

Aki (1965) estimator with Utsu’s correction for binned magnitudes.

b = log10e / (M̄ − (Mc − ΔM/2))

Poisson exceedance

Probability of at least one event in t years for annual rate λ.

P = 1 − e−λ t  ·  TR = 1/λ

Who uses it

Engineering seismologistsStructural and geotechnical engineersInsurers and planners

Standards and references

  1. Gutenberg, B. & Richter, C.F. (1944). Frequency of earthquakes in California. BSSA, 34(4), 185–188.
  2. Aki, K. (1965). Maximum likelihood estimate of b in the formula log N = a − bM. Bull. Earthq. Res. Inst., 43, 237–239.
  3. Wiemer, S. & Wyss, M. (2000). Minimum magnitude of completeness in earthquake catalogs. BSSA, 90(4), 859–869.
  4. Bird, P. (2003). An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems, 4(3), 1027.
  5. U.S. Geological Survey, ANSS Comprehensive Earthquake Catalog (ComCat).
Results support professional judgement. They do not replace a licensed engineer’s or geologist’s sign-off.

At a glance

Category
Engineering & geotechnics
Runs on
Phone, tablet and desktop browser
Export
CSV catalogue, PNG charts, PDF report
Access
Subscribers

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