Computing Methods
The methods, data sources, and models behind Intensity Lab, by topic. Each page stands alone: start with whichever one answers your question.
Intensity and earthquake data
Intensity Information & Examples
How instrumental intensity (MMI) is calculated from ShakeMap grids and station recordings, and the conversion from PGA and PGV to MMI.
USGS Earthquake Data & ShakeMap
Where event data comes from, the magnitude floor and coverage region, ShakeMap grid interpolation, and when notifications are sent.
Observed Seismic Station Data
How ShakeMap's station list identifies the instruments that recorded an event, and how their waveforms are retrieved.
ShakeMap vs. GMPE Comparison
The four NGA-West2 ground motion models, their inputs, and how their predictions compare with ShakeMap intensity.
Place & Population Data
The gazetteer of 2,002 cities and communities used for intensity reports: its source, population threshold, and coverage.
Animations and videos
Physics Animation (Blender)
One rigid-body scene, one earthquake, rendered at different sites: the objects, how ground motion drives the scene, and GPU rendering.
How We Use the BBP Simulation API
Turning a USGS earthquake into a physics-based ground motion simulation on bbpservices.net: source, sites, method, Vs30, and what comes back.
How the site is built
APIs Used & Offered
The outside services Intensity Lab depends on, and the API it offers: public endpoints, and endpoints for registered users with an API key.
Text-to-Speech Narration
How each animation's spoken narration is written, prepared for speech, and synthesized locally with Kokoro TTS.
Local Language Model
The locally hosted model behind the Seismic Chat page, with a standard set of questions used to check its answers.
Related: the MMI Scale and Instrumental Intensity pages explain what the intensity numbers and colors mean for a general audience. Questions or feedback? Submit feedback.