Verification & Validation
A simulated seismogram is only worth something if it resembles what a seismometer actually recorded. We publish two kinds of evidence that it does, and they are different work — so they get separate pages rather than one table that would have to pretend they were comparable.
SCEC validation events
Historical earthquakes the SCEC Broadband Platform developers curated for exactly this purpose, each shipping the observed recordings it should be judged against. We re-run the suite for every release of our simulation service, so the numbers below belong to a specific version rather than to the software in general.
No sweep has been recorded yet.
View the suite →
Recent earthquakes
Earthquakes we processed as they happened, simulated and then compared against recordings fetched from the seismic networks. Broader coverage than the curated suite and messier inputs — the station set is whatever was recording that day, not a set chosen for the purpose.
- Reports published
- 0
- With a full web report
- 0
View the reports →
Both pages report the same metric. Mean |bias| is ln(observed / simulated) RotD50 spectral acceleration, averaged over stations. A bias of 0.69 is a factor of two, and that is the pass band on both pages. It is declared before each run, not chosen after seeing the result.
Verification — the half that has not started
Validation asks whether a simulation matches what instruments recorded. Verification asks something different: whether simulated motions for a synthetic scenario land inside the range empirical ground motion models predict. No recordings are involved — the target is built by averaging the NGA-West2 medians. SCEC defines 16 such scenarios; across 7 methods that is 112 cells.
The suite is defined in code and pinned by tests, so when it does run its cells fill in against a denominator fixed beforehand — the only way a completeness figure means anything. Validation results, including how far each method sat from the recordings, are available to any signed-in account.