CTC Results
The CISN Testing Center (CTC) consists of scientific analysis software, CISN EEW algorithm performance reports, and earthquake observational data. This entry is a collection point for current and past results from the CTC testing center.
Contents
Daily Event Summaries
Performance summaries for specific earthquake are also plotted. These plots show time series of EEW parameters logged by ShakeAlert during real-time operations. The ShakeAlert algorithms log their trigger information, and the ShakeAlert Decision Module plots the earthquake parameters released to ShakeAlert users.
- Magnitude Forecast Time series - These present the performance of both the algorithms (Elarms, Virtual Seismologist, and OnSite) as well as the ShakeAlert Decision Modules.
- Location Error - Plot of the difference between forecast epicenter location and final ANSS epicenter
- Speed - Seconds after origin time when Decision Module Produces Alert.
- Magnitude Distribution - XY plot showing observed data (x) and ShakeAlert forecast data (y). Accurate forecasts will fall on the diagonal. Distributions above or below diagonal indicate a systematic bias in parameter forecasts.
ShakeAlert Cumulative Summaries
ShakeAlert cumulative summaries are based on a "selected" start date (current selected at 1 Sept 2011), through current date. The CTC retrieves all events in this time range from ANSS, then filters them in two ways. First, it removes all events less than M3.5. Second, it removes all events outside of the California CSEP Testing area. The CSEP testing area the includes all of California, and a little room on each edge including Nevada, Mexico, and the Pacific ocean.
The four cumulative summaries are:
- Speed Test - Shows time system took to produce a warning. Does not include distribution time from ShakeAlert to users. (Time decision Module has event forecast - event origin time)
- Location Error - Shows difference between final observed location and forecast location (in km). Uses difference between epicenter locations (rather than hypocenter locations).
- Magnitude - Shows difference between (Observed - Forecast) final magnitude. Values above zero show over underestimated magnitudes. Negative values show overestimated magnitudes
- Magnitude Distribution - Shows x-y plot with observed mag on x and forecast mag on y. Accurate forecasts will fall on a diagonal line.
- ShakeAlert Cumulative Summaries At bottom of page
- ShakeAlert Cumulative Summaries since Elarms2 at bottom of page
ShakeMap Ground Motion Observations
Ground motion data used in associated ShakeMap for each event are logged in the ShakeCast monitoring pages.
Filtered ANSS Catalog of Earthquakes
Many of the ShakeAlert evaluation tests are based on comparing ShakeAlert triggers against an observational earthquake catalog. ANSS catalog has been selected as the authoritative catalog.
Two catalog filter stages are applied to the raw catalog. First, all events outside the CSEP California Testing Region are dropped. Second, all events below M3.5 are dropped. The resulting catalog is the authoritative catalog used to compare ShakeAlert triggers against.
The ANSS earthquake catalog is plotted on California maps for different time frames, showing events over last one month, two months,four months, and six months. Maps of these event catalogs are posted here:
The filtered ShakeAlert catalog contains only M3.5 and larger events within the geographical state of California. These catalogs for specific magnitude ranges and date ranges are plotted here:
