Data Sources

USGS real-time GeoJSON feeds

The dashboard and Live Map use the USGS earthquake summary feeds (past hour, day, 7 days, 30 days; all magnitudes, M1.0+, M2.5+, M4.5+). Each feed is the complete provider set for its definition. USGS updates them about every minute; EQRadar's server caches each feed for 60 seconds. Feeds also contain non-earthquake events (quarry blasts, explosions); EQRadar shows earthquakes only.

USGS FDSN Event Web Service (catalog)

History, counts, activity charts and event details use the USGS FDSN Event Web Service with eventtype=earthquake. Results are paginated on the server (USGS allows at most 20,000 results per query, with 1-based offsets). Counts and activity charts come from the service's count endpoint, so they describe the full filtered result, not one page. Searches are cached for 5 minutes (30 minutes for windows that ended more than a day ago).

USGS Operational Aftershock Forecasts

The Risk Outlook shows USGS aftershock forecasts published for mainshocks in the past 30 days, refreshed every 15 minutes. Each forecast states its model, region, windows and uncertainty. Where no forecast exists, EQRadar says so rather than estimating.

NOAA/NWS U.S. Tsunami Warning Centers

Tsunami Alerts show the latest bulletin of each product published on tsunami.gov by the National Tsunami Warning Center (Palmer, AK) and the Pacific Tsunami Warning Center (Honolulu, HI). Each bulletin is read from the centers' JSON, CAP and text products. Earlier bulletins of the same event are retrieved for the revision timeline. Official NWS zone boundaries come from api.weather.gov. Categories are shown as published. International threat messages are not relabelled as U.S. warnings. Products refresh every minute; there is no archive before EQRadar fetched them.

USGS ShakeMap

Shaking Maps use the preferred, non-withdrawn, real-event USGS ShakeMap product of each earthquake. That includes the georeferenced intensity overlay, contours, the official legend and the official intensity grid for location estimates. ShakeMap estimates shaking intensity; it is not a damage assessment, and intensity differs from magnitude.

USGS Volcano Hazards Program

Volcanoes come from the USGS Hazard Notification System API: the U.S. volcano inventory, current Volcano Alert Levels and Aviation Color Codes, and notices. Coverage is U.S. volcanoes only. Status refreshes every five minutes. Volcanoes without a published status are shown as unknown.

Origin versions (Event Update Tracker)

Version history comes from the FDSN Event Web Service with includesuperseded=true, which returns the origin product versions USGS still retains for an event. The recently updated list uses the service's updatedafter filter. EQRadar has no database, so it does not capture its own snapshots: versions USGS no longer retains, and changes to other products, are not shown. Version data is cached for 5 minutes.

Learning Center

Lessons, quizzes and glossary definitions are written for EQRadar and bundled with the app. Each lesson and term cites the official sources it was written from (mainly USGS, NOAA and Ready.gov), with the date it was last reviewed.

Coverage and completeness

• Coverage is densest in the United States; elsewhere, smaller earthquakes may be missing. A zero count is not proof that no earthquake occurred.
• The catalog is continuously revised: magnitudes, locations and review status change, events can be deleted or merged. EQRadar replaces older versions by event ID and does not take snapshots.
• All times are stored in UTC. EQRadar keeps the time it fetched data separate from the provider's generation time and the event time.

Maps

Maps are drawn with Leaflet. Street tiles come from Esri World Street Map (© Esri and its data sources, including © OpenStreetMap contributors). Satellite imagery comes from Esri World Imagery (Esri, Vantor, Earthstar Geographics, and the GIS User Community) with an Esri labels overlay. The 3D Depth Explorer drapes Esri World Imagery over the catalog reference level as context only; earthquake depths are not measured from that terrain. Attribution appears on every map and 3D view.

Place search

USGS does not offer free-text place search. EQRadar looks up place names with the Esri World Geocoding Service through its own server, or uses your device location when you choose “Use my location”. No place or earthquake data is bundled with the app.

Attribution

Earthquake data: U.S. Geological Survey, Earthquake Hazards Program. USGS-authored data is generally in the U.S. public domain. EQRadar is not an official USGS product.