Earthquake feed. Returns recent earthquakes from USGS for any time window (hour, day, week, month) above a magnitude threshold. Includes location, magnitude, depth, tsunami flag. Each quake includes magnitude + type, depth (km), place, ISO8601 time, lat/lon, tsunami flag, USGS event URL, and felt-report count when available. Wraps USGS GeoJSON summary feeds — public domain, no auth.