Earthquakes, live

Pick a feed — Significant, M4.5+, M2.5+, M1+ or All for the past hour, day, 7 days or 30 days — and the page fetches it from the US Geological Survey. The feeds are rebuilt every minute; with Auto-refresh on, the page fetches again each minute while the tab is visible and tells you about new earthquakes (outlined on the map). Search the catalogue asks the USGS event service for any date range and magnitude, optionally within a radius of your location.

How to use it

Map — every earthquake is a circle sized by magnitude and coloured by depth (red shallow → yellow → green → blue → violet at 700 km) or by age (past hour, day, week, older). Thin red lines are the plate boundaries; thicker ones are subduction zones, where the deep earthquakes are. Drag to pan, scroll or pinch to zoom, double-click to zoom in; Pacific puts the Ring of Fire in the middle. The world map is drawn on the page with no map tiles; Street map switches to OpenStreetMap (through Leaflet, the same map as the flight tracker) when you want roads and towns.
List — filter by minimum magnitude, depth (shallow < 70 km, intermediate, deep > 300 km), felt reports, PAGER alert, the tsunami flag, or earthquakes only (the feeds also carry quarry blasts and explosions), search by place name, and sort by time, size, distance from you, depth or the USGS significance score.
Details — magnitude and its type (Mw, mb, ml, md…), what that size usually does, depth, the energy released (and the TNT equivalent), the number of Did You Feel It? reports and the highest intensity people reported, the ShakeMap intensity, the PAGER alert with what the colour means, and the tsunami flag — which marks a large earthquake in an oceanic region, not that a tsunami happened (see tsunami.gov). Links go to the event’s ShakeMap, DYFI, PAGER and moment-tensor pages on the USGS site when they exist. Aftershocks and foreshocks searches M2.5+ within 100 km from a week before to a month after.
Your location — choose a city, type coordinates, or let the browser locate you (the same place picker as the astronomy tools). Every earthquake then shows its distance and bearing, a dashed great-circle line runs from the selected earthquake to you, and the details say when its P wave and S wave reach (or reached) you, counting down if they are still on their way.
Gutenberg–Richter — the number of earthquakes at or above each magnitude, on a log scale, for what is on the map. The magnitude of completeness Mc (below it the network misses events) is found by maximum curvature plus 0.2, and the b-value by Aki’s maximum-likelihood estimate with its uncertainty. b is close to 1 in most tectonic settings — ten times as many M3s as M4s.
Magnitude and energy — compare two magnitudes: each whole step is 10× the ground motion on a seismograph and about 32× the energy (10^1.5), so an M7 releases 1000 times the energy of an M5.

Phone seismograph turns a phone into a (noisy) seismometer.

How the arrival times are worked out

The P (compressional) wave travels fastest; the S (shear) wave follows; the gap between them grows with distance — about 8 km for each second of S − P close by, which is how a single station estimates how far away a quake is. The page uses first-arrival times from the iasp91 reference Earth model (Kennett and Engdahl, 1991), computed with ObsPy’s TauP for distances from 0° to 180° and depths from 0 to 700 km and interpolated (within about a second of TauP). Beyond about 104° the Earth’s core casts a P-wave shadow: only weak diffracted P arrives until PKP, through the core, emerges beyond about 140°. Real arrivals differ by a few seconds with local geology.

Data and licences

Earthquakes: USGS real-time GeoJSON feeds and the FDSN event web service (public domain, US Government). Feeds may change as events are reviewed; magnitudes of recent events are often revised.
Plate boundaries: PB2002 (Peter Bird, An updated digital model of plate boundaries, G³ 2003, doi:10.1029/2001GC000252) as GeoJSON by Hugo Ahlenius / Nordpil (fraxen/tectonicplates), Open Data Commons Attribution Licence 1.0; rounded to 0.1° for this page.
Coastlines: Natural Earth 1:110m land (public domain).

Privacy

The page fetches the feeds and searches from earthquake.usgs.gov (CORS, no key). Only the search itself is sent; a radius search sends the centre point — your location, rounded to 4 decimal places — to the USGS. Otherwise your location stays in this browser. Street map loads Leaflet from cdnjs.cloudflare.com and map tiles from tile.openstreetmap.org, which see your IP address and the area you look at; the default world map needs neither.