How Klaxon works

Klaxon brings together what official agencies publish about earthquakes, tsunamis and volcanoes, and shows it on one map in four languages. It does not measure, forecast or warn: every figure comes from an agency, and every warning is relayed in the agency's own words. This page explains how.

Where the data comes from

• Earthquakes from the U.S. Geological Survey (USGS), checked every minute, with reports from EMSC, the Japan Meteorological Agency (JMA) and GeoNet in New Zealand, also checked every minute.
• Official tsunami messages from the Pacific and US National Tsunami Warning Centers and from JMA, checked every minute.
• Volcano alert levels from USGS, JMA and GeoNet, eruption reports from JMA, and volcanic ash from aviation warnings (SIGMETs), checked every ten minutes.
• Cyclones, floods and droughts from GDACS, checked every five minutes.

Every source, its licence and the credit it asks for are listed on the data sources page.

One earthquake, one event

Several agencies often report the same earthquake. Klaxon treats a report from EMSC, JMA or GeoNet as the same quake as a USGS event when it is within 90 seconds and 150 km of it. The map keeps the USGS magnitude, and each agency's own figures and shaking scale are shown in the event's panel.

If another agency reports a quake before USGS does, Klaxon shows it at once as an event of its own. When USGS reports it, that event gives way to the USGS one, and its page redirects there. USGS itself sometimes files one quake twice, a first estimate and a final record; when USGS links them, Klaxon folds the first into the final one. If USGS withdraws an event, Klaxon removes it.

Official warnings, word for word

Tsunami warnings, advisories and cancellations are shown exactly as the agency issued them, with its name, and are never summarised, translated into a new level or worked out by Klaxon. Test and exercise messages are left out. Volcano alert levels are shown in each agency's own terms. Under Japan's Meteorological Service Act, only licensed bodies may issue earthquake or tsunami forecasts, so for Japan Klaxon only relays what JMA has issued.

Klaxon is not an official warning service. If you are in an affected area, follow your local authorities. See the disclaimer.

News

For significant events, Klaxon gathers headlines from a short list of news outlets and news searches, once per event rather than for each visitor, and keeps only the headline, the outlet, the link and the time. Each headline links to the original story.

What Klaxon does not do

• It does not publish its own magnitudes, locations, forecasts or alert levels.
• It does not predict earthquakes or tsunami arrival times. Where an agency gives an arrival time, it is shown as issued.
• First estimates are marked as preliminary until USGS reviews them, and corrections are shown when they come.