Random earthquake generator

How to use the random earthquake generator

1. 1 Set the How many slider to draw up to eight earthquakes.
2. 2 Enter Recent days to set how far back to look, up to 365.
3. 3 Set Minimum magnitude and Maximum magnitude to narrow the results.
4. 4 Click Generate, then follow a result to the USGS event record.

Where the events come from

The data is the USGS earthquake catalog, which combines reports from seismic networks in the US and around the world. The tool asks for events from the last 30 days by default, or up to 365 if you change Recent days, and keeps the 500 most recent that fit your magnitude limits. It then picks at random from those 500. The feed is refreshed every five minutes.

Why most draws are small

With no minimum magnitude, the 500 most recent events are mostly tiny quakes, many below magnitude 2, picked up by dense sensor networks in places like California, Alaska, and Hawaii. They're real, but hardly anyone feels them. Set Minimum magnitude to 4 or 4.5 to see events from around the world. Outside the US the catalog is most complete for quakes of about 4.5 and up.

Reading a result

Magnitude measures the energy released at the source, not the shaking at any one place. Depth matters as well: a shallow magnitude 5 can do more damage than a deep magnitude 6. The Tsunami flag means the event was large and in an ocean region, so warning centres would look at it. It does not mean a tsunami happened.

Magnitude and location are often revised in the hours after an event, so follow the USGS link for the current figures.

Frequently asked questions