Earthquake magnitude describes the size of a seismic event at its source. The tracker lets visitors sort recent earthquakes by preferred magnitude and compare that value with depth, time, place, and official source details.
Magnitude is logarithmic and should not be treated as a direct damage forecast. Local intensity varies with distance, geology, depth, rupture direction, and the vulnerability of buildings and infrastructure.
How to compare magnitude values
Choose a consistent feed window and sort strongest first. Each whole-number magnitude increase represents ten times the measured wave amplitude, so small decimal differences are meaningful. For careful comparisons, check the displayed magnitude type and review status.
Why earthquakes use different magnitude types
Local magnitude, body-wave magnitude, surface-wave magnitude, and moment magnitude use different measurements suited to particular sizes and distances. The USGS can calculate several values and select a preferred magnitude based on available waveforms and method reliability.
Magnitude is different from intensity
An earthquake has one preferred magnitude at a given stage of analysis, but many intensity values across the affected area. Intensity describes observed or measured shaking at a location. Use official intensity and ShakeMap products when the question is what people or structures experienced.