IRIS Event Data Sources

IRIS does not calculate earthquake locations and magnitudes but instead collects this data from multiple agencies in the U.S. and abroad. This means you may sometimes see data that does not match those listed by another website or source.

A missing earthquake (in the case of Seismic Monitor, IEB, and other of our tools) is either due to it not being strong enough for inclusion in (Seismic Monitor has a minimum magnitude of about 4, to achieve a globally-uniform distribution), or else the earthquake may not have been reported to us.

If the magnitude, time or location seems wrong, it is probably for one of these reasons: