IRIS does not calculate earthquake locations and magnitudes but instead collects this data from multiple agencies in the U.S. and abroad. This means Seismic Monitor’s values may not always match those listed by another website or source. [For links to agencies for your region or country, look here.]
A missing earthquake is either due to it not being strong enough for inclusion in Seismic Monitor (the minimum magnitude is 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:
If in doubt, informing our administrator of suspect data is appreciated!
A more in-depth version of the above information is here .