An interesting pair of events (see attached image from the WLIN AS-1
station) from the Aleutian Islands of Alaska. Preliminary USGS
magnitudes are 6.3 and 6.5. The seismograms are very similar! Although
most large earthquakes are single events (with aftershocks following the
main shock), pairs of earthquakes (approximately the same size and
location and occurring within hours or days of each other), or even
triplets, are not uncommon.