A tsunami about half a meter high was reported in Vanuatu, but alerts around the Pacific were canceled.
A nearly identical aftershock of magnitude 7.7 occurred 15 minutes later. There was confusion for a few hours as seismologists sorted out the signalsthe first report of a 7.3 aftershock was canceled, then reissued with the larger magnitude. A better name for this pair of events is an earthquake doublet. As more data comes in, we will be able to map the rupture zones and see to what extent they overlap.
A particularly large aftershock of magnitude 7.1 followed at 10:13, with the same mechanism. When you look at the maps of the mainshock and this event, keep in mind that the subducting plate is moving eastward, opposite to the case of the Samoan quake.
Aftershocks have a small but finite chance of being bigger than the preceding event. In that case, they might well be called the mainshock and the first event renamed a foreshock.