It's one of nine in recorded history. The first one was in 1995, though, so they probably weren't looking for them down there before then. 2012 is
the only year there's been more than one quake south of -75 latitude; there have been three so far this year. So yeah. Highly unusual, but a sign of
the times. (To compare, there've been over 1,400 quakes near the north pole since 1963...)