It's been a while (months at least?), but today there is a swarm of small (3s and smaller) north of Puerto Rico, south of the subduction trench. These swarms have been common over the last few years. A swarm like this would not show up on the USGS-NEIC lists outside of USA because for most areas the quakes have to be M4.5+ to be on that list.

So, there have been bunches of these not followed by any large quake. But, there is always the chance that a swarm could be followed by a major or great quake, why not? It is a subduction zone (on a highly oblique plate boundary). If these were beneath land, I imagine that animals (and a few people) would notice the 3s if they were within a few or 10 km, and might behave oddly. But, if that happened, what do you do about that? From instruments we know there is a swarm going on, and from history of the last few years, we know that most of the time nothing happens.
Chris