At around 25:03 or so, you can see on the right side what looks like a radiation detector pole. Is there a nuke plant one one of the islands?
Notice the green saucer-looking things below the siren. We have those poles all over town as we live near a nuke plant. But ours are just a boring gray color.
Well, that makes no sense. Tsunami detection comes from buoys out in the ocean, and warnings trigger simple sirens on poles. See the other photos of tsunami warning towers on that page. And we certainly don't get tsunamis 'round these parts, on the North Atlantic coast.