How does anything live on islands where the max elevation is less than about 20 feet?


Every time I see videos of boats hitting massive waves that they have to climb like a small mountain it makes me wonder how these same storms don’t just wipe clean any and every small island in the ocean. It seems like whenever a big storm came, waves would just wash over any low lying islands in their path and take everything with them into the oceans. Yet you still see palm trees and sometimes even people and animals living on tiny islands.

In: Other

The same waves typically peter out as the sea floor elevation rises towards the island.

While it does happen, the waves produced out at sea dont carry the same force as a tidal wave, as only the surface water is raised (vs a tsunami in which the entire depth of the ocean is raised)

Well, let’s start by looking at a wave. From the surface a wave kind of looks like a ‘hill’ of water moving forward. It’s a little more accurate to think of a wave as a wheel of energy rolling through the water. Half of this energy wheel is above sea level, half is below it.

The water itself stays in place but where this wheel of energy passes, the rolling of the wheel pushes the water up. Kinda like moving your finger underneath a blanket, the blanket doesn’t move but as you move your finger, different sections of the blanket get pushed up.

If you’re ever in the swimming pool, you can replicate it with your hand. Just hold your hand vertically under the water, palm forward. When you push, your hand will displace the water causing a wave to rise. The water sinks right back down behind your hand but wherever you push your hand, the wave will go.

Now those ships climbing mountainous waves are usually in the open ocean in deep water. When storm winds push the water, massive waves are created.

Islands, on the other hand, don’t float in deep water like a boat. You can think of them more like hills on the continental shelves or the peaks of underwater mountains. Water near an island is shallow and gradually gets deeper until it drops off into the depths.

That means that when that energy wheel approaches an island, there is gradually less and less water for it to push around. On top of that, many islands are surrounded by reefs and rocky formations that break up a wave before it reaches the shore.

That doesn’t mean that waves can never bother an island. Some tiny islands really are frequently washed over when there’s a storm. Others are protected by reefs or have high points where animals can seek refuge. And truly massive amounts of force like seafloor earthquakes can create tsunamis that are almost unstoppable.

The biggest danger for really low lying land is an overall rise in sea level. Waves is just water that rises *above* sea level. There are many ways of dealing with waves. But if the sea level itself simply rises above a low lying island, that’s a whole different story.