A couple of twitter posts showed up close together that wouldn’t seem to be related at first blush: earthquakes and water droplets in space. But they are, because they’re both showing vibrational effects on liquid spheres. The earth is more like a fluid on time scales longer than when you fall and take a tumble.

Here’s a normal mode animation, depicting the earth (and exaggerated by a factor of about a gazillion) showing the various ways it might ring after an earthquake

But as far as vibrational modes go, there’s nothing special about the earth. I know I’ve posted the Alka-Seltzer video, but this video has extra demonstrations and I can’t recall if I’ve linked to it as well

The first bulk oscillation looks something like a (0,6,0) mode, or something close.

With the bubbles inside the drop, and droplets inside of that, it’s neat how the combining of droplets (~1:35) gives you more ringing; the total amount of energy in the surface tension goes down as the drop gets bigger — the volume increases faster than the surface area or, put another way, bigger spheres have less curvature per unit area, so they store less energy. That energy has to go somewhere , and that’s into a bulk vibration of the drop. There are a couple of instance of this effect in the video.