00:00Every 26 seconds, the Earth makes a tiny shake.
00:04You can't feel it, but seismic machines can.
00:07And for decades, scientists tried to figure out where it came from.
00:11Some think it's caused by underwater ocean waves,
00:14which hit the shallow edge of the continent and vibrate it like a drum.
00:19Others think it's the rumbling of a nearby volcano.
00:22But some people actually believe this proves the Earth is flat
00:26and that the pulse comes from the machinery that holds up the sky.
