If you’ve ever dropped a rock into a pond and watched the ripples go across the surface of the pond, you know that waves can carry energy quite a distance away. This makes sense to us on water, but it seems less likely to occur over land. Sure, we’ve seen the video of a road or bridge buckling during an earthquake and if we think about it long enough, it should stand to reason that the waves are moving across the surface of the land just like the surface of the water, but have you considered how far away that can happen?
A group called IRIS Education and Public Outreach has put together this video showing the seismographs in the United States just after the large earthquake near Kathmandu, Nepal this weekend. The waves that it produced lift the ground up (in red) and then lower it (in blue). These are very small motions that we couldn’t actually feel, but it was happening this far away.
If you watch closely, the waves first travel from north to south, then switch from south to north. The reason for that is the shortest distance from Nepal to the U.S. is a path over the North Pole, so the first waves to arrive were moving north to south. A little later the waves that make the long path around the globe came up from south to north.
It really is amazing that something so far away can actually have a literal ripple effect here in the middle of America.
– Storm Track Chief Meteorologist Matt Miller