Earthquake and Tsunami Class

This is actually the class that was postponed from last week. All I can say is that the events in Japan last Friday certainly altered the context of the class.

We started out reviewing the kinds of faults (slip dip and slip strike) and talked about what happened in Japan. Do you know that the Japan moved eight feet? The tectonic plate moved 59 feet! The axis of the Earth shifted by 4 inches! The tsunami reached 6 miles inland at some points! It's hard to grasp an event of that magnitude.

We talked about the Richter scale, and how logarithmic scales work (a 5 is 10 times larger than a 4, a 6 is ten times larger than the 5, etc.). The Japanese quake was at least an 8.9, and the Japanese geologists are now saying it was a 9.0.

I told the kids that all energy moves in waves. We talked a little about light waves, ocean waves and seismic waves. I had them close their eyes while I jumped on the floor (they were sitting on the floor) so they could feel the waves of energy. Then we went over to my "Spidey-Sense Seismograph."

This was fun! It's just a weighted pencil hanging from a shoebox. I pulled a paper strip through to show a (more or less) straight line. Then I had all the kids pound on the table while I drew it through again. Wow! This worked much better than the trial run when I had only one kid pounding on the table! It looked like a real seismograph printout!

We then took a large non-stick frying pan of water (the dark color helped) and the kids took turns tapping the water and watching the waves move around the pan. Then we put a glass bottle in the center so that they could see the waves separate and break around it. This is how scientists learned the Earth's core is solid. I showed them that an earthquake on the rim of the pan would send out waves to two locations on the other side of the Earth, but not directly across the Earth because the inner core is solid.

The we looked at a process known as soil liquefaction. This happens during earthquakes when the water table is high. We filled a plastic box with dry sand. I put my "building," a glass bottle of water deep into the sand. First they shook the dry sand, and the bottle fell over. Then we moistened the sand and the bottle was locked in place (no amount of shaking dislodged it). Then we added more water. To the kids' surprise, the bottle fell over with only slight shaking! The waterlogged sand acted as a fluid when it was moved.

Then we headed outside. I had several containers of water with wooden blocks. The kids could move blocks under the water to see what happened to the water surface (it mirrors the disruption below the surface exactly as the ocean does when a tsunami is formed).

The favorite outside experiment was the tsunami model. I used a plastic under bed box for this. I put a pile of sand on one end and a board on the other. Then I filled the whole thing half full of water. The kids stuck sticks into the sand to represent houses and then counted down... Mxyl lifted the board on cue and we had a perfect small tsunami!


Then it was back inside for the grand finale.

I had made a very large and fairly deep tray of jello. I put a layer of plastic wrap over it and let the kids pat it to make "earthquakes." The thing about jello is that you can actually see the lines of force, the energy waves, as they move through.

Klenda handed out three sugar cubes to each kid and they all built "houses" on the jello. They counted down and... I patted the jello vigorously! Earthquake!!! This is the "after" shot.

And then we peeled off the plastic and ate the jello, of course!