Was that an earthquake?

We haven't had a good shake in a while.

Twitter chatter (er, twatter??) about the Chiyoda line being suspended for one earlier today reminded me that I used to be on constant earthquake alert.
Over the two years I lived in Miyazaki, I can remember only one time feeling something that might have been an earthquake. I never worried about it. There weren't nearly as many things that could fall on you there, anyway. A few in a row soon after we got to Tokyo had me anxious. The same way you sometimes feel like your phone is vibrating even when you don't have it with you, I started to feel like things were swaying a bit even when they weren't. I found the US Geological Survey's international site that shows the latest earthquakes in the world for the last seven days. I was hitting refresh on it so often that I knew about the quake in China before it was on the news. But soon, it wasn't enough. It shows tremors above 2.5 in the US (did you know the Alaskan archipelago is shuddering constantly?) but only 4.5 and up everywhere else. That doesn't help for the far-off-quake-or-losing-my-marbles answers I needed.

Then I found the Japan Meteorological Agency's homepage. It maps quakes starting from a 1 on the Japanese seismic intensity scale with scattered dots showing how much different places feel them. The JMA even has space for one that hasn't happened yet - a link and a guide to the three (blinding) alert levels for the predicted Tokai earthquake, aka, the overdue big one.

I put links in the sidebar. If I've made you as nervous as I've just made myself, how bout a quick illustrated review of what to stick over your head based on where you are when it strikes? Or, better yet, enjoy the sunshine duration map, instead.