How does a seismometer work? We have here an example of a very, very primitive hardware-stores seismometer. These are all components that you can buy in a hardware store or an electronic store. The main part is this boom here and that boom is suspended on two springs. These are these two little strings that you see going up and down like a triangle. And when the ground starts shaking in this direction then this boom would move back and forth like I'm inducing now and we have a set of magnets in this part and a copper plate and copper wires in the copper colored part which is the actual mass and when you look at some of the basic laws of physics you know that when you have an electric conductor moving in the magnetic field that this induces a current. And we pick up this current here and then run it through an other device called a digitizer and then into a computer where we can store and analyze the data. Now what happens during an earthquake? Of course currently we don't have an earthquake here so let me simulate an earthquake. Now I hit the desk with my fist. The desk shook in the same way or in a similar way as it would shake when an earthquake would hit McCone Hall here and you see that this instrument moves the mass moves due to the shaking that I induced and we can see the shaking here on the screen after it went through the digitization process.