There are lots of things you could do for a geography project model to do with with earthquakes. It depends how long you have and how complex you need/want to make it really!
Something relatively simple to pull off would be to make two colliding tectonic plates. You could show a cross section of the different layers of the earth's crust, and show what happens when the two plates push against each other. Something like this would be relatively easy to make:
If you wanted to expand on this and make something a little more detailed, you could add buildings and civilisation on the top, showing the effects of seismic movement on a city- how the buildings sway and move, and other consequences on the urban landscape such as liquefaction or tsunamis.