Tectonic plates
What is a tectonic plate?
A tectonic plate is a huge slab of solid rock that is composed of continental and oceanic lithosphere. The size of tectonic plates can vary from a few hundred to a thousand kilometers across. The largest plates are the Pacific and the Antarctic plates. The thickness of plates can vary from 15km for new oceanic plates and 200km or even more for older plates.
How do tectonic plates move?
Tectonic plates move because of the composition of the rock that it's made of. Continental plates (the ones that are underneath continents) are made of granitic rock which are pretty light. The oceanic ones (the ones under oceans) are made of basaltic rock which are heavier. The difference in the plate thickness is a way of compensating for the imbalance in the weight of the two different types. Because the oceanic plates weigh a lot, the tectonic plates that are under oceans are usually 5km thicker whereas the crust under continents is much thicker than that.
Change
Like
all things in the world, tectonic plates change. They are constantly moving and
changing which happens very slowly. Some plates go under each other and some go over each
other. When tectonic plates get jammed together, they build up pressure and
suddenly move. This causes earthquakes.
What should you do in an earthquake?
How do you protect your home from an earthquake?
Canadian shield (earthquake proof zone)