Earthquakes are caused by vibrations that travel through the Earth's crust. They are measured on scales that indicate their magnitude, or size. Strong earthquakes can cause damage like cracks in the ground and broken buildings. Earthquake waves called seismic waves come in two types - P waves and S waves. The 2011 Tohoku earthquake in Japan was very powerful, measuring 7.9 in magnitude. It caused environmental damage through cracks and fires as well as economic and social impacts for Japan.

1. Earthquakes Are Awesome Mathias Vaughan Mrs. Smith 4th April 8, 2011