An earthquake occurs due to the abrupt rupture of the earth's crust. Earthquakes are measured using seismometers and their magnitude indicates their size, as measured on the Richter scale. Earthquakes can cause buildings and structures to break and collapse, roads to crack, and injure or kill people. Seismic waves, including P and S body waves, travel outward from the earthquake epicenter and are measured. The 2011 Tohoku earthquake in eastern Japan had a magnitude of 9.0 and caused significant damage through shaking, tsunamis over 10 meters high, and effects on infrastructure, lives, and the economy of Japan.