The document summarizes information about earthquakes, including:
1) Earthquakes are measured using the Richter scale, which assigns a number based on the size of the seismic waves.
2) Major earthquakes can cause significant damage by destroying buildings and killing people.
3) The 2011 Tohoku earthquake near Japan's northeast coast was very powerful, registering 9.0 on the Richter scale.
4) This large earthquake displaced GPS sensors and triggered a devastating tsunami.