The document discusses earthquakes and summarizes information about the 2011 Tohoku earthquake in Japan. It provides background on what causes earthquakes and how they are measured on the Richter scale. It then describes the damage earthquakes can cause and the different types of seismic waves. Specific details are given about the 9.0 magnitude Tohoku earthquake on March 11, 2011 near northeastern Japan, the effects it had on the environment, economy and people of Japan. The earthquake also triggered a large tsunami, with waves reaching heights of 30-50 feet and traveling over 500 mph in deep water.