A Tale of Two Earthquakes.

The article discusses four reports within the issue regarding geophysics research, including one by Sato and colleagues, Simons and colleagues, Ide and colleagues, and Vigny and colleagues. The teams illustrate the use of a network of global positioning system (GPS) detectors to show how the Earth's surface deformed before and after the Tohoku-Oki magnitude 9 (M9) earthquake in Japan on March 11, 2011 and the M9 earthquake in central Chile (Maule) on February 27, 2010, in which thousands of lives were saved as a result of early warning systems for tsunamis.