magnitude 7.9 earthquake has occurred off the coast of Peru about ninety miles south of the capital Lima. There are unfortunately reports of deaths and housing damage.
The fear now is of a tsunami. Hawaii is on the alert.
For additional geography on the earthquake check out the P-Wave Map. For instance, it took nine minutes and four seconds for the force of the Peruvian earthquake to reach Washington D.C. Also note there was a force on the antipode in Indochina.
For general background: earthquakes are measured on a logarithmic scale known as the Richter Scale. For example, an 8.0 would cause ten times more shaking and release thirty times more energy as would a 7.0. A 7.0 would cause one hundred times more shaking and release nine hundred times more energy.