earthquake.usgs.gov http://earthquake.usgs.gov/learn/topics/100_chance.php this page this page http://earthquake.usgs.gov/learn/topics/100_chance.php this page USGS Earthquakes earthquake.usgs.gov SOURCE USGS http://earthquake.usgs.gov/learn/topics/100_chance.php this page "There's a 100 percent chance of an earthquake today." USGS USGS this page