Earthquakes are a constant danger for people who live in certain areas of the world. The grinding of tectonic plates along fault lines have produced some terrible tragedies over human history. These are some of the worst.
* Haiti, Jan. 12, 2010 – A magnitude 7.0 that killed an estimated 222,570
* Sumatra, Indonesia, Dec. 26, 2004 – A magnitude 9.1 that killed an estimated 222,570
* Aleppo, Syria, Aug. 9, 1138 – An unknown magnitude that killed an estimated 230,000
* Tangshan, China, July 27, 1976 – A magnitude 7.5 that killed an estimated 255,000
* Shensi, China, Jan. 23, 1556 – A magnitude of about 8 that killed an estimated 830,000
* Here's why seismologists warned of an earthquake in California this week
* Devastating photos show aftermath of deadly Italian earthquake
