An American flag flutters on a young tree stripped of bark after a massive tornado passed through the town killing at least 116 people May 24, 2011 in Joplin, Missouri. The tornado that ripped through the town of about 50,000 people May 22, is being called the deadliest single tornado in the U.S. in 60 years. (Photo by Julie Denesha/Getty Images)

A car stands in water on Ferry Road after two magnitude 6.0 and 5.5 earthquakes struck on June 13, 2011 in Christchurch, New Zealand. The aftershocks have followed four months after the major eathquake which hit the city on February 22, 2011 resulting in the deaths of 181 people. (Photo by Martin Hunter/Getty Images)

Young girls practice acrobatic skills in the Sichuan Provincial Art School July 14, 2008 in Chengdu of Sichuan Province, China. (Photo by China Photos/Getty Images)

A copy of part of the Dead Sea Scrolls is displayed at the “Dead Sea Scrolls: Life and Faith in Biblical Times” exhibition at Discovery Times Square on December 16, 2011 in New York City. (Photo by Spencer Platt/Getty Images)

A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

In this June 20, 2015 photo, Niberta Galvez uses the bottom half of his shirt to collect coca leaves in Samugari, Peru. Coca farmers were among the locals who, in 1984, formed citizen militias to help the military beat back Shining Path rebels, reducing them to a small group of fewer than 500 who now are deeply involved in drug trafficking. (Photo by Rodrigo Abd/AP Photo)

Bibi rides her bike on the Playa during the Burning Man 2015 “Carnival of Mirrors” arts and music festival in the Black Rock Desert of Nevada, August 31, 2015. Approximately 70,000 people from all over the world are gathering at the sold-out festival to spend a week in the remote desert to experience art, music and the unique community that develops. (Photo by Jim Urquhart/Reuters)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)