1- Black Death Disaster:

The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people and peaking in Europe in the years 1346--53. The Black Death is thought to have originated in the arid plains of central Asia, where it then traveled along the Silk Road, reaching the Crimea by 1346. From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships. Spreading throughout the Mediterranean and Europe, the Black Death is estimated to have killed 30--60% of Europe's total population. All in all, the plague reduced the world population from an estimated 450 million down to 350--375 million in the 14th century. More details

2. Indian Ocean Earthquake and Tsunami:

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, 26 December 2004, with an epicentre off the west coast of Sumatra, Indonesia. The earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 ft) high. It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand. More details

3. 1783 Iceland Eruption:

Laki or Lakagígar is a volcanic fissure in the south of Iceland. Between 1783 and 1784, Laki eruption and its aftermath caused a drop in global temperatures, as sulfur dioxide was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in India. The eruption has been estimated to have killed over six million people globally, making the eruption the deadliest in historical times. More details

4. 1906 San Francisco Earthquake:

The San Francisco earthquake of 1906 struck San Francisco and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. Devastating fires broke out in the city that lasted for several days. As a result of the quake and fires, about 3,000 people died and over 80% of San Francisco was destroyed. The earthquake and resulting fire are remembered as one of the worst natural disasters in the history of the United States alongside the Galveston Hurricane of 1900 and Hurricane Katrina in 2005. The death toll from the earthquake and resulting fire is the greatest loss of life from a natural disaster in California's history. More details

5. The Great Flood:

The Great Flood

The largest floods known to have occurred in human history are those from the end of the last ice age, between 13,000 and 8,000 years ago. As the world's great glaciers began to melt, they left large freshwater lakes behind that had been precariously confined by retreating ice dams. When those ice dams failed, the floods that resulted were almost beyond comprehension.

6. Hurricane Katrina Disaster:

Hurricane Katrina formed over the Bahamas on August 23, 2005, and crossed southern Florida as a moderate Category 1 hurricane, causing some deaths and flooding there before strengthening rapidly in the Gulf of Mexico. The hurricane strengthened to a Category 5 hurricane over the warm Gulf water, but weakened before making its second landfall as a Category 3 hurricane on the morning of Monday, August 29, in southeast Louisiana. It caused severe destruction along the Gulf coast from central Florida to Texas, much of it due to the storm surge. The most significant number of deaths occurred in New Orleans, Louisiana, which flooded as the levee system catastrophically failed, in many cases hours after the storm had moved inland. Eventually 80% of the city and large tracts of neighboring parishes became flooded, and the floodwaters lingered for weeks. However, the worst property damage occurred in coastal areas, such as all Mississippi beachfront towns, which were flooded over 90% in hours. More details

7. 1883 Eruption of Krakatoa:

The 1883 eruption of Krakatoa in the Dutch East Indies (now Indonesia) began on August 26, 1883 (with origins as early as May of that year) and culminated with several destructive eruptions of the remaining caldera. On August 27, two thirds of Krakatoa collapsed in a chain of titanic explosions, destroying most of the island and its surrounding archipelago. Additional alleged seismic activity continued to be reported until February 1884, though reports of those after October 1883 were later dismissed by Rogier Verbeek's investigation. It was one of the deadliest and most destructive volcanic events in recorded history, with at least 36,417 deaths being attributed to the eruption itself and the tsunamis it created. Significant additional effects were also felt around the world. More details

8. Spanish Flu Disaster:

The 1918 flu pandemic (January 1918 -- December 1920) was an unusually deadly influenza pandemic, the first of the two pandemics involving H1N1 influenza virus. It infected 500 million people across the world, including remote Pacific islands and the Arctic, and killed 50 to 100 million of them—three to five percent of the world's population making it one of the deadliest natural disasters in human history. More details

9. Japan Earthquake and Tsunami of 2011:

Japan earthquake and tsunami of 2011 was a natural disaster that occurred in northeastern Japan on March 11, 2011. The event began with a powerful earthquake off the northeastern coast of Honshu, Japan's main island, which caused widespread damage on land and initiated a series of large tsunami waves that devastated many coastal areas of the country, most notably in the Tōhoku region. The tsunami caused nuclear accidents, primarily the level 7 meltdowns at three reactors in the Fukushima Daiichi Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents. Many electrical generators were taken down, and at least three nuclear reactors suffered explosions due to hydrogen gas that had built up within their outer containment buildings after cooling system failure resulting from the loss of electrical power. More details

10. 2011 Tornado Outbreak:

The April 25--28, 2011 tornado outbreak was the largest and one of the deadliest tornado outbreaks ever recorded, affecting the Southern, Midwestern, and Northeastern United States and leaving catastrophic destruction in its wake. While the states that were hardest hit were Alabama and Mississippi, the outbreak also produced destructive tornadoes in Arkansas, Georgia, Tennessee and Virginia, and affected many other areas throughout the Southern and Eastern United States. More details