The Titanic sank in the North Atlantic! The ship struck an iceberg at 11:40 PM on April 14 and sank at 2:20 AM on April 15. The ship had only 20 lifeboats (capacity 1,178) – enough for only about half the passengers (regulations were based on outdated tonnage rules). The nearby ship Carpathia rescued 705 survivors. The disaster exposed class discrimination: first-class passengers had higher survival rates than third-class. The wreck was discovered in 1985 by Robert Ballard. It lies at a depth of 12,500 feet (3,800 meters). The sinking remains one of the most famous maritime disasters in history.

The legend of Mrs. O'Leary's cow is famous! The Chicago Tribune reporter Michael Ahern admitted in 1893 that he had invented the story. The actual cause is unknown (perhaps a neighbor smoking a pipe). Mrs. O'Leary was exonerated in 1997 by the Chicago City Council. The fire devastated Chicago, but the city rebuilt quickly, leading to the Chicago School of architecture (skyscrapers). The Peshtigo Fire, which occurred the same night, was much deadlier but less famous because it struck a rural area. The Great Chicago Fire is commemorated with a fire hydrant at the O'Leary property (the only structure that survived on that block). The fire led to fire codes requiring brick and stone construction, not wood.

Pompeii was preserved! The eruption lasted about 24 hours. The ash preserved buildings, frescos, mosaics, furniture, food, and even the forms of people and animals (plaster casts). The cities were rediscovered in 1748 (Pompeii) and 1738 (Herculaneum). Pompeii is now a UNESCO World Heritage Site and one of the most popular tourist attractions in Italy (over 2.5 million visitors annually). The eruption is one of the most famous volcanic eruptions in history. Mount Vesuvius is still active and is considered one of the most dangerous volcanoes in the world (millions of people live near it). The last eruption was in 1944 (during WWII). The volcano has erupted dozens of times since 79 CE.

The San Francisco earthquake was a major disaster! The earthquake occurred at 5:12 AM. The initial shock was felt as far away as Oregon and Nevada. The resulting fires were more destructive than the quake; firefighters had to dynamite buildings to create firebreaks (sometimes backfiring). Over 500 city blocks were destroyed. The city was rebuilt quickly, and the 1915 Panama-Pacific Exposition celebrated its recovery. The disaster led to the establishment of the U.S. Geological Survey's earthquake monitoring program. The San Andreas Fault runs near the city. The estimated magnitude was later revised to 7.9. The death toll is uncertain (official 478, but likely over 3,000, including Chinatown residents who were not counted). Today, San Francisco has strict earthquake building codes.

The Johnstown Flood was a tragic disaster! The dam had been weakened by years of neglect; heavy rains caused it to burst. The wall of water was 40 feet high and traveled at 40 mph. The flood swept away buildings, trees, and people. Bodies were found as far away as Cincinnati, Ohio. The disaster shocked the nation. Clara Barton and the American Red Cross (founded 1881) led relief efforts for five months. The disaster led to changes in dam safety regulations. The owners were sued but were found not liable (the courts ruled the flood was an "act of God"). Public outrage led to the development of strict liability laws in some states. The Johnstown Flood is commemorated at the Johnstown Flood National Memorial (National Park Service).

No tsunami warning system existed in the Indian Ocean! The earthquake occurred at 7:58 AM local time; the tsunami struck within minutes to hours. Many people, including tourists on beaches, were caught unaware. The largest death toll was in Indonesia (over 167,000). The disaster was the first major humanitarian relief effort in the social media era (blogs, online donations). The international community pledged over $14 billion in aid. The disaster led to the Indian Ocean Tsunami Warning System (operational since 2006). The earthquake was the third-largest ever recorded. The tsunami was also recorded on sea-level gauges as far away as South Africa and Antarctica. The 2004 tsunami changed how the world prepares for disasters.

Halifax was destroyed! The explosion was the largest man-made explosion before the atomic age. It was heard hundreds of miles away. A tsunami wave (60 feet) swept the harbor. A blizzard the next day hampered rescue efforts. The explosion caused over 1,600 people to lose their sight (flying glass). The disaster led to the founding of the Halifax Children's Hospital (now IWK Health Centre). Boston sent doctors and supplies; Nova Scotia sends a Christmas tree to Boston each year in thanks. The explosion was caused by a navigational error. The blast shattered windows 50 miles away. The explosion is commemorated annually in Halifax. The Mont-Blanc anchor is preserved on the Halifax waterfront. The explosion is a key event in Canadian history.

Poor building standards were a major factor! Haiti had few building codes, and many buildings were made of unreinforced concrete. The earthquake struck a densely populated area (Port-au-Prince). The capital's infrastructure was already weak before the quake. The disaster killed over 100 United Nations personnel (including the mission chief). The earthquake also destroyed much of the country's government records. Haiti was still recovering from multiple hurricanes and tropical storms (2008). The international response was massive but criticized for coordination problems. The earthquake is one of the deadliest in the 21st century. Haiti remains one of the poorest countries in the Western Hemisphere. The 2010 earthquake had a deep and lasting impact on Haitian society.

The Black Death was bubonic plague! The plague arrived in Europe via Genoese trading ships from the Black Sea in 1347. The symptoms included swollen lymph nodes (buboes), fever, and vomiting. The disease spread rapidly due to trade routes. The plague recurred in periodic outbreaks for centuries (the Great Plague of London in 1665). The Black Death is considered one of the deadliest pandemics in human history. It permanently changed European society. The population of Europe did not recover until the 16th century. The term "quarantine" comes from the Venetian practice of isolating ships for 40 days ("quaranta giorni"). Today, plague can be treated with antibiotics. Outbreaks still occur in parts of Africa, Asia, and the Americas (but are rare). The Black Death remains a symbol of catastrophic disease.

The Hindenburg was destroyed by a hydrogen fire! The airship was filled with 7 million cubic feet of hydrogen. The fire spread rapidly; the airship was consumed in 34 seconds. Of the 97 people on board (36 passengers, 61 crew), 35 died (plus one ground crew). The cause remains controversial: static electricity, sabotage, or lightning. The disaster ended commercial airship travel. The iconic footage of the Hindenburg burning is shown frequently. The term "Hindenburg" became a metaphor for disaster. The airship had made 63 successful flights before the disaster. The wreckage was salvaged and used for munitions (WWII). The site is now a memorial. The Hindenburg disaster marked the end of the Golden Age of Airships. Modern airships use non-flammable helium.