Eye on the Storm: Hurricane Katrina Fast Facts
for National Geographic News
|September 6, 2005|
A week after one of the worst national disasters in U.S. history, the
Gulf Coast is devastated, thousands of people are displaced, and unknown
numbers have lost their lives.
How does Hurricane Katrina stack up to history's most powerful storms? Get the facts about Katrina and other deadly tempests.
When it made landfall, Katrina was a Category Four storm featuring gusts topping 140 miles an hour (225 kilometers an hour). Category Five storms Hurricane Camille, which struck the Mississippi coast in 1969, and Hurricane Allen, which made landfall near Brownsville, Texas, in 1980, both packed maximum sustained winds of about 190 miles an hour (306 kilometers an hour).
In 1899 a hurricane produced a 42-foot (13-meter) storm surgea wall of water pushed on land by strong windsin Bathurst Bay, Australia. It remains the largest surge ever recorded and more than doubles the 20-foot (6-meter) surge caused by Katrina.
The deadliest U.S. hurricane on record was a Category Four storm that hit the island city of Galveston, Texas, on September 8, 1900. Lacking today's warning forecasts, some 8,000 people lost their lives when the island was destroyed by 15-foot (5-meter) waves and 130-mile-an-hour (210-kilometer-an-hour) winds.
The most lethal known tropical storm was the Bangladesh Cyclone of 1970, one of many to have devastated that nation's vast low-lying deltas. The storm's exact human toll is unknown, but experts estimate that at least 300,000 people perished.
Officials believe that the death toll from Katrina could reach into the thousands. More than a million Gulf Coast residents have been displaced and many of the refugees were living below the poverty line before the storm struck.
According to NOAA, the U.S. locations with the highest probability for hurricane strikes are: Miami, Florida (48 percent); Cape Hatteras, North Carolina (48 percent); and San Juan, Puerto Rico (42 percent). New Orleans has about a 40 percent annual chance of a hurricane strike.
The global risk of hurricane disaster is increasing due to human activity. Populations are concentrating along the world's coastlinesparticularly in large urban areas. Improved forecasting and emergency response have lowered hurricane casualty rates, but as more people and infrastructure move into harm's way, storms are likely to become more destructive.
The primary cause of hurricane-related fatalities over the past 30 years has not been storm surge or winds, but inland flooding. Most hurricanes produce rainfall of 6 to 12 inches (15 to 30 centimenters), and slow-moving storms can be particularly dangerous for inland residents.
The word "hurricane" is derived from Hurican, the god of evil of the Carib people of the Caribbean. Hurican was himself inspired by the Mayan god Hurakan, who destroyed humans with great storms and floods.
Hurricanes are actually tropical cyclones. This generic term applies to tropical or sub-tropical ocean storms with winds topping 74 miles an hour (65 kilometers an hour). Names such as "hurricane" and "typhoon" refer to cyclones that occur in different regions, but they are the same type of storm.
A hurricane releases the bulk of its energy through cloud and rain formation. An average storm's daily cloud and rain energy output is equal to 200 times of the world's electricity-generating capacity.
New Orleans was founded in 1718 by the French. Since that time the Crescent City has weathered many storms, but its geographic position has become increasingly precarious. Miles of storm-protecting wetlands have eroded, effectively moving the city closer to the Gulf of Mexico. The city is gradually sinking lower below sea level and becoming more dependent on its extensive levee system to keep water out.
The levees that protect the city from river flooding are actually a culprit in wetland loss. They deprive the delta of periodic floods, which replenish silt and fresh water.
Previous storms have shaped the size and extent of the New Orleans levee system. In September 1947 an unnamed hurricane flooded metropolitan New Orleans to depths of about three feet (one meter). After the storm, hurricane protection levees were built along Lake Pontchartrain's south shore.
Hurricane Betsy made landfall some 50 miles (80 kilometers) east of New Orleans on September 10, 1965. Winds in the city reached 125 miles an hour (200 kilometers an hour), and the storm surge neared ten feet (three meters). After extensive flooding, the Orleans Levee Board raised existing levees to a height of 12 feet (4 meters).
The most expensive hurricane to make landfall in the U.S. was Hurricane Andrew in 1992, which caused some 25 billion dollars (U.S.) worth of damage in the Bahamas, Florida, and Louisiana. Katrina's economic costs are unknown for now but are sure to be staggering. Risk Management Solutions, a company that assesses the financial impact of natural disasters, estimated on September 2 that Katrina could drain some 100 billion dollars (U.S.) from the economy. That figure would make Katrina the costliest storm in U.S. history.
NOAA has predicted a 95 to 100 percent chance that the 2005 Atlantic hurricane season will be more active than usual. National Hurricane Center forecasters warn that the bulk of 2005's storms are likely still to come.
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