by Gary Griggs, author of Coasts in Crisis: A Global Challenge
Hurricanes Harvey and Irma, followed by Jose and Katia next in line, like commuters on the freeway headed for work. What’s going on here? We generally don’t think too much about hurricanes here in California, but it’s hard to miss the news now.
Hurricane Harvey may be the most damaging storm to ever hit the United States. And in terms of wind speed in miles per hour, Irma is reported as being the strongest hurricane ever recorded and it has yet to hit the coast of Florida. Irma is currently leaving a path of complete destruction as it blasts through the Caribbean. On the island of St. Martin, an island split between Dutch and French control, “There is no power, no gasoline, no running water. Homes are under water, cars are floating through the streets, and inhabitants are sitting in the dark in ruined houses and cut off from the outside world”. These aren’t losses that are going to be repaired or replaced in a few weeks time. It will take months to years to return to normal.
Some residents of the Atlantic coast of the US are often quoted as saying that they would much rather live with hurricanes—where at least you know they’re coming—rather than the uncertainty of earthquakes that we all live with here in California. The truth, however, is that while large earthquakes in the United States present clear dangers, they don’t begin to compare with hurricanes in terms of damage of loss of life. Our average annual death toll from earthquakes in the United States over the past century or so is about 20 per year. If fact, in the entire 240 year history of the United States, there has only been a single earthquake that led to deaths of more than 200 people, and that was the great San Francisco shock of 1906. We just don’t get big earthquakes that often, at least historically, although they will come and we shouldn’t be complacent about them.
Hurricanes, however, have been responsible for more loss of life in the United States than any other natural hazard. While California may get a damaging earthquake every decade or so, we can get multiple hurricanes in a single season, and 2017 is making that abundantly clear.
Over 60 million people along the U.S. Gulf and South Atlantic coasts live in coastal counties that are vulnerable to hurricanes and, like most coastal regions, those populations continue to increase. From 1900 to 2015, there were 631 hurricanes that affected these counties as well as the Caribbean region, or 5.4 per year on average. 245 of these, or about two each year, have been classed as major hurricanes based on damage and death tolls. On average, about 800 fatalities have been recorded yearly, but this likely is an underestimate as reliable information from older hurricanes is often lacking. Losses are unfortunately increasing every year because more people are retiring to warm hurricane-prone areas like Florida, and investment in homes and other development, and their values, are increasing.
Gary Griggs is Distinguished Professor of Earth Sciences at the University of California, Santa Cruz. He is author or coauthor of Introduction to California’s Beaches and Coast, Living with the Changing California Coast, California Coast from the Air, The Santa Cruz Coast (Then and Now), and Our Ocean Backyard.