Issue Date: February 22, 2009

The good side of disasters

Mother Nature can be devastating. But natural disasters serve valid purposes, scientists say. Without them, our Earth wouldn't resemble its current state, and we'd lose some of our most precious resources.

By Dennis McCafferty

Most oceanic islands originated through volcanic activity.

Natural disasters leave an immediate impression defined only by loss -- that of precious lives and property. But, in time, can these disasters actually contribute something positive?

Yes, they can -- and they do.

The emotional impact of disasters aside, top researchers at one of the foremost agencies for these events -- the U.S. Geological Survey, or USGS -- are constantly looking at disasters past and present. They point to a wide range of productive, even needed, contributions made possible by wildfires, earthquakes, hurricanes and other disasters.

There's a lot of bad and ugly in any disaster. But there's a significant amount of good, too. You could argue that, without disasters, the Earth wouldn't "work right." To find out why, read on:

WILDFIRES

Wildfires help seedlings and forest life stay healthy.

The bad and the ugly. In 2008, more than 80,000 wildfires burned through nearly 5.5 million acres in the United States, says the National Interagency Fire Center. Flames roared through about 500,000 acres in Southern California in October 2007, forcing an evacuation of more than 900,000 people -- the largest in state history.
The good. The truth is, without wildfires, our forests would have a difficult time existing. These fires remove much of the fuel on the surface: dead branches, needles and fallen leaves that, if left alone, would pile up, creating an even greater fire hazard. And the fires prevent the growth of what are called "ladder fuels," like the small white fir trees that grow under the larger ones. Combined with accumulated surface fuel, the ladder trees would represent a devastating hazard for the larger ones if an uncontrolled fire broke out. "Periodic fires keep the dead material from accumulating and remove the ladder fuels," says Jan van Wagtendonk, a USGS research forester in Yosemite, Calif.

Wildfires also pump nutrients into the forest soil. Here's how: Fire consumes wood and the carbon within, but not the phosphorous, potassium and other essentials in the tree. The burning tree crumbles to the ground, and nutrients are deposited to create healthier soil for tree and plant life. "Without these fires, these nutrients would stay bound within the tree for decades or even centuries," van Wagtendonk says, "and they're crucial for plant growth."

VOLCANOES
The bad and the ugly. Like water in a boiling pot left on a stove, magma erupts through the surface of the Earth, sometimes with devastating results. On May 18, 1980, Mount St. Helens erupted less than 100 miles south of Seattle, shooting debris and smoke 12 miles high and killing 57 people.
The good. Volcanoes are responsible for the existence of places like the Hawaiian Islands, the Gal‡pagos and Iceland. More volcanic activity occurs underwater than on the Earth's surface, and eruptions can provide the foundation for eventual landmasses. And much of what these volcanoes transport is "good stuff" that helps civilizations to survive, with heat and gases from magma beneath volcanoes forming deposits of lead, zinc, silver and gold. As decades pass, volcanic ash falling on the surrounding ground creates fertile soil for crops. "It's difficult to imagine the Earth without volcanic activity," says John Eichelberger, coordinator of the USGS Volcano Hazards Program. "Volcanic activity was essential to the development of life and continues to play a role in determining the environment." Another benefit, he says, is the ability to generate power. In California, energy companies have developed geothermal power plants that capture volcanic steam and use it as a power resource. "It's simple and non-polluting," Eichelberger says.

LANDSLIDES
The bad and the ugly. One of the most significant U.S. disasters this decade was the Laguna Beach, Calif., landslide of June 1, 2005, in which about 1,000 evacuated.
The good. Like earthquakes, landslides serve an aesthetic purpose. Without them, gorgeous outcroppings such as those along the South's Blue Ridge Parkway wouldn't exist. Landslides also create habitats in streams, which allow fish to thrive. True, landslides sometimes choke aquatic life by piling sediment into the water. But, in time, such landslides also will break up stream flow, as rocks act like a railroad switch on a track. The boulders slow the flow of the stream, creating pools that allow trout and other species to build habitats.

"In the case of landslides, what doesn't kill the fish might make them stronger," says Lynn Highland, coordinator of the Denver-based National Landslide Information Center.

HURRICANES

Hurricanes bring healthful sediment to wetlands.

The bad and the ugly. This decade has seen a slew of deadly hurricanes, most significantly Katrina in August 2005, which ripped through the Gulf Coast, breaching a levee system and destroying much of New Orleans and the surrounding region. About 1,000 people were killed in Louisiana alone.
The good. Wetlands can be destroyed by hurricanes, but they also can benefit from them because the storms import good dirt. Flooding from the sea brings sediment that can nourish the marsh vegetation, while adding a protective element by building the land higher. "That can be a shot in the arm," says Abby Sallenger, a St. Petersburg, Fla.-based hurricane scientist for the USGS. "The living things there need these nutrients and minerals."

EARTHQUAKES
The bad and the ugly. Horrific images of the power of earthquakes are fresh in mind, given the Sichuan disaster last May, in which at least 69,000 died. The deadliest known quake also happened in China: the 1556 Shaanxi quake, which killed more than 830,000. In the United States, the most legendary quake is the San Francisco disaster of April 1906, in which more than 3,000 were killed.
The good. A great deal of our fuel resources are made possible by the same forces that cause quakes. Miles underground, hydrocarbons are making oil and gas trapped underground. Picture these underground areas as a large carpet. Without quakes, this carpet is relatively flat, its valuable oils and gasses spread far and wide. When tectonic plates collide, however, causing the earth to rumble, the carpet bends into folds, trapping those fuels in the tops of the folds and making the drilling process possible. "Earthquakes allow the economics of digging for resources to work better because the resources are more concentrated and accessible," says David Applegate, senior science adviser on earthquakes and geologic hazards for the USGS.

And earthquakes create much of the natural beauty we value. Over time, they move the earth and pave the way for mountains and other landscapes. "Extreme events are the price we pay for living on a dynamic planet," Applegate says. "Over time, they've split continents, formed great ocean basins and built mountains. Above Salt Lake City in Utah, we have the Wasatch Mountains, formed on a fault that's still active. So earthquakes are still a potential hazard for Salt Lake City, but its mountains are the reward."

Cover photograph by Art Wolfe, Getty Images

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