Issue Date: August 7, 2005

In this article: Wildfires Tsunamis Hurricanes Earthquakes

DISASTERS

DISASTERS: WHAT CAN WE LEARN?

Experts reveal the latest findings about Mother Nature's wrath.

By Dennis McCafferty

Are we living in the Great Age of Disasters? A series of recent natural events has unleashed unimaginable destruction. In the past several months, USA WEEKEND has spoken at length with the top scientists who study natural catastrophes. Here's what they've discovered -- and are still discovering -- about nature's dark side:

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WILDFIRES
What happened: Wildfires blaze through 740,000 acres in Southern California in October 2003, destroying more than 3,500 homes and killing 22 people.
What we're learning: Just how wicked a shrub-land wildfire can be.

Californians are resigned to the reality of wildfires (as well as earthquakes and landslides) in their lives. The 2003 human-caused blazes prompted the evacuation of tens of thousands of people, serving up stirring images for cable news stations. The reach of these fires was particularly formidable. Why did they spread so far? A key reason: Unlike forest fires, the October 2003 wildfires were fueled by shrub land. As a result, scientists now have a compelling case study of that kind of disaster.

How are the two kinds of wildfires different, and why is a shrub-land fire potentially more dangerous? In a forest, the fire fuel is in saplings and dropped pine needles. But the bulk of the forest -- the tops of the tall trees, which can easily grow 100 feet or taller -- remains relatively unaffected, and firefighters can access the fire's flash points on the ground. In a shrub-land fire, though, the natural fuels for the fire are less accessible from the ground -- at the top of the plant, up to 15 feet tall -- and the shrub is vulnerable to total consumption if ignited. "You don't have a layer on the ground where a fire burns," says Susan Haseltine, associate director of biology for the U.S. Geological Survey. "With winds that clocked in at up to 50 mph and essentially quickly blew flames from one shrub to another, this wildfire was very difficult to get under control."

Scientists now are working with urban planners on development strategies in and near potential wildfire areas. Says Haseltine: "We can hopefully control the building of houses around where these blazes occur."

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TSUNAMIS
What happened: A magnitude-9.1 earthquake about 150 miles west of Sumatra triggers a tsunami on Dec. 26, 2004, that results in a reported 240,000 deaths in at least 11 countries.
What we're learning: Places once thought of as "safe" from a similar tsunami may be in danger right now.

The tsunami took not only its victims but also researchers by surprise. The rupture shook from the epicenter 750 miles northward to Myanmar (previously known as Burma). What has stunned scientists is that this part of the world was never pinpointed as a place that could produce an earthquake and resulting tsunami of these proportions.

An earthquake often occurs when tectonic plates -- huge slabs of the Earth's crust -- slam into each other, one above the other, causing friction. But in this case, one plate slid beneath another off to the side, supposedly a more benign interaction. Now scientists are rethinking which areas of the world could be ripe for a similar earthquake/tsunami. "The Aleutian Islands between Russia and Alaska are of some concern," says Eric Geist, research geophysicist of the USGS office in Menlo Park, Calif. "We're also looking at the Caribbean, just off the Puerto Rican coast."

Since 1992, scientists have worked on a computer-generated model to accurately predict -- no matter where the epicenter -- how huge a tsunami could be. They've dotted ocean waters with electronically communicating buoys that measure tsunami wave activity after earthshaking rumbles. They had predicted that a magnitude-8.5 quake would produce three minutes of shaking followed by tsunami waves lasting 10 hours. But until December 2004, scientists hadn't had a real global-sized disaster like this with which to work. The tsunami's quake was greater than 9 in magnitude, and it produced five minutes of shaking and 12 hours of tsunami waves. So scientists are refining their prediction model. "Before, nobody believed that a tsunami could last as long as this one did," says Eddie Bernard, director of the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle. "Now, we know it can. With better information, we can better predict these events and save more lives."

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HURRICANES
What happened: Four hit Florida and the Southeast in 2004, all within six weeks.
What we're learning: With the current season (the earliest since 1916) underway, last year's hurricanes shed new light on the amount of erosion and building damage that can occur.

The first Florida hurricane, Charley, made landfall last Aug. 13 with 145-mph winds. On Sept. 25, Jeanne wrapped up the season with a 120-mph storm. Throughout it all, researchers used an airplane-based, laser-mapping system to learn more about the impact of these storms on shore erosion, which among other things causes coastal buildings to fall. Ivan caused half a dozen tall waterfront buildings -- at least five stories tall -- to collapse completely. "We can show how much of the beach will disappear," says Abby Sallenger, a St. Petersburg, Fla.-based scientist for USGS, "or whether an entire island will be underwater."

Scientists discovered more about atmospheric conditions and the storms. They flew to the West Indies as Ivan brewed to see whether a pocket of super-dry air would weaken it. They dropped instrument-laden canisters that lock onto GPS satellites down into the storm and found that the air layer may have weakened the storm for about a day, but then it intensified. "We need to understand how conditions impact the strength and staying power of a hurricane," says Jason Dunion, a Miami-based NOAA researcher.

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EARTHQUAKES
What happened: Scientists wait for decades for a major earthquake to rattle Parkfield, Calif. On Sept. 28, 2004, they get one.
What we're learning: The unusually predictive element of the September earthquake allows experts to engineer models of this kind of disaster.

Parkfield, some 175 miles southeast of San Francisco, doesn't draw much attention. Once known for mining, it's now -- according to a recently posted road sign -- home to 18 people. Still, many scientists around the globe are fascinated with Parkfield. Since the mid-1800s, seven magnitude-6 earthquakes have originated in the area. Most significant: A San Andreas fault earthquake for the ages, the magnitude-7.9 Fort Tejon rumble in 1857 started in Parkfield. The most recent occurred on Sept. 28, 2004, a quake that was basically harmless.

However, the town maintains this distinction for researchers: Its earthquakes occur with nearly clockwork precision, roughly every quarter-century. As a result, like cops on a stakeout, scientists were waiting for the earthquake with their monitoring gear when it happened. They've gathered the most complete picture yet of how the ground moves in a big earthquake.

Those same scientists are now scouring their measurements of shaking, fluid pressure and stress data gathered during the rumble to come up with a clearer understanding of conditions that lead to a quake. With that, they'll be better prepared to predict disasters.

"One of the hardest things about earthquakes is that you have to wait until the earth delivers the beast to study it," says William Ellsworth, chief scientist of the USGS earthquake hazards team in Menlo Park, Calif. "But because this site has been so dependable, we were there to catch it in the act."

Cover photograph by Justin Sullivan, Getty Images