Humans are fleeting visitors on this roiling rock in the universe. On December 26, 2004, at 58 minutes and 49 seconds past midnight GMT, Mother Earth reacquainted us with this immutable fact. For millions of years, a creeping slab of Earth´s crust--the India Plate--had been grinding headlong into a similarly stubborn chunk of rock called the Burma Plate. Like a clash of Brobdingnagian armies, millennia of pent-up kinetic energy suddenly exploded from the seabed, a scant 100 miles from Sumatra, Indonesia. The ensuing force--equal to 25,000 Nagasaki-size atomic bombs detonated in tandem-- jolted the Earth from its axis, permanently shortened the length of the day, and hurled walls of seawater onto thousands of miles of coastline--from the Andaman to the Arabian--sweeping away at least 200,000 lives in an instant. What´s most terrifying about the recent tsunami is that a repeat performance is virtually guaranteed. Earth, by its very nature, is a prolific architect of mayhem and purveyor of calamity. The only thing we can do to protect ourselves is strive to learn where and when such massive natural disasters will happen--because rest assured, they will happen.

Fortunately, advances in remote-sensing satellites, computer-modeling simulations, radar, seismic monitors and weather forecasting are giving scientists an edge, in many cases enabling them to warn us when it´s time to skedaddle. Researchers use imaging satellites, for example, to track minute changes in land deformation--an otherwise undetectable pimple might mean that a fault is about to snap or a volcano about to blow.

Not that this high-tech ingenuity is necessarily making the world a safer place. The problem, experts say, is that humans are doggedly encroaching on Mother Earth´s most temperamental turf, increasingly building and living in potentially catastrophic hot zones. And more is at issue than
just our propensity to boldly skirt the â€urban interface,†as scientists describe the boundary between a safely inhabitable region and an area known to be vulnerable to nature´s wrath. Humans are also relentlessly altering or destroying the planet´s natural protection mechanisms. "If you remove angroves, damage coral reefs, and take away wetlands," argues Ellen Prager, a marine geologist and author of Furious Earth: The Science and Nature of Earthquakes, Volcanoes, and Tsunamis, "you are much more exposed to storm impact or tsunami damage."

The bad news is that the danger is only growing, because wherever population densities soar, the landscape must be transformed to sustain more and more people. The good news: Digital-imaging and mapping tools and ever more savvy computer models are improving scientists´ ability to calculate where the most deadly disasters might strike next.