Some natural disasters are more problematic than others, in terms of getting people out of harm's way. Hurricanes are the least problematic. They form well out in the ocean and can be tracked for days using sophisticated computer modeling software that does a fine job of predicting the storm's projected path. This gives public-safety officials plenty of time to evacuate the populace in the affected area.

Tornadoes are a bigger problem. In the Midwest where I live, every big summer thunderstorm potentially could morph into a tornado — and they have a tendency to pop up seemingly out of nowhere, which can be scary. The good news is that we do get some inkling of what might be coming our way. For instance, seasoned Midwesterners know that when the sky turns green, it's time to gather the children and head for the basement. Also, many towns have tornado sirens.

Seismic activity is an entirely different matter. Often, the first sign that an earthquake has occurred is when photos fly off the walls. Volcanic eruptions are worse. If you live in close proximity to a volcano, your first clue that something bad has happened could well be the mudslide that has just ripped your home off its foundation or buried your car.

The 1980 eruption of Mount Saint Helens in Washington state is a case in point. The explosion was devastating. It created a debris avalanche that measured nearly a mile at its widest point. It reduced the mountain's summit by 1300 vertical feet and created a mile-wide crater at the top. It killed 57 people, thousands of animals and millions of fish; destroyed 200 homes, 15 miles of railroad and 185 miles of highways; wiped out 47 bridges; and spread ash over 11 states. The damage totaled nearly $3 billion in today's dollars.

The eruption was preceded by two months of seismic activity, including small earthquakes and the venting of steam, which only served to tell geologists that something was brewing, not what or — more importantly — when. Today, however, scientists are better armed, as Mary Rose Roberts reports in this month's cover story. Environmental sensing technology has become far more sophisticated, and it is being used to predict a wide variety of natural disasters earlier than ever before.

That's good. Mudslides move at speeds ranging from 10 to 35 miles per hour. It's not a race any of us are going to win, unless we're given a head start.