Faced with the horrendous devastation of the Indian Ocean catastrophe, it's natural to wonder if there isn't some way not just to improve warning systems, but to actually prevent such giant earthquakes in the first place. After all, in the winter officials in many mountainous areas prevent big avalanches by triggering smaller ones with explosives, even with military cannon. Threats from forest fires are reduced in some wooded regions by permitting —- or even deliberately setting -— small "controlled burns" to prevent the accumulation of dead brush that would eventually feed a conflagration.
An earthquake is the ultimate result of slow, steady accumulation of tension in rock faces that gradually try to slip past each other, pulled by motions deep inside the Earth. The shear force builds higher and higher and the rocks resist as much as they can. Suddenly, they slip past each other, releasing the energy in seismic bursts. On land, these shocks are felt as earthquakes; under the ocean, such seaquakes lead to tsunami waves that can cross oceans in hours and then build up in the shallows of a land mass into giant waves.
It turns out that human engineering has already accidentally triggered earthquakes, providing some initial concepts of how a deliberate strategy of tension relief might be implemented. But geologists warn that replacing one big earthquake with a swarm of smaller ones might expose people to much higher total risks -- and that's assuming that such a proposal could surmount the legal and environmental hurdles likely to be put in its way. |