In the aftermath of the devastating Haiti earthquake, there are pressing scientific questions to be addressed. In particular, how far did the earthquake break extend, and what is the potential for subsequent large quakes on adjacent segments of the fault?
No seismologist can forget how, in April 1992, a magnitude 6.1 earthquake near Joshua Tree, Calif., turned out to be a forerunner of the much more massive magnitude 7.3 Landers earthquake two months later. Based on the statistics of the Haiti aftershocks so far, we can estimate a small but finite chance — about 5% — that another quake as large as 7.0 will strike Haiti in the next two years.
But although there are certainly things for seismologists to study and learn, most of the important lessons from the Haiti earthquake are old news. We have known for decades where the world’s active earthquake zones are located. Infrequent big quakes in inactive areas will surprise us once in a while, but scientists can, and have, identified cities that are in the seismic cross-hairs: Tehran; Tokyo; Los Angeles; New Delhi; Lima, Peru; Istanbul, Turkey; and Chongqing, China. Sophisticated computer programs allow us to make predictions of the impact that future big quakes will have on big cities in terms of dollars and lives.
As far as damage goes, magnitude matters. Beyond that, it’s location, location, location. The strongest shaking during an earthquake is, overwhelmingly, concentrated in immediate proximity to the fault that breaks. Thus the punch of a magnitude 6.5 quake is significantly diminished if it takes place 30 miles offshore.
It’s the direct hits that we worry about. Darts miss the bull’s-eye more often than they hit, but, where we have active faults near major cities, bull’s-eyes are, eventually, inevitable. We can’t predict the timing of earthquakes, but their devastation is all too foreseeable.
The potential for catastrophe in Haiti was well understood. Although not widely known among the public as an active earthquake zone, the Caribbean is known to scientists as a miniature Ring of Fire. Scientists have sounded alarm bells about the faults below Haiti for years, describing the potential for precisely the sort of earthquake that struck. They couldn’t say exactly when it would happen, but they stated with near certainty that it would eventually happen.
Improving resilience in a city such as Port-au-Prince is no small feat. Earthquake scientists who push for improved hazard assessment and risk mitigation in developing countries know that progress is measured, at best, in baby steps. There is no magic wand we can wave to make the world safe. In some parts of the world, resource limitations can’t be overcome. But even small steps add up, and can make a difference.
Imagine for a second that action had been taken to improve earthquake resilience for Haiti’s hospitals. It would not have taken huge resources to accomplish this much.
Many researchers conclude that our one best hope lies in training and supporting local earthquake professionals in places with high potential for risk. These individuals would then be in a position to work with local officials and decision-makers on planning for the inevitable.
The degree of earthquake resilience that we have today in California is the result of a process that began a century ago, nudged along by pioneering geologists and seismologists who first began to understand the nature of our earthquake problem. Yet even today, vulnerabilities remain in California. As in Haiti before Jan. 12, the southernmost section of the San Andreas has not produced a massive earthquake in more than two centuries. Earthquake professionals remain concerned about the likelihood of a quake much bigger in size and impact than the one in Northridge in 1994.
But the biggest potential for widespread death and injury in earthquakes is in the developing world. We watch the disasters play out on our living-room televisions, and we want to help. We want to do something.
The time to most effectively help, though, is in advance. While the horrific images from Haiti are fresh in our minds, let’s look at what can be done in other developing countries at risk for future seismic disasters.
Susan E. Hough, a seismologist with the U.S. Geological Survey in Pasadena.