Reminders from Quebec's quake
EASTERN North America is not exactly a hotbed of earthquake activity. But it can still spring unsettling surprises. Residents of southeastern Canada and the northeastern United States were recently reminded of this when a magnitude 6 quake struck 90 miles north of Quebec City. It knocked out electricity and phone service in parts of Canada and shook buildings in New York City, roughly 600 miles away.
The quake serves as a stern, though thankfully low-cost, reminder that seismic codes for buildings are as important in the East as in the West. It should also provide the incentive to develop preparedness measures where they don't exist and to refine measures where they do.
Fortunately, the quake struck in a sparsely populated part of the province; a comparable quake struck Whittier, Calif., in October 1987, killed three people, and caused $368 million in damage. One West Coast engineering firm concluded that a magnitude 6 quake on a known fault 18 miles southeast of New York City could inflict some $8 billion in damage.
Despite such estimates, quake preparedness in the East is a hard sell. In any one spot, the likelihood of a damaging quake in a given period of time is fairly small. But regionwide, the likelihood grows substantially. Since the 1700s, strong-to-catastrophic quakes have occurred near Boston; Cleveland; New York; Charleston, S.C.; St. Louis; and Memphis. The largest quake recorded in North America occurred not in San Francisco, but near New Madrid, Mo., in 1811.
Many Eastern cities have a great deal of old housing stock still in use and have high population densities. Much of the Eastern US lies atop layers of sediment that can transmit earthquake waves of a given magnitude over an area up to 100 times greater than geological formations underlying the West.
The most important move is for Eastern state and local governments to adopt seismic provisions contained in national model building codes.
Those codes have evolved largely out of the West Coast's experience; some provisions may not be suited to effects from the East's geology. But they provide a useful starting point.
The federal investment in research on Eastern quakes should be increased, as well. Geological conditions in the East make quake research a more difficult task than in the West; it took 10 years and $5 million to $10 million to develop a good model of the New Madrid fault. Work is still under way to try to understand the frequency of its quake activity. Charleston and the St. Lawrence River Valley also require further work.
But because practical codes to make buildings quake-resistant exist, state and local governments shouldn't wait for the ``definitive'' study to adopt them.
