It cracked store windows, severed gas lines, and crumbled roadways. It even triggered a tsunami warning. But in the wake of a 7.0 earthquake—the second largest in the state’s recorded history—Anchorage’s water system proved remarkably resilient. In fact, by the following day, power, water, and communications were restored in most of the affected areas, with only about 40 customers without water.
“Anchorage is prepared for these kind of emergencies,” explained Anchorage mayor Ethan Berkowitz. “People pulled together, we followed the plans that were in place, we looked after one another,” he said. “When people around the country and around the world look at this, they’re going to say ‘we want to do things the Anchorage way’ because Anchorage did this right.”
A recent study indicates however, that Seattle, WA, another earthquake-prone city, would not fare as well. The report, sponsored by Seattle Public Utilities (SPU) and carried out by independent consultants, estimates that the municipal water system would lose pressure within 24 hours of a seismic event and would require two months to restore service.
The analysis estimates that between 1,400 and 2,000 pipeline breaks are likely, with potential problems at pump stations, reservoirs, and elevated tanks. The most serious ruptures, however, would be breaks in the large transmission pipes that move water from SPU’s mountain reservoirs to the cities.
Considering the likelihood of a severe seismic event to take place within the next 50 years, the study recommends that the city spend $850 million through 2075 to mitigate water system risks posed by seismic activity.
Scott Miles, a University of Washington disaster risk-reduction expert, told The Seattle Times that while retrofitting and infrastructure improvement projects and costs may inconvenience the public, “the real disruption” would be water service getting knocked out by an earthquake.
Is seismic risk an issue that your municipality has considered? What measures do you take to mitigate risk to your system?