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Study: Seattle would lose water pressure for months in earthquake

The 2001 Nisqually Earthquake. (AP file photo)

A recent study published by Seattle Public Utilities (SPU) estimates that Seattle and the surrounding suburbs would lose water pressure in a large-scale, catastrophic earthquake.

RELATED: Is Anchorage earthquake sign of what’s to come for Seattle?

The study begins with a harrowing prediction, saying that the chance of a catastrophic earthquake similar to the 9.1 magnitude Tohoku quake in 2011 is between 15 and 20 percent in the next half-century. Additionally, there’s an 84 percent chance of a repeat of the 2001 Nisqually earthquake over that same time period.

If and when “The Big One” arrives, Seattle Public Utilities believes the city’s water system “would likely suffer significant damage,” while “water pressure could be lost throughout SPU’s water system within 16 to 24 hours.” SPU estimates that following this, it could take as much as a month before service is restored to 70 percent of customers, and two before water is restored to everyone.

So, why does Seattle appear to not be entirely ready for a massive quake?

“What we’ve discovered in the last 10 to 20 years, is that the level of seismic risk in the Puget Sound region is much higher than was thought to be the case 30 years ago,” Alex Chen, Director of Drinking Water for Seattle Public Utilities, told KIRO Radio.

When the city was first looking at potential improvements to infrastructure in the 1990s, it planned around a quake similar to the magnitude of 2001’s Nisqually quake, or the more recent 7.0 earthquake in Anchorage, Alaska last Friday.

Now, though, “what we’re planning around is something that’s much larger, and has much longer and more intense shaking than either of those two earthquakes. ”

Chen outlines a “suite of improvements” the city is currently looking at, including an enhanced emergency response, and upgrades to key pipelines, buildings, and storage facilities. In total, the necessary changes would cost upwards of $850 million over the next 50 years.

A level of secrecy

While the 13-page summary of the study released to the public is comprehensive, it’s only a fraction of the full, 722-page report. According to Chen, that stems directly from a directive from Homeland Security.

“The safety of our water supply is our number one priority, and we’re doing what it takes to protect it from terrorist attacks,” Chen said. “We work with the Department of Homeland Security to classify the study with this protected status.”

As many call for a release of more of the study, SPU is “working with Homeland Security to look at which sections of the report can be made available to the public.”

RELATED: Washington is falling way behind California on quake safety

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