Pipeline so far unscathed by North Slope’s strongest earthquake ever

ANCHORAGE, Alaska (KTUU) – Crews conducting inspections along the Trans-Alaska Pipeline have so far found no problems following Sunday’s M6.4 earthquake near Kaktovik.

Alyeska Pipeline Service Company, the firm that manages TAPS, says it has completed broad checks and aerial surveys of the pipeline and its facilities between pump stations 1 and 4, a 150-mile stretch. Starting on Tuesday, the company will begin going through everything with a fine-toothed comb. “We’re going to go back through and check for settlements, movements, any kind of smaller issues that might have presented in the last 24 hours, or that we missed the first time around,” said Alyeska spokesperson Kate Dugan. Michael West, who directs the Alaska Earthquake Center, said Sunday’s earthquake likely produced no more than a couple centimeters of vertical ground motion. That’s well within what the pipeline is designed to withstand. “Each section of the pipeline might have different designed allowances depending on the seismic activity for that zone,” Dugan said. “But as we saw for this earthquake, even in a less-likely area, the pipeline operated as it was supposed to and did not have any issues.” Anywhere that it’s above ground, the pipeline has an allowance of up to two feet of ground movement, and much more in areas near major fault lines. Near the Denali Fault Line, for example, the pipeline can handle 20 feet of lateral and 5 feet of vertical ground movement. The Denali Fault was the site of a massive 7.9M earthquake in 2002, but even that was not enough to cause main line damage to the pipeline. TAPS was operational after only a few minor repairs. Meanwhile, scientists and the Alaska Earthquake Center are still compiling data from the earthquake, which was the largest ever recorded on the North Slope. West says he thinks the shaker underscores the lack of data the center has for seismic activity in this part of Alaska. “Nobody’s ever spent a lot of time trying to understand the earthquake hazards in the Eastern Brooks Range, and I think it’s very likely that we have just historically underestimated what it’s capable of,” West said. Aftershocks continue to shake Alaska the day following massive 7.0 magnitude quake. Nick Note: this may not be the end but the start of massive quakes