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Natech Accident
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Type
Natech Near Miss
Date
2002/11/03
Time
12:00
Natural Hazard
Denali Fault Earthquake of 2002, United States, 2002
Site
Trans-Alaska Pipeline, United States
Status
Published

Units Involved

  1. Name
    Trans-Alaska Oil Pipeline
    Type
    Transport: Pipeline
    Year of Construction
    1977
    Description
    At 800 miles long, TAPS is one of the world’s largest pipeline systems, transporting Alaska North Slope crude oil from Pump Station 1 in Prudhoe Bay; then travels across the state’s terrain, including traversing three mountain ranges, three major earthquake faults, and hundreds of rivers and streams; and comes to its end in Valdez, the northernmost ice-free port in North America. Tankers are loaded at the Valdez Marine Terminal, delivering about four percent of the nation’s crude oil supply to market.

    More than half of the pipeline runs above ground – an engineering decision made due to Alaska’s prevalent permafrost.

    The Trans-Alaska Oil Pipeline carries 17% of the U.S. domestic oil supply.

Event Sequences

  1. Name
    Slight damage
    Unit
    1. Trans-Alaska Oil Pipeline
    Description
    During the 2002 Denali Fault quake, the ground was offset beneath the pipeline, and violent shaking damaged a few of the pipeline’s supports near the fault, but it did not break, averting a major economic and environmental disaster.
    Initiating EventCritical EventMajor Event
    ---

Consequences

Economic Impacts
The creative engineering solutions used in the pipeline design and the studies cost about $3 million in 1970’s. Had the pipeline ruptured in the Denali Fault quake, the lost revenue and the cost of repair and environmental clean-up could have exceeded $100 million, perhaps many times.

Lessons Learned

Lessons Learned on Equipment
The survival of the Trans-Alaska oil pipeline in the Denali Fault earthquake was the result of careful engineering to meet stringent earthquake design specifications based on geologic studies done in the early 1970’s by the U.S. Geological Survey, Woodward-Lundgren and Associates, and others in conjunction with the Alyeska Pipeline Service Company.
Those studies located the Denali Fault within a 1,900-foot (579 m) corridor crossing the pipeline route and estimated that the pipeline could be subjected to:

- a magnitude 8.0 earthquake;
- relative ground movement: 20 feet (6.1 m) horizontally, 2.5 feet (0.76 m) vertically.

The above estimates proved to be accurate for the 2002 magnitude 7.9 earthquake, in which the rupture crossed the pipeline within the 1,900-foot corridor, and the fault shifted about 14 feet (4.3 m) horizontally and 2.5 feet (0.76 m) vertically.

To accommodate the projected fault movement and intense earthquake shaking from a magnitude 8.0 quake, the zigzagging Trans-Alaska Oil Pipeline is supported on Teflon shoes that are free to slide on long horizontal steel beams at the location it crosses the Denali Fault.
ID: 95, Created: Kyriaki GKOKTSI, 2023-03-30 08:09:36 – Last Updated: Kyriaki GKOKTSI, 2023-10-16 16:53:50

Attachments

NoDescriptionFile Size
1.USGS Fact Sheet on "Rupture in South-Central Alaska: the Denali Fault Earthquake of 2002"2.41MB
Last update: 2024/04/17 | Top