Seismic monitoring & response for the Trans-Alaska Pipeline System

The 800-mile Trans Alaska Pipeline System (TAPS) passes through extremely remote regions, where there is a high potential for seismic activity. Alyeska Pipeline Service Company, the TAPS operator, has been on the forefront of seismic engineering and situational awareness, and continues to enhance its capabilities. TAPS has used earthquake monitoring since the pipeline was constructed in 1977 and recently upgraded to a fourth-generation of its monitoring system. This upgrade includes recent technology to improve accuracy and increase system redundancy, and it incorporates lessons learned during the 2018 M6.3 Kaktovik and the 2018 M7.1 Anchorage earthquakes. The modernized earthquake monitoring system includes strong-motion accelerograph stations installed at key locations along the pipeline tied into the control system to provide real-time detection of seismic events. The accelerometers also telemeter data to provide local constraints in ShakeMap so that they not only provide site-specific shaking values, but also contribute openly to constraining ground motions elsewhere so shaking at locations without stations can be better inferred. Alyeska then employs U. S. Geological Survey’s ShakeCast system to automatically ingest the ShakeMap to provide near real-time alerts of shaking as well as inspection priorities across the system, both for pipeline assets and infrastructure. TAPS stakeholders who receive ShakeCast alerts via email and text messages include controllers, engineers, and emergency managers. As part of our standard post-earthquake protocol, damage assessment checklists have been pre-deployed at multiple locations to guide these teams as they determine the integrity of TAPS following an event. This unprecedented level of situational awareness allows for rapid prioritization and deployment of damage assessment teams. The purpose of this manuscript is to expand on the details of these systems.