Climate change and seismic resilience: Key considerations for Alaska’s infrastructure and built environment

the potential risk of ground failure and infrastructure damage in southern Alaska will increase with a decrease in permafrost distribution. A practicing engineer noted, That’s our geotechnical challenge in Alaska. It’s kind of the opposite of usual. When you build on frozen ground, you have to keep it frozen. Whereas normally you’re trying to put insulation down to keep it from freezing. Furthermore, permafrost degradation may increase the seismic liquefaction potential of soils [59]. During an earthquake, the contraction of saturated granular soil particles transfers stress from particle-particle contacts to pore water, leading to increased pore water pressure and a corresponding reduction in the strength of the material [63, 64]. Liquefaction occurs when the pore water pressure rises to a critical level and the behavior of the material changes from solid-like to liquid-like [65, 66]. After the earthquake, the dissipation of excess pore water pressure leads to ground settlement. In many cases, liquefaction-induced foundation set- tlements and rotations leave buildings and other infrastructure systems irreparable, even with- out above-ground structural damage [67]. Permafrost thaw can increase the risk of seismic liquefaction by altering the physical and mechanical properties of soil. As permafrost thaws, the water held in the ice-rich soil melts and occupies the pore spaces between the soil particles. This increased degree of saturation of non-frozen water changes the soil’s susceptibility to liq-

uefaction during an earthquake. Consequently, the soil becomes more unstable and prone to soil settlements, landslides, and other forms of ground failure. Alaska has a history of well- known instances of liquefaction. An example of liquefaction-induced damage is shown in Fig 5, generated by the 1964 Great Alaskan earthquake, which led to a long runout landslide. This landslide destroyed 75 homes within the Turnagain Heights area of Anchorage [68]. A seismologist mentions, Fig 5. Liquefaction-induced long run-out landslide in Turnagain Heights Anchorage, Alaska generated by the 1964 Great Alaskan Earthquake. https://doi.org/10.1371/journal.pone.0292320.g005 PLOS ONE Climate change and seismic resilience: Key considerations for Alaska’s infrastructure and built environment PLOS ONE | https://doi.org/10.1371/journal.pone.0292320 October 18, 2023 8 / 17