Journal of Critical Infrastructure Policy
but will have an amplified effect on tall and long structures built on Puget Sound ’ s sedimentary soils . The U . S . Geological Survey ( USGS ) describes the Puget Sound as an earthquake “ hot zone ,” with a seventy-five percent or greater probability of experiencing a massive earthquake in the next 100 years . 23
Channels , Sources , and Signals Channel Clearing and Alternate Routing
Long duration violent shaking results in landslides , 24 displacement of masonry structures , 25 dam failure , fracturing of water and fuel networks , and disruption of the electrical grid . Skyscrapers , bridges , elevated roads , and pipelines are especially vulnerable
26 27
.
Saturated sedimentary soils , common to Puget Sound , tend toward liquefaction . Snohomish County , north of Seattle , tells its residents , “ A major quake threat rests in the Cascadia subduction zone off the Washington Coast . If it lets loose , experts predict widespread damage to bridges and overpasses , likely shutting down the region ’ s transportation system for weeks .” 28
Figure 1shows “ poor condition bridges ” in Washington and parts of Oregon and Idaho . 29 The second map ( Figure 2 ) identifies the principal channels used by five major grocery distribution centers ( three shown as diamonds ) serving the Puget sound region . The color-coded lines are rough approximations of comparative volumes flowing from these key sources to retail locations served by each . Together these supply and demand nodes sell approximately seventy percent of the groceries ( Food-At-Home ) consumed in the region . Figure 3 is a close-up of “ poor condition ” bridges . Even without landslides , liquefaction , and more it is obvious the post-Cascadia grocery distribution network will be seriously disrupted .
Fulfilling demand requires moving supplies . Given Puget Sound ’ s tight topography and limited road-network , alternative routing is not easy . It will be even more difficult after a major seismic event . Fundamental to channels starting to flow post-Cascadia will be :
23 Peterson , Mark , et al . 2019 . The 2018 Update of the US National Seismic Model : Overview of Model and Implications . Earthquake Spectra 36 ( 1 ) ( November 2019 ).
24 Washington State Department of Natural Resources ,
Landslides , Geologic Hazards . 25 Gilbert , Daniel and Doughton , Sandi ,
Buildings that Kill , Seattle Times , May 2016 .
24