HayWired - Engineering implications

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Hazards Societal Consequences and Risk Communication scientists coauthored several chapters in the Earthquake hazards volume of the HayWired earthquake scenario.

Cover of the HayWired Engineering Implications Report

Figure 1. Cover of the HayWired Earthquake Scenario Engineering Implications Scientific Investigations Report (Photograph copyright Deanne Fitzmaurice/San Francisco Chronicle/Polaris, used with permission)

The HayWired Earthquake Scenario—Engineering Implications is the second volume of U.S. Geological Survey (USGS) Scientific Investigations Report 2017–5013 (fig. 1), which describes the HayWired scenario, developed by USGS and its partners. The scenario is a hypothetical yet scientifically realistic earthquake sequence that is being used to better understand hazards for the San Francisco Bay region during and after a magnitude-7 earthquake (mainshock) on the Hayward Fault and its aftershocks.

Analyses in this volume suggest that (1) 800 deaths and 16,000 nonfatal injuries result from shaking alone, plus property and direct business interruption losses of more than $82 billion from shaking, liquefaction, and landslides (fig. 2); (2) the building code is designed to protect lives, but even if all buildings in the region complied with current building codes, 0.4 percent could collapse, 5 percent could be unsafe to occupy, and 19 percent could have restricted use; (3) people expect, prefer, and would be willing to pay for greater resilience of buildings; (4) more than 22,000 people could require extrication from stalled elevators, and more than 2,400 people could require rescue from collapsed buildings; (5) the average east-bay resident could lose water service for 6 weeks, some for as long as 6 months; (6) older steel-frame high-rise office buildings and new reinforced-concrete residential buildings in downtown San Francisco and Oakland could be unusable for as long as 10 months; (7) about 450 large fires could result in a loss of residential and commercial building floor area equivalent to more than 52,000 single-family homes and cause property (building and content) losses approaching $30 billion; and (8) combining earthquake early warning (ShakeAlert) with “drop, cover, and hold on” actions could prevent as many as 1,500 nonfatal injuries out of 18,000 total estimated nonfatal injuries from shaking and liquefaction hazards.

Map of the cost estimate of building damage ratios

Figure 2. Map of the San Francisco Bay region, California, showing estimated building-damage ratios (repair cost as a percent of building replacement cost) for the hypothetical magnitude-7.0 mainshock and aftershocks of the HayWired earthquake scenario on the Hayward Fault. The building-damage ratio was calculated using the public risk-analysis software Hazus-MH and considered shaking, liquefaction (soils becoming liquid-like during shaking), and landslide hazards. %, percent. (From Seligson and others, this volume.)