Understanding the Hayward Fault and Its Potential Impact
The Hayward Fault, one of the most significant geological features in the United States, stretches from east of San Francisco Bay to approximately 74 miles south of San Jose. Its unique geographical location and the high population density directly above it make it a critical concern for earthquake preparedness. The United States Geological Survey (USGS) has developed an extensive scenario called the HayWired, which forecasts the potential consequences of a major earthquake along the Hayward Fault.
Risk and Vulnerability
According to the HayWired scenario, the Hayward Fault poses a significant threat to over 3 million people in the San Francisco Bay region. The fault runs beneath the foundations of more than 300 buildings and other critical structures. One notable example is the University of California, Berkeley’s Memorial Stadium, which is nearly bisected by the fault and has been retrofitted to withstand seismic activity.
The scenario estimates that damage to property and business disruption costs could exceed $82 billion in 2016 dollars. The damage is primarily attributed to shaking, liquefaction, and landslides. Approximately 80% of the shaking damage is caused by the mainshock, with the remainder resulting from aftershocks over a 2-year period.
Consequences and Displacement
The HayWired scenario predicts severe consequences for the built environment and human displacement. Residential and commercial buildings, particularly older steel-frame high-rise office buildings and newer reinforced-concrete residential buildings in downtown Oakland and San Francisco, could become unusable for as long as 10 months.
Displacement could affect up to 152,000 households, or around 411,000 people, based on 2000 U.S. Census data, in addition to 77,000 displaced households directly due to mainshock damage. Other factors, such as utility outages and infrastructure failures, would exacerbate these numbers.
Casualties and Rescues
The HayWired scenario also estimates that in the San Francisco Bay region, 800 deaths and 18,000 non-fatal injuries could occur from building and structural damage caused by ground shaking and liquefaction hazards. Additionally, more than 2,500 people in the region could require rescue from collapsed buildings, and over 22,000 people could need assistance from stalled elevators.
The scenario highlights the widespread impacts of such an earthquake, including the potential for BART (Bay Area Rapid Transit) to be shutting down, significant stadium and infrastructure damage, electricity outages for months, and food shortages exacerbated by damaged bridges. If sea water breaches barriers, flooding would fill low areas, and moving through hazardous electrified lines would become dangerous.
Further quakes could follow, causing additional damage and instilling fear among the population, as the darkness and chaos of the aftermath set in.
Preparedness and Mitigation
Given the severity of the potential consequences, it is crucial for residents, businesses, and local governments to prioritize preparedness and mitigation strategies. Retrofitting buildings, enhancing infrastructure resilience, and improving emergency response plans are key steps.
Public education campaigns can also play a vital role in ensuring that residents are aware of evacuation routes, emergency contacts, and how to protect themselves during an earthquake. Regular drills and exercises can help build public confidence and coordination during critical times.
By leveraging the insights from the HayWired scenario, stakeholders can better prepare for the Hayward Fault’s potential impacts, mitigate losses, and reduce the overall disruption to daily life.