When the Earth Rumbles, Alameda Might Crumble

This map shows the liquefaction hazard in the East Bay with Alameda circled in dark blue. Areas in red represent the highest danger of liquefication during a magnitude 7.1 earthquake on the Hayward fault. Wet sand can become liquid-like and the ground may crack and move. This movement could damage surface structures and underground utilities. The map depicts the hazard at a regional scale and should not be used for site-specific design.
United States Geological Survey

When the Earth Rumbles, Alameda Might Crumble

Jenna Chan

Bay Area residents are well-aware of the potential earthquake risk that comes along with living in a region that is home to a multitude of faults. These include one of the more infamous ones which even has a film named after it, the San Andreas Fault, along with several others such as the Hayward, Calaveras, and Greenville faults.

The Bay Area has not experienced any major earthquakes since the Loma Prieta earthquake in 1989, which had a magnitude of 6.9 and resulted in 63 deaths as well as thousands of injuries.

Residents are always aware of the looming possibility that the “Big One”, an earthquake with a magnitude of 8 or greater, could strike at any moment and devastate communities, big and small.

Alameda, located in a liquefication zone, is particularly susceptible to major earthquake damage. Liquefication occurs when strong seismic activity loosens and weakens water-saturated soil, essentially causing it to temporarily behave like viscous liquid.

In the event of an earthquake, buildings constructed upon water-logged sediment are at far greater risk than those built on bedrock, which is less destructible because the seismic waves that pass through it are lower in amplitude and higher in frequency.

According to the United States Geological Survey (USGS), most of Bay Farm Island and parts of the Main Island would liquefy if placed under the stress of a 7.1 magnitude earthquake. If such an event were to occur, one could expect to see collapsed buildings, damage to under-ground utilities, mud boils, and landslides.

This is because Bay Farm Island and some of the West End and East End are built on landfill, which unlike bedrock, is not solid and sturdy.

Jenna Chan works with the Alameda Sun as part of the Girls Inc. Eureka! program.