When the “Big One” eventually hits, the city of Alameda will have plenty to worry about.
Like many East Bay cities, it’s covered in older, wood-frame buildings that would serve as tinder for post-quake fires. The island doesn’t have neighborhood water reservoirs, meaning there is less water readily available within city limits. And there are only five roads on and off Alameda — all in hazardous liquefaction zones.
But perhaps the most pressing concern is the structural reality of the island. Much of it is manmade. Although there have been efforts to improve the island’s earthquake readiness, including a new drinking water connection installed just last week, Alameda still faces serious concerns about its construction.
“All those apartment houses along the South Shore, that’s all soup,” said Dennis Evanosky, a longtime resident, documentarian and community historian. “Everything the water side of Otis, everything the water side of Clement, everything the water side of Main and Central, that’s all man-made land. All of it. Including schools.”
Alameda was once a peninsula, connected to Oakland until an estuary was dredged in the early 1900s, and its original landmass was much smaller than it is now. Today, only the interior island is on rock; the rest of the city was built with soft, spongy mud and clay pulled from the bay to make room for neighborhoods and the Alameda Point naval base during World War II.
“I know when I bought a house in Alameda I looked at that liquefaction map and said ‘I’m not buying anything that’s not in that original land area,’” said Danielle Mieler, the city’s sustainability and resilience manager.
Liquefaction occurs when serious shaking causes water-logged soil to lose its strength and behave like a liquid. Reclaimed land is at particular risk. Buildings could tilt and sink into the ground. Bridges and roads leading to them could be severely damaged or destroyed.
“With fill, it’s a little like a house of cards,” said Christine Goulet, director for the earthquake science center for the USGS. “Usually what happens is they dredge material from nearby sea or bay, which has a mix of clay and silt, and then they just put that in without compacting it appropriately.”
Still, that reality hasn’t prevented Alameda from developing these man-made parts of the island. Apartment buildings line the South shore, far past the original shoreline. In recent years, developers have built condos along the marina. All of them are in liquefaction zones.
“Tax base, tax base, tax base, that’s why the city let them do it,” Evanosky said. “The developers just take their money and leave.”
But the city is also feeling the pressure to build as much new housing as possible, especially with the state’s ambitious construction mandates, including building 975 affordable housing units. “We think it’s important to build housing and address the housing crisis,” Mieler said.
Updated projections warn of dire scenarios for Alameda County in the event of a major earthquake on the Hayward fault. The last major earthquake there, which historically occurs about every 150 years, was in 1868. The region is overdue.
Although many of Alameda’s concerns overlap with other East Bay cities, the confluence of potential hazards puts this small, tree-lined city at unique risk in the event of a major quake. The city and East Bay agencies are making changes that they hope can avert the worst potential outcomes. The city has a 175-page hazard mitigation plan that involves retrofitting vulnerable buildings, electrifying homes to prevent fires, and building bike and pedestrian bridges to provide more ways off the island. All the vehicle bridges have already been retrofitted.
Earlier this month, EBMUD, the East Bay’s water utility, installed a new 3,000-foot water pipeline connecting Alameda and Oakland. The city’s drinking water comes from four pipelines beneath the Oakland estuary, connections which were built in shallow, non-compacted soil known as young bay mud. It’s the type of soil that faces a high risk of liquefaction during an earthquake.
The new pipeline is now buried 160 feet below the estuary in significantly more stable mud. The pipe itself is also made of flexible, high-density polyethylene, as opposed to cast iron. Officials say the city’s water supply should now be able to withstand even the most violent quake on the Hayward Fault.
But the new pipeline alone won’t solve all water-related issues during a major earthquake. There are thousands of smaller, half-inch water lines that connect from meters to individual homes and apartments, each of which poses a failure risk. There are still three other water pipelines between Oakland and Alameda that have not yet been replaced.
Still, on a broader scale, water should now be able to flow from EBMUD’s reservoirs to the city even in the immediate aftermath of an earthquake. Installation of the pipeline was completed over the weekend, and it will be fully operational by the end of the year.
Even with the work that Alameda has done to prepare itself for the worst-case scenario, there are no guarantees.
In fact, the single safest form of earthquake preparation, according to experts, would be to entirely rebuild parts of the island.
“It’s not the fact that it’s reclaimed, it’s how it’s been built,” Goulet, the USGS scientist said. “You can remediate today.”
Infilled regions, now covered in neighborhoods, could be remade. At the Port of Los Angeles, which was also built with fill, liquefaction mitigation projects have been conducted to make the soil denser.
These are the type of cost-prohibitive projects that may never happen in Alameda. But without them, no matter what the city does, the root concern will persist.
The Marina district in San Francisco, another neighborhood built on fill, was devastated by the 1989 Loma Prieta earthquake. Entire buildings crumbled into the Earth. Evanosky sees the same outcome ahead for Alameda.
“The only difference between Alameda and San Francisco is that they’re fully aware of what they’re doing,” Evanosky said.
