Archive for the ‘Oakland hazards’ Category

Landslides of Outlook hill

5 March 2015

I’ve been surveying the low hill between Mills College and Holy Redeemer College, home of the Millsmont and Eastmont Hills neighborhoods. Its western face has no bedrock, either on the geologic map or in my experience. Here’s the relevant portion of the geologic map.

outlookmap

Its crest is supposedly Jurassic basalt, which would be part of the Franciscan assemblage. But the Hayward fault runs right along its length, and I lean toward calling it a pressure ridge. Long story short, it is squeezed up, shattered, and oversteepened, and these make it prone to landslides. Here are some, starting with the notable example at the top of 64th Avenue. This is its toe . . .

64th-beunaventura-slide

. . . and this is the view from its head, at Delmont Avenue.

64-buena-slide-top

Another is above Outlook Avenue, south of 76th Avenue. As you walk along its base, you’ll see bits of concrete from the homes that once stood here.

outlook-76-slide

Above it, on Hillmont Drive, there is a gap in the houses that offers a nice view. I have no business saying whether a landslide is responsible.

outlook-76-slide-top

Between these two obvious slides are some fine hillsides. This one, below Simson Street, makes a lovely backdrop to the Eastmont mall and, it seems, a nice informal park for the residents.

simson-field

It isn’t really vacant—all of the lots that subdivide it are extremely long for some reason. I think that spaces like this, shared without fuss by the landowners around it, are very precious.

Loma Prieta plus 25

17 October 2014

Yesterday I attended the Loma Prieta 25 Symposium at the Kaiser Center. It was a quake geek’s Woodstock, where a motley host of experts got together to schmooze, celebrate 25 years of progress since the 1989 earthquake, and look ahead. At 10:16 a.m., along with 27 million other people around the world, we participated in the ShakeOut drill.

dropcoverhold

Since the Loma Prieta earthquake, Caltrans has finished reinforcing all of the state’s freeway overpasses, EBMUD and Hetch Hetchy have strengthened their principal water mains where they cross the Hayward fault, BART has strengthened its tracks and stations, and PG&E has made huge changes to make the power and gas system more robust. The airports and ports have been upgraded. The big bridges have been fixed or replaced (with only the Golden Gate Bridge upgrade to go).

The work done since Loma Prieta has also made governments work better. The mayor of Napa, Jill Techel, had high praise for the city, county and state emergency service agencies. She said PG&E did a wonderful job during the August earthquake. The federal agency FEMA was on top of things too. And the regional authority ABAG, the main sponsor of the symposium, was charged with energy and ideas to piggyback on the public awareness that followed the Napa quake.

Magnitude-6 events like the Napa earthquake will happen 10 times as often as the “big ones” we’re warned against. Even if the big ones will surely overwhelm some aspect of our preparations, the mitigation and preparedness in place can work wonders with the smaller events like the Napa quake.

The next steps that the experts laid out, the things they want done by Loma Prieta 50, involve increasing the Bay area’s resilience to disasters. Resilience means that people will not just avoid death and injury from a major earthquake, they’ll stay in their homes and return to their jobs quickly. The work of upgrading the infrastructure needs to move beyond the backbones to the limbs and arteries: neighborhood water and gas lines, smaller bridges, individual privately owned buildings. Oakland is ready to begin a program aimed at some 1800 soft-story residences in the city. The state’s earthquake insurance chief and the state senator heading the Insurance Committee were there to describe the advances they want to make in 2015. Progress works this way: inch by inch and year by year.

Oakland Harbor will save the nation when the Big One hits

3 September 2014

harborcranes

I’m attending the Third International Conference on Earthquake Early Warning, which is happening at UC Berkeley through Friday. It’s a lively gathering of specialists and officials from earthquake country all over the world. What’s galvanizing everybody is the possibility of dramatic progress in California, now that the government has passed a law that establishes a statewide early-warning system modeled on ShakeAlert, which has been quietly beta testing for more than two years.

It came up during discussion today that the West Coast has five of America’s largest seaports, and a major earthquake that disables one or more of them will affect not just the nation’s, but the entire world’s economy. OK: the West Coast has three areas that produce major earthquakes. Ours, the Bay area’s part of the San Andreas fault complex, is the least of them. The 1906 San Francisco earthquake (M 7.8) and the similarly large 1868 Hayward quake? Those are our signature quakes, and we’re third on the list. Southern California is capable of larger ones (M 8), and Cascadia, which reaches from Cape Mendocino up past the Canadian border, produces the largest quakes by far (M 9).

A Big One that knocks out Long Beach and Los Angeles harbors will not affect Oakland. Neither will the Monster One that disables Seattle, Tacoma and Portland. Oakland Harbor will be the backup port of call after either of those events. And of course they’ll share the load if we’re out of action.

harbordolphin

In any case, Oakland Harbor is a natural facility for using an early-alert system. So is Oakland Airport—imagine an alert coming in to the control tower that strong shaking will arrive in 20 seconds. This is exactly the kind of rapid decision-making information that the airline community is trained to respond to already. I foresee our airport and our port being early early-warning adopters. BART is already part of the ShakeAlert beta testing network. Watch those guys.