Archive for the ‘Oakland hazards’ Category

Old fill and made land

6 March 2017

Between the 1840s and roughly 1960, the Bay area made colossal amounts of dry land through “reclamation,” a euphemism for filling in marshland with whatever was handy. Oakland was no exception. Here’s a portion of the geologic map centered on Jack London Square, Oakland’s original harbor. Reclaimed land, or artificial fill, is shown in pink.

jlsgeomap

We were lucky in Oakland that the waterfront was largely developed by the railroads. They had the money and foresight to do the job right, by mid-1800s standards, and the fill is pretty good. An exception is the building that houses Heinold’s First and Last Chance Saloon.

heinolds

The structure was built in 1880 of ship’s timbers, and in accordance with good practice it was placed on piles, driven into the fill and the mud beneath. But it has settled, especially after the 1906 earthquake, and the land has been built up around it. You won’t notice from the outside until you approach the door, which sits below the surrounding ground.

heinoldsdoor

Go inside (as every Oaklander should at least once), and you’re in a funhouse of ancient furniture and creaky walls covered with old papers, all set off by a crazily tilted floor. Fortunately it’s merely a bar and not some place people have to live in.

For real landfill folly, you’ll want to visit San Francisco. The land south of Market Street was originally a mixed bag — the bedrock of Rincon Hill and a ridge of sand dunes to its west offered firm ground, and Sullivan Marsh to their south surrounded Mission Bay with poor ground. On the geologic map, the old marsh is mapped as “Qaf,” or artificial fill. It extends to the Civic Center.

sfmarshgeomap

The area south of Market began to be developed around 1870, and the marsh was filled rapidly and willy-nilly. Within a few decades the good ground was occupied by grand hotels, office buildings and luxury residences while the bad ground — the made land — was full of working-class boarding houses, small shops and warehouses.

The marsh contained several meters of peat on the surface and saturated sand and mud beneath. Loading this land with landfill rubbish, then placing buildings on it, left it highly vulnerable to settling and, during earthquakes, liquefaction — complete loss of strength.

When the 1906 quake struck, the buildings on firm ground did well while the former marsh area was largely ruined. But everything south of Market, rich and poor, burned down within a day. All of it was rebuilt, just like before, as rapidly as possible. And for the next century, the made land has kept on subsiding.

Main streets, like 7th Street, were regularly built up to maintain their grade. Side streets like Natoma were not.

sfslump-4

Many homes sank at the same time the street were built up. This one is typical.

sfslump-3

At the same time, many buildings suffered differential or uneven settling, like Heinold’s did. Residents, then and now, just put up with it.

sfslump-2

Today redevelopment is replacing these tired survivers. The new blocks have a hip and trendy look now, if you don’t happen to notice the occasional straggler.

sfslump-1

Soon enough, the past will vanish from the South of Market. But just wait another century, or less if they have a major quake before then, and some of these new buildings will slowly turn into antique funhouses like Heinold’s.

Oakland has been pretty good about avoiding our own versions of Sullivan Marsh, but we do have strips of fill to watch out for.

Notes for the Aftermath

16 January 2017

I think about earthquakes often, almost every day. That’s part of what makes a geologist — not just visualizing the deep past, but living in the deep present. Turning seeing into foreseeing. In this post I’ll talk about a bad idea, a good idea and a current lesson.

The bad idea is that when the Big One hits, you’ll just saddle up your car and get clean out of town. Don’t count on it.

There are two things wrong with this idea. First, the roads will be closed. I can guarantee this, even if the freeways won’t collapse outright like the Cypress Structure did in 1989. They’ve all been upgraded. It’s not about the freeways, but about surface streets. Trees and live wires will fall in every neighborhood. Buildings will catch fire in every neighborhood. Roads will buckle in every part of town — because of landslides in the high hills and the low hills, because of ground liquefaction in the low lands. The authorities will open access in an orderly way. Be prepared to wait instead.

Second, you should leave the roads clear for more important traffic — fire trucks, utility vehicles, police vans, ambulances. There will be hundreds of fires, broken water and gas lines, downed trees and power lines, a few panicky folks waving guns around, thousands of people injured. Sit tight and help where you can.

It’s good to have your car equipped at all times, but don’t count on being able to leave fast, or soon. That stuff in the car will make a big difference regardless . . . like if you’re driving, not at home, when the quake hits.

The good idea is this: text, don’t phone. Take a deep breath, sit down for a minute and use your phone’s little keyboard.

With cell towers damaged and emergency traffic heavy, bandwidth for communications will be scarce. Voice traffic takes much more bandwidth than texting. Text one family member and have them inform the rest. They’ll already know you’ve had a big earthquake. Tell them what they really need to know about you. Don’t send video, don’t send audio. Save your battery.

So, right after “drop, cover and hold” comes “text, don’t phone.” Two easy things to remember. If you’re up for a third thing, I recommend what they say in Japan: “Put out open flames.”

The current lesson is from the tragic Ghost Ship fire. It was reported in Thursday’s East Bay Times that people have raised a lot of money for the victims, more than $2 million, but six weeks after the fire, most of the funds haven’t yet been spent. Crowdsourcing drives feel fast if you’re donating, but getting the money at the other end takes a while. Read the article for a taste of the problems — psychological, bureaucratic, logistical — that make disaster relief hard work even for trained professionals.

And this is for just one building fire with a few dozen direct victims. After the Big One the challenges will be orders of magnitude greater. Along with the red tags everywhere, there will be red tape.

I don’t say all these things to dishearten or paralyze anyone. The best way to prepare is persistently. Pick one simple, specific, achievable step. Put that on your to-do list, then check it off, then add another thing. You might decide to put some extra cash in your go-bag and keep it there.

At the same time, think about what you’ll need even more than money if it all falls down. To help with that, Oakland’s own Earthquake Engineering Research Institute has an updated “big one” scenario for the Hayward fault.

The Resilient Oakland Playbook

21 November 2016

Last month the city of Oakland released its long-awaited resilience plan, the Resilient Oakland Playbook. “Resilience” is the 21st-century name for the concept that communities can get up quickly when they’re knocked down, and avoid being knocked down in the first place.

I’ve always thought of resilience in terms of how we deal with natural hazards — earthquake, flood, landslides, sea-level rise, fire. Oakland used a definition that seems closer to familiar city politics and good-government ideas. Frankly, it read as if Mayor Schaaf had simply copied and pasted part of her recent speeches:

Resilience in Oakland means equitable access to quality education and jobs, housing security and community safety. It means building vibrant infrastructure to better prepare for shocks like earthquakes and stresses like climate change. In Oakland, resilience means catalyzing our diverse pool of talents and perspectives to tackle these challenges, both inside and outside our government, with particular focus on addressing the needs of the most vulnerable members of our community.

This will take some getting used to. The geologic hazard of earthquakes is given its due, although there are no new ideas in the playbook beyond the ongoing, snail’s-pace work of encouraging retrofits of old soft-story apartments. The Earthquake Engineering Research Institute, a major source of relevant knowledge that’s headquartered in Oakland, didn’t participate in writing the Playbook.

softstory

Emergency preparedness is represented by a seven-month “Love Your Block” initiative in the Fire Department’s valuable CORE program. That was supposed to start in October, but there’s no sign of it on the city’s website.

The geologic hazards of climate change (a possible rise in floods and wildfires) and sea-level rise are pervasive in the Playbook. That’s OK, although I consider them remote problems. They will slowly creep up on us, noticeable only if you take a snapshot every decade. We need to make long-term plans and float bond issues to deal with them.

But there’s no mention of the mud that wipes out roads in Oakland every year. A “vibrant infrastructure” has to deal with our chronic landslides.

thornhillslide

The word “landslide” isn’t in the playbook once — homebuilders in the hills, you’re free to continue business as usual. Houses on alluvial hillsides, you’re off the radar.

Oakland needs the things in the Resilience Playbook. But we need more than that — we need to cultivate what Robert Muir Wood, a writer I’ve long admired, calls a disaster culture. Last month in the L.A. Times, Wood pointed to the Dutch as exemplars, citing their centuries-long effort to win land from the sea. “What Holland created — a national narrative of resilience, shared by all the people — is what L.A. (and every city threatened by natural disaster) should aspire to. Today, with the power of information technology and education, it won’t take centuries to evolve.”

Disasters don’t wait decades, and neither can we. Maybe the Playbook is how we’ll get to resilience. I’ll be happy if it is.