HayWired, an imaginary earthquake coming in 2018

3 July 2017

Earthquakes are always a surprise, but we can be ready for them. Or, more ready. We can practice on a household basis, whether it’s a simple “Drop, Cover, Hold On” drill or a series of family meetings to go over scenarios — what if Mom’s stuck at work? What if we’re all out of town? What if we’re separated? What if our home is red-tagged?

It can be complicated. And think of how a whole city or region might practice for a major earthquake. The first requirement is a realistic picture of what would happen — a detailed, scientifically based earthquake scenario. When geologist Dale Cox first started talking to disaster responders about earthquakes, what they wanted to know most was “What exactly will the Big One be like?” He realized that his colleagues at the U.S. Geological Survey could supply realistic answers based on their research and “get the science used.”

Last week Cox told an audience at SPUR about a new scenario in the works for the Hayward fault, named HayWired. We’ll hear a lot about it on the Bay area’s unofficial Earthquake Day, April 18th, next year.

For scenario work, every region needs its own custom earthquake. Ten years ago, the first ShakeOut exercise in Southern California used a scenario quake measuring magnitude 7.8 that ruptured the San Andreas fault from the Salton Sea all the way to Lancaster.

For the Hayward fault — what Cox called “the most urbanized fault in the United States” — planners of the Hayward Fault Initiative have used a repeat of the magnitude 6.8 earthquake in 1868. They’ve also used a 7.0 quake that, unlike the 1868 event, would rupture the fault’s entire length. The new-and-improved HayWired scenario takes everything to a new level of detail and engagement.

Alameda County Courthouse before and after the 1868 Hayward fault earthquake. San Leandro Public Library (before) and Bancroft Library (after).

The HayWired scenario starts with a scientific description of the hazards connected to a hypothetical magnitude 7.05 earthquake that occurs on Wednesday, April 18, 2018 at 4:18 in the afternoon. It goes into far more detail than previous efforts, covering ground motions, landslides, liquefaction, fires, disruptions to communications and the digital economy (hence the “Wired” part of the name), and aftershocks and afterslip.

Aftershocks in the first two years after the HayWired earthquake. The largest aftershock, of magnitude 6.2, is a pretty major quake in itself. USGS image.

That description has been published as the first of three volumes. Other specialists are preparing two more volumes based on it, one on environmental and engineering impacts and the other on social and economic impacts. Those will come out in the next few months.

The HayWired earthquake originates in Oakland, 8 kilometers beneath the intersection of Skyline Boulevard and Joaquin Miller Road. For that and many other reasons, I’ll be following this project closely for you.

Oakland building stones: Serpentinite

26 June 2017

In a modest West Oakland neighborhood on Market Street is the modest West Grand Shopping Center. Its ordinary building is clad in rough stone, an exterior treatment similar to the Kaiser Building and many other examples.

But at the West Grand Shopping Center, the cladding consists of fist-sized pieces of beautiful serpentine rock.

The front side of the building is pristine. The rear side, on Myrtle Street, is a full block long and completely faced with serpentinite. Unfortunately the bottom seven feet or so has been painted over.

The mutable color of this stone, blue-green in the shade and olive-green in the sun, gives the building a real Oakland look. I don’t know where the stone came from. Our own serpentinite is usually bluish and not of this quality, except maybe in small outcrops in the Franciscan melange. Perhaps it’s from a quarry in the Mother Lode country. It must have taken a few carloads of rock and a crew of skilled artisans to put this together.

A few months back, when I was presenting the building stone verd antique, serpentinite’s dressed-up cousin, I said “You can’t do much with California serpentine except admire it.” Makes me happy to be proved partly wrong — you can always admire it, and sometimes build with it.

Brooklyn Landing, Brooklyn Creek

19 June 2017

The first Western inhabitants of this area, the Peralta family, were horse people rather than boat people. They did much of their business, with the mission and the town of San Jose in the South Bay, by land. When they did use boats, it was to transport hides and tallow from their ranch, using an embarcadero on San Antonio Creek to the east of the slough that’s now called Lake Merritt. Unlike the slough, the creek was navigable there, being several feet deep even at low tide. Although there was a better spot on the west side of the slough, the rancheros would have had to haul their wagons through the hills around the slough to reach it. They preferred the simple downhill route from their hacienda. (The Americans, with the larger vision of newcomers, took that other spot and made it the mighty harbor we know today.)

Later the town of Brooklyn formed around the Peraltas’ landing. The map below, from 1857, shows San Antonio Creek winding its way west from the Brooklyn landing (thanks Wikipedia).

Incidentally this was a true creek, according to long-standing usage in Britain and colonial America — “a small, narrow tidal inlet or estuary” as the AGI Glossary of Geology puts it. Today we use “creek” for any small stream . . . like 14th Avenue Creek (as the watershed people call it), which flowed down to the landing. If this creek had another name, maps don’t record it, and anyway I feel like calling it Brooklyn Creek. The first road, named Commerce Street, ran up along that creek. Today you can drive up it under its new name of 14th Avenue (or ride the odd little 96 line) and still see the valley walls on either side.

Long story short, the land was built out and the little harbor disappeared as first the railroads, then the freeway and then BART ran through. The geologic map shows all that as artificial fill (af).

This was once the omphalos of East Oakland. Two different horse-drawn railroads had terminals here, the Oakland, Brooklyn and Fruitvale Railroad and the Brooklyn and Fruitvale Railroad. Today little remains to mark this former place. It was still a destination when the San Francisco and Oakland Railroad sited a heavy-rail station here in 1864, and a single palm tree from the old days grows yet amid today’s anonymous tracks. And there’s tiny, seedy Vantage Point Park on the low rise that once overlooked our first harbor.

Brooklyn Creek is fully culverted now. Its outlet is probably across the transport corridor at this little cutout along the shoreline.

Today San Antonio Creek is no longer even an entity. The waterway has been replaced entirely by Oakland’s dredged-out Inner Harbor and Brooklyn Basin.