Fire on the mountain

Yesterday there was a fairly small fire in a treacherous place, the Hiller Highlands neighborhood. There was confusion in the media accounts I saw, but here is the correct version, as you can see in this view from across the freeway this morning. The streets, from top to bottom, are Charing Cross Road, Tunnel Road, Caldecott Lane and Route 24. (A typo in the Tribune, “Charring Cross Road,” may give you grim amusement.) The blaze began on Tunnel where street work took place a few months ago, and nearly reached Charing Cross. As I shot this photo, fire crews were still combing the burn area in search of embers.

The hills love fire, and the ecosystem is adapted to it, but civilization here is not. Given that we have irreversibly encroached on the hills by permitting residential construction there, we’re stuck with the price in dollars and lives in perpetuity. Not even the next major earthquake on the Hayward fault, less than a kilometer west, will change this even though the whole neighborhood would likely burn down again, just like 1991, if it happened today.

Yesterday not an hour before the fire started, I was standing on Grizzly Peak Boulevard looking down at this part of town and sensing just how dry everything is. Instead of coming down through here, as I have before, I walked down through the Grandview neighborhood to its north. Upper Grandview is an uncanny place, having been wiped out in the 1991 fire and disneyfied since. Today I was going to visit the fire site, but I got this shot because instead I took the opportunity to try the fire road above Broadway that ends overlooking the North Oakland Regional Sports Center. If you visit the park, have a look at the fire-resistant garden there. The rocks are mapped as undifferentiated Great Valley Sequence and are mostly an undistinguished gray sandstone.

Heights and flats

In the East Bay, the Hayward fault separates high ground and low, with a few exceptions. Oakland is an exception (so is San Leandro, Berkeley and points north). From Oakland’s southeastern extreme at Lake Chabot up to the Panoramic neighborhood, the fault generally has a few hills on its Bay side. If you ride BART and look up at the hills, the fault is almost entirely hidden. The hill Piedmont sits on is the largest body of rock west of the fault. So Oakland is not like Hayward or Union City, where the fault is quite stark.

But here on upper Dwight Way, at Oakland’s far north end, is a spot where the height/flats dichotomy is laid right out plain. (Click the photo for a 900×750 version.) This little canyon is the one just north of Claremont Canyon, and I don’t know if it has a name. Behind me is little Dwight Canyon and just to its north is Strawberry Canyon, where the Cal stadium sits. High rock hills lie above the fault, and a plain of deep sediment lies below, an area where seismic shaking is liable to cause ground liquefaction. Of course landslides could happen where I stand; the brown patch below looks like a landslide scar . . . pick your poison.

The Big-Enough One

The theme of this month’s Accretionary Wedge blog carnival is, “a geological event you consider most significant to you.” I know what that one is. It didn’t awaken my sense of awe and turn me toward science. It didn’t injure me or make me rich or poor. No famous historical figure was involved. But the very month my wife and I moved to Oakland, the Loma Prieta earthquake changed the city irreversibly.

Those first couple weeks of October 1989 were fun. We loved having a proper downtown with fine old buildings, great weather, a lively cultural scene and a city with real geography to it. We had moved our stuff from the house in Concord and were readying it for the next owner, so at 5:04 pm on 17 October we were out of town, cleaning the old house for the last time. It was totally empty. The shaking went on for a long time, but out there it wasn’t very strong. Driving back to Oakland a little later, we felt worse and worse as the news rolled in and the signs of damage appeared.

There was a pall over Oakland for a long time. I felt it for years, not just on the anniversaries but every time I went downtown; every time a new friend or neighbor told their earthquake stories and listened to ours; every time I saw the news from other places and people struck by earthquake. Even now the effects linger in the scars left on the map, buildings left empty and the new Bay Bridge yet unfinished. And while the downtown, the weather, the scene and the land have endured, I now have a deep-seated relationship with earthquakes, Oakland geology and the Hayward fault that gives me a pang every time I feel the little shakers from beneath our side of the bay and think of the Big One to come.

The US Geological Survey has unveiled three new publications on the Hayward fault, all of them well worthwhile. They are a four-page fact sheet on the current hazard, a 96-page field guide with tons of information and photos covering the whole length of the fault, and a Google-Earth virtual tour for deep background and visualization. Get learning!

Lowland slides

As Darby commented on an earlier post, you don’t need to be in the hills to find hazards. A good fraction of the residential landslides in Oakland get mentioned in the Tribune, and they happen downslope, too, mainly along the creeks. Last week my buddy Jef visited a notorious example along Wallace Street, downvalley from Highland Hospital. The one above, on McKillop Street in the Fruitvale neighborhood, made the news throughout 2006, and I prepared a rudimentary case study of it for my About.com site.

The clues are plain, both on the map and on the ground. Look below: Just a few steps from that pitiful collapsed house is this view toward the hills. It’s pretty; it’s worth a little extra on a home’s selling price. But why is there a big empty space in the middle of one of Oakland’s older neighborhoods? A fire might clear a lot of land, but people would rebuild. Why does McKillop Street have two parts, one here and a stub at the far end of the park? Why isn’t there a nice bluff along Sausal Creek like there is elsewhere?

The dangerous hills

The people who build in the hills are wealthy and determined. Wealth is a good thing, and it’s usually the reward for determination and risk-taking. The benevolent-looking slopes of the Oakland Hills are held so high in the air by tectonic compression and carved to their angle of repose by all forms of erosion. The long-term compression across the Hayward fault, in fact, puts the hillslopes in a chronically oversteepened state, with highly fractured bedrock and a continuous risk of slope failure.

Homebuilding in this hostile setting pits these wealthy, determined, risk-taking people in an arousing contest against geology. It’s also a contest against engineers, builders, planners, insurers and other taxpayers. Those people share that risk to various degrees. This morning’s paper reported that a guy hauling lumber to a construction site in the hills was crushed to death by his load. He couldn’t find a level spot to offload his truck, and the wood slipped onto him as he untied it.

That reminds me: Last week I passed the landslide I mentioned earlier. Another sizable chunk of it had fallen in the scarp’s implacable retreat. Farther along, Skyline Boulevard was cut off by a fresh slide, and another one had narrowed upper Tunnel Road to a single lane. That’s the infrastructure for these highly demanding neighborhoods.

Boom disneyfied

The Hiller Highlands neighborhood was wiped clean by the October 1991 Oakland Hills fire. Once a quarry site, it later became a woodsy enclave of cottages. Then all that was wiped out, and an architectural monoculture succeeded it, the precious lots built to the edges with large structures—SUV homes—financed by insurance money. The area will not achieve any charm for many decades, if ever.

This is what the big Hayward fault earthquake will do, only the transformation will be a hundred times larger and extend up and down the East Bay. And it will affect the flats as well. That is why I try, every single day, to take pleasure in Oakland as it is. One day, in the twinkling of an eye, it will be gone, or changed irrevocably.