Archive for the ‘oakland hazards’ Category

Displacement at the Altenheim

15 January 2013

The Altenheim complex is on top of the northern side of the Sausal Creek valley, just across the freeway from the reservoir near the McKillop slide. There seems to be a little ground displacement here, too.

altenheim-slump

This view shows the downhill side of the property, on MacArthur Boulevard where it takes a leftward jog north of upper Fruitvale Avenue. The more I explore the stream valleys cutting through the Fan, the more of this I see.

Collecting the Orinda

4 July 2012

Lately I’ve been putting together a rock collection for the Chabot Space & Science Center. The last rock I needed was conglomerate, and I slapped my head and said “Duh! Use the Orinda Formation.” So it came to pass that I was on the Gudde Ridge roadcut, east of the Caldecott Tunnel, admiring that distinctive body of rock. But its exposures were off limits due to the construction.

orinda formation

There were two problems. Finding exposures of the conglomerate was difficult. And once I got close to the rock itself . . .

conglomerate

. . . this magnificent stone turned out to be rotten. You may think of conglomerate as a rugged rock, with all that grit and gravel in it. Indeed it can be. But the young, minimally processed conglomerate of the Orinda Formation doesn’t hold up to sun and weather very well. The pebbles work loose and the matrix turns crumbly in a matter of decades. The stuff in that impressive set of stairstep cuts is actually ready to give way, thudding dull under the hammer and totally useless for my purpose.

In connection with the Caldecott Tunnel work, the Fish Ranch Road offramp looks like it may have some fresh exposures. But it’s fenced off.

orinda formation

In the end, I had to find my conglomerate elsewhere. The fresh stone is beautiful, though, and being able to finish the collection made my day.

orinda formation specimen

Did you see it?

11 June 2012

Oakland is peppered with landslides, whether up in the hills like this little earthflow off Grizzly Peak Boulevard or down in the flats.

landslide

Now the U.S. Geological Survey wants to collect them all, the same way it does with earthquakes. By analogy with its “Did you feel it?” earthquake reporting site, the Survey’s Landslide Hazards Program has launched a “Did you see it?” site.

And now I have submitted this landslide to the DYSI page.

Heritage in a dynamic place

10 February 2012

I gave my talk last night to the Oakland Heritage Alliance and I think it turned out well. I tried to talk about our geology not on its own terms, but weighted toward its relevance in Oakland’s general civic life. One of my slides was this lovely digital elevation model that makes the Hayward fault obvious. Click to see the whole thing. Sadly, I can’t recall exactly where I got it.

oakland DEM

Here are my concluding remarks from the talk.

Oakland is situated in an area that falls down every century or so. Today, a repeat of the 1868 earthquake would erase large areas of our city. I don’t see how we can prevent that. How can we hang on to our history in the face of nature? And how can we hang on to our history in the face of human nature? By that I refer to well-known tendencies in cities that are traumatized. Citizens have a strong, almost overwhelming urge to return to normal, and that drive is amplified in their leaders.

We have the example of San Francisco after 1906, which underwent a furious rebuilding and whose leaders had no tolerance for delay. San Francisco was the leading city of the West, and the stakes were very high. Democracy was short-circuited for a time. The development-driven city leaders, led by “mover and shaker” James Phelan, were prepared to obliterate Chinatown before the Asian-American community rallied to save it. There was no heritage community at the time, and who knows how it would have fared had there been one.

After our earthquake—and it’s coming—Oakland will still have all the geographical gifts that I showed you at the start of my talk. We can assume that the seaport and airport and rail lines and highways will be rebuilt as soon as possible. The stakes will again be very high. There will be little conflict with the heritage community over any of that. The hard part will begin once the emergency ends.

Earthquakes are part of our geography. These days we like to talk about sustainable living: in tornado country, for instance, that means everyone has a storm cellar. What does it mean in Oakland? Some of our most beautiful neighborhoods lie along the fault, and they probably will not be reoccupied once destroyed. The city that arises after the next Big One will be very different in some ways.

I think I can foresee a more sustainable Oakland in which more people will live in well designed multi-family buildings and recreate in a long greenbelt where route 13 runs today. On the other hand, much will endure. City Hall should survive thanks to its retrofit after 1989. Landmarks like Tech High, the Camron-Stanford House, Peralta Hacienda, and Dunsmuir will be restored if they survive the tumult. I know that the Oakland Heritage Alliance will be there, doing its utmost to save what can be saved. In the end, much depends on the citizenry at large: the values they hold most strongly, the values we are teaching them today, will be those that prevail.

Oakland Memorial Park (earthquake park)

23 December 2011

In the Cypress district of West Oakland is a memorial park about the 1989 earthquake, which did the majority of its killing here. The sculpture at the corner of 14th Street and Mandela Parkway represents the ladders that local residents quickly raised against the wreckage of the collapsed freeway that once ran through here.

earthquake park oakland

Looking at the sculpture toward the hills, you also notice ring-shaped berms invoking the seismic waves that rippled north through the site from the epicenter in the Santa Cruz Mountains.

earthquake park oakland

Here’s a view from the sidewalk looking the other way. The park takes up an L-shaped portion of the block, the rest of which is occupied by a fire station.

earthquake park oakland

The floor of the sculpture pad briefly describes the scene here on 17 October 1989. The edge of the park is a wall with “15 seconds” in big steel letters on it. To the right is an interpretive sign.

earthquake park oakland

This is a remarkable place that I had no inkling was here until I took a walk on Mandela Parkway yesterday. It occurs to me that there must be other memorials to the 1989 quake around the bay.


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