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.

Red Rock Quarry

9 January 2017

The Red Rock Quarry was apparently part of the Blair quarry complex in Moraga Canyon, at the west edge of Piedmont on Red Rock Road. Oakwiki reports that it was owned by the Henry Maxwell family (for whom Maxwelton Road is named). The 1947 USGS topographic map shows that the quarry was active at that time.

I took photos of the rocks here last June. The parking lot exposes the rock pretty well.

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The area is mapped as Franciscan sandstone, which underlies most of Piedmont. This locality is near the ancient thrust fault separating the sandstone from Franciscan melange to the east. Being near the fault would have subjected it to a lot of disruption, and that’s what you see here. The rock is somewhat disorganized, with massive beds on the right juxtaposed with thin-bedded mudstone in the center.

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Fractures in the massive sandstone have opened up, filled with carbonate material, then been displaced some more.

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The north edge of the parking lot exposes a nice set of turbidites. These are sequences that consist of beds of mudstone formed by repeated seafloor avalanches, separated by beds of shale that represent quiet times between avalanches.

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Blair and Maxwell made good money here and employed a lot of people. The rock was easy to dig out of the steep hillside, easy to crush without making a lot of wasteful dust, and easy to roll downhill to market. This quarry probably produced plain old crushed stone to be sold for landfill, foundations, concrete aggregate, roadbeds and the like. It was not the more desirable, cherty “phthanite” or siliceous argillite found elsewhere in Piedmont’s Franciscan rocks.

I say “probably” because I couldn’t inspect the whole pit. What I really wanted to do was examine the walls of the quarry itself, which are fenced off.

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They’re fenced off because today the quarry is the readymade site of the City of Piedmont’s corporation yard. As is often the case, this quarry was reused after its initial purpose was gone.

Siesta Valley and the De Laveaga Trail

2 January 2017

Last week I attempted the Rockridge-to-Orinda ramble by a northern route. Was strenuous, but it got me into Siesta Valley, a place I’ve had my eye on for years, for the first time. At this time of year the sun is so low that the light is terrific.

First came the climb up Tunnel and Caldecott Roads, then through Hiller Highlands up to Grizzly Peak Boulevard, a good 1200 feet higher, then down across the Fish Ranch/Claremont saddle, where it looked like this.

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That’s Gudde Ridge, in Sibley Volcanic Preserve, with Round Top on the horizon. The stairsteps in the rock are the huge roadcut for Route 24. Siesta Valley is to my left, over the ridge.

Siesta Valley is watershed land under the control of East Bay MUD, so I made sure to have my hiking permit with me. Not a soul was around, but it’s a good habit. The De Laveaga Trail runs from the top of the valley, at the Scotts Peak Trailhead, along the valley’s north flank. (It’s named for one of Orinda’s founding families — see the comments.) I took the wrong way, going straight down the valley floor on the dirt extension of Wilder Road, which leads to the back side of the Cal Shakespeare center. That meant a steep descent and subsequent climb of a few hundred feet on a pretty wet road, but I saw some bedrock of the Siesta Formation I’d otherwise have missed.

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That included this fine chunk of freshwater limestone, all of which fizzed nicely in acid, just like it should.

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Once I gained the De Laveaga Trail, the views opened up. The basalt flows of the Moraga Formation crop out well here.

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This view looks down the Siesta Valley to its continuation as Wilder Valley, across the freeway in Orinda.

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Siesta Valley is very quiet. City noise and freeway noise are kept out by the contours of the land, and on a lazy weekday afternoon I could see myself having a nice nap.

The trail leads up and over the east wall of the valley at about 1500 feet elevation, then it’s a steep 1000-foot plunge down to Orinda. This is the view north. The cattle pond is there because cattle graze these slopes.

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The sun sets so early here that it gets cold at night. Shaded puddles stayed ice-covered all that day.

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The winter haze obscured the Sierra, but not Mount Diablo and the Lamorinda hills.

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As I raced the sunset, downtown Orinda looked inviting. This is a harsh downhill, though. Uphill would be worse, I think. Nothing to do but try it sometime.

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The verdict: Siesta Valley is a challenge to reach on foot, but that’s your only choice as vehicles of all kinds are forbidden on EBMUD land. It’s an obscure piece of land that requires a permit, but it’s a gorgeous place. With rocks!