Tuesday, March 15, 2011

I Didn't Feel Like Teaching Today...

...but it was the kind of day that demands teaching.

My first day back with classes after the magnitude 9.0 quake and tsunami in Sendai, Japan, and the perfect teachable moment. Only it doesn't feel like a teachable moment. I just felt sorrow. So much is going on, and the situation seems to change hour to hour. First it was a magnitude 9.0 earthquake. Those don't happen very often, and that would be enough by itself to toss out the lesson plan of the day and discuss earthquakes and magnitude. But then there was the horrific tsunami that changed everything. 80 miles is a pretty good distance to be from a magnitude 9 quake, and it looks like the structures along Japan's coast weathered the shaking pretty well. But the tsunami raged through and erased towns, wiping them out of existence. Without the tsunami, the quake would have been a footnote. With the tsunami this event became the ultimate human tragedy. Thousands dead, hundreds of thousands homeless. It's hard to even speak of it, much less try and understand the pain and suffering that is taking place across the sea.

But then a new threat; the nuclear power stations began failing one after another in a story that is still unfolding. A human-induced tragedy superimposed over a nature event. We've concentrated radioactive substances in order to produce a form of energy, and the engineers have always told us that it can be made safe. Despite Three-Mile Island, despite Chernobyl, despite the other 30 'incidents' in the past 50 years. We've 'learned' from each of the accidents, it is said. They can't happen elsewhere. We have back up systems. We can't give up nuclear energy they say, because it is the bridge to a renewable energy future. Otherwise we'll have to burn more coal, and coal contributes to global warming. In all of the chattering among the talking heads on cable news this weekend, I have heard nothing of the threat of terrorism at nuclear power plants, nor have I heard anyone talk about where the highly radioactive waste is going to go. We've been avoiding the second problem for 50 years now. Will these questions start emerging, or will they disappear once the meltdown is complete, or once they stop the meltdown from occurring.

So the lesson plan for the day is tossed. We talk about the earthquake, the tsunami, the nuclear power plants. Questions, one after another. Some I can answer, some I cannot.

Can we have a magnitude 9 quake in California? Yes and no. The legendary San Andreas fault can produce events in the range of magnitude 8, about 1/30th of the size of the Sendai earthquake. Many other faults in California have produced dozens of quakes in the range of magnitude 6.5-7.5, and some have been very damaging. Magnitude 9? Not exactly. The Cascadia subduction zone lies off the coast of Northern California, and extends across Oregon and Washington. That system produced a magnitude 9 quake in 1700. Studies show such a quake takes place every few hundred years. Such a quake would have devastating consequences in NorCal and the Pacific Northwest.

Are the nuclear power plants going to have a full meltdown? I have no idea. I'm not an expert, and I don't know that the experts even know.

Will we be hit by a dangerous radioactive cloud? I don't think so, the experts say it will dissipate in the atmosphere and fall into the ocean before it gets here. I'm more worried about the people who live in the vicinity of the power plants. If the worst case scenario happens, the land they have lived on all their lives could be declared uninhabitable. Where will they go?

I'm glad the meltdown didn't happen here. How many of you know where your energy comes from? California has two operating nuclear power plants, both on the coast, both near fault systems. Another mothballed power plant sits unused just 80 miles from us, with all the fuel rods on site. The engineers for the plants say they're ready for whatever happens (I bite my tongue to avoid getting political).

Can a tsunami hit us in the Central Valley the way it did in Japan? No, not likely, but we have a different problem: the Sacramento Delta. The three dozen or so islands in the Delta are 'protected' by century-old levees that are prone to failure from causes as simple as excessive muskrat burrowing. The islands have sunk over the last century, and most are now below sea level. A moderate quake on nearby faults could cause widespread failure and flood the islands with seawater. If it were just lost farmlands, we could deal with it. But the intake pumps for the California Water Project are in the midst of the islands and the inundation could cut off the water supply for 20 million people for months, if not years.

What will the "Big One" do to us? It depends which "Big One" you are talking about. A repeat of the 1906 earthquake in San Francisco? Or the 1857 Fort Tejon earthquake? Or the 1872 Lone Pine quake Or another? All of them were close to magnitude 8, and if they happened again, the results would be profound. And there are dozens of other active fault zones in California. But here in the Central Valley? Harder to say. The 1906 quake was certainly felt in the region, but didn't do much damage in our town. Cities and towns on the west side of the valley will have some serious problems with shaking and liquefaction, but we are on relatively stable sediments.

Where's the best place to live? Kansas or Nebraska I should think. But watch out for tornadoes. Here in California, I would pick the Sierra foothills. Solid bedrock foundations and relatively far removed from the most active fault zones.

I have a question for the class: How many of you have an earthquake emergency kit ready at home (and in the car)? Two or three hands, including my own...

We are not ready...

Do you have questions? Use the comments section to ask and I will answer if I can, or find an answer somewhere.


Gaelyn said...

All very good questions from your students. I assume my desert survival kit will do.

How will the radioactive particles that fall in the ocean affect sea life?

GeeBec said...

"Another mothballed power plant sits unused just 80 miles from us, with all the fuel rods on site."

Are you talking about The Rancho Seco Power Plant? If so does it still impose a threat to us today?

Garry Hayes said...

Yes, I was referring to Rancho Seco. The plant has been mostly decommissioned and much of the power generating equipment removed, but 11 acres are still used for low-level waste storage, and for storage of some "dry-cask spent fuel" units that contain some high level waste. They consider them a safe form of storage. Most of the original property is now a recreational area, with 'safe' levels of radiation only a bit above background levels. Info here: http://www.world-nuclear-news.org/WR-Cleanup_complete_at_Rancho_Seco-0810097.html

Kelly said...

I have a dumb question. I am not a geologist or anything related to the sort. I'm just curious.
What is the difference in Earthquakes and aftershocks? It seems the aftershocks are powerful enough to be earthquakes so why aren't they?

Garry Hayes said...

All movements and vibrations in the crust are earthquakes. After the events are winding down, the biggest quake is the main shock. Those that preceded it are foreshocks (one of the foreshocks was a mag. 7 quake on Tuesday), and quakes that follow are the aftershocks. The aftershocks come by the hundreds or thousands, but in general decline in time in size and frequency. Usually the largest aftershocks are about a magnitude smaller than the main shock (there was a 7.2 aftershock, I think). All of these are earthquakes, however.

james said...

Interesting to hear your thoughts on the safest places to live. I'd suggest though that a lot of the Sierra foothills are less than ideal due to mining related water pollution and associated increased risks for various cancers. Would be great to see a post covering some different locations in depth and trying to find the place that is safest across multiple criteria.

Garry Hayes said...

Thanks James. You are right about the contamination (not to mention possible asbestos in some places). That would be an interesting discussion, about where the safest places are. I bet they are very boring places in most other respects! I often note that California is an interesting place to live because of the very active geological processes that go on here.