Posted by: walkingthefault | March 5, 2008

Why is Berkeley Moving?

My last post, in which I mentioned the subject of the Pacific Plate twisting slowly to the north-west, while the North American Plate slides in the other direction, generated the question “What makes the plates move anyway?” Not only is Berkeley slowly moving along as part of the edge of the Pacific Plate, but two areas of Berkeley are moving at different speeds. And it has nothing to do with politics.

La Loma Steps Exit

Would you believe it if I told you that the part of Berkeley at the top of these beautiful La Loma Steps is moving in a different direction relative to the part where the cameraman is standing? Right now, you can see that there is absolutely no evidence of that fact. But there will be very soon, and when that happens, it will be frightening.

All of the tectonic plates which make up the surface of the earth, including the ocean floors, are moving around relative to each other like slabs of congealed scum on a slowly simmering pot of soup. Berkeley is merely a couple of insignificant pieces of congealed scum sliding around right on the edge of the Pacific Plate.

Calling Berkeley a couple of insignificant pieces of congealed scum sounds like it came right out of the mouth of extreme right wing talking head Bill O’Reilly from the Fox Television Network News, but in fact that’s a good analogy. For many years, scientists have used the picture of a pot of simmering soup to illustrate the movement of the earth’s tectonic plates.

In some cases, two pieces of scum slowly crash into one another and pile the earth’s crust high up into the air, like the Himalayas, in what is known as a convergent boundary; in some cases they split apart leaving a void, as is the case underneath the center of the Atlantic Ocean, giving rise to islands like Iceland and the Azores, in what is known as a divergent boundary; and in some cases two pieces slide slowly past one another in what is called a transform boundary, resulting in a fault system like what we have here in the Bay Area.

Atomic and residual energy from the center of the earth is the source for the heat for the simmering soup with its convection currents that cause the earth’s crustal plates to move relative to one another, and the Berkeley flatlands to slide north-west a little bit faster than the Berkeley Hills. See, it’s not politics at all!

Where the Pacific Plate and the North American plate meet is at the complex series of faults known as the San Andreas Fault, the Hayward/Rodgers Creek Fault, the Calaveras Fault, and other minor faults, some yet to be discovered. It’s a mess, it really is. It wouldn’t matter if it were just a bowl of soup covered in cracking pieces of scum, but it’s the place where we live!

The story gets worse. If Berkeley were, in fact, moving slowly, we might not get devastating earthquakes every hundred or so years, but unfortunately it’s all jammed up. The two pieces of real estate on the edge of the Pacific Plate are stuck fast against each other at a line a little way up the Berkeley Hills. The piece of crust between the Hayward Fault in Berkeley and the San Andreas Fault is struggling to move north-west, but cannot right now because it is jammed, and the piece of crust between the Hayward Fault in Berkeley and the Calaveras Fault in Concord is struggling in the same way, but at a slower speed, because it is stuck where the Calaveras Fault meets the North American Plate.

Let’s take a look again at the Bay Area fault diagram (courtesy of USGS).

Bay Area Faults

Now think once more about the scum on the soup analogy, and you may understand why two pieces of Berkeley are moving, or would be, if they weren’t stuck together while the simmering soup underneath inexorably increases the pressure. One day soon, it’s got to break.  

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Responses

  1. You are correct in your assertion that we remain overly complacent in the face of this looming and inevitable event. I appreciate the persistent voices such as yours that run interference on our denial and complacency! Its a good thing that there is such a thing as retirement whereby one may have the time to compile and present such data.

    I can’t remember if you mentioned this, but it is
    a fact that the Hayward Fault has ruptured approx every 150 years, like clockwork, going back a long way, so it is going to happen!!

    At your urging I had a gas shutoff valve installed on my gas line, and I in turn strongly urge your readers to do the same. See this web page for more information: http://www.pge.com/mybusiness/edusafety/naturaldisaster/earthquake/shutoffdevices/index.shtml

    It just takes a phone call and about 400 bucks. Well worth it, I thought.

    Thanks, Andy! I look forward to reading more.

  2. Interesting walk blog.

  3. The best information i have found exactly here. Keep going Thank you


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