Walker Lane Redux

It’s been an interesting few days here in Southern California, with several large earthquakes and an ensuing aftershock sequence out in the desert near Ridgecrest. Ridgecrest, of course, is at the very southern edge of the Walker Lane—more properly part of the Eastern California Shear Zone—a region of the country that runs broadly northwest along the California/Nevada state border that I covered at length for the May 2019 issue of Wired.

[Image: My own loose sketch of the Walker Lane, using Google Maps].

To make a story short, a handful of geologists have speculated, at least since the late 1980s, that the San Andreas Fault could actually be dying out over time—that the San Andreas is jammed up in a place called the “Big Bend,” near the town of Frazier Park, and that it is thus losing its capacity for large earthquakes.

As a result, all of that unreleased seismic strain has to go somewhere, and there is growing evidence—paleoseismic data, LiDAR surveys, GPS geodesy—that the pent-up strain has been migrating deep inland, looking for a new place to break.

That new route—bypassing the San Andreas Fault altogether—is the Walker Lane (and its southern continuation into the Mojave Desert, known as the Eastern California Shear Zone).

What this might mean—and one of the reasons I’m so fascinated by this idea—is that a new continental margin could be forming in the Eastern Sierra, near the California/Nevada state border, a future line of breakage between the Pacific and North American tectonic plates.

If this is true, the Pacific Ocean will someday flood north from the Gulf of California all the way past Reno—but, importantly, this will happen over the course of many millions of years (not due to one catastrophic earthquake). This means that no humans alive today—in fact, I would guess, no humans at all—will see the final result. If human civilization as we know it is roughly 15,000 years old, then civilization could rise and fall nearly 700 times before we even get to 10 million years, let alone 15 million or 20.

In any case, these recent big quakes out near Ridgecrest do not require that the most extreme Walker Lane scenario be true—that is, they do not require that the Walker Lane is an incipient continental margin. However, they do offer compelling and timely evidence that the Walker Lane region is, at the very least, more seismically active than its residents might want to believe.

I could go on at great length about all this, but, instead, I just want to point out one cool thing: the far northern route of the Walker Lane remains something of a mystery. If you’ve read the Wired piece, you’ll know that, for the Walker Lane to become a future continental edge, it must eventually rip back through California and southeastern Oregon to reach the sea. However, the route it might take—basically, from Pyramid Lake to the Pacific—is unclear, to say the least.

One place that came up several times while I was researching my Wired article was the northern California town of Susanville. Susanville is apparently a promising place for study, as geologists might find emergent faults there that could reveal the future path of the Walker Lane.

If you draw a straight line from the Reno/Pyramid Lake region through Susanville and keep going, you’ll soon hit a town called Fall River Mills. Interestingly, following the long aftershock sequence of these Ridgecrest quakes, there was a small quake in Fall River Mills this morning.

While seeing patterns in randomness—let alone drawing magical straight lines across the landscape—is the origin of conspiracy theory and the bane of serious scientific thinking, it is, nevertheless, interesting to note that the apparently linear nature of the Walker Lane could very well continue through Fall River Mills.

[Image: The Ridgecrest quakes and their aftershocks seem to support the idea of a linear connection along the Walker Lane; note that I have added a straight orange line in the bottom image, purely to indicate the very broad location of the Walker Lane].

While we’re on the subject, it is also interesting to see that, if you continue that same line just a little bit further, connecting Pyramid Lake to Susanville to Fall River Mills, you will hit Mt. Shasta, an active volcano in northern California. Again, if you’ve read the Wired piece, you’ll know that volcanoes seem to have played an interesting role in the early formation of the San Andreas Fault millions of years ago.

In any case, in cautious summary, I should emphasize that I am just an armchair enthusiast for the Walker Lane scenario, not a geologist; although I wrote a feature article about the Walker Lane, I am by no means an expert and it would be irresponsible of me to suggest anything here as scientific fact. It does interest me, though, that aftershocks appear to be illuminating a pretty dead-linear path northwest up the Walker Lane, including into regions where its future route are not yet clear.

Insofar as the locations of these aftershocks can be taken as scientifically relevant—not just a seismic coincidence—the next few weeks could perhaps offer some intriguing suggestions for the Walker Lane’s next steps.

14 thoughts on “Walker Lane Redux”

  1. Hi Geoff,
    Wired have resurrected your article and having read it originally, I know you must be even more thrilled (if that is the correct term…in Australia we would say “chuffed”) at the perfect timing of your article.
    Keep up the great work.
    BTW I suspect Nevada might have to upgrade the seismic building codes for those nice shiny new industrial zones, but they seem to have the perfect State Geologist to help out with that…

    1. Definitely strange timing! When we felt the first big one here at our house, my fear was almost immediately outweighed by excitement over where it had struck.

  2. I only learned about the Walker Lane from your Wired article. When I heard about the July 4 quake I immediately thought of it, and checked the location of the epicenter. Bang on the Lane. How does it feel to be a prophet?

  3. Great article in Wired! I live in Salt Lake and your description of the town’s ignorance of its seismic history resonated with me. White settlers and our written documents haven’t been here in the West all that long and I think that stories like yours help drive home the idea that we have a lot to learn (and that Anglos need to pay more attention to indigenous cultures, a la https://blogs.scientificamerican.com/rosetta-stones/thunderbird-and-the-orphan-tsunami-cascadia-1700/).

  4. Read both articles on Walker Lane, fascinating ! Thanks for writing these . Like you, I’m amazed by the science since doing some GPS software a couple years ago, and I had the thought, how accurate is the mapping when we have movement like the big Chile earthquake a few years ago.

  5. I read your first exciting, entertaining, and well written article on Wired at least 50 times before the Ridgecrest historical quakes. As the first quake rolled in on July 4th, I soon discovered it on the USGS index map, and yelled with amazement, “He was right!! The mojave desert quakes all line up!!” I was waiting for you or some geologist to post a new article about these new quakes and how they related to the Walker Lane theory. (Has James Faulds or Amos Nur discovered any new evidence with new technology?) I have to look up Fall River Mills on the map and its relation to volcanos. Now I too have taken the red pill. I stand here in Los Angeles, feeling and hearing nature’s construction of a new plate boundary 150 miles away.

    1. It’s an incredibly compelling hypothesis, including some aspects of the larger idea that didn’t make it into the Wired piece (for example, the gradual northward migration of the so-called Mendocino Triple Junction—perhaops a topic for a future article…). The Fall River Mills quake could easily be nothing more than a well-timed coincidence, though, so I hope it’s clear that, in this post, I was just drawing straight lines on the map and getting excited about what they appeared to connect. In terms of true seismic relevance, I defer to the experts.
      Meanwhile, stay safe!

  6. And behold, there is a fault discovered in that exact spot that no one new about. I to have heard the walker pass hypothesis from University professors about eight years ago. I never heard about it again. I am an enthusiast, not a geologist,
    but, you can’t unsee that once you see it.

  7. Brilliant articles, saving my Wired copy. What is the origin of “Walker lane” in naming it ?
    anything to do with Walker lake in NV.

    1. Hey, PKP, sorry for the late reply to this—I didn’t realize I never responded! There are many Walker-named features in the region that go back to Joseph R. Walker. “Traveling through California, Walker and his party saw redwood forests, experienced a major earthquake, and witnessed a meteor shower”—which, it now seems, is appropriate.

  8. I located an interesting blog online titled “CASCADIA ALERT.” It speaks about the Gulf of California, Walker Lane, and area east of Cascadia mountain range in Oregon as being oceanic rift zones with volcanic activity. The whole area could someday rip apart as Baja California did from Mexico. Read his article on “A zone of continental rifting?” Very interesting to read.

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