(Roughly) Daily

“I feel the earth move under my feet”*…

 

WALKER_LANE_MAP_1

 

For more than a century, the San Andreas Fault has been considered the undisputed heavyweight champion of large-scale deformation in the West. It is here that the North American and Pacific Plates meet, jostling for position with often violent results. Eventually, the theory goes, the thin sliver of land between the fault and the ocean—from the southern tip of the Baja Peninsula to the Santa Cruz Mountains—will break off from the mainland and slide north, until LA drifts past San Francisco. But there’s at least one problem with this scenario: The San Andreas appears to have gotten jammed. Northwest of LA, near the town of Frazier Park, the fault is kinked out of alignment so dramatically that many geologists suspect the pent-up tectonic strain will have to seek release somewhere else…

[Nevada state geologist James] Faulds thinks he’s found the spot. It’s an emerging zone of instability, known as the Walker Lane, that closely follows Route 395. He believes that, over the next 8 million to 10 million years, the North American continent will unzip along this stretch of land, east of the San Andreas. The Gulf of California, which separates the Baja Peninsula from Mexico, will surge north into Nevada, turning thousands of square miles of dry land into ocean floor. (Mapmakers, if they still exist, may label the new body of water the Reno Sea.) While this geologic realignment will take long enough for human civilization to fall, rise, and fall again hundreds of times over, Faulds’ hypothesis is more than an academic curiosity. It represents a radical shift in how geologists use up-to-the-minute tools—satellite data, aerial surveys, computer simulations—to fathom age-old processes. And for residents of the West, it is an invitation to think in an altogether new way about the familiar-seeming ground beneath them. Now is the time: Already the Walker Lane region, with its booming population and burgeoning tech economy, is beginning to feel the rumblings of a new seismic regime…

The next Big One?  “Move Over, San Andreas: There’s an Ominous New Fault in Town.”

* James Taylor and Carole King

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As we ruminate on the rumbling, we might spare a thought for Richard Dixon Oldham; he died on this date in 1936.  A geologist and pioneering seismologist, he made the first clear identification of the separate arrivals of P-waves (primary waves), S-waves (secondary waves), and surface waves on seismograms.  Later, he developed the first clear evidence that the Earth has a central liquid core.

150px-RD_Oldham source

 

Written by LW

July 15, 2019 at 1:01 am

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