Urgent Warning: Geologists Discover Troubling Signs of Sierra Nevada’s Crust Shifting – What You Need to Know!

Seismologists are making exciting discoveries about California’s geology, specifically in the Sierra Nevada mountain range. They’ve found evidence of a rare phenomenon called lithospheric foundering. This process happens when the Earth’s outer layer, the lithosphere, detaches and sinks into the mantle below. Recent findings indicate this process is currently happening.

Deborah Kilb, a seismologist at the Scripps Institution of Oceanography, first noted something unusual in California’s earthquake data. In certain areas of the Sierra Nevada, earthquakes were occurring at depths of 20 to 40 kilometers — much deeper than the usual 10 to 18 kilometers seen in other parts of California. This triggered collaboration with Vera Schulte-Pelkum, a geophysicist from the University of Colorado Boulder, who was examining rock deformations in the same area. Together, they began to investigate what was happening beneath the mountain range.

Using a method called receiver function analysis, which looks at how seismic waves travel through the Earth, they created a map of the structures under the Sierra. Their study revealed that the lithosphere is actively peeling away, something that was only theorized until now. Their research, published in Geophysical Research Letters, confirmed that the dense lower part of the lithosphere had already detached millions of years ago in the southern Sierra. Now, the central Sierra is undergoing a transformation, while the northern part remains stable.

The driving force behind this process is the difference in density between the Earth’s layers. Schulte-Pelkum explained, "To make it sit higher, you have to get rid of some of the dense stuff.” So, as the dense material sinks into the mantle, lighter crustal layers are left behind, allowing mountains to rise.

Seismic images show a unique layer within the mantle, about 40 to 70 kilometers deep. In the southern Sierra, this layer seems completely detached. However, in the central range, it is still in the process of changing, indicated by deep earthquakes and distinct rock deformations.

Interestingly, these quakes might result from cooling rock due to the downward pull of material. Kilb pointed out that rock cools slowly, so this colder crust can become brittle and fracture, causing earthquakes even at deep levels where they’re rare.

Lithospheric foundering sheds light on how continental crust forms. Schulte-Pelkum noted, “We sort of owe our existence on land to these processes happening.” These movements in Earth’s crust help keep lighter minerals near the surface, creating the land masses we know.

This peeling process is gradual and goes unnoticed at the surface, yet leaves lasting geological markers. Researchers believe the southern Sierra finished its foundering around 3 to 4 million years ago, while the central part continues to evolve.

Interestingly, this phenomenon might not be unique to California. The Andes mountains could be experiencing similar processes, and even Venus shows signs of comparable activities deep within its structure.

There’s an ongoing debate regarding some anomalies beneath California’s Great Valley. While some scientists think they are a result of lithospheric foundering, others argue they’re linked to subduction, where one tectonic plate sinks beneath another. Mitchell McMillan, a geologist at Georgia Tech, noted, “There are really two competing hypotheses to explain all these data… and you don’t really get that very often in geology.”

This research illustrates that the Earth’s surface is constantly shifting, though these changes occur over vast timescales. Whether lithospheric foundering continues or not, the Sierra Nevada is on a path of gradual transformation, possibly altering its structure over hundreds of thousands to millions of years.

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