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Title: Scientists Find Rare Evidence Earth is 'Peeling' Under the Sierra
Nevada Mountains

Link: https://news.slashdot.org/story/25/04/20/0136...

"Seismologist Deborah Kilb was wading through California earthquake records
from the past four decades when she noticed something odd," reports CNN, "a
series of deep earthquakes that had occurred under the Sierra Nevada at a
depth where Earth's crust would typically be too hot and high pressure for
seismic activity..." Kilb flagged the data to Vera Schulte-Pelkum, a research
scientist at the Cooperative Institute for Research in Environmental Sciences
and an associate research professor of geological sciences at the University
of Colorado Boulder... Using the newfound data, the researchers imaged the
Sierra Nevada through a technique known as receiver function analysis, which
uses seismic waves to map Earth's internal structure. The scientists found
that in the central region of the mountain range, Earth's crust is currently
peeling away, a process scientifically known as lithospheric foundering. Kilb
and Schulte-Pelkum reported the findings in December in the journal
Geophysical Research Letters. The hypothesis lined up with previous
speculation that the area had undergone lithospheric foundering, which
happens when Earth's outermost layer sinks into the lower layer of the
mantle. Now, the study authors believe that the process is ongoing and is
currently progressing to the north of the mountain range, according to the
study... What's happening under the Sierra Nevada could offer rare insight
into how the continents formed, Schulte-Pelkum said. The finding could also
help scientists identify more areas where this process is happening as well
as provide a better understanding of earthquakes and how our planet operates,
she added... Evidence for this process has been hard to come by. It is not
visible from above ground, and it's an extremely slow process. Scientists
theorize that the south Sierra finished the process of lithospheric
foundering about 4 million to 3 million years ago, according to the study. It
appears that these natural events happen occasionally around the world,
Schulte-Pelkum said. "Geologically speaking, this is a pretty quick process
with long periods of stability in between. ... This (lithosphere foundering)
probably started happening a long time ago when we started building
continents, and (the continents) have gotten bigger over time. So it's just
sort of this punctuated, localized thing," she added... Further study within
this area could also help scientists better understand how the Earth evolves
on long timescales. If the lithospheric foundering continues underneath the
mountain range, one can speculate that the land will continue to stretch
vertically, changing the way the landscape looks now [said Mitchell McMillan,
a research geologist and postdoctoral fellow at Georgia Tech, who was not
involved with the study]. But that could take anywhere from several hundred
thousand to a few million years, he added.

Read more of this story at Slashdot.

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