Seismic Activity in Long Valley Caldera: Revealing Findings by Caltech

by Klaus Müller
8 comments
Long Valley Caldera Seismic Activity

Researchers from the California Institute of Technology employed cutting-edge imaging methods to scrutinize the escalated seismic occurrences in the Long Valley Caldera, a quiescent supervolcano in California. Their studies indicate that the seismic activity is due to cooling mechanisms, not impending volcanic activity.

A Period of Seismic Unrest in California’s Eastern Sierra Nevada

Since the 1980s, significant seismic disturbances have been observed in a portion of California’s Eastern Sierra Nevada mountain range. This area, known as the Long Valley Caldera, is positioned over an enormous inactive supervolcano. The caldera was formed approximately 760,000 years ago through a catastrophic eruption that expelled 650 cubic kilometers of ash into the atmosphere—enough to blanket the entire region of Los Angeles with a one-kilometer-thick sediment layer.

Unveiling Subsurface Insights Through Advanced Imaging

To gain clarity on the increased seismic activity in recent decades, researchers from Caltech created some of the most intricate underground images of the Long Valley Caldera to date, reaching depths of up to 10 kilometers beneath the Earth’s crust. These high-resolution images offer valuable insights into the subterranean structure beneath the caldera, revealing that the escalating seismic events are due to the release of fluids and gases as the region undergoes a cooling process.

Detailed Seismic Studies

The research was spearheaded in the laboratory of Zhongwen Zhan, PhD and professor of geophysics at Caltech. An article detailing the research was published on October 18 in the journal Science Advances.

According to Zhan, while a massive eruption is not anticipated, the cooling process could nonetheless lead to the release of enough gas and fluids to trigger earthquakes and minor eruptions. For instance, in May 1980 alone, the area experienced four earthquakes with magnitudes of 6.

High-resolution images reveal that the magma chamber under the volcano is sealed by a solidified layer of crystallized rock, which forms as the molten magma cools and solidifies.

Breakthroughs in Imaging Technology

To generate the subterranean images, seismic waves were measured through a process known as distributed acoustic sensing (DAS), which utilizes fiber-optic cables. This method enabled the team to capture more than 2,000 seismic events over an 18-month period, most of which were too minor to be felt by humans. These measurements were then processed through a machine learning algorithm to develop the resulting image.

This is the inaugural study to produce such in-depth, high-resolution images using DAS, outstripping the limitations of earlier, less detailed imaging studies.

Prospective Research Avenues

Next, the research team aims to use a 200-kilometer length of cable to delve even deeper into the Earth’s crust, to around 15 to 20 kilometers, where the cooling process of the caldera’s “central core” continues.

References

The study, titled “An upper-crust lid over the Long Valley magma chamber,” was authored by Ettore Biondi, Weiqiang Zhu, Jiaxuan Li, Ethan F. Williams, and Zhongwen Zhan and was published on 18 October 2023 in Science Advances. Additional contributors include former Caltech postdoctoral fellow Weiqiang Zhu, now affiliated with UC Berkeley; Caltech postdoctoral scholar Jiaxuan Li; and former Caltech graduate student Ethan Williams, currently at the University of Washington. Financial support for the project was provided by the National Science Foundation, the Resnick Sustainability Institute at Caltech, and the Gordon and Betty Moore Foundation.

Frequently Asked Questions (FAQs) about Long Valley Caldera Seismic Activity

What is the main focus of the Caltech researchers’ study?

The primary objective of the study conducted by Caltech researchers is to investigate the increased seismic activity in California’s Long Valley Caldera, a dormant supervolcano. The team used advanced imaging techniques to create high-resolution underground images to determine the cause of the seismic unrest.

Who is leading the research?

The research is led by Zhongwen Zhan, a PhD and professor of geophysics at the California Institute of Technology. The study is conducted in his laboratory and the findings were published in the journal Science Advances on October 18.

What methods were used for the study?

The researchers used a method called distributed acoustic sensing (DAS) which employs fiber-optic cables to capture seismic events. Over an 18-month period, the method helped in measuring more than 2,000 seismic events, most too small to be felt by humans.

What did the high-resolution images reveal?

The high-resolution images reached depths of up to 10 kilometers beneath the Earth’s crust and revealed that the increasing seismic activity is due to the release of fluids and gases as the region undergoes a cooling process.

Is the Long Valley Caldera expected to erupt soon?

The study suggests that a major supervolcanic eruption is not imminent. However, the cooling process may still lead to the release of enough gas and fluids to cause minor eruptions and earthquakes.

What are the future plans for this research?

The research team plans to employ a 200-kilometer length of cable to probe even deeper into the Earth’s crust, aiming to reach depths of around 15 to 20 kilometers, where the caldera’s “central core” continues to cool.

Who funded the research?

The research was funded by the National Science Foundation, the Resnick Sustainability Institute at Caltech, and the Gordon and Betty Moore Foundation.

What were the key technological breakthroughs of this study?

This is the first study to employ distributed acoustic sensing (DAS) to create such in-depth, high-resolution images of a supervolcano’s underground environment. It represents a significant advancement in the field of seismology.

How did machine learning contribute to this study?

A machine learning algorithm processed the seismic measurements captured through DAS, enabling the creation of a detailed image that reveals the subterranean structure beneath the Long Valley Caldera.

Who are the other contributors to this research?

In addition to Zhongwen Zhan, contributors include Ettore Biondi, Weiqiang Zhu, Jiaxuan Li, and Ethan F. Williams. Zhu is now affiliated with UC Berkeley, Li is a Caltech postdoctoral scholar, and Williams is currently at the University of Washington.

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8 comments

InvestorSam October 20, 2023 - 2:05 am

Impressive research, makes me wonder about investment opportunities in seismic tech. any1 know startups in this space?

Reply
Mandy_G October 20, 2023 - 2:41 am

so, basically we’re safe from an eruption? thats a relief but still, small quakes and eruptions? yikes!

Reply
CaliResident October 20, 2023 - 2:42 am

living near the Sierra Nevada, this is both cool and kinda scary. glad they’re looking into it though.

Reply
JohnDoe82 October 20, 2023 - 3:53 am

Whoa, never knew that such advanced tech could actually tell us if a supervolcano is gonna erupt or not. This is some next level stuff.

Reply
SciFan101 October 20, 2023 - 8:19 am

Got to say, Caltech is really leading the way in groundbreaking studies. Kudos to the team.

Reply
Skeptical_Steve October 20, 2023 - 11:16 am

Ok but how reliable is this really? I mean, they said its not gonna erupt but then again, mother nature’s got its own plans.

Reply
CuriousMinds October 20, 2023 - 6:53 pm

What happens if it actually erupts? The article says last time it sent tons of ash into the air. could be catastrophic.

Reply
EnviroGeek October 20, 2023 - 7:58 pm

Really amazed by the technology involved. distributed acoustic sensing? that’s gotta be revolutionary for the field of seismology.

Reply

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