A new research study uses seismic waves to image the underground environment in the area and finds that the lava chamber is cooling off. To develop underground images, the scientists presume what the subsurface environment looks like by measuring seismic waves from earthquakes. Earthquakes produce of 2 types of seismic waves: main (P-waves) and secondary (S-waves). There are numerous lots seismometers positioned throughout the Eastern Sierra area, Zhans technique utilizes fiber optic cable televisions (like those that offer web) to make seismic measurements in a procedure called distributed acoustic picking up (DAS). Over a year and a half, the team utilized the cable to measure more than 2,000 seismic events, most too little to be felt by people.
To respond to these concerns, Caltech researchers have developed the most comprehensive underground images to date of the Long Valley Caldera, reaching depths approximately 10 kilometers within the Earths crust. These high-resolution images expose the structure of the earth beneath the caldera and reveal that the recent seismic activity is a result of fluids and gases being released as the location cools down and settles.
Whats going on underneath the surface area of the Long Valley Caldera, the site of an enormous supervolcano eruption 760,000 years earlier? A new research study uses seismic waves to image the underground environment in the region and discovers that the lava chamber is cooling down. Earthquakes might still result from the fluids and gases launched from the lavas crystallization. Credit: E. Biondi
The work was conducted in the lab of Zhongwen Zhan (PhD 14), teacher of geophysics. A paper explaining the research was released on October 18 in the journal Science Advances.
” We do not believe the area is preparing for another supervolcanic eruption, but the cooling process might release sufficient gas and liquid to cause earthquakes and small eruptions,” states Zhan. “For example, in May 1980, there were 4 magnitude 6 earthquakes in the area alone.”
The high-resolution image reveals that the volcanos lava chamber is covered by a hardened lid of crystallized rock, formed as the liquid magma cools off and solidifies.
Innovative Imaging Techniques
To develop underground images, the researchers infer what the subsurface environment looks like by determining seismic waves from earthquakes. Earthquakes generate of two types of seismic waves: primary (P-waves) and secondary (S-waves).
There are numerous lots seismometers placed throughout the Eastern Sierra region, Zhans technique makes use of fiber optic cable televisions (like those that offer internet) to make seismic measurements in a process called dispersed acoustic sensing (DAS). Over a year and a half, the group used the cable to determine more than 2,000 seismic occasions, the majority of too little to be felt by people.
This study is the very first time that such deep, high-resolution images have actually been produced with DAS. Previous images from local tomography studies have either been confined just to the shallow subsurface environment at depths of about 5 kilometers, or covered a larger location in lower resolution.
” This is one of the first demonstrations of how DAS can alter our understanding of crustal dynamics,” states Ettore Biondi, DAS researcher at Caltech and the papers very first author. “Were thrilled to use similar technology to other regions where we wonder about the subsurface environment.”
Future Endeavors
Next, the team plans to utilize a 200-kilometer length of cable television to image even deeper into the Earths crust, to around 15 to 20 kilometers deep, where the calderas lava chamber– its “beating heart”– is cooling.
Referral: “An upper-crust cover over the Long Valley lava chamber” by Ettore Biondi, Weiqiang Zhu, Jiaxuan Li, Ethan F. Williams and Zhongwen Zhan, 18 October 2023, Science Advances.DOI: 10.1126/ sciadv.adi9878.
In addition to Biondi and Zhan, co-authors are previous Caltech postdoctoral fellow Weiqiang Zhu, now of UC Berkeley; Caltech postdoctoral scholar Jiaxuan Li; and previous Caltech graduate student Ethan Williams (MS 19, PhD 23), now of the University of Washington. Funding was offered by the National Science Foundation, the Resnick Sustainability Institute at Caltech, and the Gordon and Betty Moore Foundation.
Caltech scientists utilized advanced imaging methods to examine increased seismic activity in Californias Long Valley Caldera, a dormant supervolcano. Their findings suggest the area is not on the brink of a significant eruption however is experiencing seismic activity due to cooling procedures.
Caltech scientists utilized sophisticated imaging strategies to examine increased seismic activity in Californias Long Valley Caldera, an inactive supervolcano.
Considering that the 1980s, scientists have observed considerable periods of unrest in a region of Californias Eastern Sierra Nevada mountains identified by swarms of earthquakes along with the ground increasing and inflating by nearly half an inch each year during these durations. The activity is concerning due to the fact that the location, called the Long Valley Caldera, sits atop a massive inactive supervolcano. Seven hundred and sixty thousand years earlier, the Long Valley Caldera was formed in a violent eruption that sent out 650 cubic kilometers of ash into the air– a volume that could cover the entire Los Angeles location in a layer of sediment 1 kilometer thick.
Groundbreaking Imaging Reveals Insights
What is behind the increased activity in the last few decades? Could it be that the location is preparing to erupt again? Or could the uptick in activity actually be an indication that the danger of a huge eruption is reducing?