Beneath our feet, deep within the Earth, lies a mysterious boundary separating the Earth's fragile crust from its mantle. Known as the Mohorovičić Discontinuity, or Moho, this boundary has long fascinated scientists.
According to Saednews' Science and Technology service, a new technology developed by researchers at the California Institute of Technology (Caltech) has the potential to uncover the secrets of tectonic plates and even "sniff" earthquakes.
Researchers at Caltech can now detect even the smallest vibrations deep within the Earth by sending light pulses deep underground.
This mysterious boundary, which separates the Earth's crust from its mantle, has intrigued scientists for many years. And now, a new method is providing fresh insights into this hidden boundary. This has led the Caltech researchers to introduce a new seismic technology called Distributed Acoustic Sensing (DAS).
Using DAS, the method explores the Moho by analyzing seismic waves reflected from this boundary. By sending light pulses through a cable deep into the Earth, researchers can detect even the smallest vibrations deep beneath the surface.
James Atterholt, a postdoctoral researcher at the United States Geological Survey, says, "The Moho is a truly fascinating boundary for seismologists because it reveals what's happening inside and between tectonic plates at great depth."
The Moho lies at a depth of 12 to 43 miles beneath the Earth's surface.
Traditional methods for imaging the Moho either have low resolution or are very costly. But now, the DAS method transforms fiber optic cables into seismometers.
During an earthquake, seismic waves are emitted, some of which are reflected from the Moho.
Laser pulses sent through these cables can provide data on ground vibrations caused by earthquakes or other disturbances. This allows researchers to study the Earth's subsurface.
Interestingly, the researchers originally developed this method to analyze reflected laser light along the entire length of a fiber optic cable. This approach enables them to understand the Earth's internal movements, turning the cable into a network of small, distributed seismometers.
Distributed Acoustic Sensing (DAS) enables researchers to map the Moho's structure with high resolution over large areas, providing detailed insights into this vital geological boundary.
Atterholt explained in a press release: "This method can tell us whether major faults penetrate into the mantle, how ancient and modern processes have shaped the continents, and how strong the deep crust is in specific locations."
The team used DAS to gain new insights into the Moho by studying earthquakes with a fiber optic cable in the Mojave Desert and mapping the Moho over the course of two years.
They discovered that the Garlock Fault extends deeper into the mantle than previously thought in this region. The Garlock Fault is a key player in the seismic activity in Southern California.
However, the data also revealed that the Moho is significantly bent beneath the Coso volcanic field, an inactive volcanic area north of the Mojave.
This research provides valuable insight into the relationship between the mantle's heat source and the magma chamber in the Coso volcanic field, highlighting the region's geothermal potential.
Atterholt says, "Everything is happening deep in the lithosphere, the outermost layer of the Earth, including the crust and upper mantle. What you can do with DAS is only limited by your imagination."
This study has been published in the journal Science Advances.
