Penn State Study Looks at Using Fiber Optic Cables as an Early Warning System for Geohazards

Fiber Optic Cables as Sensors

A recent Penn State University article discusses how fiber optic cables can be used to spot geohazards such as sinkholes in a study led by the university. As mentioned in another Cabling, Installation, & Maintenance fiber sensing article, the use of fiber optic cables already in place for internet connectivity can also be used to sense vibrations providing valuable data that can be used to help civilians.

The research published in the Journal of Geophysical Research: Solid Earth shows that existing communications cables can be utilized to identify fractured zones and low-density areas hundreds of feet below the Earth's surface.

How Fiber Sensing Works

The method used involves a tool dubbed the distributed acoustic sensing (DAS) interrogator to send light through existing fiber optic cables. The interrogator, along with advanced computing methods, analyzed returning acoustic signals to detect variations in rock density while filtering out “noise” from campus activity such as students or construction.

Cost-Effectiveness Over Previous Methods

Tieyuan Zhu, associate professor of geophysics and co-author of the paper, stated, “We can rely on these signals to spot geohazards in a way that’s much more affordable and effective than traditional methods.”

The article notes that conventional geophones are costly, labor-intensive, and only create a single data point, while the DAS approach uses common traffic noises and converts them into “seismic surface waves”, providing more data and a detailed look at the surface wave speed below the cable.

The research included finding a low-density area on campus that could potentially lead to a sinkhole. Acoustic signals showed a structure with significantly lower density than the surrounding ground at the same depth. The Penn State Office of Physical Plant reviewed the findings and confirmed that the area is not an immediate threat to campus structures, though the research still provided useful information.

Real-World Applications

DAS technology is being deployed in Pittsburgh through a U.S. National Science Foundation Civic Innovation Challenge grant to help prevent geohazards.

“Sinkholes are widespread in Pennsylvania and beyond,” Zhu said. “What makes this research especially powerful is that it turns everyday traffic noise — something completely free — into a tool for locating geohazards. By using the existing fiber optic cables already in place as sensors, we can provide an affordable and scalable way to assess risks and help prevent future threats for Pennsylvanians.”