UNIVERSITY PARK, Pa. — With rising temperatures in the Arctic, communities in Alaska’s North Slope Borough are seeing the ground beneath their feet melt away.
“Climate change is thawing the frozen soil,” said Ming Xiao, associate professor of civil and environmental engineering at Penn State. “The borough spends $100 million a year just for repairs to roads, buildings and pipelines. To build resilient infrastructure in the changing Arctic, we need to understand how the soil behaves as it softens.”
Xiao is the lead investigator of a new three-year, $1.2 million project, funded by the National Science Foundation’s “Signals in the Soil” program, that seeks to bury a fiber-optic cable in Utqiaġvik, Alaska, the northernmost city in the United States. The 1.5-kilometer cable — commonly used for internet and phone service — will be turned into a long line of vibration sensors to monitor the continuous thawing of the frozen soil, also known as permafrost.
This method for collecting seismic data uses a new technology called a distributed acoustic sensing (DAS) array, which sends laser pulses through the cable to detect the velocity of seismic waves moving through the soil.
“We can get a soil sample and test it in the lab, but that is going to be discrete in separate locations and at a certain time,” Xiao said. “By measuring wave velocity with this method, we can convert that into real-time soil property changes at different locations over time, from minutes to years.”
Co-principal investigator Tieyuan Zhu, assistant professor of geophysics, recently created a DAS array using fiber-optic cables buried on the Penn State University Park campus to monitor near-surface dynamics from events like thunderstorms and flooding. The method will now be applied to a harsher climate.
“This project gives us the chance to demonstrate in Alaska how this novel technology can perform in the permafrost across two years,” Zhu said.