Underground fiber optic cables are being installed across Humboldt county and a community of federal and state scientists, including Cal Poly Humboldt researchers, think they may be able to use this technology for valuable feedback about earthquakes, and perhaps enhance the early warning system and a means to detect faults that may produce future earthquakes.
Fiber optic cable is the backbone of the internet. Currently, the world’s longest fiber optic line is being built between Humboldt County and Singapore to improve worldwide connectivity and local broadband service.
Along with installation of this long trans-Pacific cable, there is an effort to expand internet accessibility to rural regions of Humboldt County by installing shorter fiber optic cables along our highways. One such cable exists along Old Arcata Road between Arcata and Eureka.
Fiber optic cables can detect changes in the earth during earthquakes. Researchers are investigating just how the optic parameters of the cable change when shaken by an earthquake. With the cooperation of the county, city of Arcata, PG&E and local landowners, these researchers installed about 50 seismometers, instruments that respond to ground noises and movement, along the new line. They are conducting a multi-month evaluation of the line, detecting even the smallest earthquakes that occur on a daily basis within our highly seismic area. Cal Poly Humboldt Geology students have been part of the seismometer installation, battery replacement, and data recovery. They will also participate in the future analysis of the data.
“You can't understand an earthquake unless you record the wide range of frequencies that it puts out,” says Kari Stockdale, a Cal Poly Humboldt Geology student who was involved in the node installation and will continue to research the data. “Seismometers are the control that really help us understand what’s going on in the earth. The project has successfully recorded dozens of earthquakes in its first two months.”
This is a collaboration between Cal Poly Humboldt, the USGS, UC Berkeley, University of Washington, Cal Tech, Vero Communications, and OptaSense Inc. and city and county governments, including the Arcata Police Department who allowed the project to house some of their equipment.
If fiber optic cables prove to provide valuable insights into ground movements the underground cables could be used to better understand and monitor earthquakes and other geologic hazards.