One of the biggest challenges for earthquake early warning systems (EEW) is the lack of seismic stations located offshore of heavily populated coastlines, where some of the world’s most seismically active regions are located.
One of the biggest challenges for earthquake early warning systems (EEW) is the lack of seismic stations located offshore of heavily populated coastlines, where some of the world’s most seismically active regions are located.
In a new study published in The Seismic Record, researchers show how unused telecommunications fiber optic cable can be transformed for offshore EEW.
Jiuxun Yin, a Caltech researcher now at SLB, and colleagues used 50 kilometers of a submarine telecom cable running between the United States and Chile, sampling seismic data at 8,960 channels along the cable for four days. The technique, called Distributed Acoustic Sensing or DAS, uses the tiny internal flaws in a long optical fiber as thousands of seismic sensors.
Yin and colleagues used the cable data to determine earthquake locations and estimate earthquake magnitudes for one onshore (magnitude 3.7) and two offshore (magnitude 2.7 and 3.3) earthquakes during the study period.
Their results show that using this single DAS array offers an approximate three-second improvement in earthquake early warning compared to onshore DAS arrays. In a simulation run by the researchers, they found that by deploying multiple DAS arrays spaced 50 kilometers apart and working together in the area, they could improve EEW alert times in the subduction zone by five seconds.
