oldest cables are being retrieved from the ocean while new ones are constructed; scientists are progressively monitoring natural threats such as earthquakes, volcanoes, and floods throughout this worldwide network.
Distributed acoustic sensing (DAS) employs laser pulses to detect minute variations in vibration, strain, ground movement, and water flow. Conventional seismometers record ground motion at a single location. A fiber-optic cable can function as a continuous sensor over a broader area, gathering real-time, high-resolution information, and Iceland’s volcanic Grindavík eruption demonstrated how the technology can assist in monitoring hazards beyond just earthquakes. The U.S. National Science Foundation indicated that the system provided a warning 26 minutes prior to the eruption, allowing local residents to evacuate.
Caltech researchers additionally demonstrated the significant potential of this monitoring system. They tapped into an approximately 62-mile section of fiber-optic cable, collecting data comparable to that of 10,000 traditional seismometers. Their results could greatly influence seismic monitoring at a significantly reduced cost compared to conventional systems. California has over 700 seismometers, with individual costs reaching up to $50,000. A DAS system requires only one $200,000 interrogator to send laser pulses along miles of cable. This same method could also aid in underwater seismic monitoring, which becomes even more costly and challenging. In the Canary Islands, researchers transformed a submarine telecommunications cable into 11,968 strain sensors spread over roughly 75 miles. The DAS system identified local and regional earthquakes as well as seismic waves from distant oceanic earthquakes.