Dynamic strain determination using fibre-optic cables allows imaging of seismological and structural features

Area of Science:

• Geophysics
• Seismology
• Earth Science

Background:

• Dense seismic observations are crucial for natural hazard prediction and crust exploration.
• Accuracy of seismic data relies on sensor characteristics and spatial distribution.
• Conventional seismometers have limitations in spatial coverage.

Purpose of the Study:

• To demonstrate the feasibility of using conventional fiber-optic cables for dynamic strain determination.
• To achieve high-resolution, spatially un-aliased broadband strain data using distributed acoustic sensing (DAS).
• To explore the potential of global fiber-optic networks for seismic monitoring.

Main Methods:

• Deployed a 15-km-long fiber-optic cable on Reykjanes Peninsula, SW-Iceland.
• Recorded seismic signals from natural and man-made sources with 4-m spacing.
• Utilized distributed acoustic sensing (DAS) technology for strain measurement.
• Simultaneously acquired data with conventional seismometers for validation.

Main Results:

• Achieved high-resolution seismic imaging of structural features like faults and volcanic dykes.
• Inferred new dynamic fault processes with unprecedented detail.
• Validated the spectral amplitude response of DAS between 0.1 and 100 Hz against conventional seismometers.

Conclusions:

• Conventional fiber-optic telecommunication cables can be repurposed as effective seismometers.
• DAS technology offers a novel, cost-effective method for dense seismic observations.
• This approach opens new avenues for Earth hazard assessment and exploration.