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The Potential of Fiber-Optic Strain in Earthquake Early Warning

Session: Earthquake Early Warning Live in California! Current Status and Challenges II

Type: Oral

Date: 4/23/2021

Presentation Time: 02:30 PM Pacific

Description: 

The potential of using strain data in earthquake early warning (EEW) applications has been demonstrated in recent studies using borehole strainmeter records from stations along the U.S. West Coast. Fiber-optic distributed acoustic sensing (DAS) has been increasingly utilized in seismology with applications ranging from microseismic monitoring to vertical seismic profiling. DAS arrays seem to be a practical, scalable option for strain sensing, especially in areas where the installation of seismometers is neither easy nor cost-effective, such as in dense offshore arrays. In this work, we examine the data requirements for the U.S. ShakeAlert EEW System and present ways in which DAS strain data can be ingested by the different existing alerting algorithms, with and without modifications to the System. For example, using recently-developed empirical equations, a new algorithm entirely based on strain could also be developed in the future to feed estimated earthquake parameters, such as peak ground velocities and accelerations, and earthquake magnitudes directly to the ShakeAlert Solution Aggregator, where results from multiple EEW algorithms are combined into one solution. We also discuss the current state of DAS for EEW applications and what capabilities are under-studied or need to be developed, such as accurate strain amplitudes and array calibration techniques. Accurate amplitudes are needed for ground-motion parameter estimation and for earthquake magnitude estimation from strain data, but if the amplitudes are ambiguous, DAS data can still be utilized in EEW systems, for wave arrival and travel times for earthquake detection and location estimation.

Presenting Author: Noha S. Farghal

Student Presenter: No

Authors