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Potential of Distributed Acoustic Sensing Systems to Record Divergence and Curl Seismic Components

Session: Fiber-Optic Seismology I [Poster]

Type: Poster

Date: 4/23/2021

Presentation Time: 11:30 AM Pacific

Description: 

Distributed Acoustic Sensing (DAS) is gaining significant attention in the seismological community. This maturing technology is based on optical interferometry to detect broad-band ground deformation over long distances with an unprecedented high spatial resolution, making it a very attractive tool for seismological observation, in particular when long dark fibers can be interrogated. Temporary surveys to monitor urban areas, volcanoes and glaciers, for example, can also take advantage of the DAS technology thanks to the robust fiber-optic cables that are much cheaper to acquire and easier to deploy than a large-N seismic station network.

One limitation, however, is that DAS provides longitudinal strain variations instead of vector ground displacement as with conventional multi-component seismometers. With a typical linear cable layout, DAS is poorly sensitive to broadside events like vertically incident P-waves or orthogonally propagating Rayleigh waves. Helically wound cables partly address this directional sensitivity issue but such engineered cables are significantly more expensive and still do not provide omni-directional responses as typically do the vertical component seismometers or accelerometers.

In this work, we discuss the possibility of utilizing DAS technology to replace or complement conventional translational multi-component measurements. In particular, we show how non-linear cable layout configurations could enable a more complete description of the wavefield by providing access to the curl and the divergence of the displacement wavefield, thereby extending future applications of DAS.

Presenting Author: Pascal Edme

Student Presenter: No

Authors