Array processing in cryoseismology: a comparison to network-based approaches at an Antarctic ice stream

Seismicity at glaciers, ice sheets, and ice shelves
provides observational constraint on a number of glaciologi-
cal processes. Detecting and locating this seismicity, specifi-
cally icequakes, is a necessary first step in studying processes
such as basal slip, crevassing, imaging ice fabric, and iceberg
calving, for example. Most glacier deployments to date use
conventional seismic networks, comprised of seismometers
distributed over the entire area of interest. However, smaller-
aperture seismic arrays can also be used, which are typically
sensitive to seismicity distal from the array footprint and re-
quire a smaller number of instruments. Here, we investigate
the potential of arrays and array-processing methods to de-
tect and locate subsurface microseismicity at glaciers, bench-
marking performance against conventional seismic-network-
based methods for an example at an Antarctic ice stream.
We also provide an array-processing recipe for body-wave
cryoseismology applications. Results from an array and a
network deployed at Rutford Ice Stream, Antarctica, show
that arrays and networks both have strengths and weaknesses.
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Arrays can detect icequakes from further distances, whereas
networks outperform arrays in more comprehensive studies
of a particular process due to greater hypocentral constraint
within the network extent. We also gain new insights into
seismic behaviour at the Rutford Ice Stream. The array de-
tects basal icequakes in what was previously interpreted to
be an aseismic region of the bed, as well as new icequake
observations downstream and at the ice stream shear mar-
gins, where it would be challenging to deploy instruments.
Finally, we make some practical recommendations for future
array deployments at glaciers.