Locating Basal Microseismicity in Rutford Ice Stream, West Antarctica
using QuakeMigrate, for Statistical Pattern Recognition
Abstract
The Antarctic Ice Sheet remains one of the greatest sources of
uncertainty for improving predictions of sea level rise, and
constraining this uncertainty has long been a difficult challenge within
glaciology and climate science. Cryoseismology, paired with the meteoric
rise of data science applications within the geosciences, has emerged as
a promising field well suited to answering these challenges as the
improvement of sampling technology and access have resulted in a
proliferation of Antarctic seismic data. Ice flow dynamics in Antarctica
are significantly influenced by features and processes at the bed, and
basal microseismicity from tremors as ice moves across the bed can yield
valuable information for resolving the glacier subsurface. We deployed
high-frequency (up to 1000 Hz) geophone arrays at Rutford Ice Stream
over the 2018-2019 austral summer to monitor the natural source
seismicity from the base of the ice and generate an event catalog. To
efficiently process the enormous volumes of cryoseismic data to locate
events, we used the Python package QuakeMigrate which utilizes a
parallelized waveform stacking algorithm to detect coherent seismic
phase arrivals across our network. Over three months of data, we located
over 1,700,000 seismic events (majority which were microseismic) within
a 4 km x 4 km square grid around our 13-station, ~3.25
km2 area array. The detection and location of icequakes at this
resolution provides a unique opportunity to investigate the temporal,
location, and size relations between events, and we present the findings
from our data mined event catalog and document the QuakeMigrate
parameter tuning to optimize event location. The significant amounts of
data collected of the region over the past decades mean that the
literature and documentation of conditions at Rutford is more complete
relative to most of Antarctica, and our work aims to contribute towards
a comprehensive survey of an Antarctic region.