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Antarctic firn presents an exotic seismological environment in which the behaviors of propagating waves can be significantly at odds with those in other Earth media. We present a condensed view of the nascent field of ambient noise seismology in Antarctic firn-covered media, and highlight multiple unusual and information-rich observations framed through the lens of the firn's important role as a buffer for air temperature anomalies and a complex contributor to ice mass balance. We summarize key results from several recent papers depicting novel wind-excited firn resonances and point to the plethora of ways these observations could facilitate imaging and monitoring of glacial systems at single, isolated seismometers. Finally, we propose significant instrumental and computational objectives necessary to constrain resonance excitation mechanisms and broadly apply these observations as useful monitoring tools in Antarctica. [ABSTRACT FROM AUTHOR]

Antarctic firn presents an exotic seismological environment in which the behaviors of propagating waves can be significantly at odds with those in other Earth media. We present a condensed view of the nascent field of ambient noise seismology in Antarctic firn-covered media, and highlight multiple unusual and information-rich observations framed through the lens of the firn's important role as a buffer for air temperature anomalies and a complex contributor to ice mass balance. We summarize key results from several recent papers depicting novel wind-excited firn resonances and point to the plethora of ways these observations could facilitate imaging and monitoring of glacial systems at single, isolated seismometers. Finally, we propose significant instrumental and computational objectives necessary to constrain resonance excitation mechanisms and broadly apply these observations as useful monitoring tools in Antarctica. [ABSTRACT FROM AUTHOR]

The ice cap covering Antarctica has long limited our understanding of the continental-scale crustal model due to its inaccessibility and the resulting logistical difficulties when executing geophysical field work, such as seismograph deployment. Resolving a high spatial resolution crustal model for Antarctica where seismographs are sparsely distributed stimulates scientific interest in this relatively less studied continent. In this study, we utilize satellite gravity observations from the global gravity model EIGEN-6C4 to create an alternative crustal thickness model of Antarctica. The gravity data were corrected for sediments, topography and ice cover. Furthermore, we considered the gravity effect due to vertical deformation of the lithosphere caused by ice load besides the earth's curvature in the modelling. We inverted the corrected gravity data using the regularized Bott's inversion method in spherical approximation and constrained the results by seismic observations. This crustal thickness model shows a thicker average crust in East Antarctica and a thinner one in West Antarctica. The thickest crust is in the Gamburtsev Subglacial Mountains with a Moho depth of over 40 km. The thicker crust is particularly evident along the Transantarctic Mountains and the Dronning Maud lands. Comparisons with existing models show a good correlation in gravity-constrained areas. Differences appear in the sedimentary basins and crust with thickness closer to seismic point observations. Overall, our crustal model is relatively improved than the existing gravity derived models. [ABSTRACT FROM AUTHOR]

Understanding deformation in ice shelves is necessary to evaluate the response of ice shelves to thinning. We study microseismicity associated with ice shelf deformation using nine broadband seismographs deployed near a rift on the Ross Ice Shelf. From December 2014 to November 2016, we detect 5,948 icequakes generated by rift deformation. Locations were determined for 2,515 events using a least squares grid‐search and double‐difference algorithms. Ocean swell, infragravity waves, and a significant tsunami arrival do not affect seismicity. Instead, seismicity correlates with tidal phase on diurnal time scales and inversely correlates with air temperature on multiday and seasonal time scales. Spatial variability in tidal elevation tilts the ice shelf, and seismicity is concentrated while the shelf slopes downward toward the ice front. During especially cold periods, thermal stress and embrittlement enhance fracture along the rift. We propose that thermal stress and tidally driven gravitational stress produce rift seismicity with peak activity in the winter. Plain Language Summary: In Antarctica, large bodies of floating ice called ice shelves help prevent ice on land from sliding into the ocean. To predict how Antarctica might respond to climate change, we need to understand how ice shelves interact with the environment, including the atmosphere and the ocean. The largest ice shelf, the Ross Ice Shelf, is over 500,000 km2 in area, making it the largest body of floating ice in the world. In this study, we deployed nine seismographs, the same instruments used to study earthquakes, to monitor vibrations and cracking within the Ross Ice Shelf over a 2‐year period. During that time, the instruments detected nearly 6,000 fracture events along a 120‐km‐long crack in the ice shelf. We compared the timing of the cracking to air temperature data, ocean wave activity, and tides to see whether these factors influenced the crack's behavior. We found that fracture occurs most frequently just after high tide during winter and when the air is very cold. We also found that fracture at the rift is not triggered by ocean waves. This work demonstrates that Antarctic ice shelves are very sensitive to the environment and highlights the need to continue studying them. Key Points: 2,515 icequakes associated with rift deformation on the Ross Ice Shelf are located using a double‐difference location algorithmIcequake timing correlates with tidal phase diurnally and inversely correlates with air temperature on multiday and seasonal time scalesOcean swell, infragravity waves, and a significant tsunami arrival are not correlated with increased rift activity [ABSTRACT FROM AUTHOR]

SUMMARY Upper-mantle structure between 100 and 300 km depth below the northern Antarctic Peninsula is imaged by modelling P-wave traveltime residuals from teleseismic events recorded on the King Sejong Station (KSJ), the Argentinean/Italian stations (JUBA and ESPZ), an IRIS/GSN Station (PMSA) and the Seismic Experiment in Patagonia and Antarctica (SEPA) broad-band stations. For measuring traveltime residuals, we applied a multichannel cross-correlation method and inverted for upper-mantle structure using VanDecar's method. The new 3-D velocity model reveals a subducted slab with a ∼70° dip angle at 100-300 km depth and a strong low-velocity anomaly confined below the SE flank of the central Bransfield Basin. The low velocity is attributed to a thermal anomaly in the mantle that could be as large as 350-560 K and which is associated with high heat flow and volcanism in the central Bransfield Basin. The low-velocity zone imaged below the SE flank of the central Bransfield Basin does not extend under the northern Bransfield Basin, suggesting that the rifting process in that area likely involves different geodynamic processes. [ABSTRACT FROM AUTHOR]