The downstream portion of Whillans Ice Stream, West Antarctica, moves primarily by stick‐slip motion. observation motion suggests that the bed is governed velocity‐weakening physics and basal more unstable than suggested laboratory studies. cycle Plain exhibits substantial variability in both duration sticky periods slip magnitude. To understand this variability, we modeled forces acting on ice stream during stick phase cycle. ocean tides introduce changes rate at which stress applied to...

P‐to‐S receiver functions (PRFs) from the Polar Earth Observing Network (POLENET) GPS and seismic leg of POLENET spanning West Antarctica Transantarctic Mountains deployment seismographic stations provide new estimates crustal thickness across Antarctica, including Antarctic Rift System (WARS), Marie Byrd Land (MBL) dome, (TAM) margin. We show that complications arising ice sheet multiples can be effectively managed further information concerning low‐velocity subglacial sediment may...

Abstract We construct a new seismic model for central and West Antarctica by jointly inverting Rayleigh wave phase group velocities along with P receiver functions. Ambient noise tomography exploiting data from more than 200 stations deployed over the past 18 years is used to velocity dispersion maps. Comparison between ambient maps those constructed using teleseismic earthquakes confirms accuracy of both results. These maps, together function waveforms, are 3‐D shear (Vs) crust uppermost...

Abstract The seismic velocity structure of Antarctica is important, both as a constraint on the tectonic history continent and for understanding solid Earth interactions with ice sheet. We use Rayleigh wave array analysis methods applied to teleseismic data from recent temporary broadband seismograph deployments image upper mantle central West Antarctica. Phase maps are determined using two–plane tomography method inverted shear Monte Carlo approach estimate three‐dimensional structure....

Abstract We summarize new observations of the deceleration and stick–slip motion Whillans Ice Stream (WIS), Antarctica. refine location large sticky spots that resist between slip events, locations which are controlled by patterns subglacial water flow. Our examination long-term velocity time series for ice stream reveals decadal-scale is not occurring at a steady rate, but varies sub-decadal timescale. This unsteady modulates temporal evolution broad (~50 km across) surface-elevation bulge...

Antarctica's fast-flowing ice streams drain the sheet, with their velocity modulated by subglacial water systems. Current knowledge of these systems is limited to shallow portions near ice-bed interface, but hypothesized deeper groundwater could also influence streaming. Here, we use magnetotelluric and passive seismic data from Whillans Ice Stream, West Antarctica, provide first observations deep sub-ice stream groundwater. Our reveal a volume within >1-kilometer-thick sedimentary basin...

Research Article| November 01, 2004 Crustal structure of the West Antarctic rift system and Marie Byrd Land hotspot J. Paul Winberry; Winberry 1Department Geosciences, Pennsylvania State University, University Park, 16802, USA Search for other works by this author on: GSW Google Scholar Sridhar Anandakrishnan Author Article Information Publisher: Geological Society America Received: 27 Apr Revision 12 Jul Accepted: 14 First Online: 03 Mar 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology...

The ability to monitor transient motion along faults is critical improving our understand many natural phenomena such as landslides and earthquakes. Here, we usedata from a GPS seismometer network that were deployed the regularly repeating glacial earthquakes of Whillans Ice Stream, West Antarctica show unique pattern precursory slip precedes complete rupture bed ice stream. Additionally, can be independently tracked by increased levels microseismic activity, including harmonic tremor, are...

New seismic observations of harmonic tremors beneath MacAyeal Ice Stream, West Antarctica are reported. Each the two tremor events that we recorded during a six week period had sustained arrival 3 Hz energy for approximately 10 minutes. During time source location migrated few kilometers. The nature is interpreted as result resonance in subglacial water‐filled cracks and conduits. duration, monochromatic nature, movement indicate mechanism likely flow water system resulting from discharge...

Seismic source and wave propagation studies contribute to understanding structure, transport, fracture mechanics, mass balance, other processes within glaciers surrounding environments. Glaciogenic seismic waves readily couple with the bulk Earth, can be recorded by seismographs deployed at local global ranges. Although fracturing, ablating, melting, and/or highly irregular environment of active unstable hazardous, informative measurements commonly made stable proximal ice or rock sites....

Research Article| November 26, 2014 The Seismic Noise Environment of Antarctica Robert E. Anthony; Anthony aDepartment Geosciences, Colorado State University, Fort Collins, 80523 U.S.A.robert.anthony@colostate.edu Search for other works by this author on: GSW Google Scholar Richard C. Aster; Aster Douglas Wiens; Wiens bDepartment Earth and Planetary Sciences, Washington University in St. Louis, Missouri 63130 U.S.A. Andrew Nyblade; Nyblade cDepartment Pennsylvania Park, 16802 Sridhar...

Laterally continuous subglacial sediments are a necessary component for ice streaming in the modern onset regions of streams draining Siple Coast West Antarctica on basis new seismic data combined with previous results. We present geophysical results from reflection and refraction experiments upper reaches C D that highlight sedimentary basins within upstream current both streams, overlying these packages. The environment changes no‐sediment to discontinuous‐sediment continuous‐sediment...

High‐resolution reflection seismic data from Jakobshavn Isbræ, Greenland, reveal complex fabric development. Abundant englacial reflectivity occurs for approximately half the thickness of ice (the lower half), and disruption reflectors in 10–15% ice‐thickness. These depths correspond to higher impurity‐content, more easily deformed, Younger Dryas Last Glacial Maximum Stage‐3. We conclude that results contrasting velocities due changes crystal orientation ice, suggest these are caused by...

Abstract The tidally modulated, stick‐slip events of Whillans Ice Stream in West Antarctica produce seismic energy from three locations near the grounding line. Using ice velocity records obtained by combining time series colocated broadband seismometers and GPS receivers installed on stream during 2010–2011 2011–2012 austral summers, along with far‐field recordings elastic waves, we locate regions high rupture stress drop. These regions, which are analogous to “asperities” traditional fault...

Research Article| November 29, 2017 Seismic evidence for lithospheric foundering beneath the southern Transantarctic Mountains, Antarctica Weisen Shen; Shen * 1Department of Earth and Planetary Sciences, Washington University in St. Louis, Missouri 63112, USA *E-mail: weisen.shen@stonybrook.edu Search other works by this author on: GSW Google Scholar Douglas A. Wiens; Wiens Tim Stern; Stern 2School Geography, Environment Victoria Wellington, Wellington 6140, New Zealand Sridhar...

Abstract A phase‐sensitive radar (ApRES) was deployed on Totten Ice Shelf to provide the first in situ basal melt estimate at this dynamic East Antarctic ice shelf. Observations of internal dynamics tidal time scales showed that early arrivals from off‐nadir reflectors obscure true depth shelf base. Using observed deformation, base found lie 1,910–1,950‐m depth, 350–400 m greater range than reflection an ice‐ocean interface. The robustness rate increased by using multiple reflections over...

Abstract Totten Glacier is a fast‐moving East Antarctic outlet with the potential for significant future sea‐level contributions. We deployed four autonomous phase‐sensitive radars on its ice shelf to monitor ice‐ocean interactions near grounding zone and made active source seismic observations constrain gravity‐derived bathymetry models. observe an asymmetry in basal melting mean melt rates along differing by up 20 m/a. Our new model reveals that this rate coincides water column thickness...

Understanding the processes that affect streaming ice flow and mass balance of glaciers sheets requires sound knowledge their subglacial environments. Previous studies have shown an extensive deformable sediment layer favors fast ice-stream flow. However, areas high basal drag, termed sticky spots, are particular interest because they inhibit overriding ice. The stick-slip behavior Whillans Ice Stream (WIS) is perhaps most conspicuous manifestation a spot. We present new ice-thickness...

<title>Abstract</title> Understanding and predicting glacier instabilities represents one of the greatest challenges in forecasting future sea level rise. Here, we present a study Hektoria Glacier on Eastern Antarctic Peninsula, which underwent an unprecedented rate retreat ~25 km from January 2022 to March 2023. Retreat commenced after loss decade-old fast ice Larsen B embayment. This buttressing resulted 6-fold increase flow-speed that produced 40-fold thinning rate. In November 2022,...

Subglacial bed-type (bedrock or sediment) is a significant control on fast glacier-motion. Geophysical techniques provide relatively efficient means to explore variations in bed type. The GHOST project collected range of geophysical datasets variability type beneath Thwaite glacier including active source seismic and radar measurements. Over the course two seasons an array ~ 200 Magseis Fairfield ZLand 3C nodal seismometers were deployed Thwaites. primary goal this was record generated...

The Aurora Subglacial Basin (ASB), East Antarctica, contains approximately 3.5m global sea-level equivalent of marine-based ice, which primarily drains through Totten Glacier. dynamics Glacier are therefore a major influence on mass balance for the Antarctic Ice Sheet (EAIS). grounding line geometry is complex, and has undergone rapid migration over past decades, with upstream regions retrograde bed slope potentially leaving glacier vulnerable to marine ice sheet instability if were retreat...