Seismic emissions from a surging glacier: Bakaninbreen, Svalbard

Stuart, G. W.; Murray, Tavi; Brisbourne, Alex; Styles, Peter; Toon, S.M.

doi:10.3189/172756405781812538

Cited by 49 publications

(57 citation statements)

References 29 publications

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“…However, basal friction alone is unlikely to warm a significant thickness of the glacier ice and therefore does not explain the presumed down‐glacier propagation of the thermal regime. The injection of water along the frozen bed and into faults [ Stuart et al , 2005] would provide an additional source of heat into otherwise cold parts of the glacier. The possibility of planar features containing water (at least in the temperate parts of the glacier) after the surge, therefore, holds considerable importance in the surge propagation mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…The conclusions from these investigations were that a thermal boundary existed between frozen subglacial sediments down glacier of the surge front and a warm bed up glacier of it. It was argued that this boundary propagated down glacier with the surge front because of frictional heating at the bed as cold ice in front of the surge front was lubricated and warmed by the propagation of water into faults and thrust features, allowing fast flow to commence [ Stuart et al , 2005].…”

Section: Surge Of Bakaninbreenmentioning

confidence: 99%

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Distribution and character of water in a surge‐type glacier revealed by multifrequency and multipolarization ground‐penetrating radar

et al. 2008

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[1] We have investigated the distribution and character of radar scatterers in the glacier Bakaninbreen, Svalbard, using ground-penetrating radar (GPR). The GPR profiles showed scattering regions with an undulating upper boundary in both along-and across-glacier orientations. The simplest interpretation of such scattering regions would be a layer of randomly distributed scatterers with an undulating upper boundary, underlying a layer without scatterers. We propose an alternative model of scatterer distribution, in which the scatterers are confined to obliquely dipping planes. This model is shown to be able to reproduce the shape of the scattering regions observed in the field data and is consistent with previous observations of dipping thrust features in Bakaninbreen from radar data and in outcrop. Multifrequency profiles (50, 100, and 200 MHz) contained scatterers with similar measured power, indicating that the scatterers have decimeter-scale dimensions. Multipolarized antenna configurations were used to detect a preferred polarization direction for scattered radiation, which was approximately across glacier, suggesting that the scatterers are nonspherical and aligned across glacier. The scatterers are thought to be large water bodies confined to dipping planar features and elongated in the strike orientation of the planes.Citation: Barrett, B. E., T. Murray, R. Clark, and K. Matsuoka (2008), Distribution and character of water in a surge-type glacier revealed by multifrequency and multipolarization ground-penetrating radar,

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Section: Discussionmentioning

confidence: 99%

Section: Surge Of Bakaninbreenmentioning

confidence: 99%

Distribution and character of water in a surge‐type glacier revealed by multifrequency and multipolarization ground‐penetrating radar

et al. 2008

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“…Tremor episodes in glaciers may also be related to the motions of fluids contained within conduits (Métaxian et al, 2003;Stuart et al, 2005;Winberry et al, 2009;Gimbert et al, 2014;Lipovsky and Dunham, 2015;Bartholomaus et al, 2015). Several lines of evidence suggest that the WIP tremor episodes are not related to such a source process.…”

Section: Discussionmentioning

confidence: 99%

Tremor during ice-stream stick slip

Lipovsky¹,

Dunham²

2016

The Cryosphere

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Abstract. During the 200 km-scale stick slip of the Whillans Ice Plain (WIP), West Antarctica, seismic tremor episodes occur at the ice-bed interface. We interpret these tremor episodes as swarms of small repeating earthquakes. The earthquakes are evenly spaced in time, and this even spacing gives rise to spectral peaks at integer multiples of the recurrence frequency ∼10-20 Hz. We conduct numerical simulations of the tremor episodes that include the balance of forces acting on the fault, the evolution of rate-and statedependent fault friction, and wave propagation from the fault patch to a seismometer located on the ice. The ice slides as an elastic block loaded by the push of the upstream ice, and so the simulated basal fault patch experiences a loading velocity equal to the velocity observed by GPS receivers on the surface of the WIP. By matching synthetic seismograms to observed seismograms, we infer fault patch area ∼10 m 2 , bed shear modulus ∼20 MPa, effective pressure ∼10 kPa, and frictional state evolution distance ∼1 µm. Large-scale slip events often occur twice daily, although skipped events have been increasing in frequency over the last decade. The amplitude of tremor (recorded by seismometers on the ice surface) is greater during the double wait time events that follow skipped events. The physical mechanism responsible for these elevated amplitudes may provide a window into nearfuture subglacial conditions and the processes that occur during ice-stream stagnation.

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“…This concentration of energy in narrow spectral bands is a distinguishing feature of resonant systems, where the characteristic frequency is a function of the resonator dimensions. Harmonic events with extended codas have been documented during surges on the Bakaninbreen glacier (Stuart et al, 2005). These events are interpreted as resonance in water-fi lled fractures at the base of the surge front.…”

Section: Glacier Microseismicitymentioning

confidence: 99%