Tide‐modulated ice flow variations drive seismicity near the calving front of Bowdoin Glacier, Greenland

Podolskiy, Evgeny A.; Sugiyama, Shin; Funk, Martin; Walter, Fabian; Genco, Riccardo; Tsutaki, Shun; Minowa, Masahiro; Ripepe, Maurizio

doi:10.1002/2016gl067743

Cited by 46 publications

(55 citation statements)

References 31 publications

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“…If the shelf is tilted toward the continent, the rift is under compression, and we see low levels of seismicity; if the shelf is tilted seaward, the rift is subjected to additional extensional stress, and we see high levels of seismicity. Our findings are consistent with previous observations of tidally modulated glacial seismicity (Barruol et al, 2013;Podolskiy et al, 2016) and tidally modulated ice shelf flow (Brunt et al, 2010;Makinson et al, 2012). We calculate the maximum stretching stress that could affect the rift associated with this tilt to be i g L where i is the ice density, g is the acceleration due to gravity, L is the distance from the rift to the ice front, and is the tidally induced tilt angle.…”

Section: Ice Shelf Slope From Ocean Tides Controls Diurnal Patterns Isupporting

confidence: 89%

Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift

Olinger

Lipovsky

Wiens

et al. 2019

Geophysical Research Letters

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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.

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Section: Ice Shelf Slope From Ocean Tides Controls Diurnal Patterns Isupporting

confidence: 89%

Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift

Olinger

Lipovsky

Wiens

et al. 2019

Geophysical Research Letters

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“…This included ice radar and GPS measurements (Sugiyama et al, 2015;Tsutaki et al, 2016), seismic records (Podolskiy et al, 2016), automatic camera installations and borehole drilling (to record in-ternal ice deformation, englacial temperature and water pressure).…”

Section: Study Sitementioning

confidence: 99%

Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Jouvet¹,

Weidmann²,

Seguinot³

et al. 2017

The Cryosphere

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Abstract. In this paper, we analyse the calving activity of the Bowdoin Glacier, north-western Greenland, in 2015 by combining satellite images, UAV (unmanned aerial vehicle) photogrammetry and ice flow modelling. In particular, a highresolution displacement field is inferred from UAV orthoimages taken immediately before and after the initiation of a large fracture, which induced a major calving event. A detailed analysis of the strain rate field allows us to accurately map the path taken by the opening crack. Modelling results reveal (i) that the crack was more than half-thickness deep, filled with water and getting irreversibly deeper when it was captured by the UAV and (ii) that the crack initiated in an area of high horizontal shear caused by a local basal bump immediately behind the current calving front. The asymmetry of the bed at the front explains the systematic calving pattern observed in May and July-August 2015. As a corollary, we infer that the calving front of the Bowdoin Glacier is currently stabilized by this bedrock bump and might enter into an unstable mode and retreat rapidly if the glacier keeps thinning in the coming years. Beyond this outcome, our study demonstrates that the combination of UAV photogrammetry and ice flow modelling is a promising tool to horizontally and vertically track the propagation of fractures responsible for large calving events.

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“…for the solution of the problem of seismic monitoring of glaciers [8]. The project of the organization of instrumental observation station directly in the area of the Kolka glacier bed was developed in 2011.…”

Section: Development Of Seismic Observation Networkmentioning

confidence: 99%

Integrated Instrumental Monitoring of Hazardous Geological Processes Under the Kazbek Volcanic Center

Заалишвили¹

2018

GEOMATE

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Kazbek volcanic center is characterized by the complex interrelationship of various hazardous geological processes. The proximity of populated areas and infrastructure objects (the main one is the Georgian Military Road connecting Russia with South Caucasus) determines high social and economic risks of the region. Disasters of 2002 and 2014 caused by ice-rock fall govern importance of investigation of the area. It must be based on instrumental data collection and seismic monitoring is the first continuous technique covering both exogenous and endogenous processes, especially of possible volcanic activity and various postvolcanic phenomena. That's why complex observational network "Karmadon Parametric Range" was established in September 2003. The network recorded a collapse of the mass of ice and rocks in the region of the Devdorak glacier on May 17, 2014 and the movement of the formed stone-ice avalanche. Research group for the first time faced with the movement of massive extended objects seismic records processing and analysis. New techniques as energy release and wavelet-based spectral-temporal graphs were developed. Flow velocities are estimated on the basis of slope variation along the trace. As the result, determined accordance of the events of 2002 Kolka glaciers fall and the 2014 Devdorak region rockfall is probably an evidence of general formation nature of both processes. And the main aim is to determine early evidences of the future events on the basis of a new instrumental monitoring of Kazbek volcanic center system. It must reveal characteristics of the Kazbek volcano and significantly improve natural hazards safety of the region.

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Tide‐modulated ice flow variations drive seismicity near the calving front of Bowdoin Glacier, Greenland

Cited by 46 publications

References 31 publications

Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift

Tidal and Thermal Stresses Drive Seismicity Along a Major Ross Ice Shelf Rift

Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Integrated Instrumental Monitoring of Hazardous Geological Processes Under the Kazbek Volcanic Center

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