Arctic megaslide at presumed rest

Abstract

Slope failure like in the Hinlopen/Yermak Megaslide is one of the major geohazards in a changing Arctic environment. We analysed hydroacoustic and 2D high-resolution seismic data from the apparently intact continental slope immediately north of the Hinlopen/Yermak Megaslide for signs of past and future instabilities. Our new bathymetry and seismic data show clear evidence for incipient slope instability. Minor slide deposits and an internally-deformed sedimentary layer near the base of the gas hydrate stability zone imply an incomplete failure event, most probably about 30000 years ago, contemporaneous to or shortly after the Hinlopen/Yermak Megaslide. An active gas reservoir at the base of the gas hydrate stability zone demonstrate that over-pressured fluids might have played a key role in the initiation of slope failure at the studied slope, but more importantly also for the giant HYM slope failure. To date, it is not clear, if the studied slope is fully preconditioned to fail completely in future or if it might be slowly deforming and creeping at present. We detected widespread methane seepage on the adjacent shallow shelf areas not sealed by gas hydrates.

Late Cenozoic Erosion Estimates for the Northern Barents Sea: Quantifying Glacial Sediment Input to the Arctic Ocean

“…Some parts of the canyons are relatively smooth, which may indicate the deposition by contour currents. In the eastern part of the Hinlopen scar, Geissler et al () also suggested sediment wave development. This suggestion fits well with results from this study that indicate a western increase in the influence of contour currents (Figure b).…”

“…The overall quality of the bathymetric and seismic data is good. The seismic interval velocity for depth conversion was derived from Geissler and Jokat (2004). The velocity range is 2.1-2.7 km/s for the deeper strata (NB-2; Figure 4), resulting in an average velocity of 2.3 km/s (Geissler & Jokat, 2004).…”

“…The seismic interval velocity for depth conversion was derived from Geissler and Jokat (2004). The velocity range is 2.1-2.7 km/s for the deeper strata (NB-2; Figure 4), resulting in an average velocity of 2.3 km/s (Geissler & Jokat, 2004). Assuming a dominant frequency of 20-50 Hz, the wavelength range is from 40 to 250 m, giving a vertical resolution of ca.…”

“…A significant postbreakup sediment accumulation, with a thickness of up to 7 km, is found along the northern Barents Sea continental margin (Engen et al, 2008;Geissler & Jokat, 2004;Vågnes, 1996). However, due to the lack of well data and sparse seismic data coverage, the erosion estimate and the chronology of this margin are poorly constrained.…”

“…Medium to good quality seismic data of regional coverage have allowed us to better study the northwestern Barents Sea continental margin, including its glacigenic strata and sedimentary style that so far had not been studied in detail beyond the Last Glacial Maximum (LGM). We use recently acquired multichannel seismic data from various sources (Berglar et al, 2016;Engen et al, 2009;Geissler et al, 2014;Geissler & Jokat, 2004) to investigate the distribution of the Neogene-Quaternary deposits within the continental shelf, slope, and the adjacent deep-sea basin. The sedimentary processes are discussed based on seismic facies analysis focusing on the TMF development and a buried megaslide.…”