Deformation and seismic effects in the ice cover of Lake Baikal

Abstract

The mechanics of the ice cover of Lake Baikal has been studied through monitoring of its deformation and seismic effects and full-size uniaxial compression and shear tests in 2005–2007. We measured the shear strength of ice specimens and large in situ blocks (σ = 0.2−1.9 MPa) and investigated it as a function of air temperature and ice structure. Deformation was analyzed in terms of various natural controls, such as air temperature and pressure, wind, sub-ice currents, and local earthquakes. Precise strain measurements along ice cracks were used to explore the strain behavior of ice, including the cases of dynamic failure (ice shocks). Measurements by seismic station Baikal-12 were used to monitor diurnal background microseismicity variations and to record an ice quake with its magnitude (M = 0.3–0.8; E = 104–105 J) comparable to a medium-size rock burst or a small earthquake. Ice quakes were studied in terms of their nucleation, dynamics, and aftereffects, as well as the strain and seismic responses of the ice, using sub-ice explosions in the latter case. The natural conditions of deformation in the elastoviscoplastic Baikal ice are similar to lithospheric processes and thus can be employed in tectonophysical modeling with scientific and practical implications for hazard mitigation.

Cryoseismology

“…Some land‐terminating glaciers may generate low‐magnitude events due to thermal cracking of ice on marginal lakes nearby [ Carmichael et al , ]. Interestingly, multiyear passive seismic observations of the mechanical behavior of Lake Baikal ice provided a basis for treating it as a model for large‐scale lithospheric processes [ Ruzhich et al , ].…”

“…The equivalent magnitudes of seismic events at lakes are only M w = 0.2 ∼ 0.8 [Ruzhich et al, 2009;Carmichael et al, 2012]. Nevertheless, it was recently shown that thermal cracking of lake ice can induce strong vibrations in coastal high-rise buildings [Makkonen et al, 2010].…”

Friction in Cold Ice Within Outer Solar System Satellites With Reference to Thermal Weakening at High Sliding Velocities

“…Naively, icequakes should not occur because the critical patch size for nucleation is much greater than the lake ice thickness. Yet icequakes clearly nucleate on temperate lakes (Ruzhich et al, ). The slip law for friction provides insight, where P eff = P ref is the ambient pressure to compact notation and the second equality applies the steady state value of ψ in equation .…”

“…For context, warm ice on the Earth clearly behaves in a macroscopically ductile manner as at low strain rates within glaciers (e.g., Barnes et al, 1971). At high strain rates, icequakes occur as within temperate freshwater lake ice (Ruzhich et al, 2009) and at the base of glaciers (Barruol et al, 2013;Wiens et al, 2008). Snow below 250 K squeaks when stepped upon indicating brittle failure (Patitsas, 2015).…”

Comparison of nearby earthquake records made on hard rock ground and on ice cover of Lake Baikal

“…The full scale investigations of the ice cover behavior under the effect of different dynamic loads are very laborious, while temporal instability, variety of behav ior properties, and dependence of these properties on rapidly changing ice conditions additionally aggravate the obtaining of statistically valid results. It was shown in (Ruzhich et al, 2009;Timofeev et al, 2010) that the main causes of deforming and cracking for the ice in Lake Baikal are temperature changes and strong winds, and the submarine currents as well. The associ ated seismic phenomena resemble the manifestations of earthquakes or rock bumps.…”