Quantitative analysis of seismogenic shear-induced turbulence in lake sediments

Abstract

Spectacular deformations observed in lake sediments in an earthquake prone region (Lisan Formation, pre-Dead Sea lake) appear in phases of laminar, moderate folds, billow-like asymmetric folds, coherent vortices, and turbulent chaotic structures. These deformations are tied to earthquake events which are speculated to be intensified by seiche (mini Tsunami)-induced shear at the bottom of the lake.

Estimation of successive coseismic vertical offsets using coeval sedimentary events – application to the southwestern limit of the Sea of Marmara's Central Basin (North Anatolian Fault)

“…Two major questions arise for both groups: (1) how to ensure the earthquake-triggering, (2) how to identify the responsible active structure(s). For in situ disturbances, the first problem is generally solved; in particular, it benefits from analogical and/or numerical modeling (e.g., Moretti et al, 1999;Wetzler et al, 2010). For redepositional processes -which are envisaged in the present work -several recent catastrophic events could be surveyed shortly after their occurrence (Thunell et al, 1999;McHugh et al, 2011;Lorenzoni et al, 2012); the results reinforced the earthquakeinduced interpretation proposed for some "homogenite-type" layers (Chapron et al, 1999;.…”

Soft sediment deformation structures in the Lixian lacustrine sediments, eastern Tibetan Plateau and implications for postglacial seismic activity

“…12b,c), which is also a feature of the Late Pleistocene Lisan lacustrine sediments in the Dead Sea Basin Marco, 2013, 2014). Fold asymmetry and the homogeneous nature of the sediment suggest that the folding is associated with gravity-driven shear rather than inverse density (Heifetz et al, 2005;Wetzler et al, 2009;Alsop and Marco, 2013). As shown in Fig.…”

Generation of billow-like wavy folds by fluidization at high temperature in Nojima fault gouge: microscopic and rock magnetic perspectives

“…3). This differs from the exponent of −5/3 which is predicted from Kolmogorov's phenomenological picture of an energy cascade of turbulence, although such fold characteristics still imply fluid-like deformation in the fault gouge (Wetzler et al 2010). In order to understand the process of formation of the billow-like wavy folds, it is important to identify the temperature during seismic slip, but this has not been previously investigated for Nojima fault gouge.…”

“…The amplitude and wavelength of the billow-like wavy folds stemming from the same boundary are almost equal. The billow-like wavy folds in Nojima fault gouge are similar to the wavy folds induced by KH instability that were identified in Dead Sea sediments by Wetzler et al (2010). We adopted Wetzler et al 's (2010) approach of characterizing the folds by a power spectrum comprising amplitude squared (l 2 ) and the inverse of wavelength (k = 1/λ), as shown in Fig.…”

“…Brodsky et al (2009) examined a series of outcrop-scale asymmetrical flow-like intrusions of ultrafine-grained fault rock on the exhumed Kodiak Island megathrust, Alaska, using a concept of gravitational (Rayleigh-Taylor) instability to reveal a coseismic slip velocity of the order of 10 cm/s. Wetzler et al (2010) suggested that the various types of outcrop-scale deformations in the Lisan Formation, Israel, could be explained as the result of earthquaketriggered KH instability. These field investigations give no constraint of temperature conditions during the deformation.…”