Abstract
Submarine landslides are major agents of sediment mass transfer from the shallow to deep sea. Due to their rapid emplacement and tsunamigenic potential, such landslides are significant geohazards for society and off- and on-shore infrastructure. The relationship between climate change and the occurrence of submarine landslides is widely debated. However, there is a lack of continuous long-term submarine landslide records with which to comprehensively understand the relationship between climate-driven forces and submarine landslide occurrence. Here, using oxygen isotope stratigraphy in combination with tephrochronology, we date a 1 Myr continuous record of six landslide deposits (at 13.0–14.2, 323–339, 372–384, 394–413, 508–521, and 857–867 ka) recorded in a slope basin of the Nankai Trough subduction zone, off-shore Japan, which represents the major outcome of this study. The ages of the six landslides coincide mostly with interglacial periods. Thus, we propose that climate forcing might act as a preconditioning factor for slope instability in this active tectonic region.Graphical abstractLocation map, lithology, δ18O isotope stratigraphy (black dots) and tephrochronology (pink layers) of drill core C0018A (drilled within the Nankai Through during IODP Exp. 333). δ18O isotope data were correlated with the LR04 stack reference dataset (blue line) of Liesiecki and Raymo (2005). The mass transport deposits (MTD) are dated within odd numbered Marine Isotope Stages (MIS) taken from Bassinot et al. (1994).
Highlights
Earthquakes are known to trigger submarine landslides in subduction zones, and these landslides can potentially amplify the generated tsunami wave (Kawamura et al 2012; Strasser et al 2013; Tappin et al 2014), break strategically important undersea cable networks, and undercut structural foundations for oil and gas pipelines (Masson et al 2006)
Tephrochronology Based on the geochemical composition of the sampled tephras at C0018 and comparison with on-land tephras, the ages of the tephras were determined
Climate as a preconditioning factor? The data of the present study show that the MTDs recorded at site C0018 in the slope basin of the Nankai accretionary prism occur within interglacials, suggesting that the MTDs were emplaced during phases of relative high sea level and temperatures
Summary
Earthquakes are known to trigger submarine landslides in subduction zones, and these landslides can potentially amplify the generated tsunami wave (Kawamura et al 2012; Strasser et al 2013; Tappin et al 2014), break strategically important undersea cable networks, and undercut structural foundations for oil and gas pipelines (Masson et al 2006). This margin is characterized by magnitude 8+ earthquakes occurring every ~150 years on average (Ando 1975), only six large landslide deposits ( referred to as mass-transport deposits, MTDs) are recognized in the sedimentary record of drill site C0018 during the past 1 Ma (Henry et al 2012). The MTDs are recognized based on their chaotic pebbly and/or mixed lithologies with inclined layers and shear zones (Henry et al 2012; Strasser et al 2012).
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