Possible climate preconditioning on submarine landslides along a convergent margin, Nankai Trough (NE Pacific)

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 offand 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.

Tectonic Influences on Trench Slope Basin Development via Structural Restoration Along the Outer Nankai Accretionary Prism, Southwest Japan

“…Expeditions 316, 333 and 338 (Expedition 316 Scientists, 2009a, 2009bExpedition 333 Scientists, 2012;Moore et al, 2014) and postexpedition stable isotope and tephra-stratigraphy (Kremer et al, 2017). Continuous horizons were restored to subhorizontal by back slipping along faults, while restoration of beds truncated or offset by erosion (e.g., slope failure) were restored manually via geometric interpolation between the eroded and onlap surfaces (e.g., Horizons O and M between Figures S3 and S4 in the supporting information).…”

“…and C0022 (Expedition 316 Scientists, 2009a, 2009bExpedition 333 Scientists, 2012;Moore et al, 2014), and oxygen isotope and tephra-stratigraphy at C0018 help constrain the age of Horizon O to 0.9 Ma (Kremer et al, 2017). Here, we chose to use an average date for each horizon, as determined by the different dating methods, to provide a single target date for our restorations.…”

“…In this paper, we provide detailed structural reconstructions that constrain the 3-D evolution of the MSF region and provide a framework for understanding how fault slip and tectonic oversteepening could generate MTDs. Our reconstructions utilize age constraints on prominent stratigraphic horizons and MTDs within the study area, from sediment cores obtained by the International Ocean Drilling Program (IODP) (Kremer et al, 2017;Strasser et al, 2009Strasser et al, , 2011Strasser et al, , 2012Strasser et al, , 2014 and high-resolution, 3-D seismic reflection data from the NanTroSEIZE volume (Moore et al, 2009). Following the end member OOST definitions from Morley (1988), we address the sequential development of the MSF from its inception as a frontal thrust prior tõ 2.2 Ma, through its reactivation as an OOST~1.95 Ma, to its eventual abandonment at~1 Ma, via a comprehensive structural restoration.…”

Three-dimensional mapping and kinematic characterization of mass transport deposits along the outer Kumano Basin and Nankai accretionary wedge, southwest Japan

“…However, as noted by Moore and Strasser (2016), the recurrence interval for landsliding in the Kumano Basin appears to be about 0.05 to 0.1 Ma, which is much less frequent than the recurrence interval for Nankai's great earthquakes. Kremer et al (2017) suggested that this difference could be due to slopes being preconditioned to fail because of climate forcing during interglacial periods. However, they were unable to resolve the relative contributions of tectonic versus climate preconditioning factors, and Urlaub et al (2013) showed that the ages of landslides on passive margins can be described by a temporally random Poisson distribution and therefore do not show a positive correlation between the frequency of major slope failures on passive margins and sea level changes during the past 0.18 Ma.…”

Structural Controls on Slope Failure Within the Western Santa Barbara Channel Based on 2‐D and 3‐D Seismic Imaging

“…Most studies rely on a reconstruction of events based on marine geophysical and geological records. For example, multibeam bathymetry data are now routinely used to characterize the morphological expression of failures and associated deposits (e.g., Hill et al, 2020; Watson et al, 2020), seismic reflection data are used to map the substrate architecture of failure zones (e.g., Berndt et al, 2012; Brothers et al, 2018), and measurements from seafloor drilling/coring provide constraints on geotechnical parameters and the age of sedimentary units involved in the failure process (e.g., Ikari et al, 2011; Kremer et al, 2017). Studies focused on incipient failure or on preconditioning factors have been conducted along many margins around the world (e.g., Bryn et al, 2005; Kvalstad et al, 2005; Piedade et al, 2018; Song et al, 2020), including regions undergoing compressional tectonics and uplift (e.g., Alves et al, 2014; Gee et al, 2007; Gross et al, 2018; Ikari et al, 2011); however, such studies are limited along the U.S. West Coast.…”