Giant submarine landslides in gas hydrate provinces.: a comparison of the Nile and Amazon deep-sea fans

The objective of the MEGA project is to address key open questions regarding the causes and triggering mechanisms of megaslides on passive continental margins. Although we know that these causes can be complex and potentially include multiple pre-conditioning and triggering factors (Urlaub et al. 2015; Vanneste et al. 2013, d’Acremont et al., 2022), we choose to focus the project on testing hypotheses regarding the relation of megaslides to the spatio-temporal dynamics of gas hydrate systems. In particular, the project will test two main available hypotheses that megaslides may be generated 1) by GHSZ thinning driven by thermobaric changes in the oceans, in response to climate forcing over glacial-interglacial to anthropogenic timescales (top-down dynamics), and/or 2) by transient fluctuations in subsurface fluid flow and gas venting (bottom-up dynamics). In addition, MEGA will assess the tsunamigenic consequences of such megaslides on coastlines, as enormous volumes of sediment can be potentially destabilized in quasi instantaneous time steps, in effect addressing the question: do megaslides imply mega-hazards?