Abstract Landslides are common in aquatic settings worldwide, from lakes and coastal environments to the deep sea. Fast-moving, large-volume landslides can potentially trigger destructive tsunamis. Landslides damage and disrupt global communication links and other critical marine infrastructure. Landslide deposits act as foci for localized, but important, deep-seafloor biological communities. Under burial, landslide deposits play an important role in a successful petroleum system. While the broad importance of understanding subaqueous landslide processes is evident, a number of important scientific questions have yet to receive the needed attention. Collecting quantitative data is a critical step to addressing questions surrounding subaqueous landslides. Quantitative metrics of subaqueous landslides are routinely recorded, but which ones, and how they are defined, depends on the end-user focus. Differences in focus can inhibit communication of knowledge between communities, and complicate comparative analysis. This study outlines an approach specifically for consistent measurement of subaqueous landslide morphometrics to be used in the design of a broader, global open-source, peer-curated database. Examples from different settings illustrate how the approach can be applied, as well as the difficulties encountered when analysing different landslides and data types. Standardizing data collection for subaqueous landslides should result in more accurate geohazard predictions and resource estimation.

Abstract The study area is situated along the obliquely converging boundary of the Caribbean and South American plates in eastern offshore Trinidad. Major structural elements in the shelf break and deep-water slope regions include growth and counter-regional faults to the south and large transpressional faults to the north. Well logs and biostratigraphic data were analyzed for 24 wells in the study area to refine previous deposi-tional environment interpretations. Transgressive and regressive cycles were interpreted on the basis of well log patterns and depositional facies shifts. Six T/R cycles were interpreted within the Pliocene to Recent stratigraphic succession. Shelf-edge trajectories were also mapped for each of the six T/R cycles on the basis of earlier stratigraphic correlations. Net-to-gross (NTG) ratios were calculated for each component of the T/R cycles and plotted against total thicknesses and net-sand values. In addition, NTG trends were mapped for each interval and analyzed on the basis of their proximity to the corresponding shelf edge. Mapping of shelf-edge trajectories (SETs) revealed that (1) SETs migrate northeasterly across the Columbus basin through time and (2) shelf-edge orientations parallel the strike of growth faults in the south but deflect to the northeast near the Darien ridge, indicating strong, underlying structural control. NTG plots and maps also revealed that (1) for transgressive units, NTG values never exceed 60%, and they are inversely proportional to total thickness; (2) for regressive cycles, NTG values are highly variable, ranging from 35% to 90%; (3) NTG values increase as the shelf break is approached; and (4) distribution of NTG ratios is also controlled by accommodation space created by local structures.