Submarine gravity flows are responsible for the largest sediment accumulations on the planet, but are notoriously difficult to measure in action. Giant flows transport 100s of km³of sediment with run-out distances over 2000 km. Sediment concentration is a first order control on flow dynamics and deposit character. It has never been measured directly nor convincingly estimated in large submarine flows. Here we reconstruct the sediment concentration of a historic giant submarine flow, the 1929 “Grand Banks” event, using two independent approaches, each validated by estimates of flow speed from cable breaks. The calculated average bulk sediment concentration of the flow was 2.7–5.4% by volume. This is orders of magnitude higher than directly-measured smaller-volume flows in river deltas and submarine canyons. The new concentration estimate provides a test case for scaled experiments and numerical simulations, and a major step towards a quantitative understanding of these prodigious flows.

Instrumental records reveal that intense tropical cyclone (TC) activity varies with tropical sea surface temperature (SST) on annual-decadal scales. Drivers of intense TC activity at the centennial-millennial scale are less clear, due to the sparseness of pre-observational reconstructions. Here, we present a new 2 kyr continuous activity record of intense TCs from offshore eastern China. Our reconstruction indicates that this site witnessed enhanced TC activity during relatively warm periods, with a widespread increase in TC activity during the later part of the Little Ice Age. This latter observation reveals that enhanced TC activity was synchronized with increased Asian dust emissions during the Little Ice Age. TC activity was also lower in the late Roman Warm Period, when SST was higher but Asian dust emissions were lower than in the early phase. Such patterns suggest a centennial-millennial link between TC climatology and a combination of SST changes and Asian dust levels.

This study examines the influence of the strength of Atlantic Meridional Overturning Circulation (AMOC) on storminess at different latitudes in the North Atlantic, based on a new 6.5‐Kyr record of large storms from the Scotian Shelf (Eastern Canada) that provides the first >3.5‐ka record from middle latitudes. Comparison with a compilation of other paleostorm records shows that peaks in storminess are at times synchronous (4.5–2.5 and since 0.5 ka) between low and middle latitudes but in the intervening period (2.5–0.5 ka) were latitudinally asynchronous. Synchronous (asynchronous) behavior correlates with sustained increase (decrease) of AMOC. Regime shifts in storm activity between low and middle latitudes were more frequent since 2.5 ka, related to increased frequency of abrupt climate changes. These findings indicate a latitudinal response of storm activity due to abrupt climate change, which is critical to correctly assess future storm risks along the North Atlantic coastline.

The 1929 Grand Banks submarine landslide on the southwestern Grand Banks of Newfoundland was triggered by a M_w 7.2 strike‐slip earthquake. It is the first studied example of a submarine mass movement known to have caused a turbidity current and tsunami. The event resulted in 28 casualties and caused severe economic damage. The St. Pierre Slope is the main source area for the sediment failure. It contains translational and probable retrogressive surficial failures (1,700‐m water depth. These observations contradict what might be expected for a tsunamigenic event; thus, the objective of this study is to look for other potential causal mechanisms. A comprehensive analysis of 2‐D seismic reflection data of various resolutions and multibeam bathymetry allowed mapping of new stratigraphic and structural features. Numerous, low‐angle (~17°) faults are present throughout the Quaternary section of the St. Pierre Slope that are associated with seafloor escarpments (750‐ to 2,000‐m water depth). These faults have up to 100‐m high displacement and are interpreted as part of a massive (~560 km³), complex slump. There are multiple décollements (250‐ and 400‐ to 550‐m below seafloor) within this slump and there is indication for slumping in at least two directions. Evidence suggests slumping as a result of the 1929 earthquake occurred along these faults, with ~100‐m seafloor displacement in places. The 1929 submarine landslide therefore involved two failure mechanisms: massive slumping (~500‐m thick) and consequent widespread, surficial (<25 m) sediment failure. Both failure mechanisms likely contributed to tsunami generation.