The turbidity current

Assembled from 12 blocks · 2 evidence · 5 related

1. Story
2. A dense, sediment-laden flow that runs down a submarine slope under gravity, and the natural process that does most of the damage cables suffer from the sea rather than from people. Because the suspended sediment makes the water denser than the water around it, the flow accelerates rather than dissipating, funnels into submarine canyons, and can travel for hundreds of kilometres across the abyssal plain at speeds measured in metres per second. It was inferred, rather than observed, from cables: after the Grand Banks earthquake of 18 November 1929 a series of transatlantic telegraph cables broke not simultaneously but in order, progressively further from the epicentre, over about thirteen hours — and in 1952 Bruce Heezen and Maurice Ewing argued from the timing of those breaks, and from cores showing coarse sediment far out on the plain, that a single sediment flow had run down the slope and cut them one after another. The 2006 Pingtung earthquake off Taiwan reproduced the pattern in the fibre era, with breaks stepping down the canyon system into the Manila Trench over hours. Cable breaks are, in other words, one of the few instruments science has ever had for observing this process, and the timing of an outage doubles as a velocity measurement.
3. Knowledge
4. The turbidity current
5. Connections
6. The Grand Banks earthquake breaks cables in sequence
7. The Hengchun earthquake doublet off southern Taiwan
8. Cables in the Luzon Strait break in sequence over nine hours
9. Four cables fail off Côte d'Ivoire and thirteen countries lose connectivity
10. Evidence
11. Supports the inference of turbidity currents from the sequential failure of transatlantic telegraph cables after the Grand Banks earthquake of 18 November 1929 — twelve cables broken, the later failures stepping outward over about thirteen hours — and the corroborating sediment evidence from cores on the abyssal plain. V55 verification basis: NOT read. The paper title, journal and argument were carried by retrieved search results; the figures for cable numbers and elapsed time come from those summaries and from later literature citing the paper, not from the paper itself.
12. Supports the account of the 2006 Luzon Strait cable failures as a sequential process driven by earthquake-triggered sediment density flows running down submarine canyons into the Manila Trench, with flow speeds of several metres per second inferred from break timings. V55 verification basis: NOT read; retrieved in summary only. Published break counts for the 2006 event differ between analyses — eight, nine, eleven, thirteen and twenty-two all appear — and this pack states the range rather than adopting one.