How Coriolis forces can limit the spatial extent of sediment deposition of a large-scale turbidity current

Abstract: The rotation rate of the Earth controls the deposition scale of turbidity currents when their flow transit-time is comparable to one day. Using laboratory experiments it is shown that the maximum length-scale L of deposition is set by the scale where the Rossby number of the current is equal to one. The dimensionless Rossby number is defined as Ro = U / fL, where U is a depth-averaged velocity of the turbidity current and f is the Coriolis parameter. In these new laboratory experiments the Coriolis parameter is varied by changing the platform rotation rate and there is good agreement between experimental observations and the prediction that the extent of the deposition scales as L ~(4/ π)1/4(g′V / f)1/4, where g′ is the reduced gravity and V the initial volume of the sediment-laden material. This scaling implies that the depositional patterns will vary with latitude, and that at higher latitudes one would expect smaller, thicker deposits. Using this scaling implies that the 200–400 km spatial extent of the turbidite arising during the 1929 Grand Banks earthquake had Ro ~1, and so Coriolis forces controlled the length-scale of the turbidite deposition. [Copyright &y& Elsevier]