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same minimal values as in the calm periods. This regime was
revealed between 4-11 and 21-29 February.
3. Benthic storms, associated initially with a sharp increase in current
speed, which can maintain relatively stable speeds to produce 24-
hour means of as much as 8 cm/sec 21 and one-hour means of 13-
15 cm/sec 22 . The benthic storm measured by Demidova and
Kontar 23 lasted about two weeks (the first half of March).
Approximately the same periods (several weeks) of increased
velocity have also been found in the longer duration observations
by Hayes 24 .
The general direction of near-bottom currents in the province has
been postulated to be dominated by the flow of Antarctic Bottom Water
(AABW) to the northeast 25 . This water is introduced to the region through
the deep Clarion and Clipperton passages. Flowing along the main fault
zones to the northeast, a part of it presumably branches off in the
numerous seabed valleys and depressions, potentially influencing local
current distributions. However, as shown in table 3, the measured benthic
currents available to this study all indicate current directions in direct
opposition to the north-northeast direction predicted by indirect methods.
At the site of the bottom station BS-3, north-northwest and south-southeast
directions dominated the observations. This direction is consistent with the
bearing of isobaths at the site. The mean velocity vector for BS-3 is
southeast. Analogous results were obtained for the other two stations.
According to several recent studies 26 , the submeridional valleys of
erosional nature are widely developed in these parts of the province.
According to all observations to date, the calm and active regimes
discussed above are characterised by opposing current directions. The
mean direction at the period of low activity is often north-northwest,
consistent with the basic advection of AABW, whereas the flow during
benthic storms is often SSE. Hayes 27 describes earlier experiments of
longer duration in which this same trend of current reversal during different
regimes is evident. Interestingly, this inferred direction of sediment
transport along the seabed valleys to the SSE corresponds to the direction
of general decrease of ocean depths rather than their increase. (See also
Section 3.3. above.)
INTERNATIONAL SEABED AUTHORITY 118