We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The sequence of events around the epicentre of the 1929 Grand Banks earthquake: initiation of debris flows and turbidity current inferred from sidescan sonar.
- Authors
Piper, David J. W.; Cochonat, Pierre; Morrison, Martin L.
- Abstract
Continental slope sediment failures around the epicentre of the 1929 ‘Grand Banks’ earthquake have been imaged with the SAR (Système Acoustique Remorqué) high-resolution, deep-towed sidescan sonar and sub-bottom profiler. The data are augmented by seismic reflection profiles, cores and observations from submersibles. Failure occurs only in water depths greater than about 650 m. Rotational, retrogressive slumps, on a variety of scales, appear to have been initiated on local steep areas of seabed above shallow (5–25 m) regional shear planes covering a large area of the failure zone. The slumps pass downslope into debris flows, which include blocky lemniscate bodies and intervening channels. Clear evidence of current erosion is found only in steep-sided valleys: we infer that debris flows passed through hydraulic jumps on these steep slopes and were transformed into turbidity currents which then evolved ignitively. Delayed retrogressive failure and transformation of debris flows into turbidity currents through hydraulic jumps provide a mechanism to produce a turbidity current with sustained flow over many hours.
- Subjects
DEBRIS avalanches; TURBIDITY currents; EARTHQUAKES
- Publication
Sedimentology, 1999, Vol 46, Issue 1, p79
- ISSN
0037-0746
- Publication type
Article
- DOI
10.1046/j.1365-3091.1999.00204.x