Chatham / Challenger project - Voyage 1 Multibeam Survey

In August 2006 transects of the Chatham Rise and Challenger Plateau were surveyed using NIWA’s Research Vessel Tangaroa high resolution multibeam system. The transects were carefully located to traverse 28 different environmental variables which may influence the distribution and abundance of seabed animals.

Vessel Scanning Seabed.

Much of the area surveyed was soft sediments, except where old volcanic rocks emerged above the sediment to form rocky banks such as Mernoo and Veryan Bank on the Chatham Rise; patches of rough ground on the eastern Chatham Rise near the Chatham Islands and the shallower part of the Challenger Plateau.

The survey exceeded expectations providing excellent transect coverage of both areas and additional coverage during transit and a run of good weather.

Most transects were multi-beamed twice providing total swath widths of 2 to 5 Km, depending on the water depth. Even though the Chatham Rise is extensively fished, multibeam data has only been collected from limited areas in the past. This survey provides the first extensive coverage of the area. The transects covered on the Challenger Plateau were also new.

Multibeam Survey Chart.

Multibeam Survey Chart 2.

A vertical profile across Transect 1 on the Chatham Rise shows the depth changes across the rocky Mernoo Bank and the soft-sediment flanks of the Chatham Rise.

This is a 2D profile taken along Transect-1 from the north (left) to south (right). Vertical exaggeration is 30x. Colours relate to depth-red is shallow.

2D Profile of sea-bed.

Unusual blips discovered along Transect 2 on the Veryan Bank show a series of depressions up to 5 m deep in vertical profile at about 570 m water depth. These are likely to be methane seeps from the sea-bed. Shown area is 13km long by 8km wide.

Sea-bed section chart. Sea-bed section chart 2.

This section on the south side of Transect-5 shows iceberg scour marks. These marks were formed about 20 000 years ago. The scours are between 200 and 500m across and 10m deep. Bottom depth is 450. Shown area is 11km long by 5 km wide.
Previous | Next
Updated : 16 November 2007