Abstract:
The United Nations Convention on the Law of the Sea requires nations to justify claims to "legal" Continental Shelf (LCS) beyond the 200 n mile Exclusive Economic Zone (EEZ), according to formulae set out in Article 76 of that Convention. The area between and adjacent to the EEZs generated by Lord Howe and Norfolk Islands is one example where Australia can make such a claim and is the subject of this survey proposal. A program of seismic traverses has been designed which will cross the 2500 m contour (to define its location), the probable foot-of-slope, and areas beyond the foot-of-slope having potential to host sediment of significant thickness. These crossings will occur at a sufficient number of sites to allow: (1) definition of the 100 n mile cut-off beyond the 2500 m contour, (2) definition of the Hedberg Line 60 n mile beyond the foot-of-slope, and (3) determination of the sediment thickness distribution. The upper limit of seismic traverse length is estimated to be 3800 km, based on the assumption that most traverses will extend beyond the foot-of-slope to around the Hedberg Line, to test the sediment thickness criterion. This, however, is probably an overestimate. With knowledge of sediment thickness distribution gained during acquisition, some traverses may be truncated before the Hedberg distance is traversed. Following a desk-top study conducted jointly with New Zealand scientists in May 1996, there is a high probability of this proposed work being done co-operatively with New Zealand, since they also have a requirement to define LCS beyond their EEZ in the same region. However, this proposal is designed to provide the additional data required by Australia independently of any participation by New Zealand.