New Zealand Journal of Geology and Geophysics

ISSN: 0028-8306 (Print) 1175-8791 (Online) Journal homepage: http://www.tandfonline.com/loi/tnzg20

Gravity base stations in the south-west Pacific Ocean E. I. Robertson To cite this article: E. I. Robertson (1965) Gravity base stations in the south-west Pacific Ocean, New Zealand Journal of Geology and Geophysics, 8:3, 424-439, DOI: 10.1080/00288306.1965.10426414 To link to this article: http://dx.doi.org/10.1080/00288306.1965.10426414

Published online: 12 Jan 2012.

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Date: 28 January 2017, At: 22:21

424

[JUNE

GRAVITY BASE STATIONS IN THE SOUTH-WEST PACIFIC OCEAN E. I.

ROBERTSON

Geophysics Division, Department of Scientific and Industrial Research, Wellington (Received for publication 13 April 1964)

ABSTRACT

Since 1950, gravity base stations have been established in the South-west Pacific Ocean area by G. P. Woollard's group at the University of Wisconsin, P. Stahl of France, and the New Zealand Department of Scientific and Industrial Research. Full details, including free-air and Bouguer anomalies, are given for bases in the Auckland, Cook, Fiji, Kermadec, Macquarie, New Caledonia, Samoa, Society, Tokelau, and Tonga Islands.

INTRODUCTION

Many gravity base stations have been established in the South-west Pacific Ocean area since 1950 by G. P. Woollard's group at the University of Wisconsin. The results obtained by numerous observers using Worden gravity meters have been published by Woollard and Rose (1960), who used the Washington D.C. (Commerce Floor) datum of 980 118'7 mgal. In 1953 P. Stahl (1958) used a Worden gravity meter to establish gravity bases at Macquarie Island and Auckland Island while en route from Port-Martin in Antarctica to Tasmania. The published gravity values are effectively on the same datum as Woollard and Rose's (1960) bases, because Stahl's value for Cambridge Airport at Hobart (Tasmania) is 980443'0 mgal, which is almost identical with Woollard and Rose's value of 980443·2 mgal, and Stahl considers that his Macquarie and Auckland Island values may be in error by at least one milligal. Between 1959 and 1963 the New Zealand Department of Scientific and Industrial Research (D .S.I.R.) established 20 additional bases on islands in the South-west Pacific Ocean using a Worden gravity meter, and also replaced four bases that can no longer be occupied chiefly owing to airport alterations. The gravity values were computed on the Woollard and Rose (1960) datum, the value for Whenuapai Airport near Auckland (New Zealand) being 979940'8 mgal, which is identical with the New Zealand Potsdam value (Cowan and Robertson, 1964). The extensive network of bases in New Zealand has not been included in this paper because detailed information has already been published by Robertson and Reilly (1960) and Cowan and Robertson (1964). N.Z. ,. Geol. Geophys, 8 : 424-39

1965]

ROBERTSON - GRAVITY BASE STATIONS

425

BASES ESTABLISHED BY THE UNIVERSITY OF WISCONSIN

Cook Islands Woollard and R06e's (1960) Aitutaki Island station at the Teal Flying Boat Base has not been included in the list of bases given in Table 1 because the flying boat service has ceased and a more convenient base (Aitutaki A) has since been established by D.S.I.R. Fiji Islands (a) Nausori. Woollard and Rose's Nasourie Airport station on Viti Levu Island, which is "on concrete abutment over ditch", has been renamed Nausori because this is the accepted spelling and was used in earlier publications. (b) Woollard and Rose's Nandi Airport station on Viti Levu Island has not been included because it is no longer accessible. It has been replaced by Nandi A which was tied to the original station by D.S.I.R. in 1960. New Caledonia Tontouta. Woollard and Rose's Tontouta Airport station near Nournea is "at south-west corner of hangar". Samoa (a) Apia. In 1950 C. Muckenfuss of the University of Wisconsin group established a station at Apia Observatory on Upolu Island wh06e gravity value is 18'8 mgal greater than Faleolo Airport Station (G. P. Woollard, pers. comm). This station is on the concrete base of the transit pier. (b) Woollard and Rose's Faleolo Airport station on Upolu Island has not been included because it is no longer accessible. It has been replaced by Faleolo A which was tied to Apia by D.S.I.R. in 1962. (c) Woollard and Rose's Tafuna Air Field station on Tutuila Island has not been included because it is no longer accessible. It has been replaced by Tafuna A which was tied to Apia by D.S.I.R. in 1962. Society Islands (a) Bora Bora. Woollard and Rose's Bora Bora Island Airstrip station is "3 ft from the wall of the passenger terminal, near the center of the building on the side facing the airstrip". Their Bora Bora Fly Boat Base station on the opposite side of the island has not been included because the flying boat service has ceased. (b) Tahiti. Woollard and Rose's Tahiti Island Fly Boat Base station is "in customs building to left of the counters as one faces the water, near the center of the lobby, adjacent to a bamboo divan". Tonga Islands Fua Amottl. Woollard and Rose's Fua-Amotu Airport station on Tongatapu Island is "on ground at entrance to NAC hut".

[JUNE

N.z. JOURNAL OF GEOLOGY AND GEOPHYSICS

426

BASES ESTABLISHED BY P. STAHL

Auckland Islands Auckland Island. Stahl's Auckland Island station is on the remains of the 1872 German Expedition's large pier at Port Ross. The full name, Auckland Island, has been retained to avoid confusion with the Auckland pendulum station in New Zealand. Macquarie Islands Macquarie. Stahl's Macquarie Island station IS 1ll the centre of the floor of the anemometer building in the ANARE camp. BASES ESTABLISHED BY THE NEW ZEALAND DSIR Between 1959 and 1963 the D.S.I.R. established eight new gravity bases (Aitutaki, Atiu, Mangaia, Manihiki, Mauke, Mitiaro, Penrhyn, and Rarotonga) in the Cook Islands, one (Niue) on Niue Island, three (Kandavu, Lambasa, and Suva) in the Fiji Islands, one (Raoul) in the Kermadec Islands, two (Fagatogo and Salelo'lo'ga) in the Samoa Islands, three (Atafu, Fakaofo, and Nukunono) in the Tokelau Islands, and one (Vavau) in the Tonga Islands. The original Aitutaki station became difficult to locate after the old Araura School was burnt down in 1961. A replacement station 140"

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