Holocene fringing reefs and sea-level change in Mangaia Island, Southern Cook Islands

Mauke, Mitiaro and Atiu: geomorphology of Makatea Islands in the southern Cooks

“…In profile K these stand up to 1.23 m above datum, as steep-sided platforms with pitted and eroded upper surfaces (figures 31 and 32). These residuals may represent a fossil algal ridge, similar to those described from Mangaia, southern Cooks (Yonekura et al 1986(Yonekura et al , 1988 and Suwarrow, northern Cooks , indicating the former position of the reef margin prior to the Holocene sea level highstand of ca 1.0 m between ca 6000-2000 a B.P. in this part of the Pacific (Pirazzoli and Montaggioni 1988).…”

“…These features taken together resemble the emerged benches, high notches at 2-3 m, uplifted microatolls at 0.95-1.5 m, and raised and eroding reef flats described by Yonekura et al (1986Yonekura et al ( , 1988 on the northwest coast of Mangaia, except that the Mitiaro, Mauke and Atiu elevations are somewhat greater than those on Mangaia. Yonekura et al (1986Yonekura et al ( , 1988 show that the features on Mangaia all date from a high stand of the sea at 1.0-1.7 m above present in the interval 5000-ca 3150 years B.P., after which sea level fell to its present level or less, when contemporary reef flats and notches began developing.…”

“…Yonekura et al (1986Yonekura et al ( , 1988 show that the features on Mangaia all date from a high stand of the sea at 1.0-1.7 m above present in the interval 5000-ca 3150 years B.P., after which sea level fell to its present level or less, when contemporary reef flats and notches began developing. These differences may result from flexural control.…”

New Marine ΔR Values for the South Pacific Subtropical Gyre Region

“…Fluctuation in sea levels over time in response to climate change is also well documented for the South Pacific islands (Pirazzoli and Montaggioni 1988;Yonekura et al 1988;Dickinson et al 1999;Moriwaki et al 2006). Although climate change will have an influence on the wider marine reservoir, as documented by the coral core records, the impact to the more restricted environs inhabited by many marine shellfish could potentially be of greater significance.…”

T waves from the great 1994 Bolivian deep earthquake in relation to channeling of S wave energy up the slab

“…Efficient propagation of high frequency oceanic upper mantle phases (Po and So) has long been documented [Walker, 1977;Talandier and Bouchon, 1979] and modeled [Mallick and Frazer, 1990], but it remains unclear why the bulk of the T wave hitting Mangaia would convert to So rather than Po. Mangaia is an unusual island, featuring exceptionally old exposed volcanics [Turner and Jarrard, 1982], and an uplifted limestone ting, with a small recent fringing reef [Yonekura et al, 1988]. The exact morphology of the slope of the island structure and its effect on the acoustic-to-seismic conversion remain speculative.…”