Macdonald Volcano | John Seach


(Tamarii seamount)
Austral Islands, French Polynesia

28.98 S, 140.25 W
summit elevation -39 m
Submarine volcano

Note: A volcano with a similar name "McDonald Island" is located in South Indian Ocean.

Macdonald Volcano is located on the hotspot which formed the Austral-Cook island chain. The volcano consists of a submarine plateau with summit spatter cones. Pumice observed in 1928 and 1936 may have originated from Macdonald seamount.

Macdonald Seamount was discovered in May 1967 following a strong seismic swarm detected by hydrophone.

2005 Earthquakes
A seismic swarm was detected at Macdonald Volcano in October 2005. Seismicity was weak and did not indicate a submarine eruption. Over five days there were 423 small and medium amplitude T-wave events recorded at the seamount.

1987-89 Eruptions
Detection of T-phase acoustic waves on 4th June 1987 indicated and eruption at Macdonald Volcano, which lasted for 4 hours. Eruptions were detected on 6-7 July 1987. An eruption was reported on 11th October 1987. Discoloured water was noted above the vent and bursting gas bubbles burst on the surface. Shallow submarine explosions occurred from 2-5 September 1988. Seismic activity was detected from 26 September-5 October, 12-24 October, and 12-14 December 1988. Explosions occurred from 25-29 December 1988. Eruptions occurred from 19-20 January 1989.

Further reading
Chemine, J-L., et al. "Gas-rich submarine exhalations during the 1989 eruption of Macdonald Seamount." Earth and Planetary Science Letters 107.2 (1991): 318-327.

Johnson, R.H. and Malahoff, A., 1971. Relation of Macdonald volcano to migration of volcanism along the Austral chain. Journal of Geophysical Research, 76(14), pp.3282-3290.

Macdonald Volcano Eruptions

1987-89, 1986, 1983, 1982, 1980-81, 1979, 1977, 1967, 1936?, 1928?