Historical Background of the Expeditions
Prior to our 1999 diving expedition, several cruises had taken place in the
framework of the Franco-German VIP collaboration in the area of the Pitcairn
hotspot. The first comprehensive investigation comprising bathymetry and sampling of the Pitcairn hotspot was done in 1989 during the MIDPLATE cruise
(Leg 65) of the FS SONNE. In addition, during the same cruise, it was planned to
investigate a volcanic chain that extended further to the East prior to reaching
Easter Island, which was our port of call. This cruise lasted about 6 weeks, with
departure from Valpariso Chile on October 28, and arrival at Papeete Tahiti on
December 6, 1989. The volcanoes that form the Pitcairn hotspot, which is located
about 80 km east of the Island of Pitcairn in a previously uncharted region of the
South Pacific ocean near 25°20
0 S and 129°19
0 W, were discovered during this
1989 cruise of the FS SONNE (Leg 65) (Stoffers et al. 1989).
The preliminary map of the Pitcairn hotspot that was made during this cruise
was done with the German-made Hydrosweep multichannel bathymetry instrument. This gave us an overview on the distribution of the major volcanic edifices
of the region. Further and more detailed investigation was conducted during the
Polynaut cruise with the N.O. L’ATALANTE in 1999. The N.O. L’ATALANTE was
equipped with a more sophisticated and more recent multichannel bathymetry
system (Simrad EM 12), which enabled us to conduct a more detailed and
extensive survey of the Pitcairn hotspot. Jacques Dubois, a geophysicist from
IPGP (Institut de Physique du Globe in Paris), headed this cruise on the N.O.
L’ATALANTE. Originally, the chief scientist was supposed to be Jean Louis
Cheminée but he was unable to participate on the cruise due to family reasons.
I had helped Jean-Louis prepare the original cruise proposal and was involved in
the scientific planning.
A meeting prior to the departure of the cruise was held in Brest at IFREMER,
presided by the port-captain, Armel Lestrat. He was worried about our cruise
because it included diving on active submarine volcanoes. This was a potential
problem since a few weeks earlier it had been reported (by the World’s seismic
network monitoring system) that a tremor was observed in the area of the Pitcairn
hotspot. We all remembered the last experience in 1989 when an eruption had
taken place while Cyana was diving on the Macdonald volcano in the Austral
hotspot chain and we also remembered that the ship had had to quickly evacuate
the site.
Despite this worry, the Polynaut cruise with the N.O. L’ATALANTE and the
submersible Nautile started on August 22, and ended in Papeete (Tahiti) on
September 26, 1999. The cruise was intended to investigate the geodynamic and
volcanic setting of three hotspot regions: the Society, Pitcairn and Macdonald
(Austral) hotspots. However this last target, had to be skipped because when we
arrived on the site of the Macdonald seamount, on September 16, bad weather
conditions prevented us from working. The bad weather lasted 72 h and did not
seem to be getting better. The pounding of the waves under the keel was so great
Historical Background of the Expeditions
323
Prior to our 1999 diving expedition, several cruises had taken place in the
framework of the Franco-German VIP collaboration in the area of the Pitcairn
hotspot. The first comprehensive investigation comprising bathymetry and sampling of the Pitcairn hotspot was done in 1989 during the MIDPLATE cruise
(Leg 65) of the FS SONNE. In addition, during the same cruise, it was planned to
investigate a volcanic chain that extended further to the East prior to reaching
Easter Island, which was our port of call. This cruise lasted about 6 weeks, with
departure from Valpariso Chile on October 28, and arrival at Papeete Tahiti on
December 6, 1989. The volcanoes that form the Pitcairn hotspot, which is located
about 80 km east of the Island of Pitcairn in a previously uncharted region of the
South Pacific ocean near 25°20
0 S and 129°19
0 W, were discovered during this
1989 cruise of the FS SONNE (Leg 65) (Stoffers et al. 1989).
The preliminary map of the Pitcairn hotspot that was made during this cruise
was done with the German-made Hydrosweep multichannel bathymetry instrument. This gave us an overview on the distribution of the major volcanic edifices
of the region. Further and more detailed investigation was conducted during the
Polynaut cruise with the N.O. L’ATALANTE in 1999. The N.O. L’ATALANTE was
equipped with a more sophisticated and more recent multichannel bathymetry
system (Simrad EM 12), which enabled us to conduct a more detailed and
extensive survey of the Pitcairn hotspot. Jacques Dubois, a geophysicist from
IPGP (Institut de Physique du Globe in Paris), headed this cruise on the N.O.
L’ATALANTE. Originally, the chief scientist was supposed to be Jean Louis
Cheminée but he was unable to participate on the cruise due to family reasons.
I had helped Jean-Louis prepare the original cruise proposal and was involved in
the scientific planning.
A meeting prior to the departure of the cruise was held in Brest at IFREMER,
presided by the port-captain, Armel Lestrat. He was worried about our cruise
because it included diving on active submarine volcanoes. This was a potential
problem since a few weeks earlier it had been reported (by the World’s seismic
network monitoring system) that a tremor was observed in the area of the Pitcairn
hotspot. We all remembered the last experience in 1989 when an eruption had
taken place while Cyana was diving on the Macdonald volcano in the Austral
hotspot chain and we also remembered that the ship had had to quickly evacuate
the site.
Despite this worry, the Polynaut cruise with the N.O. L’ATALANTE and the
submersible Nautile started on August 22, and ended in Papeete (Tahiti) on
September 26, 1999. The cruise was intended to investigate the geodynamic and
volcanic setting of three hotspot regions: the Society, Pitcairn and Macdonald
(Austral) hotspots. However this last target, had to be skipped because when we
arrived on the site of the Macdonald seamount, on September 16, bad weather
conditions prevented us from working. The bad weather lasted 72 h and did not
seem to be getting better. The pounding of the waves under the keel was so great
Historical Background of the Expeditions
323