The Society Hotspot
The Society Island chain and its hotspot region are located in the South Pacific
Ocean and cover a total area of about 65,000 km
2 . The volcanic edifices increase
in age from the currently active Mehetia island (W148°04
0 -S17°52
0 ), located at the
border of the hotspot and surrounded by an abyssal hill region, to the Maupiti
emerged volcano (W152°15
0 -S16°27
0 ), located 440 km to the northwest, with an
age of 4.34 Ma old (Duncan et al. 1974) (Fig. 9.4).
The area covered by the Society hotspot itself is about 15,000 km
2 , and comprises about eighteen volcanic cones more than 500 meters tall formed on an ancient
oceanic crust that is 65 million years old. From seismic monitoring (Talandier and
Okal 1984; Okal et al. 1980) and based on field observations in the area, it was
inferred that at least six volcanoes, located above the 3750 m contour line, are still
active. Earthquake swarms were monitored by the Polynesian seismic station, which
gave the location of the epicenters and was able to detect volcanic activities. Also,
direct field observation and sampling of freshly erupted lava and hydrothermal
venting helped us to localize recent volcanic episodes.
The individual cones are found to be grouped around seven major volcanic centers, which include: (1) the Teahitia volcano (2100 m high) at 17°32
0 S-148°50
0 W,
(2) the newly discovered edifice called Cyana located to the south of Teahitia at
17°55
0 S-148°50
0 W, (3) The Rocard volcano east of Teahitia, (4) Turoi seamount
west of Teahitia, (5) the Moua-Pihaa seamount rising to 3500 m above the sea floor,
(6) Volcano # 17 north of Mehitia and (7) the island of Mehetia, which rises 450 m
above sea level. In addition, other smaller edifices less than 500 m tall are scattered
around the larger volcanoes. One group of small edifices, called the Seismic
Fig. 9.4 Map of the Society
volcanic chain in the South
Pacific. The reconstruction of
the bathymetry was done by
A. Bonneville (personal
communication) from a
compilation of multichannel
data. A series of volcanic
edifices varying in size from
500 m to more than 1000 m
have been constructed during
hotspot activity, the limit of
which is indicated by a thick,
darker contour line
(\4000 m)
312
9 Hotspots
The Society Island chain and its hotspot region are located in the South Pacific
Ocean and cover a total area of about 65,000 km
2 . The volcanic edifices increase
in age from the currently active Mehetia island (W148°04
0 -S17°52
0 ), located at the
border of the hotspot and surrounded by an abyssal hill region, to the Maupiti
emerged volcano (W152°15
0 -S16°27
0 ), located 440 km to the northwest, with an
age of 4.34 Ma old (Duncan et al. 1974) (Fig. 9.4).
The area covered by the Society hotspot itself is about 15,000 km
2 , and comprises about eighteen volcanic cones more than 500 meters tall formed on an ancient
oceanic crust that is 65 million years old. From seismic monitoring (Talandier and
Okal 1984; Okal et al. 1980) and based on field observations in the area, it was
inferred that at least six volcanoes, located above the 3750 m contour line, are still
active. Earthquake swarms were monitored by the Polynesian seismic station, which
gave the location of the epicenters and was able to detect volcanic activities. Also,
direct field observation and sampling of freshly erupted lava and hydrothermal
venting helped us to localize recent volcanic episodes.
The individual cones are found to be grouped around seven major volcanic centers, which include: (1) the Teahitia volcano (2100 m high) at 17°32
0 S-148°50
0 W,
(2) the newly discovered edifice called Cyana located to the south of Teahitia at
17°55
0 S-148°50
0 W, (3) The Rocard volcano east of Teahitia, (4) Turoi seamount
west of Teahitia, (5) the Moua-Pihaa seamount rising to 3500 m above the sea floor,
(6) Volcano # 17 north of Mehitia and (7) the island of Mehetia, which rises 450 m
above sea level. In addition, other smaller edifices less than 500 m tall are scattered
around the larger volcanoes. One group of small edifices, called the Seismic
Fig. 9.4 Map of the Society
volcanic chain in the South
Pacific. The reconstruction of
the bathymetry was done by
A. Bonneville (personal
communication) from a
compilation of multichannel
data. A series of volcanic
edifices varying in size from
500 m to more than 1000 m
have been constructed during
hotspot activity, the limit of
which is indicated by a thick,
darker contour line
(\4000 m)
312
9 Hotspots