atmosphere is due to the two major volcanic explosions of 1991, or is due to manmade chemicals, has not yet been clearly resolved.
Unfortunately, volcanic eruptions are still very hard to predict. With all we
know, we still cannot inform others about how magma can or will flow into
underground conduits nor how long it will take before generating volcanic
activities.
Underwater Eruptions: First Observation
Reports on the eruptions of submarine volcanoes are rare. However, a few historical
cases have been reported. In 1925, a Japanese research vessel sank above a submarine volcano in the northwestern Pacific. In 1968, a sailing boat passing near a
submarine volcano in the south Pacific in the vicinity of Tubuai in the Austral island
chain felt under water earthquakes due to the eruption of a shallow seamount,
named the Macdonald seamount (See Chap. 9). In 1963, a submarine volcano rose
to the surface at about 50 km southeast of Iceland forming the island of Surtsey.
Another active submarine edifice, the Kicken Jenny, in the Lesser Antilles rose to a
height of about 230 m above sea level in 1939 and it has been active ever since
(Lopes 2005).
In November 2008, the ‘‘Vents Program’’ discovered two on-going eruptions in
the area of the Tonga-Kermadec ridge in the southwestern Pacific, one at West
Mata Volcano near Tonga Island, and the other on the northeastern Lau basin
spreading-ridge area. The following year, in May 2009, deep-seated submarine
volcanic eruptions were observed from a ROV during the ‘‘Ridge cruise and
Margin’’ project funded by the National Science Foundation and the National
Oceanographic and Atmospheric Administration (NOAA). This expedition was
supposed to explore the sites of these two eruptions aboard the R/V Thompson
using the ROV JASON 2 at 1174 and 1208 m depths.
A report written by David Clague was put on the Web:
The two Jason’s ROV dives at West Mata volcano discovered two active volcanic vents.
The first and deeper vent, named the Hades vent, on the southwest rift was erupting both
effusively and explosively at the same time on both days. Small bursts were occurring at
one end of an erupting fissure perhaps 5 m long while pillow lavas were being extruded
from the other end. By the next night the activity had become more vigorous, sometimes
blowing glowing bubbles as much as a meter across. The second shallower vent, named
Prometheus, was located very near the summit of the volcano and about 100 m away from
the first vent. The eruption here was entirely explosive with low-level, but nearly continuous fire fountains throwing ejecta into the water during both dives. Both vents were
obscured much of the time by billowing sulfurous gas emissions, but bright orange lava
was seen in both vents. The orange glowing lava was visible for minutes at a time.
Joe Resing, chief scientist of the expedition wrote:
Here, in the seven days of this cruise we have seen active extrusions of lava on the
seafloor. We have seen explosions with flashes of light. We have seen molten rock
forming new earth.
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5 Earth’s Mantle Melting and Volcanism
Unfortunately, volcanic eruptions are still very hard to predict. With all we
know, we still cannot inform others about how magma can or will flow into
underground conduits nor how long it will take before generating volcanic
activities.
Underwater Eruptions: First Observation
Reports on the eruptions of submarine volcanoes are rare. However, a few historical
cases have been reported. In 1925, a Japanese research vessel sank above a submarine volcano in the northwestern Pacific. In 1968, a sailing boat passing near a
submarine volcano in the south Pacific in the vicinity of Tubuai in the Austral island
chain felt under water earthquakes due to the eruption of a shallow seamount,
named the Macdonald seamount (See Chap. 9). In 1963, a submarine volcano rose
to the surface at about 50 km southeast of Iceland forming the island of Surtsey.
Another active submarine edifice, the Kicken Jenny, in the Lesser Antilles rose to a
height of about 230 m above sea level in 1939 and it has been active ever since
(Lopes 2005).
In November 2008, the ‘‘Vents Program’’ discovered two on-going eruptions in
the area of the Tonga-Kermadec ridge in the southwestern Pacific, one at West
Mata Volcano near Tonga Island, and the other on the northeastern Lau basin
spreading-ridge area. The following year, in May 2009, deep-seated submarine
volcanic eruptions were observed from a ROV during the ‘‘Ridge cruise and
Margin’’ project funded by the National Science Foundation and the National
Oceanographic and Atmospheric Administration (NOAA). This expedition was
supposed to explore the sites of these two eruptions aboard the R/V Thompson
using the ROV JASON 2 at 1174 and 1208 m depths.
A report written by David Clague was put on the Web:
The two Jason’s ROV dives at West Mata volcano discovered two active volcanic vents.
The first and deeper vent, named the Hades vent, on the southwest rift was erupting both
effusively and explosively at the same time on both days. Small bursts were occurring at
one end of an erupting fissure perhaps 5 m long while pillow lavas were being extruded
from the other end. By the next night the activity had become more vigorous, sometimes
blowing glowing bubbles as much as a meter across. The second shallower vent, named
Prometheus, was located very near the summit of the volcano and about 100 m away from
the first vent. The eruption here was entirely explosive with low-level, but nearly continuous fire fountains throwing ejecta into the water during both dives. Both vents were
obscured much of the time by billowing sulfurous gas emissions, but bright orange lava
was seen in both vents. The orange glowing lava was visible for minutes at a time.
Joe Resing, chief scientist of the expedition wrote:
Here, in the seven days of this cruise we have seen active extrusions of lava on the
seafloor. We have seen explosions with flashes of light. We have seen molten rock
forming new earth.
138
5 Earth’s Mantle Melting and Volcanism