Science Report / Cruise Summary
Bill Chadwick, Chief Scientist
Our NeMO 2003 expedition has been a tremendous
success. We came out here with a long list of things we wanted to do and
not very much time to do them in. However, we were able to do almost everything
we had planned, thanks to good weather and the hard work of the ship's
crew, the ROPOS group, and the scientists on board.
The top
of one of many large black smokers at the ASHES vent field.
It is now 5 years since the 1998 eruption
at Axial Volcano. After the dramatic changes we saw right after the eruption
(new lava on the seafloor, new hydrothermal vents becoming established
and colonized, and warm water and microbial blooms almost everywhere),
we have documented a slow decline in hydrothermal systems in the eruption
area since then. Some vents gradually declined in temperature while others
stopped venting altogether. So before this expedition, we did not know
if more, or perhaps even all of the sites that we had been monitoring
would now be completely dead; the heat and chemicals from the 1998 eruption
now completely dissipated. But that is not what we found. . Instead we
found that the hydrothermal vents on the 1998 lava flow are still very
much active and appear to have reached a kind of steady state.
Lava pillars on the west edge of the
1998 eruption area.
Many of the vents we visited this year
appear very similar to the way they looked last year, or may even be more
robust that before. For example, at Marker 33 (one of our main monitoring
sites on the new lava flow) the temperature and extent of venting now
seems steady after several years of decline and new tubeworm bushes are
have colonized nearby, suggesting that the site is now established and
stable. From camera tows in the 1980's and 90's, we know that the southeast
side the Axial Volcano's caldera (where the 1998 eruption occurred) was
the site of extensive hydrothermal venting and biological communities
before the 1998 eruption. Now 5 years later, this same area seems to again
be a persistent site of deep hydrothermal circulation that taps heat from
a bigger and more stable source than just the heat delivered to the surface
from the 1998 lava flow. So Axial seems to be returning to a steady state
system after the perturbations caused by the 1998 eruption.
Likewise, we are adapting our research
strategies from documenting the rapid changes associated with the eruption,
to a longer-term monitoring effort in anticipation of future events. NeMO
Net is the cornerstone of this interactive monitoring effort. Much of
our research is focused on trying to discover relationships between the
volcanic, hydrothermal and biological systems at Axial. We suspect they
are all profoundly interrelated and we are designing and deploying instrumentation
that will reveal these relationships. In the meantime, we will keep our
vigil until the next time that earthquakes begin to rumble Axial again,
lava erupts, and biological communities are destroyed and quickly reestablished
all over again. It is a remarkable cycle of death and rebirth. And it
is all happening out here, but normally out of view at the bottom of the
ocean. We are pleased to be able to bring you a little of the drama that
is unfolding beneath the waves. Thank you for your interest in the NeMO
and the results of our 2003 expedition. We hope you'll join us again next
year.
