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Systematic annual surveys
of hydrothermal plumes over the Juan de Fuca Ridge began in 1984. In 1986,
when a very impressive, large, nearly circular plume ("megaplume")
was discovered over the northern portion of the Cleft segment on the Juan
de Fuca Ridge, the impact of episodic volcanic events on hydrothermal
activity was realized. As a result of this discovery, the VENTS program
began to emphasize the importance of long-term monitoring the hydrothermal
environment at this site. This includes annual CTD/chemical surveys, acoustic
monitoring to listen for seismic
activity along the Juan de Fuca and Gorda Ridges, moored sensors to
provide time series records of temperature, optical properties and currents
in the water overlying the ridge, and preparedness for rapid
response in the event seismic activity indicates a volcanic eruption
is in progress.
We have been increasingly
better prepared to respond to and observe the effects of each event between
1986 and 1998, starting with the fortuitous observation of an event plume
(Cleft Segment, 1986) to having a full
set of moored instruments monitoring the seafloor and overlying water
during the entire period prior to, during and for some time after an event
(Axial Volcano, 1998). As a result,
we've been able to develop the concept of and begin to implement the New
Millenium Observatory (NeMO) in order to examine the relationships
between volcanic events and the chemistry and distribution of hydrothermal
vents, particularly in regard to their influence on the microbial biosphere
that depend on them below the seafloor.
What we've been learning about
hydrothermal systems at our nearby off-shore laboratory has had significance
to the broader context of global hydrothermal processes as well, so another
goal of this program has been to assess the contribution of hydrothermal
discharge to global chemical and thermal budgets. Collaborations with
non-NOAA researchers, and the development of innovative
instruments to facilitate these collaborations has been an important
element for pursuing this research efficiently.
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