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. What is a Hydrothermal Plume?
. -View venting plume movie
-Animation of seawater circulation and venting
world's mid-ocean ridges imageseafloor spreading system drawing
Mid-Ocean Ridges are places where the Earth's tectonic plates gradually move apart. As they do, magma rises up to fill the gap, sometimes leading to submarine volcanic eruptions. This shallow magma provides a heat source, creating many seafloor hot springs along the ridges. These hot springs, or "vents", transport heat and chemicals into the ocean. Learn more about hydrothermal circulation
Hydrothermal plumes are created and sustained by the heat of volcanic processes along the Mid-Ocean Ridge system that circles the globe. Hydrothermal systems consists of circulation zones where seawater interacts with rock, thereby changing chemical and physical characteristics of both the seawater and the rock. The altered seawater, called hydrothermal fluid, is injected back into the ocean at hydrothermal vent fields and forms hydrothermal plumes. These plumes are often black or white with the color coming from mineral particles that precipitate rapidly as hot hydrothermal fluids (with temperatures as high as 340oC) mix with cold seawater (usually about 1-2oC) at or just below the vent orifice. Some hydrothermal fluids may be cooler and nearly absent of particles, but the hottest plumes are generally colored black and are called "black smokers."
Hydrothermal plumes can be detected in seawater overlying vent fields, and beyond, because they have a distinctly different physical and chemical signature from the surrounding seawater. The heat and particle content of hydrothermal plumes are two readily measurable parameters. These parameters are usually elevated relative to unaffected seawater, and measurable differences can be detected as far as tens to hundreds of kilometers away from the vent fields. The NOAA-VENTS Plume Studies Group has pioneered methods for measuring and mapping hydrothermal plumes based on the detection of these temperature and particle anomalies.

The distribution and intensity of hydrothermal plumes is variable in both space and time. Volcanic activity on the seafloor can produce enormous and profound changes in hydrothermal discharge. The importance of this impact was first realized with the discovery of a "megaplume" in 1986, and subsequent verification of fresh lava flows on the seafloor in the same area. Since that time, a major objective of the NOAA-EOI Program has been to monitor for and respond to volcanic events occurring on mid-ocean ridges off the west coast of the United States to assess the impact of these events on the ocean environment, particularly with respect to the thermophile and hyperthermophile microbial community they release into the ocean, and to track the subsequent evolution of hydrothermal systems.

  Hydrothermal Plumes:
What are hydrothermal plumes? | Why Study? | History | Study Areas | Methods