Vent fluids were below seawater chlorinity. Marker 6 diffuse vent in 1992. By 1990, a blanket of hydrothermal sediment several cm thick covered the area that looked very fresh in 1988. Vent fluid chemistry changed dramatically from 1988 to 1990. Steady venting from black smoker vents generates hydrothermal plumes that rise typically 100-300 meters above the seafloor.
Event plumes associated with volcanic activity are much larger and rise higher in the water column.
PMEL has designed instruments to monitor hydrothermal plumes and mid-ocean ridge volcanic and tectonic processes. Also shown is the PMEL manifold sampler designed to take multiple high-temperature hydrothermal fluid samples in titanium syringes. Photo taken in November 1994 from the Japanese submersible Shinkai 6500. Worm colonies around a diffuse hydrothermal vent at 17 34'S on the Southern East Pacific Rise. Crabs on a talus slope near high-temperature vents at 18 26'S on the Southern East Pacific Rise.