And we wonder what is heating our seas.
“As the remotely operated vehicle (ROV) descended into the blue depths above the Alarcón Rise, the control room was abuzz with anticipation,” wrote Monterey Bay Aquarium Research Institute (MBARI) geologist Julie Martin in her April 22nd cruise log. “Today we [are] planning to dive on one of the strangest environments in the deep sea: a hydrothermal vent field.”
Adding to the team’s excitement was the fact that this hydrothermal vent field had never been explored before. In fact, it had only just been discovered… by a robot.
The Alarcón Rise is a 31-mile- (50-km) long spreading center in the Gulf of California. Along ocean spreading ridges like the Alarcón Rise, the seafloor is splitting apart as lava wells up from underneath.
Thirty one miles long, incredibly close to the United States, and never before explored.
In February of this year, MBARI researchers embarked on a three-month-long expedition to the Gulf of California, the long, narrow body of water between Baja California and mainland Mexico.
In April, marine geologists studied the Alarcón Rise, an active volcanic region near the mouth of the gulf. Volcanic “spreading centers” such as the Alarcón Rise are hotbeds of volcanic activity, where underwater volcanoes spread lava across the seafloor and hydrothermal vents spout water heated by magma beneath the seafloor to over 550 degrees Fahrenheit. “The floor of the Gulf of California is full of these vents,” says the MBARI website.
“FULL of these vents”! Heating the water to 2½ times the boiling point! And we wonder what is heating our seas?
Years earlier, in 2003, chief scientist David Clague and colleague Robert Vrijenhoek spent two dives unsuccessfully searching for vents within just a few kilometers of the newly discovered site. At that time, they chose their dive sites based on only low-resolution maps of the seafloor and “the presence of abnormally warm water in the area.” (Italics added)
This time, however, Clague’s team knew exactly where to look, because two weeks earlier, MBARI’s autonomous underwater vehicle (AUV), the D. Allan B., had spotted the tall chimney structures.
MBARI’s mapping AUV is a specialized robotic submersible that uses three types of sonar to map features on the seafloor as little as 15 centimeters (five inches) tall.
Over the past couple of years, the mapping AUV has generated several new discoveries, including a recent underwater lava flow. Also, since 2006, it has discovered previously unknown chimneys at three locations along the Juan de Fuca Ridge off the Washington-Oregon coast.
Thanks to Russ Steele and Gregory Ludvigsen for these links