Finding the Fire Beneath the Waves
by Leslie Irwin, OAR Communications Specialist
Walker spends her time surveying and mapping the ocean floor and sampling the water column to identify sites of submarine volcanic activity and deep sea vents. By locating these vent sites, we can learn more about our earth’s crust and predict future tectonic activity. Vents are formed when seawater flows under the seafloor crust of an ocean ridge and is heated by molten rock, up to 400oC. Walker describes,
“The high temperatures allow metals and other elements to dissolve into the water. When the water returns to the seafloor surface, it disperses upwards, spreading the dissolved material, like hydrogen sulfide, into the surrounding ocean waters in the form of a vent. Some chemosynthetic ocean microbes have evolved to use these compounds for energy, independent of sunlight, and give rise to entire vent ecosystems with unique animals like clams and tubeworms.”
Hydrothermal microbes are useful for biotechnical applications, and the hydrothermal venting environment creates natural laboratory for studying the effects of ocean acidification on marine biological communities. These nutrient rich waters only exist at vent sites, so by locating vents, we can learn more about these dynamic and rich ecosystems on the ocean floor.
Walker’s father was among the first physical oceanographers to explore the deep sea environment using acoustic detection technology during the Cold War in order to locate submarines, leading to the early studies of the sounds that whales make. He even played a role in the development of the acoustic surveillance systems that produced sea floor data that his daughter’s team initially relied on for their research! It comes as no surprise that after first pursuing a degree in physical therapy, Walker felt uninspired. Instead she was drawn to the resources and the independence that a path in research afforded, and changed her studies to pursue a BS in Oceanography at the University of Washington. Her father’s influence has not gone unrecognized.
Working with PMEL’s Vents program from its inception, Walker’s research group spent much of the 1980’s and 90’s finding particulate signatures of active venting and listening for acoustic signals indicating elusive submarine eruptions, but always weeks after the event. It took until 2003 in the Lau Basin at the Northwest Rota volcano. 550 meters below the surface, for the discovery of the first active submarine eruption, which Walker was a part of. Their continued surveying of vent sites along the Marianas Trench through 2006 revealed a diversity of geological settings and ecosystems, and was instrumental in establishing the Marianas Trench Marine National Monument.
Their second discovery came between 2008 and 2009 with the eruption of West Mata, southwest of Samoa, at a depth of over 1200 meters below the surface.
Milestones like that kept her going.
“In this field, I get to see things no one else has,” Walker says. “There is always something new to discover. When I was young, we were starting to explore space, and I was worried that there would be nothing left for me to find. My father reminded me how wrong I was, and the research I do every day is proof that our oceans have so much left to reveal.”
Thirty years later, Walker still marvels that her job has maintained its relevance to scientific discovery, and it couldn’t be more rewarding.
“It was like discovering the Titanic! You just don’t get to make these kind of discoveries in any other line of work. I’ve been so lucky!”
While Walker attributes much of her career path to luck, it also required a serious belief in herself, and saying ‘yes’ to every opportunity that came her way. Initiative is key, she insists. Growing up on the east coast, Walker had always wondered what it would be like to see a volcano.
“Now I get to chase volcanos for a living, only underwater!”
Sharon L. Walker has been an oceanographer for the Pacific Marine Environmental Laboratory since 1979. She received her B.S. in Oceanography from the University of Washington in 1981.