The Red Dress
WILLIAM WILCOCK had been monitoring the volcano for months as the tremors around its base grew more frequent. Such swarms of small quakes might, under normal circumstances, have stirred thoughts of alerting the authorities and perhaps warning residents nearby. But these weren’t normal circumstances. This volcano was 1.5 kilometres under the sea, and its nearest neighbours were a lot of tube worms and crabs.
Wilcock is a marine geophysicist at the University of Washington, Seattle, and part of an ambitious project to explore the 70 per cent of our planet’s surface that is invisible beneath the waves. Known as the Ocean Observatories Initiative, its aim is to wire up sections of the sea floor to an array of sensors that will continuously monitor in real time everything down there – from chemistry and currents to the ebb and flow of life. Wilcock’s volcano, Axial seamount some 500 kilometres off the US Pacific north-west coast, was laced with more cables than the average suburban neighbourhood.
Volcanoes exemplify our ignorance of the deep ocean. We didn’t know underwater volcanoes encircled the planet until the 1950s, when cartographer Marie Tharp mapped the mid-Atlantic ridge. Using echo-sounding data from research cruises, she showed that this long rise in the Atlantic sea floor – extending, she would later find, almost from pole to pole – wasn’t one ridge, but two bisected by a valley (see “Land under”).
The true significance only became clear when Tharp and her colleague Bruce Heezen completed a map of the southern Atlantic. The ridges were fault lines where new ocean crust was emerging from the mantle and spreading, forcing the continents apart …
