What Lies Beneath

Researchers who study the movement of the earth beneath the sea have had their efforts limited by the ocean's watery depths. New technological advances are on the verge of helping them better predict deep-sea earthquakes and tsunamis.

The crustal plates that lie beneath miles of ocean are in constant movement, shifting imperceptibly every second. But the seismologists who track them have had to rely on an investigative schedule dictated by the calendar, rather than the clock.

Their routine hasn't changed for decades: They regularly climb aboard research vessels that motor to offshore locations when weather permits, drop a series of sensors, and return weeks or months later to retrieve the data recorded.

The fundamental problem with such gathering methods, though, is that it prevents any real time analysis, and often leaves marine seismologists in the dark as current events unfold. However, those days may be changing. The confluence of advances in sensor technology, fiber-optic communications, and software that manages the delicate balance of underwater instrumentation has made permanent ocean observatories a reality.

Prototypes are in operation now off the coasts of the U.S. and Japan. 

With new attention on their efforts as a result of the devastation caused by the South Asian tsunami, oceanographers and seismologists caution that the ability to forecast earthquake and tsunami risk remains a distant goal. But the acquisition of real-time data from the largely unstudied portions of the earth's crust beneath the world's oceans will provide a comprehensive view of underwater seismic activity that has never been seen.

The shift in ocean science that will result from that new knowledge, researchers say, will be nothing short of tectonic.

The new information will be "as fundamental to studying the ocean as satellites were to studying the earth," says Frank Rack, director of ocean drilling programs for the Joint Oceanographic Institutions (JOI), a research consortium based in Washington, D.C.

Established in 1976, JOI is a nonprofit association of 20 academic institutions that collaborate on research in marine geology, geophysics, and oceanography.

Until recently, marine seismologists have had to forego the research advantages accorded by the permanent observatories their land-based counterparts enjoy. Ship-based monitoring is inherently temporary. Studying the long-term physical, chemical and biological changes that take place within the ocean requires an established base on and beneath the seafloor.

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The JOI's ocean-drilling program has helped fill the gap, creating 20 seismic and hydrologic ocean-based observatories, according to Rack. By tunneling thousands of meters beneath the subseafloor and filling the 10-to-30-inches-wide boreholes with measurement devices that detect motion, pressure, and temperature, researchers were able to improve the quality of the signal recorded.

"It's a quieter environment for seismometers," away from the interference caused by wind and water currents and able to detect more subtle events, says Rack.