Magazine article Oceanus

Seeding the Oceans with Observatories

Magazine article Oceanus

Seeding the Oceans with Observatories

Article excerpt

Ship-borne expeditions have been the dominant means of exploring the oceans in the 20th century. Scientists aboard ships made the observations and gathered the data that confirmed the revolutionary theory of plate tectonics, which demonstrated that the earth is a complex, multi-faceted system that changes over time. But that revelation also exposed a major shortcoming of the ship-based exploratory approach: its very limited ability to quantify change.

Geoscientists now realize that the earth is dynamic. It cannot be studied adequately in a static manner by simply examining limited regions for short periods. Traditional mapping and sampling strategies provide only infrequent, intermittent snapshots of myriad, ongoing, interlinked, global processes that actively shape the earth and have impacts on society.

Consider these three examples:

* El Nino events, especially in 1982-1983 and 1997-1998, clearly demonstrated the profound societal impacts of dynamic earth and ocean processes and the importance of understanding their behavior.

* Over the past two decades, geoscientists have discovered entirely new ecosystems around hydrothermal vents, whose existence is linked to ongoing or episodic volcanic and magmatic processes on and below the seafloor near mid-ocean ridges. The vents have generated exciting new lines of inquiry about the origin of life on Earth and the possibility of life on other planetary bodies that are similarly endowed with water and volcanism.

* Less well-known but certainly equally complex processes occur at subduction zones, where old seafloor sinks back into the mantle. These processes occur on scales of tens to thousands of kilometers over months to hundreds of millions of years, yet they generate catastrophic earthquakes and tsunamis that occur in seconds over small areas around the Pacific "Rim of Fire," for example. Subduction processes also play an important role in recycling chemicals to the mantle, and they are a primary cause of tectonic uplift and mountain- and island-building on Earth.

To fully understand the causes and effects of all these phenomena, we need a much better grasp of Earth's complex, dynamic processes before, as, and after they occur. This will entail a significant philosophical and cultural change in the way we conduct our science. It will require a coordinated investment in a new mode of marine geoscience investigations: the establishment of long-term ocean observatories. Such observatories offer an essential means to observe interrelated processes over time and to fill in the rather extensive gaps in remote ocean regions where data on deep Earth structures and properties have never been collected.

While scientists have maintained observatories on land for centuries, the practice has not yet received broad support in the oceans. But many national deep-water geoscience initiatives have recently embraced strategies involving seafloor observatories to investigate the earth, including the Ridge Inter-Disciplinary Global Experiments (RIDGE), the MARGINS study of rifted and convergent plate boundaries, the Ocean Seismic Network (OSN), and efforts with the eponymous names BOREHOLE and CABLE, which seek to take advantage of Ocean Drilling Program (ODP) boreholes and submarine cables for geosciences research. Since 1997, scientists involved in these initiatives have joined in a planning effort supported by the National Science Foundation to lay the groundwork for a proposed longterm observatory program called Dynamics of Earth and Ocean Systems (DEOS). And this philosophy is also being embraced in other disciplines of ocean sciences as well as internationally, so there is an unprecedented opportunity and need for cross-disciplinary, multi-national coordination of scientific objectives and infrastructure.

Observing dynamic global processes

Current and planned seafloor observatory efforts come in two flavors:

1) "Active Process" observatories are located where particular Earth systems are presently most active near the surface. …

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