Global Seismic Network Now Extends To The Deep Oceans

April 28, 1998

Ocean Drilling Program'S New Technology To Open Exploration Of Earth'S Interiors

This month, scientists with the Ocean Drilling Program (ODP) will install one of many planned Geophysical Ocean Bottom Observatories (GOBO), in which a permanent seismograph station will be established on the sea floor for monitoring earthquake activity. ODP is funded in large part by the National Science Foundation (NSF).

"Installing a seismic station in an ocean basin will be like filling in missing portions of a mirror or lens in a telescope," says Bruce Malfait, director of ODP at NSF. "It will allow us to examine regions of the earth's interior that are only poorly imaged at present by stations on a few islands, or the 30% of the earth's surface occupied by continents."

The global network of on-land seismic stations provides sufficient earthquake monitoring capabilities for large parts of the earth's surface in continental regions and on some islands. However, oceanic regions that cover approximately 70 percent of the earth's surface remain largely unmonitored, creating large "holes" in worldwide data coverage for low magnitude earthquakes and for earth's deep interior.

Scientists aboard the research vessel JOIDES Resolution will drill into the oceanic basement of the Indian Ocean, a region of the world where there is a lack of ocean-bottom seismograph stations. The expedition, referred to as ODP Leg 179, began when the ship departed Cape Town, South Africa, on April 21. It concludes with a port call in Darwin, Australia, on June 6.

"During the past 10 years our knowledge of deep earth interior processes has greatly improved with the development of new generations of global seismic monitoring networks," says John Casey of the University of Houston, co-chief scientist for the expedition. "The need for ocean-bottom observatories is driven by the lack of observations in large tracts of the world ocean where neither continents nor islands are available to place observatories."

Before laying the groundwork for the new seismic observatory, ODP will test a new drilling system designed to drill large-diameter casing into hard fractured rock on the sea floor. The new drilling system, called water hammer drilling, uses a percussion drill similar to a jackhammer but is driven by fluid rather than air. If the tests are successful, reentry systems will be placed on the boreholes, allowing scientists to return to these locations to conduct future experiments.

National Science Foundation

Related Ocean Articles from Brightsurf:

The ocean has become more stratified with global warming
A new study found that the global ocean has become more layered and resistant to vertical mixing as warming from the surface creates increasing stratification.

New opportunities for ocean and climate modelling
The continuous development and improvement of numerical models for the investigation of the climate system is very expensive and complex.

The ocean responds to a warming planet
The oceans help buffer the Earth from climate change by absorbing carbon dioxide and heat at the surface and transporting it to the deep ocean.

How the ocean is gnawing away at glaciers
The Greenland Ice Sheet is melting faster today than it did only a few years ago.

Something old, something new in the ocean's blue
Microbiologists at the Max Planck Institutes in Marburg and Bremen have discovered a new metabolic process in the ocean.

New threat from ocean acidification emerges in the Southern Ocean
Scientists investigating the effect of ocean acidification on diatoms, a key group of microscopic marine organisms, phytoplankton, say they have identified a new threat from climate change -- ocean acidification is negatively impacting the extent to which diatoms in Southern Ocean waters incorporate silica into their cell walls.

Ocean acidification 'could have consequences for millions'
Ocean acidification could have serious consequences for the millions of people globally whose lives depend on coastal protection, fisheries and aquaculture, a new publication suggests.

Ocean warming is accelerating
Observational records of ocean heat content show that ocean warming is accelerating.

The long memory of the Pacific Ocean
Cold waters that sank in polar regions hundreds of years ago during the Little Ice Age are still impacting deep Pacific Ocean temperature trends.

Ocean fertilization by unusual microbes extends to frigid waters of Arctic Ocean
Microbes that provide natural fertilizer to the oceans by 'fixing' nitrogen from the atmosphere into a form useable by other organisms are active in the cold waters of the Bering and Chukchi Seas.

Read More: Ocean News and Ocean Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to