Subduction zone mechanics

Ancient Faults & Water Are Sparking Earthquakes Off Alaska

Ancient faults that formed in the ocean floor millions of years ago are feeding earthquakes today along stretches of the Alaska Peninsula, and likely elsewhere, a new study suggests.

by |November 16, 2015
Langseth CUPA video snip

Come Aboard: A Look at the R/V Marcus Langseth

A new video produced by Columbia University tells the story of what the research vessel Marcus G. Langseth is all about.

by |October 15, 2015
Crew aboard the R/V Marcus G. Langseth deploy hydrophone streamers for seismic mapping of the sea floor. Courtesy of Greg Mountain.

Mapping Land Claimed by Sea Level Rise

Understanding how coastal areas changed as the ocean rose in the past could help communities protect themselves from storm surge flooding in the future as the oceans warm and sea levels rise.

by |August 19, 2015
R/V Marcus G. Langseth

The R/V Marcus G. Langseth: Ocean Explorer

The Marcus G. Langseth, a research vessel operated by Lamont-Doherty Earth Observatory, traverses the world’s oceans conducting marine seismic studies that contribute to new understanding of Earth systems. The ship typically spends half the year or more on research expeditions led by Lamont-Doherty scientists and colleagues from other research institutes.

by |December 9, 2013

Holidays on the High Seas

With round-the-clock shifts, there are precious opportunities for Santa to slip onto a research ship unseen. But slip in he did, leaving treats and gifts around the R.V. Langseth to brighten our day.

by |December 27, 2011
WHOI OBS is craned on board.

Retrieving Instruments from the Deep

Over the first 22 days aboard the R/V Marcus G. Langseth, we’ve zigged and zagged our way over a 360×240 mile region of the Pacific plate, first dropping instruments to the seafloor, and then shooting airguns to them (see previous posts). The final step is to recover a subset of the instruments:  34 ocean-bottom seismometers… read more

by |December 27, 2011
Float supporting a 9-gun array being deploy aft of ship.  Guns hang below float.  Yellow cables carry compressed air to three identical arrays previously deployed.

The Art of Sound in the Ocean

The NoMelt experiment aims to image the structure of an oceanic plate, including its deepest reaches up to 70 km beneath the seafloor.  One of our primary means to do so is to create sound (acoustic) waves in the ocean from the ship, and record those waves at receivers on the seafloor, after they have… read more

by |December 21, 2011
Short-period OBS being deployed by WHOI technicians.  Sensor and recording package contained within glass spheres in orange casing.   Anchor hangs from the bottom.

Deploying Instruments on the Seafloor in the Deep Ocean

Oceanic plates are born at mid-ocean ridges, where hot mantle rocks are brought very close to the surface, partially melt, and then cool and crystallize. The newly formed rocks move outwards from the mid-ocean ridge, making way for the next batch of hot rock rising from below. Inch by inch, over millions of years, oceanic… read more

by |December 13, 2011
The Langseth at dock in Honolulu.  Bridge cabins/labs are to the right; waist-deck where OBS operations occur is in the center; and the large aft streamer platform is on the left.  Top center is the PSO observation tower, over 85 ft above the waterline.

Rolling into Open Water in the Central Pacific

We nicknamed our project NoMelt because we seek to characterize a mature, pristine oceanic plate far from its volcanic origin at a Mid-Ocean Ridge, and away from areas of pronounced volcanism and melting that subsequently alter the structure of the plate.  Our site in the central Pacific fits these scientific needs. However, one downside is… read more

by |December 5, 2011
Google Earth map of the experiment (dubbed NoMelt) in the central Pacific Ocean basin.

Probing an Oceanic Plate

Everything that we understand about the rhythms of the Earth’s surface – the slow growth of mountain chains, the creeping expansion of the ocean basins, the abrupt upheaval of a major earthquake, the explosive eruption of a volcano – is viewed through the context of plate tectonics.  This simple yet highly successful model for describing… read more

by |November 30, 2011