http://blogs.ei.columbia.edu From a ship in remote Pacific waters, a team of researchers is plumbing the mysteries of what drives and defines the giant tectonic plates that make up the ocean floors and continents. Join Lamont-Doherty Earth Observatory seismologist James Gaherty aboard the R/V Marcus G. Langseth, as he and colleagues peer up to 400 kilometers beneath one of earth’s oldest, deepest sections of seafloor. Fri, 24 May 2013 19:28:34 +0000 en-US hourly 1 http://wordpress.org/?v=3.5.1 http://blogs.ei.columbia.edu/2013/01/15/recovering-sea-spiders-and-heading-home/ http://blogs.ei.columbia.edu/2013/01/15/recovering-sea-spiders-and-heading-home/#comments Tue, 15 Jan 2013 22:42:26 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=33516 The NoMelt project is more than just a seismic experiment; it also has an important magnetotelluric (MT) component. MT instruments measure natural magnetic and electric fields on the seafloor, allowing scientists to estimate the electrical conductivity of the underlying rocks. Conductivity is highly sensitive to tiny amounts of water and molten rock within the upper mantle and thus can help distinguish whether the mantle is “wet” (and thus easy to deform) or “dry” (rigid and plate-like).]]> http://blogs.ei.columbia.edu/2013/01/15/recovering-sea-spiders-and-heading-home/feed/ 1 http://blogs.ei.columbia.edu/2013/01/10/santa-comes-bearing-an-obs/ http://blogs.ei.columbia.edu/2013/01/10/santa-comes-bearing-an-obs/#comments Thu, 10 Jan 2013 16:44:19 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=33488 Recovering OBS instruments from the ocean floor is always a tricky business, especially in our case; these instruments have been sitting beneath more than 3.5 miles of water for over a year. With cold, tired batteries powering the instruments’ acoustic transponders, communicating with them through miles of ocean currents amounts to a whispered conversation on a stormy night.]]> http://blogs.ei.columbia.edu/2013/01/10/santa-comes-bearing-an-obs/feed/ 0 http://blogs.ei.columbia.edu/2012/12/30/transiting-the-pacific/ http://blogs.ei.columbia.edu/2012/12/30/transiting-the-pacific/#comments Sun, 30 Dec 2012 23:18:30 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=33322 Today marks our sixth day aboard the R.V. Melville on a journey to a remote region of the Pacific to retrieve seismic instruments that have been quietly recording earthquake signals on the ocean floor for the past year. We have covered more than 2,600 km thus far but must cruise for another two and a half days before we reach the NoMelt project site. ]]> http://blogs.ei.columbia.edu/2012/12/30/transiting-the-pacific/feed/ 0 http://blogs.ei.columbia.edu/2012/12/30/one-year-later-return-to-the-nomelt-site/ http://blogs.ei.columbia.edu/2012/12/30/one-year-later-return-to-the-nomelt-site/#comments Sun, 30 Dec 2012 23:03:15 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=33313 On December 18, 2012, the Research Vessel Melville departed San Diego to recover remainder of the NoMelt instruments and data. The expedition includes two scientists from Columbia’s Lamont-Doherty Earth Observatory: Post-doctoral scientist Patty Lin and graduate student Natalie Accardo. Natalie is sending regular reports from the ship.]]> http://blogs.ei.columbia.edu/2012/12/30/one-year-later-return-to-the-nomelt-site/feed/ 0 http://blogs.ei.columbia.edu/2011/12/27/holidays-on-the-high-seas/ http://blogs.ei.columbia.edu/2011/12/27/holidays-on-the-high-seas/#comments Tue, 27 Dec 2011 21:35:00 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=21414 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.]]> http://blogs.ei.columbia.edu/2011/12/27/holidays-on-the-high-seas/feed/ 1 http://blogs.ei.columbia.edu/2011/12/27/retrieving-instruments-from-the-deep/ http://blogs.ei.columbia.edu/2011/12/27/retrieving-instruments-from-the-deep/#comments Tue, 27 Dec 2011 17:39:07 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=21389 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 [...]]]> http://blogs.ei.columbia.edu/2011/12/27/retrieving-instruments-from-the-deep/feed/ 0 http://blogs.ei.columbia.edu/2011/12/21/the-art-of-sound-in-the-ocean/ http://blogs.ei.columbia.edu/2011/12/21/the-art-of-sound-in-the-ocean/#comments Wed, 21 Dec 2011 14:38:40 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=21345 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 [...]]]> http://blogs.ei.columbia.edu/2011/12/21/the-art-of-sound-in-the-ocean/feed/ 0 http://blogs.ei.columbia.edu/2011/12/13/deploying-instruments-on-the-seafloor-in-the-deep-ocean/ http://blogs.ei.columbia.edu/2011/12/13/deploying-instruments-on-the-seafloor-in-the-deep-ocean/#comments Tue, 13 Dec 2011 13:22:53 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=21003 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 [...]]]> http://blogs.ei.columbia.edu/2011/12/13/deploying-instruments-on-the-seafloor-in-the-deep-ocean/feed/ 2 http://blogs.ei.columbia.edu/2011/12/05/rolling-into-open-water-in-the-central-pacific/ http://blogs.ei.columbia.edu/2011/12/05/rolling-into-open-water-in-the-central-pacific/#comments Tue, 06 Dec 2011 00:48:22 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=20601 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 [...]]]> http://blogs.ei.columbia.edu/2011/12/05/rolling-into-open-water-in-the-central-pacific/feed/ 0 http://blogs.ei.columbia.edu/2011/11/30/probing-an-oceanic-plate/ http://blogs.ei.columbia.edu/2011/11/30/probing-an-oceanic-plate/#comments Wed, 30 Nov 2011 12:36:49 +0000 Jim Gaherty http://blogs.ei.columbia.edu/?p=20289 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 [...]]]> http://blogs.ei.columbia.edu/2011/11/30/probing-an-oceanic-plate/feed/ 4