. . . And Your Questions!

Fire + Ice: Exploring for Volcanoes Beneath the Arctic
The Arctic Mid-Ocean Ridge Expedition
July 31 - October 3, 2001

Ever wonder what the inside of the Earth is made of? Ever imagine undersea volcanoes — or animals that live around the hot water near hydrothermal vents? Now you have some of the world's leading scientists at your disposal, from all the way in the Arctic!

We invited users to ask the scientists aboard the USCG Healy. Here are your questions and our answers:

Q:  What is a knot?

A:  Here’s how it works. There are 60 miles to a degree of latitude, and since there are 60 minutes per degree, one minute of latitude is a nautical mile. A nautical mile is about one and a seventh normal land miles, or 1.83 km.

 

Q:  Why do sailors use knots instead of miles?

A:  Knots are very convenient for navigation at sea, because if you go 10 knots, you cover 1° in 6 hours. The arithmetic becomes much simpler. At the equator it is especially, because a degree of longitude and latitude are the same. But up here, near the pole, a degree of longitude is very short. Where we are going, a degree of longitude is only 6 miles! At the North Pole, all longitude lines converge, and you would be standing on all longitudes at once!

 

Q:  Hello! I think what your all looking for is so interesting!!!!! My question is are you expecting to find some undiscovered marine life around the hydrothermal vents??? Keep up the great work and good luck to you all!

Julie Cunningham-Goulart

A:  This is the first scientific investigation of the Gakkel ridge that has a chance to find hydrothermal sites. We will find more or less where they are, but will not have the chance to send down deep camera systems to photograph them. Therefore it is likely that new species are there, but unlikely that we will find them on this trip! This trip will set up future investigations that will be able to examine the vent sites visuallly.

Charlie

Q:  Hello out there and good luck! May name is Agneta Andersson, 46, from Sweden. I take a chance and hope you have time to answer my question.

Do you see any jellyfish where you are? Do you intend to make a survey of them? For me it is the most beautiful animal in the world.

Thanks!
Agneta Andersson
Trollhättan, Sweden

A:  On August 11, we found a beautiful jellyfish in one of the dredges. It is small, only about an inch across, and by the time it came aboard, it had lost most of its tentacles. Like most jellies, the outer body has no color—it is clear. The center is very dark red. Jellyfish, and other animals that look like jellyfish, live at all depths of the ocean. Although it is hard for us to know how deep this animal was living, it may have been floating around thousands of meters below the surface of the ocean.

Charlie

 

Q:  I really enjoyed the video posted on your page, the storm looked very scary. I was curious as to if you have under water remote video systems on board? Looking forward to more video posting, hopefully of the ridge itself.

Safe sailing,
Darrin

A:  We do not have deep sea video onboard, but the German ship Polarstern has a TV-Grad which has a camera connected to a sampling device and can take a picture of the bottom. They also have a camera sled. Two days ago we found a potential hydrothermal vent and I went to the German ship for a camera run. The video was black and white and of low quality, but we saw some extinct chimneys. Still pictures from the camera run should be color and of higher quality.

Charlie

 

Q:  What does "extension" mean at an ocean ridge?

A:  Ridges are where sea floor spreading takes place, which means a crack is continually opening on the sea floor. This crack often is filled by magma, and the new crust that is created can just move away from the spreading center. But sometimes the spreading has to be accomodated by extension of the plate. This extension is reflected in faults and dismemberment of the sea floor adjacent to the ridge. Extension is the spreading that is not magmatic.

 

Q:  What is a geophysical transect?

A:  The geophysical transect is one of the major objectives of the German geophysicists. We will steam from the Gakkel Ridge, where the ocean crust is being created now, to the northern edge of the basin, which is the Lomonosov Ridge. The Lomonosov Ridge used to be connected to north Siberia and was separated from there by the spreading of the Gakkel. The mission is investigating how the crust changes with age.

The Polarstern will deploy seismometers on the ice and also a seismic streamer with listening devices behind their ship. They fire off loud sounds in the water with air guns«essentially making big bubbles in the water. The sound bounces off and through the crust below and reveals its structure. The streamer is delicate and can be destroyed by the ice. So the Healy steams in front to clear a path. It sends out its helicopters to search for a route through the ice along which we will not have to stop. If we stop, the Polarstern has to reel in its streamer, which is time-consuming and risks the instrumentation.

 

Q:  Attention Joel Donohue and Paul Schmieder, I have heard that serpentine can be found within the North American craton. How can a mineral associated with an MOR be found on dry land? Have you started dredging?

Thanks,
Bryant Reasnor

A:  Paul responds: here is the answer to the serpentine question. Serpentine can form whenever olivine is altered. Since olivine is a common mineral, even on continents, you can get lots of serpentine there. Many rocks on continents also had their origin in the oceans. In fact almost all clays formed as layers under water--usually in the ocean. There are pieces of ocean crust that also have been uplifted onto continents during plate convergence. These slices, called ophiolites, have huge areas of the mantle that are mostly converted to serpentinite.

 

Q:  Finally I find a site where I can get some info. I wanted to know about how much lava pours out of a volcano a second?

Thank you.
From, Jamie

A:  Magma flow rates are highly variable. Sometimes a "dome" of silicic magma will form very slowly, maybe a cubic meter per second, and grow over a period of months to years. But the most explosive eruptions, such as Krakatoa, erupt hundreds of cubic kilometers of magma in less than a day.

Basaltic eruptions are less variable. We do not really know the flow rates beneath the ocean, because an eruption has never been observed there. But based on basaltic eruptions on land, you can have 20 cubic kilometers erupting in a few months, or you can have much smaller eruptions.

Much more thorough information would be available in any textbook on volcanology, and possibly on the web site of the Smithsonian Institution in Washington, where they have lots of volcano data. McBirney has written a good volcanology text. You might also check the Volcano World site.

We do not have direct access to that information up here near the North Pole!

 

Q:  Have you found anything in the dredges that seemed totally out of place?

A:  We have found much more diversity in these dredges than any of us have experienced on other ridges. The unusual samples include all kinds of dropstones from the ice sheet-- we have big and small rocks from all over Siberia. There have alse been many sediments with cm-sized glass spherules in them. We're not sure how these form yet-- I have never seen them in the Atlantic or Pacific. Then there is the mineral burnisite (not sure of the spelling) which is a dead ringer for graphite.

The large variety of organisms in the dredges has also been a surprise. The biologist on board believes we have recovered several new species.