Tuesday, October 23, 2012

Two Fascinating Volcanoes

Sorry to post the same article as earth science again, but it is a timely topic.  Given our recent discussions of seafloor geology, including hot spots and nemataths, I thought this was appropriate...


Geologists recently concluded a study attempting to figure out whether Mauna Loa and Kilauea are connected.  There has long been speculation that they are connected due to their close proximity.

 Read on for some more...


Connection Between Hawaii's Dueling Volcanoes Explained

ScienceDaily (Oct. 23, 2012) — A new Rice University-led study finds that a deep connection about 50 miles underground can explain the enigmatic behavior of two of Earth's most notable volcanoes, Hawaii's Mauna Loa and Kilauea. The study, the first to model paired volcano interactions, explains how a link in Earth's upper mantle could account for Kilauea and Mauna Loa's competition for the same deep magma supply and their simultaneous "inflation," or bulging upward, during the past decade.
The study appears in the November issue of Nature Geoscience.
The research offers the first plausible model that can explain both the opposing long-term eruptive patterns at Mauna Loa and Kilauea -- when one is active the other is quiet -- as well as the episode in 2003-2007 when GPS records showed that each bulged notably due to the pressure of rising magma. The study was conducted by scientists at Rice University, the University of Hawaii, the U.S. Geological Survey (USGS) and the Carnegie Institution of Washington.
"We know both volcanoes are fed by the same hot spot, and over the past decade we've observed simultaneous inflation, which we interpret to be the consequence of increased pressure of the magma source that feeds them," said lead author Helge Gonnermann, assistant professor of Earth science at Rice University. "We also know there are subtle chemical differences in the lava that each erupts, which means each has its own plumbing that draws magma from different locations of this deep source.
"In the GPS records, we first see inflation at Kilauea and then about a half a year later at Mauna Loa," he said. "Our hypothesis is that the pressure is transmitted slowly through a partially molten and thereby porous region of the asthenosphere, which would account for the simultaneous inflation and the lag time in inflation. Because changes in pore pressure are transmitted between both volcanoes at a faster rate than the rate of magma flow within the porous region, this can also explain how both volcanoes are dynamically coupled, while being supplied by different parts of the same source region."
Gonnermann said the transmission of pressure through the permeable rock in the asthenosphere is akin to the processes that cause water and oil to flow through permeable layers of rock in shallower regions of Earth's crust.
"When we fitted the deformation, which tells us how much a volcano inflates and deflates, and the lava eruption rate at Kilauea, we found that our model could simultaneously match the deformation signal recorded over on Mauna Loa," said James Foster, co-author and assistant researcher at the University of Hawaii School of Ocean and Earth Science and Technology. "The model also required an increase in the magma supply rate to the deep system that matched very nicely with our interpretations and the increased magma supply suggested by the jump in CO2 emissions that occurred in late 2003."
Mauna Loa and Kilauea, Earth's largest and most active volcanoes, respectively, are located about 22 miles apart in the Hawaii Volcanoes National Park on the island of Hawaii. They are among the planet's most-studied and best-instrumented volcanoes and have been actively monitored by scientists at USGS's Hawaiian Volcano Observatory (HVO) since 1912. Kilauea has erupted 48 times on HVO's watch, with a nearly continuous flank eruption since 1983. Mauna Loa has erupted 12 times in the same period, most recently in 1984.
"To continue this research, we submitted a proposal to the National Science Foundation (NSF) earlier this summer to extend our study back in time to cover the last 50 years," Foster said. "We plan to refine the model to include further details of the magma transport within each volcano and also explore how some known prehistoric events and some hypothetical events at one volcano might impact the other. This work should help improve our understanding of volcanic activity of each volcano."
Gonnermann said there has been disagreement among Earth scientists about the potential links between adjacent volcanoes, and he is hopeful the new model could be useful in studying other volcanoes like those in Iceland or the Galapagos Islands.
"At this point it is unclear whether Hawaii is unique or whether similar volcano coupling may exist at other locations," Gonnermann said. "Given time and ongoing advances in volcano monitoring, we can test if similar coupling between adjacent volcanoes exists elsewhere."
Study co-authors include Michael Poland and Asta Miklius, both of HVO; Benjamin Brooks of the University of Hawaii; and Cecily Wolfe of the University of Hawaii and the Carnegie Institution of Washington.
The research was supported by the USGS and the NSF. The Kilauea and Mauna Loa GPS networks are supported by grants from the USGS, NSF and NASA and operated in collaboration by the USGS, Stanford University and the Pacific GPS Facility at the University of Hawaii.
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The above story is reprinted from materials provided byRice University. The original article was written by Jade Boyd.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. Helge M. Gonnermann, James H. Foster, Michael Poland, Cecily J. Wolfe, Benjamin A. Brooks, Asta Miklius.Coupling at Mauna Loa and Kīlauea by stress transfer in an asthenospheric melt layer. Nature Geoscience, 2012; DOI: 10.1038/ngeo1612
 APA

 MLA
Rice University (2012, October 23). Connection between Hawaii's dueling volcanoes explained.ScienceDaily. Retrieved October 23, 2012, from http://www.sciencedaily.com­/releases/2012/10/121023134810.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

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Sunday, October 21, 2012

Permian Extiction

Fascinating article below on the Permian Extinction, one of if not the most lethal in the earth's history.  Yes, this is the same article as the I put on the ES blog.  It has very much to do with oceanography as well.

 Read on...


Tropical Collapse in Early Triassic Caused by Lethal Heat: Extreme Temperatures Blamed for 'Dead Zone'

ScienceDaily (Oct. 18, 2012) — Scientists have discovered why the 'broken world' following the worst extinction of all time lasted so long -- it was simply too hot to survive.
The end-Permian mass extinction, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world's species. Typically, a mass extinction is followed by a 'dead zone' during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early Triassic period which followed, lasted for a perplexingly long period: five million years.
A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.
Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: "Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years."
It is also the first study to show water temperatures close to the ocean's surface can reach 40°C -- a near-lethal value at which marine life dies and photosynthesis stops. Until now, climate modellers have assumed sea-surface temperatures cannot surpass 30°C. The findings may help us understand future climate change patterns.
The dead zone would have been a strange world -- very wet in the tropics but with almost nothing growing. No forests grew, only shrubs and ferns. No fish or marine reptiles were to be found in the tropics, only shellfish, and virtually no land animals existed because their high metabolic rate made it impossible to deal with the extreme temperatures. Only the polar regions provided a refuge from the baking heat.
Before the end-Permian mass extinction, Earth had teemed with plants and animals including primitive reptiles and amphibians, and a wide variety of sea creatures including coral and sea lillies.
This broken world scenario was caused by a breakdown in global carbon cycling. In normal circumstances, plants help regulate temperature by absorbing Co2 and burying it as dead plant matter. Without plants, levels of Co2 can rise unchecked, which causes temperatures to increase.
The study, published Oct. 19 in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date.
Sun and his colleagues collected data from 15,000 ancient conodonts (tiny teeth of extinct eel-like fishes) extracted from two tonnes of rocks from South China. Conodonts form a skeleton using oxygen. The isotopes of oxygen in skeletons are temperature controlled, so by studying the ratio of oxygen isotopes in the conodonts he was able to detect temperature levels hundreds of millions of years ago.
Professor Paul Wignall from the School of Earth and Environment at the University of Leeds, one of the study's co-authors, said: "Nobody has ever dared say that past climates attained these levels of heat. Hopefully future global warming won't get anywhere near temperatures of 250 million years ago, but if it does we have shown that it may take millions of years to recover."
The study is the latest collaboration in a 20-year research partnership between the University of Leeds and China University of Geosciences in Wuhan. It was funded by the Chinese Science Foundation.
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The above story is reprinted from materials provided byUniversity of Leeds, via EurekAlert!, a service of AAAS.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. Yadong Sun, Michael M. Joachimski, Paul B. Wignall, Chunbo Yan, Yanlong Chen, Haishui Jiang, Lina Wang, and Xulong Lai. Lethally Hot Temperatures During the Early Triassic Greenhouse. Science, 2012; 338 (6105): 366-370 DOI: 10.1126/science.1224126
 APA

 MLA
University of Leeds (2012, October 18). Tropical collapse in Early Triassic caused by lethal heat: Extreme temperatures blamed for 'Dead Zone'.ScienceDaily. Retrieved October 21, 2012, from http://www.sciencedaily.com­/releases/2012/10/121018141844.htm
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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
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Tuesday, October 16, 2012

Coral Reefs

Given today's class discussion about the stages in coral reef development, I think this photo essay from National Geographic is rather timely.

 As always, National Geographic's photos are unparalleled in their quality.  Gorgeous images.  Each has a quality caption, too.

 Enjoy.

Nat Geo - Mesoamerican Reef Article
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Sunday, October 14, 2012

The Gulf Stream


News Release

Scientists Uncover Diversion of Gulf Stream Path in Late 2011

Warmer waters flowed to shelfbreak south of New England

FOR IMMEDIATE RELEASE
Media Relations Office
October 11, 2012
(508) 289-3340
At a meeting with New England commercial fishermen last December, physical oceanographers Glen Gawarkiewicz and Al Plueddemann from the Woods Hole Oceanographic Institution (WHOI) were alerted by three fishermen about unusually high surface water temperatures and strong currents on the outer continental shelf south of New England.
“I promised them I would look into why that was happening,” Gawarkiewicz says.
The result of his investigation was a discovery that the Gulf Stream diverged well to the north of its normal path beginning in late October 2011, causing the warmer-than-usual ocean temperatures along the New England continental shelf.  
The researchers’ findings, “Direct interaction between the Gulf Stream and the shelfbreak south of New England,” were published in the August 2012 issue of the journal Scientific Reports.
To begin to unravel the mystery, Gawarkiewicz and his colleagues assembled data from a variety of sources and recreated a record of the Gulf Stream path during the fall of 2011.  First, they tapped into data collected by a program called eMOLT, a non-profit collaboration of fishing industry, research, academic and government entities, run by James Manning of National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center. For more than a decade the program has recorded near-bottom ocean temperatures by distributing temperature probes to lobstermen. 
Manning and scientists from WHOI, including Robert Todd and Magdalena Andres, analyzed a time series of temperatures from two eMOLT sites, OC01 and TA51, which were located over the outer continental shelf near the shelfbreak, and identified two events when temperatures suddenly increased by 6.2 and 6.7°C, respectively, to highs of more than 18°C.
“These are very dramatic events for the outer continental shelf, at least 2°C warmer than we’ve seen since 2001,” says Gawarkiewicz. “Near-bottom temperatures of 18°C on the outer shelf are extremely high for late autumn.” The maximum recorded temperature in December 2011 was the warmest bottom temperature recorded in 6 years of records at the OC01 site.
In typical years, the warm Gulf Stream waters only indirectly influence ocean currents and temperatures near the continental shelfbreak south of New England when eddies, called warm core rings, pinch off from the Gulf Stream and drift toward the outer continental shelf. Such rings normally drift past a site after a few weeks, and therefore cause only limited warming of the water on the outer shelf.
Gawarkiewicz and his colleagues collected additional data on water temperature and salinity from December 4, 2011 through January 4, 2012, from instruments on temporary test moorings placed 12 km south of the shelfbreak by the Ocean Observatories Initiative (OOI). The researchers compared those salinity measurements to historical data, and discovered that high salinity levels – consistent with the salinity of waters carried by the Gulf Stream – coincided with the warming periods. 
The extent and duration of the two 2011 warming events combined with the high salinity observed by the researchers suggested the cause was not a transient warm core ring, but the Gulf Stream itself that carried warm, salty water to the outer shelf.
To solidify that finding, Gawarkiewicz received serendipitous help from students in the Marine Advanced Technology Education (MATE) program at Cape Fear Community College in Wilmington, NC, who had deployed a surface drifter during the period coinciding with the two warming events. Drifters use satellites to transmit their positions roughly every six hours, key information for the WHOI scientists, who analyzed the drifter tracks and speeds.
“Drifters around the edges of warm core rings drift toward the continental shelf at about 1 knot,” Gawarkiewicz says. “But we saw the drifter cut across the slope towards the shelf at about 2.5 knots. It only took it eight days to travel from Cape Fear, North Carolina, to a point 40 miles south of Georges Bank, a total distance of 580 miles.”
The periods of high speeds for the drifters coincided with the records for high temperatures on the outer shelf, which told the scientists that the core of the Gulf Stream had diverted to 39.9°N at 68°W – 125 miles north of its mean position, further north than had ever been recorded by satellite altimeters at this particular longitude.
The temporary shift in Gulf Stream path observed last fall potentially has significant longer-term implications. Studies have shown that temperature increases of 2°C have caused major shifts in silver hake populations, for example, and in spring 2012, migratory bluefish and striped bass were observed off the coast of Cape Cod much earlier than in previous years. But, the scientists say, more research is needed to determine just how the Gulf Stream’s behavior in 2011 affected the continental shelf ecosystem and marine organisms.
It is unclear what might have caused this shift in the Gulf Stream path.  It occurred shortly after Hurricanes Irene and Katia drenched the east coast with rain, and this might have impacted the Gulf Stream separation from the continental shelf near Cape Hatteras. Another possibility is that a cold core ring, an eddy south of the Gulf Stream core, might have deflected the Gulf Stream.  Further research will be necessary to determine exactly how and why this occurred, which will be helpful in the long term in predicting Gulf Stream motions.
In the meantime, Gawarkiewicz and his colleagues will be keeping an eye on what the Gulf Stream does this fall, with the hope of someday being able to predict such a shift. “We’re checking in from time to time to monitor it. We’ll be talking to the fishermen, and academics, and keeping an eye on things,” he says.
Fishermen David Spencer, Fred Mattera, and Norbert Stamps first alerted the researchers to the anomaly. Profile data were made available by the OOI, which is funded by the National Science Foundation and managed by the Consortium for Ocean Leadership. Tim Shaw and David Calhoun at Cape Fear Community College provided drifter data. WHOI scientists on this project were supported by the NSF, the Cooperative Institute for the North Atlantic Region, the Penzance Endowed Fund in Support of Assistant Scientists, and the Postdoctoral Scholar Program at WHOI.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with Earth and humanity, and to communicate an understanding of the ocean’s role in the changing global environment.
Originally published: October 11, 2012
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