Volcano monitoring will target hazard threat to Marianas, US military and commercial jets




Mariana Islands at map-right, east of the Philippine Sea, and just west of the Mariana Trench in the ocean floor.
Mariana Islands at map-right, east of the Philippine Sea, and just west of the Mariana Trench in the ocean floor.

Technology designed to detect nuclear explosions and enforce the world’s nuclear test-ban treaty now will be pioneered to monitor active volcanoes in the Northern Mariana Islands near Guam. The island of Guam soon will be the primary base for forward deployment of U.S. military forces in the Western Pacific.

The two-year, $250,000 project of the U.S. Geological Survey and Southern Methodist University in Dallas will use infrasound – in addition to more conventional seismic monitoring – to “listen” for signs a volcano is about to blow. The plan is to beef up monitoring of lava and ash hazards in the Northern Mariana Islands, a U.S. commonwealth.

The archipelago’s active volcanoes threaten not only residents of the island chain and the U.S. military, but also passenger airlines and cargo ships. The USGS project calls for installing infrasound devices alongside more traditional volcano monitoring equipment – seismometers and global positioning systems.

Scientists at SMU, which the USGS named the prime cooperator on the project, will install the equipment and then monitor the output via remote sensing. The project is a scientific partnership of the USGS, SMU and the Marianas government.

Infrasound hasn’t been widely used to monitor volcanoes, according to noted volcano expert and SMU geology professor James E. Quick, who is project chief. Infrasound can’t replace seismometers but may help scientists interpret volcanic signals, Quick said.

“This is an experiment to see how much information we can coax out of the infrasound signal,” he said. “My hope is that we’ll see some distinctive signals in the infrasound that will allow us to discriminate the different kinds of eruptive styles – from effusive events that produce lava flows, or small explosive events we call vulcanian eruptions, to the large ‘Plinian’ events of particular concern to aviation. They are certain to have some characteristic sonic signature.”

SMU geologists in recent decades pioneered the use of infrasound to monitor nuclear test-ban compliance, and they continue to advance the technology. For the USGS project, they’ll install equipment on three of the Marianas’ 15 islands. In the event magma begins forcing its way upward, breaking rocks underground and ultimately erupting, seismometers will measure ground vibrations throughout the process, while GPS will capture any subtle changes or deformities in the surface of the Earth, and infrasound devices will record sound waves at frequencies too low to be heard by humans. Infrasound waves move slower than the speed of light but can travel for hundreds of miles and easily penetrate the earth as well as other material objects.

Nine Mariana Islands have active volcanoes. On average, the archipelago experiences about one eruption every five years, said Quick, who was previously program coordinator of the USGS Volcano Hazards Program. Most recently a volcano erupted in 2005 on the island of Anatahan, the largest historical eruption of that volcano, according to the USGS. It expelled some 50 million cubic meters of ash, the USGS reported, noting at the time that the volcanic plume was “widespread over the western Philippine Sea, more than 1300 nautical miles west of Anatahan.” A volcano that erupted on the island of Pagan in 1981 has been showing many signs of unrest, Quick said.

Besides the USGS volcano project, SMU has been active in the Marianas through a memorandum of agreement to help the local government search for alternative energy sources, in particular geothermal.

The Marianas volcano project is part of a larger USGS program that is investing $15.2 million of American Recovery and Reinvestment Act funds to boost existing monitoring of high-risk volcanic areas in partnership with universities and state agencies nationwide.

In targeting the Marianas, the USGS cited the evacuation of residents from the northern islands after the 1981 eruption on Pagan, as well as the threat to the main island of Saipan and to nearby Guam. A U.S. territory, Guam is expected to be home to about 40,000 U.S. military and support personnel by 2014, including 20,000 Marines and dependents redeployed from Okinawa. The Marines will use the island as a rapid-response platform for both military and humanitarian operations. The military also has proposed using the Northern Marianas for military exercises.

The USGS cited also the threat of volcanic ash plumes to commercial and military planes. Air routes connect Saipan and Guam to Asia and the rest of the Pacific Rim, as well as Northeast Asia to Australia, Indonesia, the Philippines and New Zealand.

Worldwide from 1970 to 2000 more than 90 commercial jets have flown into clouds of volcanic ash, causing damage to those aircraft, most notably engine failure, according to airplane maker Boeing.

Volcanic ash plumes can rise to cruise altitudes in a matter of minutes after an eruption, Quick said. Winds carry plumes thousands of miles from the volcanoes, he explained, and then the plumes are difficult or impossible to distinguish from normal atmospheric clouds.

Monitoring by remote sensing allows USGS scientists to alert the International Civil Aviation Organization’s nine Volcanic Ash Advisory Centers as part of ICAO’s International Airways Volcano Watch program. The centers then can issue early warnings of volcanic ash clouds to pilots.

“Monitoring on the ground gives early warning when an eruption begins, as well as an indication that an eruption might be imminent,” Quick said. “The contribution by the USGS and its university partners for volcano monitoring is to provide that earliest warning – or even a pre-eruption indication – that a volcano is approaching eruption so that the volcanic ash advisory centers can get the word out and alerts can be issued.”

The USGS objective is for infrasound on Saipan, four seismometers on Anatahan, which currently has only one functioning seismometer, two seismometers on Sarigan, and GPS on Anatahan, Sarigan and Saipan.

Improved monitoring, Quick said, even might allow evacuated islanders to return to their homes – especially understandable for the island of Pagan, given its freshwater lakes, lush forests, black and white sand beaches and abundant fishing.

“A lot of people would like to move back, but it’s considered unsafe absent monitoring,” he said. “If we can establish monitoring networks on these islands, then I think it becomes more practical for people to think about returning. Properly monitored, one should be able to give adequate warning so that people could evacuate.”

Seamounts reach a pinnacle in upcoming issue of Oceanography

<IMG SRC="/Images/979091882.jpg" WIDTH="350" HEIGHT="133" BORDER="0" ALT="This part of the back cover of the March 2010 issue of the journal Oceanograhy depicts seven seamounts formed by the Louisville hotspot in the South Pacific that were surveyed during the AMAT02 Expedition in 2006 (Peter Lonsdale, Scripps Institution of Oceanography, chief scientist) using R/V Roger Revelle. As part of the Integrated Ocean Drilling Program (IODP), this site survey provided key data to prepare for IODP Expedition 330 (December 2010) that aims to drill four seamounts in the Louisville seamount trail. Using paleomagnetic and geochronological data from the drilled basalts, this project attempts to answer the question of whether the deep Hawaiian and Louisville mantle plumes, the two longest-lived primary hotspot systems in the Pacific, have moved in concert or independently. – The Oceanography Society”>
This part of the back cover of the March 2010 issue of the journal Oceanograhy depicts seven seamounts formed by the Louisville hotspot in the South Pacific that were surveyed during the AMAT02 Expedition in 2006 (Peter Lonsdale, Scripps Institution of Oceanography, chief scientist) using R/V Roger Revelle. As part of the Integrated Ocean Drilling Program (IODP), this site survey provided key data to prepare for IODP Expedition 330 (December 2010) that aims to drill four seamounts in the Louisville seamount trail. Using paleomagnetic and geochronological data from the drilled basalts, this project attempts to answer the question of whether the deep Hawaiian and Louisville mantle plumes, the two longest-lived primary hotspot systems in the Pacific, have moved in concert or independently. – The Oceanography Society

Lying beneath the ocean is spectacular terrain ranging from endless chains of mountains and isolated peaks to fiery volcanoes and black smokers exploding with magma and other minerals from below Earth’s surface. This mountainous landscape, some of which surpasses Mt. Everest heights and the marine life it supports, is the spotlight of a special edition of the research journal Oceanography.

These massive underwater mountains, or seamounts, are scattered across every ocean and collectively comprise an area the size of Europe. These deep and dark environments often host a world teeming with bizarre life forms found nowhere else on Earth. More than 99 percent of all seamounts remain unexplored by scientists, yet their inhabitants, such as the long-lived deepwater fish orange roughy, show signs of habitat destruction and over exploitation from intense international fishing efforts.

Scientists from Scripps Institution of Oceanography at UC San Diego and colleagues from the National Oceanic Atmospheric Administration, Oregon State University, University of British Columbia and Woods Hole Oceanographic Institution were among those who contributed their expertise in seamount chemistry, physics, geology, hydrology, oceanography, biology and fisheries conservation to this special interdisciplinary effort to delve into the extremely broad research supported by seamounts and to communicate the science and threats facing them to the public.

“One of the key goals of this special issue was to bring together the extremely diverse seamount research community that ranges from fisheries science and conservation all the way to mantle geochemistry,” said Hubert Staudigel a research geologist at Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps and the lead guest editor of the special issue. “In my eyes, this volume of Oceanography goes beyond that by presenting amazing new research in a way that the public can understand and get excited about.”

“This issue of Oceanography offers a broad perspective on seamount research of all major disciplines to raise awareness of the diversity of seamount research and to promote collaboration among seamount scientists,” wrote the editors of the issue, which represents the most comprehensive volume of peer-reviewed research on the subject to date.

“I was pleased to see how many of the contributions in this special issue deal with very practical and societally important issues of seamounts,” said U.S. Geological Survey Director Marcia McNutt.

Ice shelves disappearing on Antarctic Peninsula

This image shows ice-front retreat in part of the southern Antarctic Peninsula from 1947 to 2009. USGS scientists are studying coastal and glacier change along the entire Antarctic coastline. The southern portion of the Antarctic Peninsula is one area studied as part of this project, and is summarized in the USGS report, “Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947—2009” (map I—2600—C).
This image shows ice-front retreat in part of the southern Antarctic Peninsula from 1947 to 2009. USGS scientists are studying coastal and glacier change along the entire Antarctic coastline. The southern portion of the Antarctic Peninsula is one area studied as part of this project, and is summarized in the USGS report, “Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947—2009” (map I—2600—C).

Ice shelves are retreating in the southern section of the Antarctic Peninsula due to climate change. This could result in glacier retreat and sea-level rise if warming continues, threatening coastal communities and low-lying islands worldwide.

Research by the U.S. Geological Survey is the first to document that every ice front in the southern part of the Antarctic Peninsula has been retreating overall from 1947 to 2009, with the most dramatic changes occurring since 1990. The USGS previously documented that the majority of ice fronts on the entire Peninsula have also retreated during the late 20th century and into the early 21st century.

The ice shelves are attached to the continent and already floating, holding in place the Antarctic ice sheet that covers about 98 percent of the Antarctic continent. As the ice shelves break off, it is easier for outlet glaciers and ice streams from the ice sheet to flow into the sea. The transition of that ice from land to the ocean is what raises sea level.

“This research is part of a larger ongoing USGS project that is for the first time studying the entire Antarctic coastline in detail, and this is important because the Antarctic ice sheet contains 91 percent of Earth’s glacier ice,” said USGS scientist Jane Ferrigno. “The loss of ice shelves is evidence of the effects of global warming. We need to be alert and continually understand and observe how our climate system is changing.”

The Peninsula is one of Antarctica’s most rapidly changing areas because it is farthest away from the South Pole, and its ice shelf loss may be a forecast of changes in other parts of Antarctica and the world if warming continues.

Retreat along the southern part of the Peninsula is of particular interest because that area has the Peninsula’s coolest temperatures, demonstrating that global warming is affecting the entire length of the Peninsula.

The Antarctic Peninsula’s southern section as described in this study contains five major ice shelves: Wilkins, George VI, Bach, Stange and the southern portion of Larsen Ice Shelf. The ice lost since 1998 from the Wilkins Ice Shelf alone totals more than 4,000 square kilometers, an area larger than the state of Rhode Island.

The USGS is working collaboratively on this project with the British Antarctic Survey, with the assistance of the Scott Polar Research Institute and Germany’s Bundesamt fűr Kartographie und Geodäsie. The research is also part of the USGS Glacier Studies Project, which is monitoring and describing glacier extent and change over the whole planet using satellite imagery.

Team finds subtropical waters flushing through Greenland fjord

Recent changes in ocean circulation in the North Atlantic are delivering larger amounts of subtropical waters to the high latitudes. A research team led by Fiamma Straneo, a physical oceanographer at Woods Hole Oceanographic Institution, found that subtropical waters are reaching Greenland's glaciers, driving melting and likely triggering an acceleration of ice loss. Melting ice also means more fresh water in the ocean, which could flood into the North Atlantic and disrupt a global system of currents, known as the Ocean Conveyor. - Credit: Jack Cook, Woods Hole Oceanographic Institution
Recent changes in ocean circulation in the North Atlantic are delivering larger amounts of subtropical waters to the high latitudes. A research team led by Fiamma Straneo, a physical oceanographer at Woods Hole Oceanographic Institution, found that subtropical waters are reaching Greenland’s glaciers, driving melting and likely triggering an acceleration of ice loss. Melting ice also means more fresh water in the ocean, which could flood into the North Atlantic and disrupt a global system of currents, known as the Ocean Conveyor. – Credit: Jack Cook, Woods Hole Oceanographic Institution

Waters from warmer latitudes – or subtropical waters – are reaching Greenland’s glaciers, driving melting and likely triggering an acceleration of ice loss, reports a team of researchers led by Fiamma Straneo, a physical oceanographer from the Woods Hole Oceanographic Institution (WHOI).

“This is the first time we’ve seen waters this warm in any of the fjords in Greenland,” says Straneo. “The subtropical waters are flowing through the fjord very quickly, so they can transport heat and drive melting at the end of the glacier.”

Greenland’s ice sheet, which is two-miles thick and covers an area about the size of Mexico, has lost mass at an accelerated rate over the last decade. The ice sheet’s contribution to sea level rise during that time frame doubled due to increased melting and, to a greater extent, the widespread acceleration of outlet glaciers around Greenland.

While melting due to warming air temperatures is a known event, scientists are just beginning to learn more about the ocean’s impact – in particular, the influence of currents – on the ice sheet.

“Among the mechanisms that we suspected might be triggering this acceleration are recent changes in ocean circulation in the North Atlantic, which are delivering larger amounts of subtropical waters to the high latitudes,” says Straneo. But a lack of observations and measurements from Greenland’s glaciers prior to the acceleration made it difficult to confirm.

The research team, which included colleagues from University of Maine, conducted two extensive surveys during July and September of 2008, collecting both ship-based and moored oceanographic data from Sermilik Fjord – a large glacial fjord in East Greenland.

Sermilik Fjord, which is 100 kilometers (approximately 62 miles) long, connects Helheim Glacier with the Irminger Sea. In 2003 alone, Helheim Glacier retreated several kilometers and almost doubled its flow speed.

Deep inside the Sermilik Fjord, researchers found subtropical water as warm as 39 degrees Fahrenheit (4 degrees Celsius). The team also reconstructed seasonal temperatures on the shelf using data collected by 19 hooded seals tagged with satellite-linked temperature depth-recorders. The data revealed that the shelf waters warm from July to December, and that subtropical waters are present on the shelf year round.

“This is the first extensive survey of one of these fjords that shows us how these warm waters circulate and how vigorous the circulation is,” says Straneo. “Changes in the large-scale ocean circulation of the North Atlantic are propagating to the glaciers very quickly – not in a matter of years, but a matter of months. It’s a very rapid communication.”

Straneo adds that the study highlights how little is known about ocean-glacier interactions, which is a connection not currently included in climate models.

“We need more continuous observations to fully understand how they work, and to be able to better predict sea-level rise in the future,” says Straneo.

Projection shows water woes likely based on warmer temperatures

Keith Cherkauer, an assistant professor of agricultural and biological engineering, surveys the Wabash River, one of many that could experience an increase in winter and spring flooding based on rising temperatures in the next century. -  Purdue Agricultural Communication photo/Tom Campbell
Keith Cherkauer, an assistant professor of agricultural and biological engineering, surveys the Wabash River, one of many that could experience an increase in winter and spring flooding based on rising temperatures in the next century. – Purdue Agricultural Communication photo/Tom Campbell

Several Midwestern states could be facing increased winter and spring flooding, as well as difficult growing conditions on farms, if average temperatures rise, according to a Purdue University researcher.

Keith Cherkauer, an assistant professor of agricultural and biological engineering, ran simulation models that show Indiana, Illinois, Wisconsin and Michigan could see as much as 28 percent more precipitation by the year 2070, with much of that coming in the winter and spring. His projections also show drier summer and fall seasons.

“This was already a difficult spring to plant because of how wet it was. If you were to add another inch or so of rain to that, it would be a problem,” said Cherkauer, whose findings were published in the early online version of the Journal of Great Lakes Research. “It could make it difficult to get into fields. There’s also a potential for more flooding.”

Cherkauer used three different scenarios based on the amount of carbon that could be emitted into the atmosphere in the coming decades. Carbon calculations were based on assumptions including population, technological advancements, the economy and other factors.

Those scenarios were used in two climate projection models from the Intergovernmental Panel on Climate Change that give climate predictions from the years 1950 through 2099. Cherkauer said in years from 1950 to 2007 where actual climate data differed slightly from projections, the difference was subtracted to give a better projection for the future.

He calculated that winters in the four states could be between 2.7 degrees to 5.4 degrees Fahrenheit warmer by 2077 than today. Summers could be between 3.6 degrees and 10.8 degrees Fahrenheit warmer.

Those projections were then put into the Variable Infiltration Capacity Model – which simulates how precipitation moves through land surface environments – to predict stream flow for six rivers: the Chippewa River, Wisconsin River, Illinois River, Wabash River, Grand River and Rock River.

Cherkauer estimates that increased precipitation would result in about a 20 percent increase in peak and mean flows for the Wabash River, for instance.

Daily river flow would be lower during the summer and fall despite an expected increase in thunderstorms and heavy-rain events. Overall precipitation would be down in those seasons, he said, and heavy rains from time to time would still leave prolonged periods without precipitation.

“This area is not going to be short of water, but we may not have it at the right times,” Cherkauer said. “We probably need to figure out how to store the excess water from the spring so we have it in the summer when we need it.”

He said there are several possible avenues for storing spring water, from damming rivers to create reservoirs, to refilling aquifers that are pumped for water in the summer.

Cherkauer said next he wants to study how climate predictions would affect drought conditions, as well as how the projections on stream flow would impact aquatic life and ecology. NASA funded his research.

Upside-down answer for deep Earth mystery

Cin-Ty Lee is a researcher at Rice University. -  Tommy LaVergne/Rice University
Cin-Ty Lee is a researcher at Rice University. – Tommy LaVergne/Rice University

When Earth was young, it exhaled the atmosphere. During a period of intense volcanic activity, lava carried light elements from the planet’s molten interior and released them into the sky. However, some light elements got trapped inside the planet. In this week’s issue of Nature, a Rice University-based team of scientists is offering a new answer to a longstanding mystery: What caused Earth to hold its last breath?

For some time, scientists have known that a large cache of light elements like helium and argon still reside inside the planet. This has perplexed scientists because such elements tend to escape into the atmosphere during volcanism. However, because these elements are depleted in the Earth’s upper mantle, Earth scientists are fairly certain the retained elements lie in a deeper portion of the mantle. Researchers have struggled to explain why some gases would be retained while others would rise and escape into the air. The dominant view has been that the lowermost mantle has been largely isolated from the upper mantle and therefore retains its primordial composition.

In the new study, a team of researchers from Rice, the University of Michigan and the University of California-Berkeley suggests that a particular set of geophysical conditions that existed about 3.5 billion years ago — when Earth’s interior was much warmer — led to the formation of a “density trap” about 400 kilometers below the planet’s surface. In the trap, a precise combination of heat and pressure led to a geophysical rarity, an area where liquids were denser than solids.

Today, liquids generated in the mantle are less dense than solids and therefore rise to the surface to form volcanoes. However, several billion years ago, a hotter mantle permitted deeper melting and generated dense liquids that stalled, crystallized and eventually sank to the bottom of the mantle.

“When something melts, we expect the gas to get out, and for that reason people have suggested that the trapped elements must be in a primordial reservoir that has never melted,” said lead author Cin-Ty Lee, associate professor of Earth science at Rice. “That idea’s become problematic in recent decades, because there’s evidence that suggests all the mantle should have melted at least once. What we are suggesting is a mechanism where things could have melted but where the gas does not escape because the melted material never rises to the surface.”

Lee said the rise of less dense, melted material from Earth’s interior is the process that created Earth’s crust. Suggesting that melted material might sink instead literally turns conventional wisdom on its head. But the “upside-down” model can explain several geochemical and geophysical oddities in addition to the trapped gases, which suggests that it is a plausible hypothesis.

“I hope this generates a lot of interest,” Lee said. “There are seismic methods that can be used to test our idea. Even if we turn out to be wrong, the tests that would be needed to falsify our hypothesis would generate a lot of new information.”

Permafrost line recedes 130 km in 50 years

Pictured are lichen and shrub-covered palsas surrounded by a pond resulting from melting permafrost in a bog near the village of Radisson, Canada. -  Serge Payette
Pictured are lichen and shrub-covered palsas surrounded by a pond resulting from melting permafrost in a bog near the village of Radisson, Canada. – Serge Payette

The southern limit of permanently frozen ground, or permafrost, is now 130 kilometers further north than it was 50 years ago in the James Bay region, according to two researchers from the Department of Biology at Université Laval. In a recent issue of the scientific journal Permafrost and Periglacial Processes, Serge Payette and Simon Thibault suggest that, if the trend continues, permafrost in the region will completely disappear in the near future.

The researchers measured the retreat of the permafrost border by observing hummocks known as “palsas,” which form naturally over ice contained in the soil of northern peat bogs. Conditions in these mounds are conducive to the development of distinct vegetation-lichen, shrubs, and black spruce-that make them easy to spot in the field.

In an initial survey in 2004, the researchers examined seven bogs located between the 51st and 53rd parallels. They noted at that time that only two of the bogs contained palsas, whereas aerial photos taken in 1957 showed palsas present in all of the bogs. A second assessment in 2005 revealed that the number of palsas present in these two bogs had decreased over the course of one year by 86% and 90% respectively.

Helicopter flyovers between the 51st and 55th parallels also revealed that the palsas are in an advanced state of deterioration over the entire James Bay area.

While climate change is the most probable explanation for this phenomenon, the lack of long term climatic data for the area makes it impossible for the researchers to officially confirm this. Professor Payette notes, however, that the average annual temperature of the northern sites he has studied for over 20 years has increased by 2 degrees Celsius. “If this trend keeps up, what is left of the palsas in the James Bay bogs will disappear altogether in the near future, and it is likely that the permafrost will suffer the same fate,” concludes the researcher affiliated to the Centre d’études nordiques.

CryoSat to observe Earth’s ice cover

Using a sophisticated radar altimeter called SIRAL (Synthetic Aperture Radar Interferometric Radar Altimetry), CryoSat-2 will make accurate measurements of the thickness of floating sea-ice so that seasonal to inter-annual variations can be detected. It will also survey the surface of continental ice sheets to detect small elevation changes. - Credits: ESA - AOES Medialab
Using a sophisticated radar altimeter called SIRAL (Synthetic Aperture Radar Interferometric Radar Altimetry), CryoSat-2 will make accurate measurements of the thickness of floating sea-ice so that seasonal to inter-annual variations can be detected. It will also survey the surface of continental ice sheets to detect small elevation changes. – Credits: ESA – AOES Medialab

The European Space Agency is about to launch the most sophisticated satellite ever to investigate the Earth’s ice fields and map ice thickness over water and land: lift-off scheduled for 25 February.

ESA’s ice mission satellite CryoSat will be placed into orbit 700 km above Earth by a Russian Dnepr rocket to be launched from the Baikonur Cosmodrome in Kazakhstan.
Lift-off is scheduled to take place at 14:57 CET (13:57 UTC) on Thursday 25 February 2010. The launcher is operated by the international space company Kosmotras.

CryoSat will be the third of ESA’s Earth Explorer satellites in orbit, following on from GOCE (launched in March 2009) and SMOS (launched in November 2009). It was originally due to be the first in the Earth Explorer series, but the first satellite was lost as a result of a launcher failure in October 2005.

The 700 kg CryoSat spacecraft – whose name comes from the Greek kruos meaning icy cold – carries the first all-weather microwave radar altimeter. The instrument has been optimized for determining changes in the thickness of both floating sea ice, which can be up to several meters, and polar land ice sheets, which in Antarctica can be up to five kilometers. The mission will deliver data on the rate of change of the ice thickness accurate to within one centimeter.

Recent record-lows in the extent of summer Arctic sea-ice cover demonstrate that significant changes are occurring in the polar regions. Ice cover has been mapped from space for many years by satellites such as Envisat. But to understand more about how climate change is affecting these sensitive regions, there is also an urgent need to determine how ice thickness is changing. Data from CryoSat will lead to a better understanding of the dynamics of ice mass, provide the scientific community with valuable information on this variable and contribute to climate change studies.

US minerals sector declined in 2009

The value of U.S. mineral production significantly declined in 2009.

The value of raw, nonfuel minerals mined in the United States was $57.1 billion in 2009, a decline of 20 percent over the past year. The value of materials domestically processed and refined from these raw minerals was $454 billion in 2009, a 25 percent decline from that of 2008.

Also over the past year, U.S. dependence on foreign sources for minerals has increased, continuing a trend that has been evident for more than 30 years. The United States relied on foreign sources to supply more than 50 percent of domestic consumption of 38 mineral commodities in 2009, and was 100 percent reliant on imports for 19 of those.

Minerals are a fundamental component to the U.S. economy. Final products, such as cars and houses, produced by major U.S. industries using mineral materials made up approximately 13 percent (more than $1.9 trillion) of the 2009 gross domestic product.

The U.S. Geological Survey recently released the Mineral Commodity Summaries 2010, and this annual report addresses events, trends, and issues in the domestic and international mineral industries and includes statistics on about 90 mineral commodities. The report is used by public and private sector analysts regarding planning and decision making for government and business.

“Over the last year, there has been reduced production of almost every mineral commodity and lower prices for most metals,” said USGS Mineral Resources Program Coordinator Kathleen Johnson. “This report allows for timely research and analysis of our nation’s minerals sector.”

A decline in the U.S. housing market during 2009 caused reductions in the production and consumption of construction materials. Declines in automobile and durable goods manufacturing resulted in reduced production and consumption of metals including copper, iron, steel, lead, and platinum-group metals.

Gold was one notable exception to the downward trend in metal prices, reaching an all time high of $1,215.21 per troy ounce in early December 2009. Iron ore was among the largest to decline and decreased by nearly 50 percent in production quantity and value over the last year.

Antarctic ice shelf collapse possibly triggered by ocean waves

This is Peter Bromirski of the University of California - San Diego. -  Scripps Institution of Oceanography, UC San Diego
This is Peter Bromirski of the University of California – San Diego. – Scripps Institution of Oceanography, UC San Diego

Depicting a cause-and-effect scenario that spans thousands of miles, a scientist at Scripps Institution of Oceanography at the University of California – San Diego and his collaborators discovered that ocean waves originating along the Pacific coasts of North and South America impact Antarctic ice shelves and could play a role in their catastrophic collapse.

Peter Bromirski of Scripps Oceanography is the lead scientist in a new study published in the journal Geophysical Research Letters that describes how storms over the North Pacific Ocean may be transferring enough wave energy to destabilize Antarctic ice shelves. The California Department of Boating and Waterways and the National Science Foundation supported the study.

According to Bromirski, storm-driven ocean swells travel across the Pacific Ocean and break along the coastlines of North and South America, where they are transformed into very long-period ocean waves called “infragravity waves” that travel vast distances to Antarctica.

Bromirski, along with coauthors Olga Sergienko of Princeton University and Douglas MacAyeal of the University of Chicago, propose that the southbound travelling infragravity waves “may be a key mechanical agent that contributes to the production and/or expansion of the pre-existing crevasse fields on ice shelves,” and that the infragravity waves also may provide the trigger necessary to initiate the collapse process.


The researchers used seismic data collected on the Ross Ice Shelf to identify signals generated by infragravity waves that originated along the Northern California and British Columbia coasts, and modeled how much stress an ice shelf suffers in response to infragravity wave impacts. Bromirski said only recently has technology advanced to allow scientists to deploy seismometers for the extended periods on the ice shelf needed to capture such signals.

The study found that each of the Wilkins Ice Shelf breakup events in 2008 coincided with the estimated arrival of infragravity waves. The authors note that such waves could affect ice shelf stability by opening crevasses, reducing ice integrity through fracturing and initiating a collapse. “[Infragravity waves] may produce ice-shelf fractures that enable abrupt disintegration of ice shelves that are also affected by strong surface melting,” the authors note in the paper.

Whether increased infragravity wave frequency and energy induced by heightened storm intensity associated with climate change ultimately contribute to or trigger ice shelf collapse is an open question at this point, said Bromirski. More data from Antarctica are needed to make such a connection, he said.

In separate research published last year, Bromirski and Peter Gerstoft of Scripps Oceanography showed that infragravity waves along the West Coast also generate a curious “hum”–subsonic noise too low for humans to hear.