Early-career investigator discovers current volcanic activity under West Antarctica

This image shows a researcher digging out a seismographic instrument in Antarctica. -  Douglas Wiens, Washington University in St. Louis
This image shows a researcher digging out a seismographic instrument in Antarctica. – Douglas Wiens, Washington University in St. Louis

Scientists funded by the National Science Foundation (NSF) have observed “swarms” of seismic activity–thousands of events in the same locations, sometimes dozens in a single day–between January 2010 and March 2011, indicating current volcanic activity under the massive West Antarctic Ice Sheet (WAIS).

Previous studies using aerial radar and magnetic data detected the presence of subglacial volcanoes in West Antarctica, but without visible eruptions or seismic instruments recording data, the activity status of those systems ranged from extinct to unknown. However, as Amanda Lough, a doctoral candidate at Washington University in St. Louis, points out, “Just because we can’t see …below the ice, doesn’t mean there’s not something going on there.”

“This [study] is saying that we have seismicity, which means [this system] is active right now,” according to Lough. “This is saying that the magmatic chamber is still alive; that there is magma that is moving around in the crust.”

Lough published her discovery in this week’s issue of Nature Geoscience along with her advisor Douglas Wiens, a professor of earth and planetary sciences at Washington University in St. Louis, and a team of co-authors.

NSF has a presidential mandate to manage the U.S. Antarctic Program, through which it coordinates all U.S. science on the Southernmost continent and in the Southern Ocean and the logistical support which makes the science possible.

The characteristics of the seismic events, including the 25- to 40-kilometer (15- to 25-mile) depth at which they occurred, the low frequency of the seismic waves, and the swarm-like behavior rule out glacial and tectonic sources, but are typical of deep long-period earthquakes. Deep long-period earthquakes indicate active magma moving within the Earth’s crust and are most often associated with volcanic activity.

The two swarms of seismic activity were detected by instruments deployed to obtain data on the behavior of the WAIS as part of the NSF-funded POLENET project, a global network of GPS and seismic stations. Wiens is a POLENET principal investigator.

Lough plotted the location of the swarms and realized their proximity to the Executive Committee Range, a cluster of volcanoes that were believed to be dormant, in Marie Byrd Land. She consulted with a volcanic seismologist to confirm that the frequency content and the waveforms of the seismic signals were indicative of a volcanic system.

The location of the current seismicity, about 55-60 kilometers (34-37 miles) south of Mt. Sidley, is where current volcanic activity would be predicted to occur based on the geographic locations and the ages of the lava of the known volcanoes in the Executive Committee Range. The seismic swarms were also located near a subglacial high-point of elevation and magnetic anomalies which are both indicative of a volcano.

In some volcanic systems, deep long period earthquakes can indicate an imminent eruption, but Lough sent samples of her data to volcano seismologists who “didn’t see seismic events that would occur during an eruption.” However, the elevation in bed topography did indicate to Lough and her colleagues that this newly discovered volcano had erupted in the past.

Radar data showed an ash layer trapped within the ice directly above the area of seismic and magmatic activity. Lough initially thought that the ash layer might have evidence of a past eruption from the volcano detected in this study, but based on the distribution of the materials and the prevailing winds, the ash most likely came from an eruption of nearby Mt. Waesche about 8000 years ago. The dating of the ash layer did confirm that Mt. Waesche, believed to have last been active around 100,000 years ago, erupted much more recently than previously thought.

Only an extremely powerful eruption from the active magmatic complex discovered in this study would break through the 1- to 1.5-kilometer (0.6-0.9 miles) thick ice sheet overlying the area, but this research extends the range of active volcanism deeper into the interior of the WAIS than previously known. Should an eruption occur at this location, the short-term increase in heat could cause additional melting of the bottom of the ice sheet, thereby increasing the bed lubrication and hastening ice loss from WAIS.

‘Highway from hell’ fueled Costa Rican volcano

Volcanologist Philipp Ruprecht analyzed crystals formed as Irazú's magma cooled to establish how fast it traveled. -  Kim Martineau
Volcanologist Philipp Ruprecht analyzed crystals formed as Irazú’s magma cooled to establish how fast it traveled. – Kim Martineau

If some volcanoes operate on geologic timescales, Costa Rica’s Irazú had something of a short fuse. In a new study in the journal Nature, scientists suggest that the 1960s eruption of Costa Rica’s largest stratovolcano was triggered by magma rising from the mantle over a few short months, rather than thousands of years or more, as many scientists have thought. The study is the latest to suggest that deep, hot magma can set off an eruption fairly quickly, potentially providing an extra tool for detecting an oncoming volcanic disaster.

“If we had had seismic instruments in the area at the time we could have seen these deep magmas coming,” said the study’s lead author, Philipp Ruprecht, a volcanologist at Columbia University’s Lamont-Doherty Earth Observatory. “We could have had an early warning of months, instead of days or weeks.”

Towering more than 10,000 feet and covering almost 200 square miles, Irazú erupts about every 20 years or less, with varying degrees of damage. When it awakened in 1963, it erupted for two years, killing at least 20 people and burying hundreds of homes in mud and ash. Its last eruption, in 1994, did little damage.

Irazú sits on the Pacific Ring of Fire, where oceanic crust is slowly sinking beneath the continents, producing some of earth’s most spectacular fireworks. Conventional wisdom holds that the mantle magma feeding those eruptions rises and lingers for long periods of time in a mixing chamber several miles below the volcano. But ash from Irazú’s prolonged explosion is the latest to suggest that some magma may travel directly from the upper mantle, covering more than 20 miles in a few months.

“There has to be a conduit from the mantle to the magma chamber,” said study co-author Terry Plank, a geochemist at Lamont-Doherty. “We like to call it the highway from hell.”

Their evidence comes from crystals of the mineral olivine separated from the ashes of Irazú’s 1963-1965 eruption, collected on a 2010 expedition to the volcano. As magma rising from the mantle cools, it forms crystals that preserve the conditions in which they formed. Unexpectedly, Irazú’s crystals revealed spikes of nickel, a trace element found in the mantle. The spikes told the researchers that some of Irazú’s erupted magma was so fresh the nickel had not had a chance to diffuse.

“The study provides one more piece of evidence that it’s possible to get magma from the mantle to the surface in very short order,” said John Pallister, who heads the U.S. Geological Survey (USGS) Volcano Disaster Assistance Program in Vancouver, Wash. “It tells us there’s a potentially shorter time span we need to worry about.”

Deep, fast-rising magma has been linked to other big events. In 1991, Mount Pinatubo in the Philippines spewed so much gas and ash into the atmosphere that it cooled Earth’s climate. In the weeks before the eruption, seismographs recorded hundreds of deep earthquakes that USGS geologist Randall White later attributed to magma rising from the mantle-crust boundary. In 2010, a chain of eruptions at Iceland’s Eyjafjallajökull volcano that caused widespread flight cancellations also indicated that some magma was coming from down deep. Small earthquakes set off by the eruptions suggested that the magma in Eyjafjallajökull’s last two explosions originated 12 miles and 15 miles below the surface, according to a 2012 study by University of Cambridge researcher Jon Tarasewicz in Geophysical Research Letters.

Volcanoes give off many warning signs before a blow-up. Their cones bulge with magma. They vent carbon dioxide and sulfur into the air, and throw off enough heat that satellites can detect their changing temperature. Below ground, tremors and other rumblings can be detected by seismographs. When Indonesia’s Mount Merapi roared to life in late October 2010, officials led a mass evacuation later credited with saving as many as 20,000 lives.

Still, the forecasting of volcanic eruptions is not an exact science. Even if more seismographs could be placed along the flanks of volcanoes to detect deep earthquakes, it is unclear if scientists would be able to translate the rumblings into a projected eruption date. Most problematically, many apparent warning signs do not lead to an eruption, putting officials in a bind over whether to evacuate nearby residents.

“[Several months] leaves a lot of room for error,” said Erik Klemetti, a volcanologist at Denison University who writes the “Eruptions” blog for Wired magazine. “In volcanic hazards you have very few shots to get people to leave.”

Scientists may be able to narrow the window by continuing to look for patterns between eruptions and the earthquakes that precede them. The Nature study also provides a real-world constraint for modeling how fast magma travels to the surface.

“If this interpretation is correct, you start having a speed limit that your models of magma transport have to catch,” said Tom Sisson, a USGS volcanologist based at Menlo Park, Calif.

Olivine minerals with nickel spikes similar to Irazú’s have been found in the ashes of arc volcanoes in Mexico, Siberia and the Cascades of the U.S. Pacific Northwest, said Lamont geochemist Susanne Straub, whose ideas inspired the study. “It’s clearly not a local phenomenon,” she said. The researchers are currently analyzing crystals from past volcanic eruptions in Alaska’s Aleutian Islands, Chile and Tonga, but are unsure how many will bear Irazú’s fast-rising magma signature. “Some may be capable of producing highways from hell and some may not,” said Ruprecht.

Locating tsunami warning buoys

Australian researchers describe a mathematical model in the International Journal of Operational Research that can find the ten optimal sites at which tsunami detection buoys and sea-level monitors should be installed. The model could save time and money in the installation of a detection system as well as providing warning for the maximum number of people should a potentially devastating tsunami occur again in the Indian Ocean.

A magnitude 9.3 shook the sea floor off the coast of Aceh, in northern Sumatra, Indonesia, on 26 December 2004. The quake led to an overwhelming tsunami with waves as high as 10.5 m travelling at up to 8 m per second. Within two hours the tsunami had reached Colombo, in Sri Lanka and then the east coast of India. Almost eight hours later, fishing villages on the east coast of Africa in Kenya and Somalia felt its impact. There was no warning for the people affected and almost a quarter of a million lives were lost across eleven nations fringing the Indian Ocean.

In 2005, the first steps to install a tsunami warning system in the Indian Ocean were being taken, with plans to deploy 24 tsunami detection buoys. The author of the study, Layna Groen and Lindsay Botten of the Department of Mathematical Sciences, at the University of Technology, and Katerina Blazek previously at Sinclair Knight Merz, in Sydney, NSW, Australia, suggest that their model has significant implications for the construction and maintenance of the tsunami warning system in the Indian Ocean.

The Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organisation (UNESCO) planned the establishment of the Indian Ocean Tsunami Warning and Mitigation System (IOTWS). The detection/alert system is the crucial component consisting of seismic detectors, sea-level monitors and deep-sea pressure sensors attached to deep ocean buoys.

Groen and colleagues have focused on the latter two components as being critical to an adequate warning system. They point out that relatively few detection buoys are yet in place and a number of sea-level monitoring stations are still to be constructed. Their study, which uses the well-known modeling tool “Mathematica”, should help the IOTWS decision makers in determining where the remaining buoys should be placed.

The team’s analysis supports the positioning of the 40 proposed buoys, but points out that just 1o buoys would be adequate for warning the maximum number of people. They add that the same mathematical modeling approach could be applied to tsunami detection in the Atlantic Ocean, the Mediterranean, Caribbean, and Black Seas.

“The imperative for this is made clear in the UNESCO Intergovernmental Oceanographic Committee estimate that ‘by the year 2025, three-quarters of the world’s population will be living in coastal areas’, and ‘The expanded tsunami network that the Intergovernmental Oceanographic Commission of UNESCO is coordinating is just the first step in building a global tsunami warning system designed to monitor oceans and seas everywhere’.”

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.”

Seismic noise unearths lost hurricanes

Seismologists have found a new way to piece together the history of hurricanes in the North Atlantic-by looking back through records of the planet’s seismic noise. It’s an entirely new way to tap into the rich trove of seismic records, and the strategy might help establish a link between global warming and the frequency or intensity of hurricanes.

“Looking for something like hurricane records in seismology doesn’t occur to anybody,” said Carl Ebeling, of Northwestern University in Evanston. “It’s a strange and wondrous combination.”

The research is attempting to address a long-standing debate about whether the warming of sea-surface waters as a result of climate change is producing more frequent or more powerful hurricanes in the North Atlantic. It’s a tough question to answer.

Before satellite observations began in the 1960s, weather monitoring was spotty. Ships, planes, and land-based monitoring stations probably missed some hurricanes, which tend to last for about a week or so, Ebeling said. This type of uncertainty poses a problem for scientists, who can’t identify trends until they know what the actual numbers were.

To fill in the historical blanks, Ebeling and colleague Seth Stein are looking to seismic noise, an ever-present background signal that bathes the surface of the Earth. Seismic noise derives its energy from the atmosphere and then gets transmitted through the oceans into the solid earth, where it travels as waves. Seismometers record the noise as very low-amplitude wiggle patterns with much larger, obvious signals that come from earthquakes. Subtle changes in seismic noise frequency and amplitude have long been ignored.

Ebeling and Stein analyzed digital seismograms dating back to the early 90s from two monitoring stations: one in Harvard, Mass., and one in San Juan, Puerto Rico. For this study, the researchers looked at seismograms recorded during known hurricanes in an attempt to see whether patterns produced during hurricanes look predictably different from patterns produced during regular storms or when there are no storms at all.

Their preliminary results suggest that hurricanes do indeed produce recognizable patterns, and the waves generated by hurricanes travel large distances. The Harvard station recorded signals from Hurricane Andrew more than a thousand kilometers away.

“There’s definitely something there that shows this can be workable,” Ebeling said. “This is something new and interesting.”

At least one major hurdle remains before scientists will be able to pull together a complete hurricane history out of the seismic records. For most of the 20th century, seismograms recorded data on rolls of paper. Those records, which contain hundreds of thousands of hours of data, will need to be digitized. Ebeling is looking for an efficient way to do that.

Finding trapped miners

This diagram shows the layout of a system that University of Utah scientists developed to find miners trapped by mine cave-ins. The system was tested in a utility tunnel on campus, and at an abandoned copper mine near Tucson, Ariz. The diagram shows how sound receivers known as geophones are lined up on the ground surface above a mine tunnel. Each red star within the tunnel represents a 'base station' comprised of a sledgehammer and an iron plate bolted to the mine wall. In the event of a mine collapse, the miners try to reach the nearest base station, where they use the sledgehammer to bang on the iron plate. The pattern of seismic waves 'heard' by the geophones is analyzed in a computer to pinpoint the miners' location. -  University of Utah.
This diagram shows the layout of a system that University of Utah scientists developed to find miners trapped by mine cave-ins. The system was tested in a utility tunnel on campus, and at an abandoned copper mine near Tucson, Ariz. The diagram shows how sound receivers known as geophones are lined up on the ground surface above a mine tunnel. Each red star within the tunnel represents a ‘base station’ comprised of a sledgehammer and an iron plate bolted to the mine wall. In the event of a mine collapse, the miners try to reach the nearest base station, where they use the sledgehammer to bang on the iron plate. The pattern of seismic waves ‘heard’ by the geophones is analyzed in a computer to pinpoint the miners’ location. – University of Utah.

University of Utah scientists devised a new way to find miners trapped by cave-ins. The method involves installing iron plates and sledgehammers at regular intervals inside mines, and sensitive listening devices on the ground overhead.

“We developed an approach to find the location of trapped miners inside a collapsed mine, regardless of noise from the environment around the mine,” says Sherif Hanafy, an adjunct associate professor of geology and geophysics at the University of Utah and first author of a study demonstrating the technique.

The method records “seismic ‘fingerprints’ generated by a trapped miner banging on the mine wall, and uses those fingerprints to locate him. Each different location in the mine that is banged has a unique fingerprint,” says Gerard Schuster, a professor of geology and geophysics at the University of Utah and the study’s senior author.

“We hope to make it easier to find out if miners are alive after a collapse and, if they are alive, where they are located,” he adds. “It’s not guaranteed to work every time, but looks promising from the tests we did. This is not rocket science; it’s rock science.”

The new study was published in this month’s issue of The Leading Edge, a journal of the Society of Exploration Geophysicists.

The researchers and a number of Utah graduate students tested the system twice. One test was in a utility tunnel beneath the University of Utah campus. The other test was in much deeper tunnels in an abandoned copper mine near Tucson, Ariz.

“We got 100 percent accuracy,” Hanafy says.

Schuster says more testing is needed to make sure the method will work in deeper mines, such as coal mines, which can be a few thousand feet deep. He says that while the method was tested only in horizontal mines tunnels, it also should work in vertical shafts.

Along with Hanafy and Schuster, the study’s coauthors are Weiping Cao, a doctoral student in geology and geophysics, and M.K. “Kim” McCarter, a professor of mining engineering at the University of Utah. In addition to his Utah affiliation, Hanafy is an associate professor of geophysics at Cairo University in Egypt.

How the Method Can Find Trapped Miners

The system developed by the Utah researchers would be installed in stages as a mine is excavated. Components include:

  • each tunnel’s length. At each station, a 4-inch-by-4-inch iron plate is bolted to the wall, and a sledgehammer is placed near each plate.

  • On the surface, cables are strung along the ground above each tunnel or shaft, and “geophones” are spaced at regular intervals along the cables. Geophones listen for seismic waves created when miners use the sledgehammer to bang on an iron plate.
  • Once the system is installed, and as the mine expands and base stations are added, each base station is “calibrated,” meaning its plate is whacked and the seismic waves are recorded by the geophones overhead. Each base station has a distinct seismic wave “fingerprint.” So if miners are trapped and bang the metal plate at the nearest base station, the resulting seismic recording will allow rescuers to determine precisely which base station plate was thumped, and thus where the miners are located.

Listening stations would record the seismic wave pattern from each geophone. The collective pattern would be compared – by a computer – with the calibration seismograph recordings collected prior to the collapse. A match identifies the base station or stations where survivors have gathered and walloped the iron plate.

Schuster hopes a company will commercialize the miner-location system. A patent is pending on the method, and University of Utah technology commercialization officials have discussed it with a variety of mining companies.

The system would include perhaps 100 geophones and 100 base stations, and cost about $100,000 for a typical mine – an amount Schuster considers inexpensive.

“It’s like having a fire extinguisher on every floor. How much does that cost?”

Schuster says the system could be expanded – at about double the cost – to allow two-way communications, instead of just signals from trapped miners to rescuers on the surface. Two-way communication would require a computer and geophone at each underground base station to pick up signals from people on the surface.

Hanafy says if miners were unable to reach the nearest base station, simply banging on a mine wall with a rock should produce a “fingerprint” that identifies the nearest base station.

A Method Born from Oil Exploration and the Crandall Canyon Mine Disaster

Schuster’s research, which is funded by 20 oil and gas companies, focuses on developing improved methods to use seismic waves to make three-dimensional images identifying the location of oil, gas and mineral deposits. He will switch to adjunct status at the University of Utah this summer to become a geosciences professor at King Abdullah University of Science and Technology in oil-rich Saudi Arabia.

His work on the miner-locating method was triggered by Utah’s Aug. 6, 2007, Crandall Canyon coal mine collapse, which resulted in the deaths of six miners and, 10 days later, three rescuers. Schuster had just returned from a five-month sabbatical in Saudi Arabia, working on a system to use seismic signals to locate the “fluid front” of underground oil being pushed toward a well by injected steam or carbon dioxide gas.

Schuster says the technology in the miner-locating system is one that exploration geophysicists have used since the 1970s to search for oil, and later was adapted by the military to locate submarines with quiet propulsion systems. Just as efforts to determine an earthquake’s location looked at only a small part of the seismic wave signal, so did old efforts to look for submarines by using sound generated by sonar, he says.

With the new technology, “we look at the entire signal,” which Schuster compares with analyzing an entire fingerprint rather than one or two whorls in that fingerprint.

The researchers first tested their system in November 2007 near the David Eccles School of Business on the University of Utah campus. Graduate students set up 25 base stations in a 150-foot-long stretch of tunnel that carries steam pipes and other utilities 10 feet beneath the surface.

Hanafy says they spaced the base stations anywhere from 1.6 feet to 13 feet apart, and whacked each one with a 16-pound sledgehammer while geophones on the surface recorded the seismic waves. Geophones were aligned 115 feet away instead of directly over the tunnel – a way to mimic recording seismic waves from a much deeper tunnel.

“We had 25 base stations inside the tunnel, and we calculated the result for each one assuming a trapped miner was at each one of these,” he says. “We were able to locate exactly where each bang was coming from,” even when stations were only 1.6 feet apart.

The Utah scientists tested the method at more realistic depths at the old Arizona copper mine, where they placed 25 base stations 1.6 feet apart in a 100-foot-deep tunnel, and another 25 base stations 2.5 feet apart in an underlying 150-foot-deep tunnel. On the surface, 120 geophones were set up along a 200-foot-long line running above the two tunnels. Every bang on a base station was accurately located.

Schuster says that to “simulate battlefield conditions” at a working mine, a computer was used to simulate “white noise” that drowned out the real seismic signals by a 2,000-to-1 ratio. He says the seismic signature of a bang on a base station plate still could be distinguished.

“It’s like at a cocktail party you have 2,000 people talking at the same time in different conversations, and somehow you can home in on one conversation,” he says.

Scientists cable seafloor seismometer into California’s earthquake network

A newly-laid, 32-mile underwater cable finally links the state’s only seafloor seismic station with the University of California, Berkeley’s seismic network, merging real-time data from west of the San Andreas fault with data from 31 other land stations sprinkled around Northern and Central California.

Laying of the MARS (Monterey Accelerated Research System) fiber-optic cable was completed in 2007 by the Monterey Bay Aquarium Research Institute (MBARI) to power and collect data from a cluster of scientific instruments nearly 3,000 feet below the surface of Monterey Bay, 23 miles from the coastal town of Moss Landing. A broadband seismometer that had been placed on the seafloor in 2002 was connected to the cable on Feb. 27, 2009, obviating the need to send a remotely operated vehicle (ROV) every three months to replace the battery and collect data.

“Before, we had to wait three months to even know if the instruments were alive,” said Barbara Romanowicz, director of the Berkeley Seismological Laboratory and a UC Berkeley professor of earth and planetary science. Now, she said, “we can use the data from the seafloor station in real time together with those from the rest of the Berkeley Digital Seismic Network” to determine the location, magnitude and mechanism of offshore earthquakes, learn about the crust at the edge of the continental plate and understand better the hazards of the San Andreas fault system that runs north and south through the state.

According to Romanowicz, earthquake monitoring systems around the world have been trying to place seismometers on the seafloor for decades to cover the 71 percent of the Earth’s surface that is beneath the oceans. Islands have generally provided the only offshore data – the Berkeley network has one seismic station on the Farallon Islands – but these provide only spotty coverage.

Because the state’s main fault system, the San Andreas, runs along the Northern California coast, seafloor monitors are particularly critical. All but one station – the Farallon station – are east of the fault, making it hard to gain a comprehensive view of the fault system.

“Even though we correct for this lopsidedness, the calculations would be even more reliable if we could include data from more stations west of the fault; with the addition of MOBB, we achieve this goal,” wrote Berkeley Seismological Laboratory research geophysicist Peggy Hellweg on the lab’s SeismoBlog, http://seismo.berkeley.edu/blogs/seismoblog.php.

Also, while basic, disposable seismometers can be thrown overboard to collect data for short periods of time, more expensive broadband seismometers, which can detect a wide range of vibrational frequencies and a large amplitude range, are preferred. The latter are necessary to gather the data needed for modeling earthquakes and eventually providing a few tens of seconds’ warning of impending ground shaking.

Romanowicz teamed up with the institute more than 12 years ago to develop a seafloor seismic observatory. For three months in 1997, in collaboration with the Berkeley Seismological Laboratory and a team from France, MBARI placed a broadband seismometer on the floor of Monterey Bay to test the equipment and installation procedures. The Monterey Ocean Bottom Broadband (MOBB) station was permanently situated on an underwater ridge in April 2002.

With MOBB data coming back to UC Berkeley only once every three months, it could not be used in real-time earthquake monitoring. It has proved valuable in other studies, however, including an investigation of long-period ocean waves, called infragravity waves, that are thought to generate a low-frequency hum in Earth.

This hum – which has a period of 100-500 seconds, too low for humans to hear – was discovered in 1998 and ascribed to atmospheric turbulence. But in 2004, Romanowicz and UC Berkeley colleague Junkee Rhie showed that the source of the hum was in the oceans and related to storms. Somehow, 10-second ocean waves generated by storms interact with each other to produce longer period infragravity waves, which then interact locally to thump the seafloor and create the hum. The specifics are still unclear, although the interactions of the long waves with the ground likely occur near the shore.

“How the interactions of waves couple to the ground is still an open question,” said Romanowicz. “MOBB will allow us to compare seismic data with data from buoys to determine the temporal and spatial relationships between ocean waves, infragravity waves and seismic waves.”

Earth’s hum as well as ocean currents and breaking surf all make the seismic data from MOBB noisier than data from land stations, Romanowicz said, which means MOBB data must be processed to remove the noise before it can be integrated with other seismic data in the network. She and UC Berkeley colleagues are working on real-time algorithms that can do such processing quickly. The data from the ocean floor seismometer will soon be available, along with other broadband seismic data from land-based stations, at the Northern California Earthquake Data Center: http://www.ncedc.org/), an archive of earthquake date maintained by UC Berkeley and the U.S. Geological Survey.

If MOBB turns out to provide useful data for the Northern California seismic network, it will be a prototype for other seafloor seismic stations she hopes to emplace along the coast from below Monterey to Point Reyes.

US-led international research team confirms Alps-like mountain range exists

Flying twin-engine light aircraft the equivalent of several trips around the globe and establishing a network of seismic instruments across an area the size of Texas, a U.S.-led, international team of scientists has not only verified the existence of a mountain range that is suspected to have caused the massive East Antarctic Ice Sheet to form, but also has created a detailed picture of the rugged landscape buried under more than four kilometers (2.5 miles) of ice.

“Working cooperatively in some of the harshest conditions imaginable, all the while working in temperatures that averaged -30 degrees Celsius, our seven-nation team has produced detailed images of last unexplored mountain range on Earth,” said Michael Studinger, of Columbia University’s Lamont-Doherty Earth Observatory, the co-leader of the U.S. portion of the Antarctica’s Gamburstev Province (AGAP) project. “As our two survey aircraft flew over the flat white ice sheet, the instrumentation revealed a remarkably rugged terrain with deeply etched valleys and very steep mountain peaks.”

The National Science Foundation (NSF), in its role as manager of the U.S. Antarctic Program, provided much of the complex logistical support that made the discoveries possible. NSF also supported U.S. researchers from Columbia University, Washington University in St. Louis, Pennsylvania State University, the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, the U.S. Geological Survey (USGS) and the Incorporated Research Institutions in Seismology (IRIS).

The initial AGAP findings–which are based on both the aerogeophysical surveys and on data from a network of seismic sensors deployed as part of the project–while extremely exciting, also raise additional questions about the role of the Gamburtsevs in birthing the East Antarctic Ice Sheet, which extends over more than 10 million square kilometers atop the bedrock of Antarctica, said geophysicist Fausto Ferraccioli, of the British Antarctic Survey (BAS), who led the U.K. science team.

“We now know that not only are the mountains the size of the European Alps but they also have similar peaks and valleys,” he said. “But this adds even more mystery about how the vast East Antarctic Ice Sheet formed.”

He added that “if the ice sheet grew slowly then we would expect to see the mountains eroded into a plateau shape. But the presence of peaks and valleys could suggest that the ice sheet formed quickly–we just don’t know. Our big challenge now is to dive into the data to get a better understanding of what happened” millions of years ago.

The AGAP survey area covered roughly 2 million square kilometers of the ice sheet.

The initial data also appear to confirm earlier findings that a vast aquatic system of lakes and rivers exists beneath the ice sheet of Antarctica, a continent that is the size of the U.S. and Mexico combined.

“The temperatures at our camps hovered around -30 degrees Celsius, but three kilometers beneath us at the bottom of the ice sheet we saw liquid water in the valleys,” said AGAP U.S. Co-leader Robin Bell, also of Lamont Doherty. “The radar mounted on the wings of the aircraft transmitted energy through the thick ice and let us know that it was much warmer at the base of the ice sheet.”

The AGAP data will help scientists to determine the origin of the East Antarctic Ice Sheet and the Gamburtsevs’ role in it. It will also help them to understand the role the subglacial aquatic system plays in the dynamics of ice sheets, which will, in turn, help reduce scientific uncertainties in predictions of potential future sea level rise. The most recent report of the Intergovernmental Panel on Climate Change (IPCC) said that it is difficult to predict how much the vast ice sheets of Greenland and Antarctica will contribute to sea-level rise because so little is known about the behavior of the ice sheets.

The data also will be used to help locate where the world’s oldest ice is located.

The AGAP discoveries were made through fieldwork that took place in December and January, near the official conclusion of the International Polar Year (IPY), the largest coordinated international scientific effort in five decades. Ceremonies marking the conclusion of IPY fieldwork will take place in Geneva, Switzerland on Feb. 25.

NSF is the lead U.S. agency for IPY. Through the Antarctic Program, NSF manages all federally funded research on the southernmost continent.

Fully in the spirit of IPY, noted Detlef Damaske of Germany’s Federal Institute for Geosciences and Natural Resources, teams of scientists, engineers, pilots and support staff from Australia, Canada, China, Germany, Japan, the U.K. and the U.S. pooled their knowledge, expertise and logistical resources to deploy two survey aircraft, equipped with ice-penetrating radar, gravimeters and magnetic sensors as well as the network of seismometers, an effort that no one nation alone could have mounted.

“This is a fantastic finale to IPY,” added Ferraccioli.

Bell meanwhile, noted that AGAP is “emblematic of what the international science community can accomplish when working together.”

In one of the most ambitious, challenging and adventurous ‘deep field’ Antarctic IPY expeditions, AGAP scientists gathered the terabytes of data needed to create images of the enigmatic Gamburtsevs, first discovered by Russian scientists in 1957 during the International Geophysical Year (IGY), the predecessor to IPY.

While the planes made a series of survey flights, covering a total of 120,000 square kilometers, the seismologists flew to 26 different sites throughout an area larger than the state of Texas using Twin Otter aircraft equipped with skis, to install scientific equipment that will run for the next year on solar power and batteries.

The seismology team, from Washington University, Penn State, IRIS, and Japan’s National Institute of Polar Research, also recovered ten seismographs that have been collecting data since last year over the dark Antarctic winter at temperatures as low as -73 degrees Celsius (-100 degrees Fahrenheit).

“The season was a great success,” said Douglas Wiens, of Washington University in St. Louis. “We recovered the first seismic recordings from this entire part of Antarctica, and operated seismographs over the Antarctic winter at temperatures as low as -100 F for the first time. Now, we are poring over the data to find out what is responsible for pushing up mountains in this part of Antarctica.”

Catching quakes with laptops

The interactive program built around the BOINC screensaver, designed for classroom activities.  Recent earthquakes and sites of major historic earthquakes are indicated; information about these events can be retrieved by clicking on them. -  Quake Catcher Network Project
The interactive program built around the BOINC screensaver, designed for classroom activities. Recent earthquakes and sites of major historic earthquakes are indicated; information about these events can be retrieved by clicking on them. – Quake Catcher Network Project

Inside your laptop is a small accelerometer chip, there to protect the delicate moving parts of your hard disk from sudden jolts.

It turns out that the same chip is a pretty good earthquake sensor, too-especially if the signals from lots of them are compared, in order to filter out more mundane sources of laptop vibrations, such as typing.

It’s an approach that is starting to gain acceptance. The project Quake Catcher Network (QCN), already has about 1500 laptops connected in a network that has detected several tremors, including a magnitude 5.4 quake in Los Angeles in July. Led by Elizabeth Cochran at the University of California, Riverside, and Jesse Lawrence at Stanford University, QCN uses the same BOINC platform for volunteer computing that projects like SETI@home rely on.

One of the benefits of this new technology is price: Research-grade earthquake sensors typically cost between $10,000 and $100,000. Of course, they are much more sensitive, and can detect the subtle signals of far-away quakes that laptops will never pick up. But Lawrence notes that, “with many more cheap sensors, instead of guessing where strong motions were felt by interpolating between sensors, we should be able to know where strong motions were felt immediately, because we have sensors there.”

Another advantage is that QCN sensors can record the maximum ground shaking. Many high-sensitivity sensors cut short the full extent of the oscillations they are measuring even for moderate earthquakes. Lawrence argues that with enough sensors, eventually “we should have the ability to triangulate earthquakes for earthquake early warning, providing several seconds of warning before the earthquake hits neighboring populated regions.”

There is a catch with the QCN sensors, though: getting accurate coordinates for their position. At present, since most laptops do not have GPS, the project relies on coordinates that the users type in. Fortunately, rough coordinates can also be automatically retrieved from network routers that the laptop is connected to, as a backup.

It all started with teenage mutant ninjas

Laptop accelerometers were never meant to be used this way. But in 2005, a benign hacker group called the teenage mutant ninjas figured out how to access the “sudden motion sensor” in Apple computers. A year later, David Griscom at the company Suitable Systems wrote SeisMac as an educational tool for IRIS, a group of U.S. earthquake seismologists.

Cochran had the idea that this approach could be linked with BOINC. Carl Christensen, a distributed computing expert, was recruited to implement QCN in BOINC last year. A first limited release was made in March of this year, and by April the network had already detected its first quake, in Reno, Nevada.

Christensen is now working on integrating stand-alone sensors that attach to desktop machines with USB connections (since desktops don’t get bumped around like laptops, they don’t have built-in sensors). These USB sensors can be as cheap as $30, and the idea is to have large numbers of them sponsored as educational tools for schools.

Lawrence notes that “the USB accelerometers will provide a stable backbone, without which the ever-changing configuration of laptops would not be quite as reliable. The USB accelerometers can also mount directly to the floor, which means they will have better sensitivity to ground motions.”

So this is not just a neat outreach opportunity-it could one day save lives.

Oil, Gas Seismic Work Not Affecting Sperm Whales

Noise can be irritating and possibly harmful for everything from mice to humans – and maybe even 60-foot whales in the Gulf of Mexico.

In recent years, there has been concern that man-made noise may be a cause of stress for dolphins, whales and other marine mammals, but the results of a five-year study show that noise pollution – especially noise generated by seismic airguns during geophysical exploration for oil and gas — seems to have minimal effect on endangered sperm whales in the Gulf of Mexico, say researchers from Texas A&M University who led the project and released their 323-page report today at the Houston Museum of Natural Science.

The multi-year $9 million study, the largest of its type ever undertaken and formally titled Sperm Whale Seismic Study in the Gulf of Mexico , was conducted by the Minerals Management Service and featured cooperation with the Office of Naval Research, the National Science Foundation and the National Fish and Wildlife Foundation. The project brought together researchers from eight universities, but it was managed overall by Texas A&M’s Department of Oceanography, with research scientist Ann Jochens and professor Doug Biggs serving as principal investigators.

“The bottom line is that airgun noise from seismic surveys that are thousands of yards distant does not drive away sperm whales living in the Gulf,” Biggs explains.

“However, some individual whales feeding at depth reduced the rate at which they searched acoustically for their prey when scientists carried out controlled exposure experiments by bringing seismic surveys close by the whales. As a result, the oil and gas industry has agreed to a best-practice attitude that seismic surveys should shut down temporarily when towed airguns come within one-third of a mile of whales or groups of whales in the Gulf.”

Though not often seen, sperm whales are regular visitors to and residents in the Gulf of Mexico . They are the largest of all toothed whales and can reach lengths of 60 feet or more and live 60 years or longer. Their primary diet is squid and fish and they have been known to dive as deep as 7,000 feet. Humans no longer hunt them for their oil, but the whale in Herman Melville’s classic novel Moby Dick was a sperm whale.

Sperm whales are not often seen because they prefer to stay in the deep waters of the Gulf, usually in depths of 3,000 feet or more and at least 150 miles offshore, Biggs says.

“Sperm whales go to where their food source is, and that means very deep water. So folks that do see them are marine mammal observers who ride the seismic survey vessels and the workers on the big oil and gas rigs, and even that does not happen often,” Biggs adds.

The primary concern facing the scientific research group was noise – there’s more of it in the world’s oceans than you might think. A study by the Scripps Institution of Oceanography shows that the world’s oceans are 10 times noisier since the 1960s, and at any one time, there are as many as 30,000 ships circling the globe.

Biggs says that over the course of five summers, 98 sperm whales were tagged with devices that relayed back critical data such as measurements about sound levels and behavioral aspects of whales, including tracking their movements. Of particular concern was the effect that loud low-frequency noises, such as those created by seismic activity, might have on sperm whales in the area.

Oil and gas companies prospect for subsea reservoirs by firing air guns during their seismic work, which government regulators thought might negatively affect sperm whale behavior. Also, the sheer volume of work being done in the Gulf was another concern: The Gulf of Mexico accounts for almost 70 percent of the oil and gas extracted from U.S. waters and there are thousands of oil and gas platforms in the region.

But the study found no unusual effects of controlled exposure to seismic exploration on the swimming and diving behavior by sperm whales in the Gulf, and also revealed a wealth of data about sperm whale biology and habitat.

“We now know that the sperm whales in the Gulf appear to be their own distinct stock — they show genetic and social differences from other sperm whales around the world,” Biggs says.

“There are believed to be about 500 to 1,500 sperm whales that reside in the Gulf. Most of these are family groups of females and maturing young. When one family group socializes with another family group in the Gulf, they make very distinct sounds. Even though the family groups are visited by males that come into the Gulf from other oceans, their ‘clicking’ sounds, called codas, the Gulf sperm whales make appear to be different from most others made by sperm whale groups in other parts of the world.

“The five-year study has greatly contributed to our knowledge of sperm whales, especially those found in the Gulf of Mexico . It’s also raised new questions we need to know more about, such as their feeding and breeding patterns. There’s still a lot we don’t know about these huge creatures.”