Subtle shifts in the Earth could forecast earthquakes, tsunamis

University of South Florida graduate student Jacob Richardson stands beside a completed installation.  The large white disc is the dual frequency antenna.  A portable solar panel that powers the system is visible in the foreground. -  Photo by Denis Voytenko
University of South Florida graduate student Jacob Richardson stands beside a completed installation. The large white disc is the dual frequency antenna. A portable solar panel that powers the system is visible in the foreground. – Photo by Denis Voytenko

Earthquakes and tsunamis can be giant disasters no one sees coming, but now an international team of scientists led by a University of South Florida professor have found that subtle shifts in the earth’s offshore plates can be a harbinger of the size of the disaster.

In a new paper published today in the Proceedings of the National Academies of Sciences, USF geologist Tim Dixon and the team report that a geological phenomenon called “slow slip events” identified just 15 years ago is a useful tool in identifying the precursors to major earthquakes and the resulting tsunamis. The scientists used high precision GPS to measure the slight shifts on a fault line in Costa Rica, and say better monitoring of these small events can lead to better understanding of maximum earthquake size and tsunami risk.

“Giant earthquakes and tsunamis in the last decade – Sumatra in 2004 and Japan in 2011 – are a reminder that our ability to forecast these destructive events is painfully weak,” Dixon said.

Dixon was involved in the development of high precision GPS for geophysical applications, and has been making GPS measurements in Costa Rica since 1988, in collaboration with scientists at Observatorio Vulcanológico y Sismológico de Costa Rica, the University of California-Santa Cruz, and Georgia Tech. The project is funded by the National Science Foundation.

Slow slip events have some similarities to earthquakes (caused by motion on faults) but release their energy slowly, over weeks or months, and cannot be felt or even recorded by conventional seismographs, Dixon said. Their discovery in 2001 by Canadian scientist Herb Dragert at the Pacific Geoscience Center had to await the development of high precision GPS, which is capable of measuring subtle movements of the Earth.

The scientists studied the Sept. 5, 2012 earthquake on the Costa Rica subduction plate boundary, as well as motions of the Earth in the previous decade. High precision GPS recorded numerous slow slip events in the decade leading up to the 2012 earthquake. The scientists made their measurements from a peninsula overlying the shallow portion of a megathrust fault in northwest Costa Rica.

The 7.6-magnitude quake was one of the strongest earthquakes ever to hit the Central American nation and unleased more than 1,600 aftershocks. Marino Protti, one of the authors of the paper and a resident of Costa Rica, has spent more than two decades warning local populations of the likelihood of a major earthquake in their area and recommending enhanced building codes.

A tsunami warning was issued after the quake, but only a small tsunami occurred. The group’s finding shed some light on why: slow slip events in the offshore region in the decade leading up to the earthquake may have released much of the stress and strain that would normally occur on the offshore fault.

While the group’s findings suggest that slow slip events have limited value in knowing exactly when an earthquake and tsunami will strike, they suggest that these events provide critical hazard assessment information by delineating rupture area and the magnitude and tsunami potential of future earthquakes.

The scientists recommend monitoring slow slip events in order to provide accurate forecasts of earthquake magnitude and tsunami potential.

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The authors on the paper are Dixon; his former graduate student Yan Jiang, now at the Pacific Geoscience Centre in British Columba, Canada; USF Assistant Professor of Geosciences Rocco Malservisi; Robert McCaffrey of Portland State University; USF doctoral candidate Nicholas Voss; and Protti and Victor Gonzalez of the Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional.

The University of South Florida is a high-impact, global research university dedicated to student success. USF is a Top 50 research university among both public and private institutions nationwide in total research expenditures, according to the National Science Foundation. Serving nearly 48,000 students, the USF System has an annual budget of $1.5 billion and an annual economic impact of $4.4 billion. USF is a member of the American Athletic Conference.

Offshore islands amplify, rather than dissipate, a tsunami’s power

This model shows the impact of coastal islands on a tsunami's height. -  Courtesy of Jose Borrero/eCoast/USC
This model shows the impact of coastal islands on a tsunami’s height. – Courtesy of Jose Borrero/eCoast/USC

A long-held belief that offshore islands protect the mainland from tsunamis turns out to be the exact opposite of the truth, according to a new study.

Common wisdom — from Southern California to the South Pacific — for coastal residents and scientists alike has long been that offshore islands would create a buffer that blocked the power of a tsunami. In fact, computer modeling of tsunamis striking a wide variety of different offshore island geometries yielded no situation in which the mainland behind them fared better.

Instead, islands focused the energy of the tsunami, increasing flooding on the mainland by up to 70 percent.

“This is where many fishing villages are located, behind offshore islands, in the belief that they will be protected from wind waves. Even Southern California residents believe that the Channel Islands and Catalina will protect them,” said Costas Synolakis of the USC Viterbi School of Engineering, a member of the multinational team that conducted the research.

The research was inspired by a field survey of the impact of the 2010 tsunami on the Mentawai Islands off of Sumatra. The survey data showed that villages located in the shadow of small offshore islets suffered some of the strongest tsunami impacts, worse than villages located along open coasts.

Subsequent computer modeling by Jose Borrero, adjunct assistant research professor at the USC Viterbi Tsunami Research Center, showed that the offshore islands had actually contributed to — not diminished — the tsunami’s impact.

Synolakis then teamed up with researchers Emile Contal and Nicolas Vayatis of Ecoles Normales de Cachan in Paris; and Themistoklis S. Stefanakis and Frederic Dias, who both have joint appointments at Ecoles Normales de Cachan and University College Dublin to determine whether that was a one-of-a-kind situation, or the norm.

Their study, of which Dias was the corresponding author, was published in Proceedings of the Royal Society A on Nov. 5.

The team designed a computer model that took into consideration various island slopes, beach slopes, water depths, distance between the island and the beach, and wavelength of the incoming tsunami.

“Even a casual analysis of these factors would have required hundreds of thousands of computations, each of which could take up to half a day,” Synolakis said. “So instead, we used machine learning.”

Machine learning is a mathematical process that makes it easier to identify the maximum values of interdependent processes with multiple parameters by allowing the computer to “learn” from previous results.

The computer starts to understand how various tweaks to the parameters affect the overall outcome and finds the best answer quicker. As such, results that traditionally could have taken hundreds of thousands of models to uncover were found with 200 models.

“This work is applicable to some of our tsunami study sites in New Zealand,” said Borrero, who is producing tsunami hazard maps for regions of the New Zealand coast. “The northeast coast of New Zealand has many small islands offshore, similar to those in Indonesia, and our modeling suggests that this results in areas of enhanced tsunami heights.”

“Substantial public education efforts are needed to help better explain to coastal residents tsunami hazards, and whenever they need to be extra cautious and responsive with evacuations during actual emergencies,” Synolakis said.

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The research was funded by EDSP of ENS-Cachan; the Cultural Service of the French Embassy in Dublin; the ERC; SFI; University College Dublin; and the EU FP7 program ASTARTE. The study can be found online at http://rspa.royalsocietypublishing.org/content/470/2172/20140575.

Extinct undersea volcanoes squashed under Earth’s crust cause tsunami earthquakes, according to new

New research has revealed the causes and warning signs of rare tsunami earthquakes, which may lead to improved detection measures.

Tsunami earthquakes happen at relatively shallow depths in the ocean and are small in terms of their magnitude. However, they create very large tsunamis, with some earthquakes that only measure 5.6 on the Richter scale generating waves that reach up to ten metres when they hit the shore.

A global network of seismometers enables researchers to detect even the smallest earthquakes. However, the challenge has been to determine which small magnitude events are likely to cause large tsunamis.

In 1992, a magnitude 7.2 tsunami earthquake occurred off the coast of Nicaragua in Central America causing the deaths of 170 people. Six hundred and thirty seven people died and 164 people were reported missing following a tsunami earthquake off the coast of Java, Indonesia, in 2006, which measured 7.2 on the Richter scale.

The new study, published in the journal Earth and Planetary Science Letters, reveals that tsunami earthquakes may be caused by extinct undersea volcanoes causing a “sticking point” between two sections of the Earth’s crust called tectonic plates, where one plate slides under another.

The researchers from Imperial College London and GNS Science in New Zealand used geophysical data collected for oil and gas exploration and historical accounts from eye witnesses relating to two tsunami earthquakes, which happened off the coast of New Zealand’s north island in 1947. Tsunami earthquakes were only identified by geologists around 35 years ago, so detailed studies of these events are rare.

The team located two extinct volcanoes off the coast of Poverty Bay and Tolaga Bay that have been squashed and sunk beneath the crust off the coast of New Zealand, in a process called subduction.

The researchers suggest that the volcanoes provided a “sticking point” between a part of the Earth’s crust called the Pacific plate, which was trying to slide underneath the New Zealand plate. This caused a build-up of energy, which was released in 1947, causing the plates to “unstick” and the Pacific plate to move and the volcanoes to become subsumed under New Zealand. This release of the energy from both plates was unusually slow and close to the seabed, causing large movements of the sea floor, which led to the formation of very large tsunami waves.

All these factors combined, say the researchers, are factors that contribute to tsunami earthquakes. The researchers say that the 1947 New Zealand tsunami earthquakes provide valuable insights into what geological factors cause these events. They believe the information they’ve gathered on these events could be used to locate similar zones around the world that could be at risk from tsunami earthquakes. Eyewitnesses from these tsunami earthquakes also describe the type of ground movement that occurred and this provides valuable clues about possible early warning signals for communities.

Dr Rebecca Bell, from the Department of Earth Science and Engineering at Imperial College London, says: “Tsunami earthquakes don’t create massive tremors like more conventional earthquakes such as the one that hit Japan in 2011, so residents and authorities in the past haven’t had the same warning signals to evacuate. These types of earthquakes were only identified a few decades ago, so little information has been collected on them. Thanks to oil exploration data and eyewitness accounts from two tsunami earthquakes that happened in New Zealand more than 70 years ago, we are beginning to understand for first time the factors that cause these events. This could ultimately save lives.”

By studying the data and reports, the researchers have built up a picture of what happened in New Zealand in 1947 when the tsunami earthquakes hit. In the March earthquake, eyewitnesses around Poverty Bay on the east coast of the country, close to the town of Gisborne, said that they didn’t feel violent tremors, which are characteristic of typical earthquakes. Instead, they felt the ground rolling, which lasted for minutes, and brought on a sense of sea sickness. Approximately 30 minutes later the bay was inundated by a ten metre high tsunami that was generated by a 5.9 magnitude offshore earthquake. In May, an earthquake measuring 5.6 on the Richter scale happened off the coast of Tolaga Bay, causing an approximate six metre high tsunami to hit the coast. No lives were lost in the New Zealand earthquakes as the areas were sparsely populated in 1947. However, more recent tsunami earthquakes elsewhere have devastated coastal communities.

The researchers are already working with colleagues in New Zealand to develop a better warning system for residents. In particular, new signage is being installed along coastal regions to alert people to the early warning signs that indicate a possible tsunami earthquake. In the future, the team hope to conduct new cutting-edge geophysical surveys over the sites of other sinking volcanoes to better understand their characteristics and the role they play in generating this unusual type of earthquake.

Great earthquakes, water under pressure, high risk

The largest earthquakes occur where oceanic plates move beneath continents. Obviously, water trapped in the boundary between both plates has a dominant influence on the earthquake rupture process. Analyzing the great Chile earthquake of February, 27th, 2010, a group of scientists from the GFZ German Research Centre for Geosciences and from Liverpool University found that the water pressure in the pores of the rocks making up the plate boundary zone takes the key role (Nature Geoscience, 28.03.2014).

The stress build-up before an earthquake and the magnitude of subsequent seismic energy release are substantially controlled by the mechanical coupling between both plates. Studies of recent great earthquakes have revealed that the lateral extent of the rupture and magnitude of these events are fundamentally controlled by the stress build-up along the subduction plate interface. Stress build-up and its lateral distribution in turn are dependent on the distribution and pressure of fluids along the plate interface.

“We combined observations of several geoscience disciplines – geodesy, seismology, petrology. In addition, we have a unique opportunity in Chile that our natural observatory there provides us with long time series of data,” says Onno Oncken, director of the GFZ-Department “Geodynamics and Geomaterials”. Earth observation (Geodesy) using GPS technology and radar interferometry today allows a detailed mapping of mechanical coupling at the plate boundary from the Earth’s surface. A complementary image of the rock properties at depth is provided by seismology. Earthquake data yield a high resolution three-dimensional image of seismic wave speeds and their variations in the plate interface region. Data on fluid pressure and rock properties, on the other hand, are available from laboratory measurements. All these data had been acquired shortly before the great Chile earthquake of February 2010 struck with a magnitude of 8.8.

“For the first time, our results allow us to map the spatial distribution of the fluid pressure with unprecedented resolution showing how they control mechanical locking and subsequent seismic energy release”, explains Professor Oncken. “Zones of changed seismic wave speeds reflect zones of reduced mechanical coupling between plates”. This state supports creep along the plate interface. In turn, high mechanical locking is promoted in lower pore fluid pressure domains. It is these locked domains that subsequently ruptured during the Chile earthquake releasing most seismic energy causing destruction at the Earth’s surface and tsunami waves. The authors suggest the spatial pore fluid pressure variations to be related to oceanic water accumulated in an altered oceanic fracture zone within the Pacific oceanic plate. Upon subduction of the latter beneath South America the fluid volumes are released and trapped along the overlying plate interface, leading to increasing pore fluid pressures. This study provides a powerful tool to monitor the physical state of a plate interface and to forecast its seismic potential.

Shale could be long-term home for problematic nuclear waste

Shale, the source of the United States’ current natural gas boom, could help solve another energy problem: what to do with radioactive waste from nuclear power plants. The unique properties of the sedimentary rock and related clay-rich rocks make it ideal for storing the potentially dangerous spent fuel for millennia, according to a geologist studying possible storage sites who made a presentation here today.

The talk was one of more than 10,000 presentations at the 247th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, taking place here through Thursday.

About 77,000 tons of spent nuclear fuel currently sit in temporary above-ground storage facilities, said Chris Neuzil, Ph.D., who led the research, and it will remain dangerous for tens or hundreds of thousands of years or longer.

“Surface storage for that length of time requires maintenance and security,” he said. “Hoping for stable societies that can continue to provide those things for millennia is not a good idea.” He also pointed out that natural disasters can threaten surface facilities, as in 2011 when a tsunami knocked cooling pumps in storage pools offline at the Fukushima Daiichi nuclear power plant in Japan.

Since the U.S. government abandoned plans to develop a long-term nuclear-waste storage site at Yucca Mountain in Nevada in 2009, Neuzil said finding new long-term storage sites must be a priority. It is crucial because nuclear fuel continues to produce heat and harmful radiation after its useful lifetime. In a nuclear power plant, the heat generated by uranium, plutonium and other radioactive elements as they decay is used to make steam and generate electricity by spinning turbines. In temporary pool storage, water absorbs heat and radiation. After spent fuel has been cooled in a pool for several years, it can be moved to dry storage in a sealed metal cask, where steel and concrete block radiation. This also is a temporary measure.

But shale deep under the Earth’s surface could be a solution. France, Switzerland and Belgium already have plans to use shale repositories to store nuclear waste long-term. Neuzil proposes that the U.S. also explore the possibility of storing spent nuclear fuel hundreds of yards underground in layers of shale and other clay-rich rock. He is with the U.S. Geological Survey and is currently investigating a site in Ontario with the Canadian Nuclear Waste Management Organization.

Neuzil explained that these rock formations may be uniquely suited for nuclear waste storage because they are nearly impermeable – barely any water flows through them. Experts consider water contamination by nuclear waste one of the biggest risks of long-term storage. Unlike shale that one might see where a road cuts into a hillside, the rocks where Neuzil is looking are much more watertight. “Years ago, I probably would have told you shales below the surface were also fractured,” he said. “But we’re seeing that that’s not necessarily true.” Experiments show that water moves extremely slowly through these rocks, if at all.

Various circumstances have conspired to create unusual pressure systems in these formations that result from minimal water flow. In one well-known example, retreating glaciers in Wellenberg, Switzerland, squeezed the water from subsurface shale. When they retreated, the shale sprung back to its original shape faster than water could seep back in, creating a low-pressure pocket. That means that groundwater now only flows extremely slowly into the formation rather than through it. Similar examples are also found in North America, Neuzil said.

Neuzil added that future glaciation probably doesn’t pose a serious threat to storage sites, as most of the shale formations he’s looking at have gone through several glaciations unchanged. “Damage to waste containers, which will be surrounded by a filler material, is also not seen as a concern,” he said.

He noted that one critical criterion for a good site must be a lack of oil or natural gas that could attract future interest.

The analogue of a tsunami for telecommunication

Development of electronics and communication requires a hardware base capable for increasingly larger precision, ergonomics and throughput. For communication and GPS-navigation satellites, it is of great importance to reduce the payload mass as well as to ensure the signal stability. Last year, researchers from the Moscow State University (MSU) together
with their Swiss colleagues from EFPL performed a study that can induce certain improvements in this direction. The scientists demonstrated (this paper was published in Nature Photonics) that the primary source of noise in microresonator based optical frequency combs (broad spectra composed of a large number of equidistant narrow emission lines) is related to non-linear harmonic generation mechanisms rather that by fundamental physical limitations and in principle reducible.

On December 22st, a new publication in Nature Photonics is appearing where they extend their results. Michael Gorodetsky, one of the co-authors of this paper, professor of the Physical Faculty of MSU affiliated also in the Russian Quantum Centre in Skolkovo, says that the study contains at least three important results: scientists found a technique to generate stable femtosecond (duration of the order of 10-15 seconds) pulses, optical combs and microwave signals.

Physicists used a microresonator (in this particular case, a millimeter-scale magnesium fluoride disk was used, where whispering-gallery electromagnetic oscillations may be excited, propagating along the circumference of the the resonator) to convert continuous laser emission into periodic pulses of extremely short duration. The best known analogous devices are mode-locked lasers that generating femtosecond, high-intensity pulses. Applications of these lasers range from analysis of chemical reactions at ultra-short timescales to eye-surgery.

“In mode-locked femtosecond lasers complex optical devices, media and special mirrors are normally used. However we succeeded in obtaining stable pulses just in passive optical resonator using its own non-linearity,” — Gorodetsky says. This allows, in future, to decrease drastically the size of the device.

The short pulses generated in the microresonator are in fact what is known as optical solitons (soliton is a stable, shape-conserving localized wave packet propagating in a non-linear medium like a quasiparticle; an example of a soliton existing in nature is a tsunami wave). “One can generate a single stable soliton circulating inside a microresonator. In the output optical fiber, one can obtain a periodic series of pulses with a period corresponding to a round trip time of the soliton.” — Gorodetsky explains.

Such pulses last for 100-200 femtoseconds, but the authors are sure that much shorter solitons are achievable. They suggest that their discovery allows to construct a new generation of compact, stable and cheap optical pulse generators working in the regimes unachievable with other techniques. In the spectral domain, these pulses correspond to the so-called optical frequency “combs” that revolutionized metrology and spectroscopy and brought to those who developed the method a Nobel Prize in physics in 2005 ( American John Hall and German Theodor Haensch received the Prize “for their contributions to the development of laser-based precision spectroscopy, including the optical frequency comb technique”). Currently existing comb generators are much larger and more massive.

At the same time, as the scientists show, a signal generated by such a comb on a photodetectors a high-frequency microwave signal with very low phase noise level. Ultra-low-noise microwave generators are extremely important in modern technology; they are used in metrology, radiolocation, telecommunication hardware, including satellite communications. Authors note that their results are critical for such applications as broadband spectroscopy, telecommunications, and astronomy.

Global map to predict giant earthquakes

A team of international researchers, led by Monash University’s Associate Professor Wouter Schellart, have developed a new global map of subduction zones, illustrating which ones are predicted to be capable of generating giant earthquakes and which ones are not.

The new research, published in the journal Physics of the Earth and Planetary Interiors, comes nine years after the giant earthquake and tsunami in Sumatra in December 2004, which devastated the region and many other areas surrounding the Indian Ocean, and killed more than 200,000 people.

Since then two other giant earthquakes have occurred at subduction zones, one in Chile in February 2010 and one in Japan in March 2011, which both caused massive destruction, killed many thousands of people and resulted in billions of dollars of damage.

Most earthquakes occur at the boundaries between tectonic plates that cover the Earth’s surface. The largest earthquakes on Earth only occur at subduction zones, plate boundaries where one plate sinks (subducts) below the other into the Earth’s interior. So far, seismologists have recorded giant earthquakes for only a limited number of subduction zone segments. But accurate seismological records go back to only ~1900, and the recurrence time of giant earthquakes can be many hundreds of years.

“The main question is, are all subduction segments capable of generating giant earthquakes, or only some of them? And if only a limited number of them, then how can we identify these,” Dr Schellart said.

Dr Schellart, of the School of Geosciences, and Professor Nick Rawlinson from the University of Aberdeen in Scotland used earthquake data going back to 1900 and data from subduction zones to map the main characteristics of all active subduction zones on Earth. They investigated if those subduction segments that have experienced a giant earthquake share commonalities in their physical, geometrical and geological properties.

They found that the main indicators include the style of deformation in the plate overlying the subduction zone, the level of stress at the subduction zone, the dip angle of the subduction zone, as well as the curvature of the subduction zone plate boundary and the rate at which it moves.

Through these findings Dr Schellart has identified several subduction zone regions capable of generating giant earthquakes, including the Lesser Antilles, Mexico-Central America, Greece, the Makran, Sunda, North Sulawesi and Hikurangi.

“For the Australian region subduction zones of particular significance are the Sunda subduction zone, running from the Andaman Islands along Sumatra and Java to Sumba, and the Hikurangi subduction segment offshore the east coast of the North Island of New Zealand. Our research predicts that these zones are capable of producing giant earthquakes,” Dr Schellart said.

“Our work also predicts that several other subduction segments that surround eastern Australia (New Britain, San Cristobal, New Hebrides, Tonga, Puysegur), are not capable of producing giant earthquakes.”

Study uncovers new evidence for assessing tsunami risk from very large volcanic island landslides

A core is extracted from the seabed. -  Russell Wynn
A core is extracted from the seabed. – Russell Wynn

The risk posed by tsunami waves generated by Canary Island landslides may need to be re-evaluated, according to researchers at the National Oceanography Centre. Their findings suggest that these landslides result in smaller tsunami waves than previously thought by some authors, because of the processes involved.

The researchers used the geological record from deep marine sediment cores to build a history of regional landslide activity over the last 1.5 million years. They found that each large-scale landslide event released material into the ocean in stages, rather than simultaneously as previously thought.

The findings – reported recently in the scientific journal Geochemistry Geophysics Geosystems – can be used to inform risk assessment from landslide-generated tsunamis in the area, as well as mitigation strategies to defend human populations and infrastructure against these natural hazards. The study also concluded that volcanic activity could be a pre-condition to major landslide events in the region.

The main factor influencing the amplitude of a landslide-generated tsunami is the volume of material sliding into the ocean. Previous efforts, which have assessed landslide volumes, have assumed that the entire landslide volume breaks away and enters the ocean as a single block. Such studies – and subsequent media coverage – have suggested an event could generate a ‘megatsunami’ so big that it would travel across the Atlantic Ocean and devastate the east coast of the US, as well as parts of southern England.

The recent findings shed doubt on this theory. Instead of a single block failure, the landslides in the past have occurred in multiple stages, reducing the volumes entering the sea, and thereby producing smaller tsunami waves. Lead author Dr James Hunt explains: “If you drop a block of soap into a bath full of water, it makes a relatively big splash. But if you break it up into smaller pieces and drop it in bit by bit, the ripples in the bath water are smaller.”

The scientists were able to identify this mechanism from the deposits of underwater sediment flows called turbidity currents, which form as the landslide mixes with surrounding seawater. Their deposits, known as ‘turbidites’, were collected from an area of the seafloor hundreds of miles away from the islands. Turbidites provide a record of landslide history because they form from the material that slides down the island slopes into the ocean, breaks up and eventually settles on this flatter, deeper part of the seafloor.

However, the scientists could not assume that multistage failure necessarily results in less devastating tsunamis – the stages need to occur with enough time in between so that the resulting waves do not compound each other. “If you drop the smaller pieces of soap in one by one but in very quick succession, you can still generate a large wave,” says Dr Hunt.

Between the layers of sand deposited by the landslides, the team found mud, providing evidence that the stages of failure occurred some time apart. This is because mud particles are so fine that they most likely take weeks to settle out in the ocean, and even longer to form a layer that would be resistant enough to withstand a layer of sand moving over the top of it.

While the authors suggest that the tsunamis were not as big as originally thought, they state that tsunamis are a threat that the UK should be taking seriously. The Natural Environment Research Council (NERC) is investing in a major programme looking at the risk of tsunamis from Arctic landslides as part of the Arctic Research Programme, of which NOC is the lead collaborator. The EU have also just funded a £6 million FP7 project called ASTARTE, looking at tsunami risk and resilience on the European North Atlantic and Mediterranean coasts, of which NOC is a partner.

The current study was funded by NERC, through a NOC studentship.

California seafloor mapping reveals hidden treasures

This is a kelp greenling fish swimming above a seafloor of mixed gravel, cobble and rock outcrop with scattered shell. Fish is approx. 20 cm (8 inches) long. Image acquired 1 km (0.62 miles) offshore Half Moon Bay, Calif., at a depth of 14 meters (46 ft). Also in the image are encrusting sponges, red algae (seaweed), and orange cup corals. -  US Geological Survey
This is a kelp greenling fish swimming above a seafloor of mixed gravel, cobble and rock outcrop with scattered shell. Fish is approx. 20 cm (8 inches) long. Image acquired 1 km (0.62 miles) offshore Half Moon Bay, Calif., at a depth of 14 meters (46 ft). Also in the image are encrusting sponges, red algae (seaweed), and orange cup corals. – US Geological Survey

Science and technology have peeled back a veil of water just offshore of California, revealing the hidden seafloor in unprecedented detail. New imagery, specialized undersea maps, and a wealth of data from along the California coast are now available. Three new products in an ongoing series were released today by the U.S. Geological Survey – a map set for the area offshore of Carpinteria, a catalog of data layers for geographic information systems, and a collection of videos and photos of the seafloor in state waters along the entire California coast.

“A program of this vast scope can’t be accomplished by any one organization. By working with other government agencies, universities, and private industry the USGS could fully leverage all its resources,” said USGS Pacific Region Director Mark Sogge. “Each organization brings to the table a unique and complementary set of resources, skills, and know-how.”

The USGS is a key partner in the California Seafloor Mapping Program, a large, unique, and historically ambitious collaboration between state and federal agencies, academia, and the private sector to create a comprehensive base-map series for all of California’s ocean waters. Scientists are collecting sonar data, video and photographic imagery, seismic surveys, and bottom-sediment data to create a series of maps of seafloor bathymetry, habitats, geology, and more, in order to inform coastal managers and planners, government entities, and researchers. With the new maps, decision makers and elected officials can better design and monitor marine reserves, evaluate ocean energy potential, understand ecosystem dynamics, recognize earthquake and tsunami hazards, regulate offshore development, and improve maritime safety.

“The Ocean Protection Council recognized early on that seafloor habitats and geology were a fundamental data gap in ocean management,” said California’s Secretary for Natural Resources and Ocean Protection Council Chair John Laird. “After an impressive effort by many partners to collect and interpret the data, the maps being produced now are providing pioneering science that’s changing the way we manage our oceans.”

“Our collaboration with the state and more than 15 other partners is critical to the success of this program. We’ve come together to make the maps, and then to use them. We all like to say that you can’t manage it, monitor it, or model it if you don’t know what the ‘it’ is, and our seafloor mapping gives that important ‘it’ to the entire coastal management and research community,” said the USGS’ lead researcher on this project, Sam Johnson.

USGS California Seafloor Mapping Program Map Series

The heart of the USGS California Seafloor Mapping Program effort is a series of map sets. To date, three sets have been published, including the most recent one released today covering the area “Offshore of Carpinteria,” USGS Scientific Investigations Map 3261. Each of the map sets includes 10 or more sheets, illustrating different features of the seafloor, including geology, bathymetry, habitats, and geology within the three-nautical-mile limit of California’s state waters. The maps are created through the collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. Fourteen other map sets are being formatted for publication; the California State Waters Map Series is planned to comprise 83 such seafloor map sets spanning the entire coast of California.

USGS California Seafloor Mapping Program Data Catalog


Underlying the series of published seafloor map sets are large geospatial digital files, including bathymetry, acoustic backscatter, offshore geology and geomorphology, faults, folds, potential marine habitats, seafloor character, sediment thickness, visual observations of bottom habitat from video, and more. These data sets are now available through a new California State Waters Map Series Data Catalog for users to create their own maps or engage in further investigations of the seafloor. The catalog, USGS Data Series 781, provides all GIS data layers associated with the map sets published by the California Seafloor Mapping Program. Data will be continually added to the data series catalog as new seafloor map sets are published. All data files can be viewed and downloaded at no charge. As the California Seafloor Mapping Program continues to produce new maps, they -and all the background data- will be made available online.

USGS California Seafloor Mapping Program Video & Photo Portal


The unique set of seafloor images (video and still photography) collected by the USGS from the U.S.-Mexico border to the Oregon state line is now available via a new California Seafloor Mapping Program Video and Photograph Portal. More than 500 hours of video and 87,000 photographs were collected and are now posted in the online portal for viewing. Scientists are using these data to ground-truth their interpretations of sonar data, to provide a framework for understanding seafloor ecosystems, and to create maps of seafloor materials and habitats. The video and photo portal is based on an interactive map, allowing users to zoom into a particular area, and see the imagery available. The video and still photographs of the same locations are displayed simultaneously, just as they were acquired along the track-line.

A journey through Cuba’s culture and geology

Few destinations capture the imagination like Cuba; a forbidden fruit to U.S. citizens since the 1960s. Recently, 14 earth scientists from the U.S.-based Association for Women Geoscientists travelled there to explore its geology and culture.

The expedition is chronicled in the August issue of EARTH Magazine. While Cuba is an intriguing destination as an actor on the global political stage, its geological history captures events that tell scientists even more about the history of the planet.

While there, the scientists studied rocks that captured the extra-terrestrial impact attributed to the demise of the dinosaurs – including shocked quartz and tsunami deposits. The scientists also learned about how local limestone was used to build forts intended to protect Cuba’s harbors from pirate attacks. Their guide even took them to sites that represent the breakup of the supercontinent Pangaea. The rocks observed in Cuba have been shown to be closely related to the Mediterranean.

Any earth scientist would agree the geologic history contained on this island is astounding. More importantly, these scientists visited Cuba to experience UNESCO World Heritage sites, and share in “people-to-people” experiences between two cultures that continue to be divided. Read more about the geological diversity of Cuba, including miles of underground cave networks and risks posed by a San Andreas-like fault at: http://bit.ly/152DT0u.

Don’t miss other exciting stories this month’s issue of Earth available at the Digital Newsstand: http://www.earthmagazine.org/digital. Read about the improvements scientists are making in hurricane forecasts, water challenges faced by a tropical paradise, and the discovery of sauropod embryos in southern China.