marine science and the coast


CORVALLIS, Ore. - The newest studies on the Cascadia Subduction Zone off the coast of the Pacific Northwest have identified a "clustering" of great earthquakes of the type that would cause a major tsunami, yielding a historical record with two distinct implications - one that's good, the other not.

According to scientists at Oregon State University, this subduction zone has just experienced a cluster of four massive earthquakes during the past 1,600 years, and if historical trends continue, this cluster could be over and the zone may already have entered a long quiet period of 500 to 1,000 years, which appears to be common following a cluster of earthquake events.

Alternatively, the current cluster of earthquakes may have one or more events left in it - some clusters within the past 10,000 years have had clusters of up to five events - and within a cluster, the average time interval between earthquakes is 300 years. Since the last major Cascadia earthquake occurred in the year 1700, the next event may well be imminent.

"The Cascadia Subduction Zone has the longest recorded data about its earthquakes of any major fault in the world," said Chris Goldfinger, an associate professor of marine geology at OSU and one of the leading experts on this fault zone. "So we know quite a bit about the periodicity of this fault zone and what to expect. But the key point we don't know is whether the current cluster of earthquake activity is over yet, or does it have another event left in it."

The two most recent major earthquakes on this fault occurred in the year 1700 and approximately the year 1500, Goldfinger said. Those two events were only 200 years apart, and it's now been 305 years since the last one. From this perspective, there's some reason to believe the next major earthquake could happen soon.

As the death toll and catastrophic destruction from the East Asia earthquake of last Monday continues to mount, more and more attention is turning to the local version of that geologic setting - the Cascadia Subduction Zone.

According to Goldfinger, there are only two places in the United States with active subduction zones, or major areas where one of the Earth's great plates are being subducted, or forced underneath the other. One is in Alaska, the site of the great earthquake of 1964. The other is the Cascadia zone, a 600-mile long fault zone that runs from Cape Mendocino in California to Vancouver Island in southern British Columbia.

Major studies have been done on this fault zone, many of them at OSU, and they have identified 19-21 major earthquake events during the past 10,000 years. During at least 17 of these events, the entire fault zone appears to have ruptured at once, causing an earthquake around magnitude 9, and major tsunamis.

"There's some variation in intensity, the last event in 1700 appeared to be about average," Goldfinger said. "To track these events we use radiocarbon dating of deposits of sand called turbidites, which come from marine landslides. These deep-sea cores give us a pretty accurate picture of when and where an earthquake event happened."

According to Goldfinger, there are remarkable geologic parallels between what just happened in East Asia and what could happen in the Pacific Northwest. The Asian event happened where the India plate was being subducted beneath the Burma microplate, and it ruptured - for the first time since 1833 - along a 600-mile front that is just about the same length as the Cascadia Subduction Zone.

That earthquake happened as the Indian plate moved towards the northeast beneath Asia, just like the Juan de Fuca plate is in the Pacific Northwest before it disappears beneath the North American plate.

What happened in Asia may give a vivid demonstration of the geologic future of the Pacific Northwest. For hundreds of years, these subduction zone plates remain locked, releasing little of their tension. The plate which is being subducted is forced down, while the plate above bulges upwards. Then, in a few minutes of violence every few centuries, the forces are released. The upper plate moves seaward, and a massive tsunami can be produced along with catastrophic destruction from earthquake shaking.

"In the case of the Cascadia Subduction Zone, you could have an area of ocean sea floor that's 50 miles wide and 500-600 miles long suddenly snap back up, causing a huge tsunami," Goldfinger said. "At the same time, we could expect some parts of the upper, or North American plate to sink one to two meters. These are massive tectonic events. Subduction zones produce the most powerful earthquakes and tsunamis in the world."

The question, Goldfinger says, is not whether or not the Cascadia Subduction Zone will break again. It's when. And that's where the study of past events may shed light on the present.

Following are the earthquake events on this fault zone during the past 9,800 years:

  • Oldest recorded earthquake, 9,800 years before present
  • 800-year gap with no major earthquakes
  • Three earthquake events, 8,300 to 9,000 years before present
  • 700-year gap with no major earthquakes
  • Five earthquake events, 5,700 to 7,600 years before present
  • 1,000 year gap with no major earthquakes
  • Two earthquake events, 3,900 to 4,700 years before present
  • 500-year gap with no major earthquakes
  • Three earthquake events, 2,500 to 3,400 years before present
  • 700- to 900-year gap with no major earthquakes
  • Four earthquake events from 1,600 years before present to today

"We're going to continue to study the geology of these events and identify the patterns and likelihood of future events as best we can," Goldfinger said. "A few things are clear. There are clusters of earthquake events on the Cascadia Subduction Zone, and there are big gaps. And we're either in a cluster right now or at the end of one."

"Whether the current cluster is over yet, we just don't know," he said. "One possibility is that we could be done with this cluster and looking at a period of many hundreds of years before the next earthquake."

"The other distinct possibility is we could still be in a cluster of events. If that's the case, the average time interval between earthquakes within a cluster is already up. We would be due just about any day."

Media Contact: 

Chris Goldfinger, 541-737-5214

OSU’s Hatfield Marine Science Center to Host Earth Day Events

NEWPORT, Ore. – Four researchers from Oregon State University will discuss issues related to climate change during a series of Earth Day presentations on Saturday, April 21, at OSU’s Hatfield Marine Science Center in Newport.

The lectures, which are free and open to the public, will be held in the Hennings Auditorium of HMSC’s Visitor’s Center.

Karen Shell, from OSU’s College of Oceanic and Atmospheric Sciences, will speak on “Uncertainty and Climate Change.” Her talk begins at 10:30 a.m.

At 12:30 p.m., Mark Hixon, a professor of zoology, will discuss “Ocean Warming: Threats to the Pacific Northwest.”

Peter Clark, a professor of geosciences and an expert on glaciers and polar ice, will give a lecture on “Ice and Sea Level Changes: Where Are We Headed?” that begins at 1:30 p.m.

Jeffrey Shaman, from the College of Oceanic and Atmospheric Sciences, will blend his studies of human health and atmospheric sciences in a talk called “Change, Human Health and Local Ecology.” It begins at 3 p.m.

For more information, contact Bill Hanshumaker of OSU Extension Sea Grant, at 541-867-0167. He is the public marine education specialist at OSU’s Hatfield Marine Science Center.

Media Contact: 

Bill Hanshumaker,

OSU Oceanographers to Study at the North Pole for Clues to Arctic, Global Circulation

CORVALLIS, Ore. – A team of scientists, including two oceanographers from Oregon State University, will explore the frigid waters beneath the North Pole this April for clues to the circulation patterns of the Arctic Ocean.

The project is particularly important, researchers say, because fresh water from the Arctic – via melting ice or continental runoff – has a major influence on the circulation of other oceans, including the Atlantic and Pacific.

“The Arctic is an extremely sensitive valve that regulates heat exchange and the deep circulation of the world’s oceans,” said Robert Collier, a professor in OSU’s College of Oceanic and Atmospheric Sciences. “Yet we don’t really know a lot about how the upper 1,000 meters of the Arctic Ocean circulates. These kinds of observations are critical to better understanding how the oceans may respond to global climate change.”

Collier will join OSU doctoral student Matt Alkire on the project, which will take them to “Barneo,” a remote outpost operated by a Russian logistics team just a handful of kilometers from the North Pole. There, from their tent camp, the researchers will travel by small plane to some 30 sites around the North Pole where they will land, drill holes in the ice, and take a series of measurements down to a depth of 1,000 meters.

They will run continuous water sampling profiles, collecting data on temperature, salinity, water chemistry and oxygen levels; and they will collect water samples to analyze chemical “tracers” that reveal the source of the water.

Kelly Falkner, an OSU professor of oceanography, helped establish this observatory effort and has made several trips to the North Pole over the past years. She is on an assignment from OSU to the National Science Foundation, where she is interim director for NSF’s Antarctic Ocean and Climate Science program, coinciding with the International Polar Year.

“The International Polar Year is significant because the scientific community can learn a great deal about these integrated systems when everyone focuses on them at one time, pooling our limited resources,” Collier said. “The last equivalent was the International Geophysical Year, which brought long-lasting significant changes in our knowledge about the Earth.

“Our knowledge of the poles and their integration with global earth systems should increase greatly through this and partner projects,” he added.

The temperature near the outpost this week was minus-18 degrees (F), with steady 30-mile-per-hour winds.

But there is more to the weather than meets the eye, the scientists say. During the last couple of decades, the atmospheric pressure and winds over the Arctic and North Atlantic have shifted, causing changes in ocean circulation and source waters. Scientists are still unsure if those shifts are due to global climate change or natural cycles.

“We’ve never observed these large changes before, partly due to the difficulty of working in this region,” Collier said.

Alkire’s research suggests that the distribution of source waters in the Arctic may be returning to their more traditional pattern, responding to the change in atmospheric conditions under way. The degree to which these changes are natural cycles, or human-influenced, is literally and figuratively up in the air.

“This underscores the importance of long-term observatories throughout the world’s oceans,” Collier pointed out. The research is part of the North Pole Environmental Observatory, a project supported by the National Science Foundation.

Collier said the research also is important to gain more insights into the role the Arctic Ocean plays in sequestration of atmospheric carbon dioxide. High-latitude waters pull in anthropogenic CO2 from the atmosphere, and the currents transport it to the deep oceans.

“The Arctic plays a critical role in controlling the transport of atmospheric gases into the deep oceans, and although we know the basic mechanisms, there is much we don’t know about the details of how the machinery works,” Collier said.

Interested persons can follow the scientists and field programs online at: http://psc.apl.washington.edu/northpole/NP2007Reports.html

Media Contact: 

Bob Collier,

NOAA Researcher to Lecture at OSU on Ocean C0² and Acidificatio

CORVALLIS, Ore. – Christopher Sabine, a leading researcher from the Pacific Marine Environmental Laboratory in Seattle, will give a free public lecture on Friday, Jan. 11, at Oregon State University that outlines ocean carbon dioxide uptake and the increasing acidification of the world’s oceans.

The event is part of “Frontiers,” a visiting scholar series sponsored by OSU’s College of Oceanic and Atmospheric Sciences.

Sabine’s lecture, which begins at 4 p.m. in Gilfillan Auditorium on the OSU campus, is titled “The Good, the Bad and the Ugly: Ocean Uptake of Atmospheric CO2, Ocean Acidification, and the Future Global Carbon Cycle.”

Sabine works at the PMEL lab operated by the National Oceanic and Atmospheric Administration. His research focuses on the air-sea exchange of carbon dioxide at the ocean surface, and the overall global carbon exchange.

While at OSU, Sabine will give a more technical lecture aimed at faculty and graduate students. That talk, on Thursday, Jan. 10, begins at 1 p.m. in Burt Hall Room 193. It is titled “High-resolution Ocean and Atmospheric pCO² Time-series Measurements from Open Ocean and Coastal Moorings.”

Media Contact: 

Zanna Chase,

Saving Nemo: Researchers Hope to Reduce Mortality in Marine Ornamental Fish

CORVALLIS, Ore. – Oregon State University researchers are working to help more aquarium fish survive the often hazardous journey from where they’re collected until they arrive in pet shops and home aquaria.

The result may not only be healthier fish and happier pet owners, but significant environmental and economic benefits.

Jerry Heidel, director of OSU’s Veterinary Diagnostic Laboratory, and Tim Miller-Morgan, an OSU veterinarian with the Oregon Sea Grant Extension, have partnered with Hollywood Aquariums in Lake Oswego and Sea Dwelling Creatures, Inc., a Los Angeles-based fish importer and distributor, in the project funded by Oregon Sea Grant.

The collaboration allows the researchers to examine causes of mortality at all stages of the supply chain, from the fish capture on tropical coral reefs to purchase by hobbyists. SDC, Inc. provides fish to retailers and aquaria throughout the United States and internationally, including Monterey Bay Aquarium, SeaWorld and the National Aquarium in Baltimore.

The marine fish aquarium hobby is growing by approximately 1 percent a year, Miller-Morgan says, faster than any other pet ownership sector. And nearly 99 percent of the fish are caught in the wild, not raised in captivity. Typical mortality rates for the more commonly shipped species range from about 5 percent to 12 percent, according to previous studies conducted by Heidel and Miller-Morgan.

The OSU researchers conducted broad mortality surveys of all fish species imported by SDC, Inc., and in their newest study will focus on a few key species, including the popular green chromis and the false percula clownfish, of “Finding Nemo” fame. The most expensive fish they will study is the Imperator angelfish, which can retail for $200 or more.

Preliminary observations suggest that water quality and handling, rather than parasitic or bacterial infections, are the biggest problems faced by marine fish shipped to the U.S. for the pet trade.

“These animals are hit with multiple stressors throughout the chain of custody, and water quality may be the thing that pushes them over the edge,” said Miller-Morgan.

In particular, Heidel and Miller-Morgan have noted that water in which marine ornamental fish have been shipped typically has low pH – the water is more acidic than normal – and high ammonia levels, both of which can cause stress to the animals.

They also suspect that high carbon dioxide in the water is responsible for some fish deaths. In high concentrations, CO2 can cause acidosis – a condition that limits the amount of oxygen the fish can carry in their blood.

Miller-Morgan traveled with partners from SDC, Inc. to Indonesia in 2005, where they examined exporters’ animal husbandry practices and storage and shipping facilities. He noted that once the fish are collected from a reef, they commonly sit on a boat in water-filled plastic bags for as long as three weeks. The longer a fish is held on the boat, he theorizes, the more likely it is to be stressed if it is eventually shipped.

The first step of the new project is to collect baseline data on fishes’ blood chemistry, comparing fish shipped from the South Pacific to SDC Inc.’s Los Angeles facility with cinnamon clownfish at OSU’s Hatfield Marine Science Center in Newport that will serve as control fish. Carl Schreck of OSU’s Department of Fisheries and Wildlife, an expert in stress response in fishes, will assist with the blood work.

The investigators will also measure water quality and analyze stress during shipping. They expect to recommend measures that exporters can take to reduce shipping stress, most likely through improving water quality and changing fish handling prior to shipping.

Heidel and Miller-Morgan will share the study’s results as widely as possible to the industry.

“We’d like to focus on ‘train the trainer’ efforts by which we can achieve an exponential dissemination of this information,” said Heidel.

The benefits of their findings should be both economic and environmental. Shipping mortality significantly decreases the profit margin of all involved in the process.

“In general, ornamental fish importers’ two biggest business costs are labor, which is fairly fixed, and fish mortalities,” Miller-Morgan pointed out.

In addition, Heidel said “if fewer fish die in transit, the industry won’t have to go back to the reef quite as often to collect more,” thereby lessening the industry’s impact on tropical reef systems.

“Our goal with all of this work is conservation through quality health management,” said Miller-Morgan.


Tim Miller-Morgan,

OSU’s Hatfield Marine Science Center Offers “Flotsam Fest”

NEWPORT, Ore. – The variety of floats, bottles, fishing gear and other souvenirs that wash up on the shores of Oregon beaches – the “flotsam and jetsam” – is the focus of the first one-day Flotsam Fest on Saturday, Jan. 12, at Oregon State University’s Hatfield Marine Science Center.

The event will feature displays and lectures, as well as an opportunity for beachcombers to bring their finds to the center.

“If you’ve brought home something from the beach and you aren’t sure what it is, bring it on over,” said William Hanshumaker, the center’s public marine education specialist. “We’ll try to identify it for you.”

Beachcombers are often enchanted by that which is thrown up on the shore by relentless Pacific Ocean waves, but some of these materials – like rope from crab pots and balls of fishing line – can be hazardous to wildlife, Hanshumaker pointed out.

Kim Raum-Suyan, a marine mammal biologist from Newport, will address sea lion entanglement in an illustrated talk in the Hennings Auditorium at 11:30 a.m. Raum-Suyan is a contract scientist who works with OSU and the Alaska Department of Fish and Game, specializing in research on Steller sea lions.

Skye Moody, author of “Washed Up,” will speak at 1:30 p.m. on flotsam and jetsam, and conduct a book signing.

The center is open from 10 a.m. to 4 p.m. for the Flotsam Fest.

Media Contact: 

Bill Hanshumaker,

OSU Class Heading to Antarctica; Spots Open for Public

CORVALLIS, Ore. – Oregon State University students and members of the public will have a unique opportunity to learn first-hand about the effects of climate change and human impacts on the environment in Antarctica during a special class that will take them to the remote continent for two weeks.

“This is a tremendous opportunity for undergraduate and graduate students, and the general public, to explore one of the most remote and least understood – yet most fascinating – regions on Earth,” said Michael Harte, director of OSU’s Marine Resource Management Program, who will lead the trip.

“The Antarctic is where the rubber meets the road, when it comes to global environmental change,” Harte added. “It is the proverbial canary in the coal mine.”

Participants in the field course will see how human impacts, both immediate and from afar, alter ecosystems on a global scale. By observing and studying these changes in a pristine environment, Harte said, the group will gain insight into potential environmental changes that may be in store for the Pacific Northwest, including declining snow packs, shrinking glaciers and changing vegetation patterns.

Changes in Antarctica may also affect Oregon even more directly, Harte pointed out.

“Vast ice shelves, some as large as small states, have collapsed in this region of Antarctica in the last decade due to climate change,” he said. “With these natural barriers gone, ice flows much faster into the southern ocean from the frozen continent’s ice fields. This new ice is a major contributor to the expected sea level rise that threatens our Pacific Northwest coastal communities many thousands of miles away.”

This Study Abroad program will leave for Antarctica in December 2008. Participants will study and conduct research on the Antarctic Peninsula and the tip of South America. Fieldwork will be carried out from a commercial Antarctic expedition vessel and Zodiacs, from which the participants will study Antarctic wildlife, search for signs of environmental change, and explore the impact of humans on a fragile environment.

The group also will spend four days exploring the natural and cultural systems of Tierra del Fuego on the South American continent.

Harte said he is especially excited about leading a diverse group of students and members of the public to the Antarctic Peninsula.

“This is an opportunity for us to collectively discover how interconnected our global environment is and how unsustainable activities in developed countries can have an impact on the remote ecosystems of the globe that, in turn, react in ways that threaten our own way of life.”

Students and members of the public who wish to go on the trip must sign up for the course by Feb. 15. Class size is limited to about 20 persons. Students may sign up for undergraduate or graduate sections.

Participants who sign up for the class will take an online course in fall term of 2008, taught by faculty at OSU and Gateway Antarctica in Christchurch, New Zealand. The program is offered through OSU, under the auspices of the American Universities International Programs. More information, including costs, is available at: http://oregonstate.edu/international/ by typing “Antarctica” in the search engine box. Or call Kristy Spikes at OSU’s International Programs at 541-737-3006.

“This hands-on, experiential learning program, in an area few people have a chance to visit, is an extraordinary opportunity,” Harte said.

Media Contact: 

Michael Harte,

'Nonlinear' Ecosystem Response Offers Options to Environmental Gridlock

CORVALLIS, Ore. – The preservation of coastal ecosystem services – such as clean water, storm buffers or fisheries protection – does not have to be an all-or-nothing approach, a new study indicates, and a better understanding of how ecosystems actually respond to protection efforts in a “nonlinear” fashion could help lead the way out of environmental-versus-economic gridlock.

There may be much better ways to provide the majority of environmental protection needed while still maintaining natural resource-based jobs and sustainable communities, scientists from 13 universities and research institutes will suggest Friday in a new article in the journal Science.

“The very concept of ecosystem-based management implies that humans are part of the equation, and their needs also have to be considered,” said Lori Cramer, an associate professor of sociology at Oregon State University.

“But ecosystem concerns have too often been viewed as an all-or-none choice, and it doesn’t have to be that way,” Cramer said. “What we are learning is that sometimes a little environmental protection can go a long way, and leave room for practical compromises.”

In their analysis, a diverse group of scientists from four nations analyzed the values and uses of mangrove forests in Thailand – a hot spot of concern about coastal ecosystems being degraded and losing their traditional value of storm protection, wood production and fish habitat. These saltwater forests are frequently being replaced with commercial shrimp farms.

In the past, the scientists said, it was often assumed that the environment responded to protection efforts in a “linear” fashion – in other words, protecting twice as much of a resource generated twice the amount of protection. But the new study and others like it are making it more clear that ecosystems respond in a “nonlinear” fashion – protection of a small percentage of a resource might result in a large percentage of the maximum benefit that can be gained.

If the data are available to help quantify goods and services, researchers say, values can be attached to them and used to reach societal compromises. This might lead to most – but not all – of an environmental resource being protected, and some – but not all – of resources available for commercial use. The combined value of the ecosystem protection and commercial development may approach, or even exceed the value of a “hands-off” approach.

“Part of the problem now is that a lot of the data we need to make this type of assessment simply isn’t available,” said Sally Hacker, an OSU associate professor of zoology. “Biological, economic and sociological data could be enormously helpful to reaching better management decisions, and this is something we need to improve.”

Fairly good data were available in the case of the Thailand mangrove forests, however, and researchers used it to make their case. On a given area of mangrove forest there, the assigned value of ecosystem services – storm protection, biological habitat, etc. – was determined to be about $19 million with a “hands-off” approach and no commercial use whatsoever.

But with a full range of uses, which included leaving 80 percent of the area in mangrove forests and gaining almost all of their flood protection ability, the value was found to be $17.5 million, Hacker said. And this allowed for a commercial shrimp fishery, gathering of wood products, fishing and other commercial uses.

“At some point we have to get beyond this ‘either-or’ mentality when it comes to land and ocean management,” Cramer said. “Insisting that our ecosystems be either totally protected, or totally developed, just leads to polarization, entrenched positions and a loss of communication. We can do better than that, and a good scientific approach can help show the way.”

In the final analysis, the researchers said, everything should be on the table – the value of ecosystem services, the protection of species and the environment, jobs, tourism, protection of human life, even cultural and community values.

“Shrimp farming may be a person’s livelihood, and that cannot be ignored,” Cramer said. “At the same time these mangrove forests help protect human lives and healthy ecosystems, and you can’t ignore that either. The good news is that when we understand the nonlinear nature of ecosystem response, some of these compromises become possible.”

The concepts being developed, the researchers said, are directly relevant to the debate over marine reserves in Oregon. The challenge there will be to balance an adequate amount of biological protection, and a careful analysis of the areas to be protected, with the needs and concerns of coastal communities, they said.

In like fashion, they said, such approaches may be relevant to many other societal debates – whether it’s health care or the preservation of protective marshes around New Orleans – in which values can be assigned to various services and compromises reached.

Media Contact: 

Sally Hacker,

Beaches Ravaged by Tsunami Still Eroding

CORVALLIS, Ore. – The catastrophic damage of the 2004 Indian Ocean earthquake was mostly done within a few hours, but that was just the beginning of a different process that may take up to a decade or more to complete – the stabilization of new beaches and landforms in areas ravaged by this disaster.

In continued studies, researchers at Oregon State University and the U.S. Geological Survey are finding that the beaches may continue to shift and change for several more years, as the lands adjust both to the tsunami impacts and the sudden drop of some nearby land by three to six feet.

Meanwhile, some roads constructed in the push for recovery after the disaster already are being threatened by eroding beaches and lapping water. Houses have been rebuilt on stilts in areas that properly should now be considered ocean, not land. And beach experts are closely studying this process – not only to learn more, but to make sure that when the Pacific Northwest tries some day to recover from its own massive tsunami, the decisions will be informed by good science.

“In Banda Aceh, the city most severely hit by the tsunami, some people are using fill, raised roadbeds and stilts to build their homes in what is essentially an intertidal zone,” said Peter Ruggiero, an OSU assistant professor of geosciences. “It’s amazing the energy they are putting into this, but it is apparent that much of this land may just disappear. You can see palm trees in the ocean, on what used to be dry land. Right now some areas look like a little Venice.

“And with some regularity, when we were looking at a new highway in Indonesia that already needs rip-rap to prevent the ocean from claiming it, I was visualizing Highway 101 on the Oregon Coast,” Ruggiero said. “Our input may be too late to help the Indonesians in their recovery from this disaster, but hopefully we may learn a lot here that will some day help the U.S. recover from the tsunami in our future.”

There’s little realization, Ruggiero said, that after a tectonic and geologic event the magnitude of the one in Indonesia, the ocean will take years to adjust to a new equilibrium, one in which shorelines are largely stable and neither eroding or building. And predicting exactly what the ocean will give, and what it will take away, is a very new science – one that will get a major boost from what is now being learned during the Indonesian recovery. The research is being funded by the U.S. Geological Survey.

“Never before with modern scientific monitoring tools have we been able to so rigorously study a tsunami disaster such as this, literally on film from the moment it occurred to many years later,” Ruggiero said. “There have already been some surprises in places, where we’ve found the sand being moved and then re-distributed, and we’ll find out more as we go. But this process is nowhere near complete yet.”

On Dec. 26, 2004, a 9.2 magnitude earthquake triggered one of the deadliest natural disasters in modern world history, which included tsunami waves that reached up to 100 feet high. The waves scoured the ocean floor with their enormous energy and deposited huge amounts of sand and debris some distances inland, while other material was stripped away and washed out to sea. More than 225,000 people died in 11 countries.

“We have been able to study both the ocean floor and the inland effects, and are monitoring changes through time,” Ruggiero said. “We’ve discovered sandbars created by the tsunami in some shallow ocean waters that otherwise would not be there, and they appear to be gradually rebuilding some of the beaches.”

But receiving less attention at the time of the disaster, Ruggiero said, was the subsidence of some nearby areas by three to six feet – a result of land that had been “pushed up” by a subduction zone for centuries, only to drop back down suddenly during the earthquake. This resulted in an instant change of sea level over broad areas of coastal Indonesia that is still working itself out.

“As a result of the coastal subsidence, we’re still seeing beaches in retreat, which may continue for some time,” Ruggiero said. “Spits and inlets will form. We’re going to try to understand the forces at work and make predictions about where the ultimate shoreline will be, then come back in later years and see if we were right or not. We should learn a lot from this process.”

That knowledge, he said, may help scientists not only to better understand past tsunamis, but also to assist in recovery from those yet to occur. And one of the prime candidates for such an event is the Pacific Northwest coast of the United States and Canada, where the Cascadia Subduction Zone is nearly a geologic twin to its Indonesian counterpart. It’s believed that this zone has had several subduction zone earthquakes in the past 1,000 years, the last of which may have occurred in 1700.

“We’re already learning, just from what we’ve observed in Indonesia, that you must be very cautious what setbacks to allow for new construction and rebuilding after a major tsunami or land subsidence,” Ruggiero said. “Hopefully we’ll be able to develop computer models that will allow us to predict the final shape of the shorelines with more accuracy. And those shores may be dramatically different that the ones we now have.”

Media Contact: 

Peter Ruggiero,

Multimedia Downloads

Indonesia ravaged by the 2004 tsunami.

Stumps of dead trees slowly decay in what used to be the shoreline, rather than ocean, of parts of Indonesia ravaged by the 2004 tsunami.

Study Finds 2004 Oregon Quakes Were in “Locked” Area of Tectonic Plate Boundary

CORVALLIS, Ore. – A pair of modest earthquake clusters that occurred off the Oregon coast in 2004 may be more significant than scientists initially realized after detailed analysis of the main shocks by researchers at Oregon State University.

The newly published study found that the quakes probably occurred on the fault that forms the boundary between the North American and Juan de Fuca plates at a depth where the fault is thought to be “locked.” While earthquakes occur frequently in the upper and lower plates in the Cascadia subduction zone, there haven’t been any instrumentally recorded quakes on this boundary, according to Anne Trehu, a professor in the College of Oceanic and Atmospheric Sciences at Oregon State University and lead author.

Results of the study were announced this week in the journal Geology, published by the Geological Society of America.

“We don’t really know what they mean,” Trehu said of the clusters. “But this is an area with a great deal of paleoseismic evidence for very large earthquakes, so documenting such activity is significant. As we learn more about seismic behavior and associate that with the structure of the plates and faults, we will be in a better position to develop models for what might happen and when.”

Research by one of Trehu’s colleagues, OSU’s Chris Goldfinger, suggests that there may have been as many as 23 major earthquakes in the Cascadia subduction zone over the past 10,000 years. The last known major plate boundary earthquake took place on Jan. 26 in the year 1700, rupturing the entire subduction zone. Scientists know a fair amount about that earthquake, estimated at magnitude 9.0, because of written records of a corresponding tsunami in Japan, as well as plentiful geologic evidence.

The moderate 2004 earthquakes off the central Oregon coast were felt as far east as the Willamette Valley, but did little if any damage to coastal communities. The first, of magnitude 4.9, occurred on July 12 just off Newport. It was followed on Aug. 19 by a magnitude 4.8 earthquake just to the south, near Waldport. Smaller earthquakes occurred near the same spots in August of 2007.

The research by Trehu and colleagues Jochen Braunmiller and John Nabelek found that they occurred about 10-15 kilometers below the surface, and just 10-15 kilometers off the coast.

Most of the earthquakes in the Pacific Northwest have occurred in the upper plate and some have occurred in the lower plate, Trehu said. But portions of the boundary region – where the Juan de Fuca plate is being subducted beneath the North American plate – have been without recent seismic activity and are thought to be locked.

“These earthquakes are telling us something about the nature of the plate boundary,” Trehu said. “It could be that they result from sudden slips on strong patches of the plate boundary, whereas most of the plate boundary slips without generating earthquakes large enough to be recorded on land. Or they could reflect weak patches on an otherwise locked fault.”

Trehu recently installed a temporary onshore/offshore seismic array to try to determine which of those possibilities has the most merit. Her project was funded by the Marine Geophysics and EarthScope programs of the National Science Foundation.

The subduction of the Juan de Fuca plate beneath the North American plate is a slow and intermittent process. Averaged over geologic time – in this case, many millions of years – the plates move past each other at a rate of about 4.5 centimeters a year, Trehu said.

Beneath the continental margin, where the plate boundary is relatively cold, this motion takes place during infrequent and irregular intervals – as do the large earthquakes that may take place. Where the plate boundary is deeper, the plate motion occurs in slow events that take place at regular intervals in a phenomenon known as episodic tremor and slips, or ETS.

Another objective of the NSF-funded seismic array is to test whether ETS can trigger slips on the shallow part of the subduction fault.

“Evidence in the paleoseismic record shows that these plates tend to get stuck for a while, and then unstuck, resulting in major earthquakes,” Trehu noted. “Just what it is that triggers major quakes, though, is the million dollar question. For seismic researchers, it is the Holy Grail.”

Media Contact: 

Anne Trehu,