August '05 Newsletter

Civil engineering professor Steven Glaser can't see the Hayward Fault from his office in UC Berkeley's historic Hearst Memorial Mining building, but he knows it's there. "Just on the other side of that structure over there is the fault," he says, gesturing towards a window. Is he worried? Not really. Thanks to a recent $90.6-million renovation, the building now rests on 134 stainless steel and rubber "base isolators" which act like shock absorbers in the event of a quake. "As long as we move less than 37 or 39 inches, we're OK," he says with a shrug.

Of course, Glaser knows not everybody can be so cavalier. For people living in earthquake-prone places like California and Japan, the possibility of a major quake is an uncomfortable fact of life. And while seismic engineering, like the Berkeley-developed system used in Hearst Memorial, has greatly improved since the '89 quake rocked the Bay Area, there's still plenty of room for improvement.

Enter Terra-Scope™, a CITRIS-sponsored and NSF-funded project aimed at taking an existing seismological technology, the vertical seismic array, and using MEMS (micro-electromechanical systems) to make it small, cheap, and easy enough for anyone building or retrofitting a site to use. After several years of work, Glaser believes the system is almost ready for its first trial run. He plans to place two miniature vertical seismic arrays on either side of the Hayward Fault that transects Berkeley's Memorial stadium, which will soon be undergoing seismic renovations of its own.

At its most basic, a seismic array is a network of seismographs, instruments that record ground movement, spread across a geographic area. First developed in the late 1950s to monitor underground nuclear explosions, they have become a key tool in understanding how terrain responds to earthquakes. In the case of vertical seismic arrays, they are arranged deep into the Earth rather than spread across the surface, providing detailed information about how the seismic waves change as they past through the various layers of soil, information that's especially useful if you are retrofitting or constructing a building.

"With a vertical seismic array, you would know what types of accelerations, what types of ground motions the structure you had there would be subjected to so you could retrofit it or design for it. And it helps us intellectually understand a bit better how sites behave in general," says Glaser. There's also a preventative use. The smaller, initial portion of the earthquake called a P-wave, when detected by VSAs, could activate automatic shutdowns of train systems seconds before the big one hit, preventing earthquake-triggered train derailments. Meanwhile foreshocks can predict large-scale site behavior based on small foreshocks.

Unfortunately, current VSAs are too pricey to be used for construction projects. "Right now these cost hundreds of thousands to millions of dollars to install. We're trying to make it so that each pod would cost in the $5000 to $10,000 range. If it's cheap enough, every structure could have one," Glaser explains.

In Glaser's system, seismic waves traveling through the Earth would strike a series of networked pods arranged vertically along a 2-inch diameter hole. As the waves passed through each pod, it would record a range of readings: acceleration, tilt, and pore pressure. When the aftershocks followed, a built-in memory buffer would allow the pod to record those while still processing the main quake's impact. The combined measurements would be transmitted to a base station to be interpreted and posted online.

Of course, nobody wants to wait until the "big one" to find out whether they're standing on shaky ground. A key part of Glaser's system is a computer model of the soil that uses the VSA's data from smaller "microearthquakes" to predict what would happen in larger ones. To test their model, Glaser and his team analyzed data acquired by standard vertical seismic arrays during the massive 1995 earthquake in Kobe, Japan, and then ran the same analysis on much smaller foreshocks. What Glaser found is based on the small quakes the model "could predict, wiggle for wiggle, what the output was going to be" for a large quake.

"We've found that a very simple model works better than a complicated model," he explains. The streamlined data means less for the device to process and the user to wade through. "Instead of having to send lots of data, we would like to send information," Glaser says.

This is not the first time Glaser has used MEMS devices for seismological research. This current work springs out of a CITRIS project from 2001. He and several other CITRIS researchers instrumented a building with wireless sensors that would detect when it had suffered potentially hazardous structural damage in a quake. There are also plans to use sensors developed by Glaser to detect movement of soil in the retaining walls CITRIS's new headquarters.

For more information:

Terra-Scope™- a MEMS-based Vertical Seismic Array
(PDF file)

Steven Glaser's Web site

Intelligent Sensor Motes for Vertical Seismic Arrays

"Casting the Sensor Net" by Gregory T. Huang
(Wireless News Factor, July 9, 2003)

National Workshop of Future Sensing Systems

MEMS and Nanotechnology Clearinghouse

"Smart Buildings Admit Their Faults" by David Pescovitz
(Lab Notes, November 2001)

"Hearst Memorial Mining Building reopens"
(Berkeleyan, September 19, 2002)

"Architect for Memorial Stadium Renovation Announced"
(Cal Football, May 9, 2005)

The Pacific Ocean is a familiar sight to coastal Californians, yet what happens below the surface remains unknown to most of us. In hopes of cracking that mystery, Dr. Daniel P. Costa, a CITRIS-affiliated professor of Ecology and Evolutionary Biology at UC Santa Cruz, and colleagues Barbara Block at Stanford University, Steve Bograd at NMFS, and Randy Kocehvar of the Monterey Bay Aquarium have launched an ambitious project aimed at exploring and mapping the Pacific with unprecedented detail. To accomplish this ambitious goal, his team has enlisted some very unusual research assistants.

Who better to reveal the mysteries of the deep than those who live there? Named Tagging of Pacific Pelagic (TOPP), Costa’s project is equipping Pacific Ocean dwellers with the latest in sensor and satellite communication technology to provide an “organism’s eye” view of their habitats. California sea lions, massive Humboldt squid, albacore tuna, sooty shearwaters, and humpback whales are just some of the 21 species recording the depth, temperature, salinity, chlorophyll content, and precise location of their whereabouts on a nearly continual basis, with a few of these 1850 animals transmitting their journeys 4-6 times a day via satellite to TOPP’s Web site .

“These animals give us an ability to sense environments that otherwise aren’t accessible with the current technology,” says Costa, who is one of four principal investigators on the project.

Take the northern elephant seal, whose foraging trips throughout the northeastern Pacific and coastal regions can last anywhere from two to nine months and involve many long dives deep below the ocean’s surface. Just one seal can cover 90 kilometers in a day. Based on whether a seal is diving or near the surface or somewhere in between, researchers can determine what it’s up to at any given time or place along the way.

By combining the small-scale data and behavioral information from these elephant seals and other tagged critters with large-scale information on ocean color, temperature and ocean height collected by physical and biological oceanographers, Costa believes a much better understanding of the ocean will emerge.

“It’s a win-win. Physical oceanographers can add this incredible data stream to their existing data sets and can do a better job untangling the physical oceanography of the North Pacific Ocean. Together we can create a better understanding of the habitat these animals live in, which leads to significant increases in our understanding of how animals work and what they do below the surface,” he says.

That knowledge is important not only in and of itself, but also because it can be used to aid climatologists in their understanding of global climate change. It can assist fisheries in making better decisions on where and when to fish so that they don’t over-harvest or accidentally ensnare endangered species. Based on improved behavior knowledge, protected areas can be carved out near breeding and feeding grounds. Additionally, one of TOPP’s main goals is to pioneer new technology and techniques for mapping oceans and share that information so that future researchers can start to map their corners of the world. A similar mapping project is already underway in the Antarctic using TOPP-developed technology.

Although tagging marine animals with sensors has been going on since the 1960s, only in the past decade has the right combination of technologies existed that enable TOPP’s approach. Satellite capabilities have made it feasible to track the precise location of tagged animals, while the miniaturization of electronics have helped make the equipment less obtrusive. The sensors themselves have become capable of retrieving, processing, storing, and transmitting increasing amounts of data. The ability to compress and send that information to satellites which then transmit it to TOPP’s Web site is yet another piece of the puzzle that’s only recently fallen into place. Finally, there’s the monumental task of managing all these data sets.

“One of my main interests in working with researchers at CITRIS is that those guys are on the cutting edge of developing these types of tools,” says Costa.

TOPP, which kicked off its planning stage in late 2000 with 70 participants from five countries, is a pilot program of the Census of Marine Life (COML), a ten-year project which according to its Web site aims “to assess and explain the diversity, distribution, and abundance of marine life in the oceans” by 2010.

“The idea is to ratchet up our understanding of the ocean and marine life--where it is and how it lives in the ocean--and these efforts will be akin to the human genome project, catalyzing an increased knowledge,” says Costa.

For more information:

Tagging of Pacific Pelagics

Census of Marine Life

Daniel Costa’s CITRIS Corporate Sponsor Day presentation ( PDF | Video )

Daniel Costa’s Web site