Time is of the Essence
CGS, Partners Working to Provide Early Warning of Earthquakes
There may not be a line item on the CGS budget for Rosetta Stone software, but becoming bilingual is a key to providing early warning of an impending earthquake. For CGS’ seismic instruments, that is, not the staff.
CGS’ Strong Motion Instrumentation Program (SMIP) has installed earthquake monitors throughout the state. They are designed to do one thing, and do it well: provide data on how earthquake shaking impacts the building, bridge, or other structure to which they’re attached or, in some cases, the ground into which they’ve been placed. The information helps engineers improve building codes and make structures more resilient to earthquake ground shaking.
But SMIP is in the process of replacing some of those instruments – the “free field” variety, not those attached to a structure – so they can do two jobs: continue to provide strong motion data and also contribute to the state’s developing earthquake early warning network.
“The new instruments can do both – symbolically, they can speak French and switch to German when they need to,” said Dr. Tony Shakal, the Supervising Geologist who heads SMIP. “The old instruments could only speak French, and only through one pathway, the phone lines. The new instruments will be able to speak both and communicate over phone lines as well as the cellular system.”
Early warning relies on immediate, dependable communication, and big earthquakes have a way of messing with that. So having a couple of options to ensure the flow of information is critical.
Not only do the new instruments parlezvous and sprechensie, they also can communicate at different rates, depending on whether they’re sending data to SMIP processing center headquarters or to the early warning central computers at the California Institute of Technology in Pasadena and U.C. Berkeley’s seismology lab in Menlo Park.
Another significant difference between the old instruments and their replacements is that the new ones will transmit data all day long, every day. The old ones basically worked a part-time job.
“The early warning centers get a continuous stream of readings, even if it’s just vibration associated with everyday road noise – trucks going by – or nothing at all,” said. “Our old instruments wait for an earthquake and then harvest the data.”
SB 135 (2013) committed California to develop and fund an earthquake early warning system by July 2015, a deadline later extended to July 2016. CGS, the U.S. Geological Survey, the California Institute of Technology, U.C. Berkeley, and the private sector all are involved. Full implementation is expected to cost about $25 million, with an annual maintenance budget of about $12 million, according to State Geologist Dr. John Parrish, who heads CGS. The Governor’s Office of Emergency Services has been tasked with securing the funding, and may get some help from Congress: On October 29, three dozen representatives of Western states asked President Obama to put $16.1 million into the USGS budget next year for the system.
For the last year and a half, Parrish has been involved in management-level meetings while SMIP staff and others in CGS have been involved in technical meetings about how the network would be integrated across three other early warning systems in some phase of development.
s of October 1, CGS and partners had more than 400 instruments in place for the initial phase of the network. Ultimately, the state will be covered by about 1,100 instruments – including about 150 operated by SMIP -- capable of providing early warning.
“We’re concentrating initially in the high-population areas that have significant earthquake histories -- the greater Los Angeles area and the Bay Area,” Parrish said. These are some of the highest risk areas in the state.”
The instruments, Shakal noted, must be “in the right strategic locations to be effective at providing early warning.” To illustrate, he sketched a pattern of connected circles that looked somewhat like bubble wrap.
“You have to place the instruments at a certain distance from the epicenter,” he continued. “The closer to the epicenter the better, certainly, but the idea is to have a density where there’s an instrument in the middle of a 10-kilometer `bubble’ in urban areas and a 20-kilometer `bubble’ in more rural areas.”
A denser array wouldn’t work, according to Parrish, because of a scientific principle called “TMI.”
“You can’t have too many instruments involved because you don’t want to overload the computers that are analyzing the incoming data,” he said. “The computer has only a couple of seconds to take in and process the data. If that process is too slow, you can’t get the warning out in time.”
arthquakes send out two sets of waves from the epicenter: primary or p-waves, which are faster but don’t pack much of a punch, and secondary or s-waves, which are relatively slower and do most of the damage. The p-waves travel between 3,600 mph and 16,000 mph, depending on the rock type in the ground. The sensors pick up the p-waves and trigger a warning before the slightly slower s-waves arrive.
During the 2014 Napa earthquake, scientists in Berkeley received about 10 seconds of warning that shaking was coming using their developmental system. Ultimately, downtown Los Angeles could get close to a minute of advance notice of a big quake occurring on the San Andreas Fault near the Salton Sea. That, however, is a best-case scenario for advance notice.
“The thing about early warning in California, we’re not like the models in Japan or Mexico,” Parrish said. “Their major faults are 100 miles offshore, so their early warning systems can give communities in the interior of the country up to a couple of minutes’ warning. In California, we live right on top of our most dangerous faults. Our warning systems are most likely only going to give us an alert a few seconds in advance of the heavy shaking.
“One of the models that we put forward was to use the 10 seconds or so to lock down California’s moving infrastructure prior to the seismic waves hitting. Mechanical responses can lock down vital industrial operations such as assembly lines. Elevator systems can shut down, fire doors can be raised, cranes at container docks can be halted, schools can be notified, trains or subways can at least start to slow down. Machines can react in a nanosecond; that’s where the real benefit will be.”
If you’re driving your car you might get enough warning to pull over to the side of the road. If you’re a doctor, you can stop operating. If you’re a dentist, you can stop drilling. If you’re a mechanic, you can get out from under the car that’s on a lift.
Parrish pointed out that the advent of an early warning system doesn’t mean that people shouldn’t take the personal preparation steps that are recommended now, including having enough supplies to last until help arrives and a plan to reunite if a quake occurs while the family is scattered.
“The average person is going to have just enough time to take cover,” he said. “So we’ll still recommend that people practice the drop, cover and hold on drill, as they do in the Shakeout.“
And because earthquakes can happen at night – and not everyone can manage to get out of bed and under a desk in 10 seconds – it’s important that people fasten down or remove objects that might fall on them in heavy shaking.“Ultimately, it may be more important to improve the infrastructure and bring older buildings up to code,” Parrish said, adding: “The buildin g code is what we’re really counting on to save lives.”
Hand in hand with getting the early warning system fully implemented is educating the public about how to use that information.
People should be safe in modern high rises or on major bridges, even in a maximum credible earthquake, Parrish believes. But even if those structures survive a big quake, that doesn’t mean society is out of the woods.
“Currently, our building codes mandate that we build to `life safety’ standards; that is, to make sure that a building doesn’t collapse,” he said. “However, a lot of buildings in the commercial centers could be uninhabitable after a big earthquake. So the discussion among scientists, planners and engineers is whether we ought to build to an even higher standard to ensure that the buildings are useable after a major earthquake and everyday activities can continue. Right now, only hospitals are held to that standard. The newest ones are built like tanks.”
“How do you convey a warning of imminent danger without causing panic?” Parrish said. “How does the public know how to react? Currently, the limited early warnings we have go to the police and fire departments rather than the general public. We want the emergency services providers to be ready to react. What about the person who happens to be driving over the Golden Gate Bridge; when we say `earthquake coming!’ are they likely to stop because they know the bridge is going to survive the earthquake, or are they going to panic, speed up, and cause an accident?”
Parrish offered another caveat: The warnings have to have near-100 percent accuracy; if not, the public will soon tune out the alerts.
Still, he added: “It’s a great ideal. It will be beneficial. We’ll save infrastructure and allow the economy to spring back faster after a big earthquake.”
Even though ramping up the early warning efforts is a big task, Shakal said the timing was “quite serendipitous” for SMIP.
“The manufacturer of our old instruments no longer makes or supports them, so we’ve been scavenging parts from broken instruments to keep other ones running,” he said. That’s a limited game going forward. The new instruments have some very positive features … They will not only contribute to early warning, but they’ll improve our ability to do our primary mission through improved robustness of the instrumentation. It’s a win-win.”
Back to Top of Page
CGS’ Tony Shak al Honored
Longtime Head of Strong-Motion Program Gets Prestigious Award
Two earthquakes, spaced about a decade apart, prompted Tony Shakal to divert from his chosen career path and become the award-winning supervisor of an award-winning program for CGS.
The first was the devastating 1971 San Fernando Earthquake, a magnitude 6.6 temblor that killed 65 and injured 2,000. Although Shakal was clear across country, in Boston, at the time, he was moved by the event. “I read that a veterans’ hospital had collapsed and I thought to myself, `geez, those guys have already fought in a war, and now this happens,’ ” Shakal recalled. “I was in graduate school (at the Massachusetts Institute of Technology) at the time studying civil engineering, and it made me think about a different aspect of engineering -- building things resistant to the forces of earthquakes, and you need data to do that.”
Shakal shifted his emphasis to seismology and after receiving his doctorate took a position at the Lawrence Livermore National Laboratory in the Bay Area. That’s when the second earthquake occurred. The 1980 quake was significantly smaller than the San Fernando event, magnitude 5.8, and didn’t cause any fatalities. But it did millions of dollars of damage around the sprawling laboratory campus and shook Shakal into another personal seismic shift.
“Nothing like the experience of being shaken in a strong earthquake to make you think,” he said, adding: “It moved me from the theoretical side to real world applications. We had some people from the Division of Mines and Geology (the former name of CGS) visit the lab, and I asked them when the strong-motion records would be available. They said, `it’s going to be a while.’ I was disappointed with that answer. When the opportunity to join the strong motion program came up a short time later, I decided to explore it. I’m happy to say that now we can share data within minutes of an earthquake. In fact, it’s automatically posted on the Web worldwide.”
That’s one of the reasons that Shakal, who has been with CGS’ Strong Motion Instrumentation Program (SMIP) for 32 years and led it for 27, is the recipient of the 2014 Bruce A. Bolt medal. The award is presented jointly by the Seismological Society of America, the Consortium of Organizations for Strong-Motion Observation Systems, and the Earthquake Engineering Research Institute.
“This is a tremendous honor, no doubt,” Shakal said. “Bruce Bolt headed the Seismic Safety Commission for many years and was highly respected in both the seismological and engineering communities. It’s gratifying that not only my work, but more importantly the work of our program, is recognized and valued by our peers. For a time, Bolt also headed our Advisory Committ ee, which has been helpful in keeping us focused”
According to the announcement, the award “was established to recognize individuals worldwide whose accomplishments involve the promotion and use of strong-motion earthquake data and whose leadership in the transfer of scientific and engineering knowledge into practice or policy has led to improved seismic safety.”
The announcement further noted that SMIP “operates the largest and most advanced strong-motion network in the United States.” That includes 5,000 accelerometers to measure strong motion at nearly 1,200 stations around California – more than 850 free-field ground stations, more than 80 bridges, and 200 buildings. The announcement hailed SMIP as “the largest strong-motion component in the U.S. Geological Survey’s Advanced National Seismic System” and pointed out that the program’s data is used in the California Building Code to make structures more earthquake resilient.
In 2006 – the 100thanniversary of the Great San Francisco Earthquake – SMIP received the Applied Technology Council/Engineering News Record joint award as the Best Seismic Program of the Twentieth Century.
“My heartfelt congratulations to Tony for this well-deserved honor, as well as my sincere appreciation for the contributions he and his staff have made both to science and public safety,” DOC Director Mark Nechodom said. “SMIP’s work is truly remarkable, and so crucial to helping not just Californians, but also the world’s communities to better protect themselves, their property, and their economies from the catastrophic effects of earthquakes.”
“Everyone at CGS who has worked with Tony over the years is very excited about his receiving this grand award,” State Geologist John Parrish said. “It truly could not have been given to a more deserving individual. Under Tony’s leadership, the CGS Strong Motion Program has achieved both national and international recognition as the best there is – and it doesn’t get any better than that.”
In turn, Shakal called CGS “a great place to contribute to progress,” adding that at DOC, “it seems like there’s a real focus on getting things done.” Naturally, he had high praise for the SMIP staff.
“Moh Huang heads our engineering efforts, and he has probably planned more seismic sensor locations in structures from blueprints than any person on Earth,” Shakal said. “Carl Petersen does a great job of managing and coordinating our crews out in the field, where they are installing stations as well as maintaining the 1,200 stations already out there. Hamid Haddadi and his group are doing a wonderful job of getting the data out there on the Web to share it with engineers and scientists all over the world, which is unprecedented. I’m privileged to work with such talented, dedicated people.”
While Shakal has many reasons to be proud of SMIP, including automated recovery of data, he’s perhaps most proud of a change in perspective instituted 15 years or so ago, when the program went a step beyond its mandate of measuring strong shaking.
“The question we asked was, now that we are learning what the shaking is, does the building code accommodate that shaking?” Shakal said. “We wanted to get the data analyzed by the people who write the code, and not just take measurements.”
After three decades, you might think that Shakal has seen it all. But he is constantly invigorated by new challenges, new information and new ways of doing things.
“There are some developments we’re working on right now, in fact,” he said, “things that evolving technology has made possible.”
One example of that is SMIP’s “QuakeRocks” – relatively low-cost recording instruments hidden inside a fake rock made of Fiberglas that can be placed out in the open without much fear of tampering. SMIP’s field crews are installing those in several locales close-in to faults where few records have been obtained. Additionally, SMIP is currently placing sensors on two bridges in Long Beach, one of which is the first of its kind in California, meaning it eventually will provide unique data.
“There’s never a dull moment,” Shakal said. “We set traps for earthquakes. It’s like any trap: you have to wait. In our case, we’re waiting for good shaking records.”
In other words, he’s rooting for an earthquake?
“Only if it’s in the right place and no one gets hurt,” he said with a smile.
Back to Top of Page
SMIP Bridges a Data Gap
CGS Program Puts Instruments on New Bay Span & at Devil’s Slide
For most state workers, Labor Day weekend means a relaxing long weekend and perhaps the last barbeque blowout of the summer. Not so for the technicians who install seismic monitors for CGS’ Strong Motion Instrumentation Program (SMIP). They, like their colleagues at Caltrans, had a lot of work to do.
With little potential commuter traffic to disrupt, Caltrans closed the Bay Bridge -- used by about 280,000 vehicles daily -- over the Labor Day weekend. That gave Caltrans and SMIP alike the opportunity to do some much-needed work without having to play dodge-car. The much-anticipated new eastern span of the bridge opened for traffic going into San Francisco the night of September 2.
“We were able to access areas that we normally can’t, so we took the opportunity to do some repair work on the western span,” said Dr. Tony Shakal, the supervising geologist in charge of SMIP. “A number of our sensors had stopped working, but we managed to bring them back up to full operational level.”
SMIP’s accelerographs collect data about the response of buildings and structures to ground motion. After an earthquake, the information – used to improve public safety, and help emergency responders and local planners – is transmitted from the instruments to central computers at headquarters in Sacramento (see the information box at left).
The Bay Bridge is only one of many Bay Area structures the program has instrume nted. Others include the new Rincon Tower, the Golden Gate Bridge and San Francisco City Hall. Each project poses unique challenges, but the Bay Bridge may have been the “uniquest” to date. The eastern span runs from Oakland to Yerba Buena Island in San Francisco Bay. It is divided into four parts:
♦ The self-anchored section, featuring a single 525-foot tower, which Shakal called “the most visually dramatic and really the most interesting and most advanced part, in terms of engineering.”
♦ The Yerba Buena Island transition structure, where traffic transitions from side by side to above and below from the island to San Francisco.
♦ The 1.2-mile Skyway, parallel five-lane viaducts running from the self-anchored section toward Oakland.
♦ The Oakland touchdown section on the eastern landfall.
SMIP fully instrumented the Skyway section three years ago; the self-anchored and transition sections are about 60 percent complete. SMIP hasn’t had the opportunity to do much on the Oakland landfall portion yet.
“Over Labor Day, Caltrans was demolishing concrete, pouring new concrete, scrambling as fast as they could on that part,” Shakal said. “We haven’t instrumented there yet; they’re not ready for us.”
The self-anchored section (SAS) was a bit of a head-scratcher for SMIP because, Shakal noted, it’s “not a typical suspension bridge. The design is very unusual.”
A Caltrans Web site devoted to the bridge project explains the section thusly: Traditional suspension bridges have two separate main cables with smaller suspender cables connected to them. These cables support the roadway deck and are anchored to separate structures in the ground. By contrast, although there appear to be two main cables on the SAS, there is actually just one continuous main cable that is anchored within the decks at the eastern end. This cable is carried over the tower and wrapped around the two side-by-side decks at the western end.
“People say, driving through, it has sort of a cathedral effect,” Shakal added. “The way it’s designed makes it more important to instrument what the cables themselves are doing, because they have a different role than on traditional bridges. Putting instruments high on the cables – that’s a first for us. It will be a unique set of data, our first opportunity to record the motion of the cable. We’re not quite sure what we’ll get from the readings, but we’ve tried to design it so wind doesn’t trigger our instrumentation.”
Steve Fife, Donald Leiser, Adam Bollinger, Victor Fong and Vladimir Golod placed 54 instruments on the self-anchored section. All told, the new eastern span will have almost 200 sensors (the western span has about 80). Fife was the only member of the crew who went on the cable.
“Walking the cable and then sitting at an angle facing down and leaning out to put the sensors in – that was a new experience,” he said. “They always tell you `don’t look down’ so you don’t get nervous, but I didn’t have much choice. You don’t know how you’re going to deal with it until you actually do it. I just tried to focus on what I had to do and not think about where I was.
“Years ago, I went to the top of the Golden Gate Bridge towers to place instruments, and that was cool, too. But at least there was something under me there. This was a unique experience. I’m glad I got to do it.”
Once Fife secured the instruments to the platform, he walked up the cable to the top of the tower and across to the other side to place more sensors, then down the cable. The work was done over a couple of days.
“The view was awesome, and not many people get to see it,” he said. “That climb was something else. The cable gets more and more vertical as you get closer to the top. The last couple of sections, you’re moving your feet, but you’re mainly pulling yourself along by the handrails.”
The new span – billed as the largest single public works project in state history -- was 11 years in the making. The project was necessitated by the 1989 Loma Prieta earthquake, which caused a section of the bridge east of Yerba Buena Island to collapse. Caltrans engineers say the replacement will last a century and a half, and be able to take the largest earthquake anticipated in the next 1,500 years.
Farther south, on the San Mateo County coastline, SMIP has completed its instrumentation of a Caltrans bridge and tunnel set in the area of the notorious Devil’s Slide. Since 1940, landslides have made Highway 1 impassable in that area several times. The highway is now routed through the mountain.
“Installing instruments in a tunnel is always an unusual situation, but so much prep work was done by our staff – mainly Carl Petersen and Moh Huang – and Caltrans at the blueprint stage that we had relatively few hitches,” Shakal said. Caltrans went through a mountain and then over a canyon to try to avoid the road that kept washing out.”
SMIP and Caltrans officials are also working on another project: the fourth bore of the Caldecott Tunnel, which carries State Route 24 under the Berkeley Hills to connect Oakland with Contra Costa County. Construction of the 3,389-foot long, 41-foot wide tunnel began in February 2010, and excavation was finished in August 2012.
“Caltrans’ work will be done in the next month or so,” Shakal said. “Their electrical contractors are running cable to central locations, and if they’re terminated correctly in pigtails, we can hook up our sensors without any difficulty.”
SMIP has instruments in the third tunnel bore, but will have a more robust array in the new one.
“We only put sensors in half the (bore three) structure, assuming that there was symmetry and any records would be very similar,” Shakal explained. “Today, the approach is to instrument the entire structure, so we’ll have a set of sensors every 1,000 feet or so.”
Elsewhere, SMIP is preparing to instrument a state courthouse in San Bernardino that is near both the San Andreas and San Jacinto faults.
“The challenge is to install instrumentation that will not interfere with the courts or with the jail operations in the same building,” Shakal noted.
SMIP also is involved as California dips a toe into the issue of creating an earthquake early warning system, something in place in Japan and some other countries that experience frequent large quakes. Governor Brown recently signed SB 135, which instructs the Office of Emergency Services to develop a system based on the California Integrated Seismic Network (CISN).
SMIP has the bulk of earthquake sensors in the network, which also includes the U.S. Geological Survey, Caltech and UC Berkeley. The Los Angeles Times noted that the legislation called for a public-private partnership to create the proposed system and provided no additional General Fund support. The estimated price tag is $80 million to start up and operate the system for five years.
State Geologist Dr. John Parrish, head of CGS, explained that the CISN partners divvy up $2.5 million in funding now and, unless additional money is found, they’ll simply have to focus on early warning rather than current priorities and develop a statewide system over time.
“Our instruments are geared toward strong motion,” Parrish explained. “In order to put out an early warning, you need weak motion data. We can adjust our instruments to do both jobs by putting another little gizmo on them at a cost of about $15,000 per site. Of course, that will only be needed in certain strategic locations important to early warning, not at all the locations where we have them now.
“The biggest expense will be keeping the communications lines open at all times, whether it’s a phone line, cell service or internet connection, and to monitor that in real time. The way it works now is that when our sensors feel strong motion, they wake up and transmit to SMIP headquarters, which is more economical.”
Parrish predicted that an early warning system will become reality in California eventually, and that one determining factor will be the federal budget, which of course impacts USGS.
“I don’t know where their priorities will be,” he said. “We may have to move forward at a relatively slow pace.”
In March, a USGS test provided about 30 seconds of warning of a magnitude 4.7 earthquake in Riverside County. In Japan, many residents received notification up to 40 seconds prior to a major 2011 earthquake. However, Parrish cautioned that some of California’s major cities are closer to large faults than those in Japan, so there will be less time to react. Also, he noted that Japan’s system – regarded as the gold standard – produces a fair number of false alerts.
Currently, SMIP’s involvement in early warning consists of contributing data from a set of specialized instruments. Some of these are located in the California Valley, just south of Parkfield in eastern Monterey County, which is thought to be a likely spot for the next major earthquake to start.
“The California Valley is at the northern end of the southern segment of the San Andreas Fault,” Shakal said. “We have stations on each side of the fault that have been upgraded to provide real-time data to Caltech in Pasadena. The thinking goes that if an earthquake starts there, our data will travel at the speed of light to Pasadena, and they’ll be able to provide several seconds of warning to the public of a magnitude 6 or larger earthquake.
“This is one of only a few spots that have instruments that are specially designed for this purpose; that’s the problem they’re facing now – getting funds for more sensors with real-time communications out in the field. Typically we’re recording strong motion data for engineering purposes. But that same data can be used to produce a warning as well. Do you remember the old orange juice ad – `it’s not just for breakfast anymore’? The same is true of our data now.”
Back to Top of Page
A Towering Achievement
CGS, USGS Complete Seismic Instrumentation of S.F. Landmark
Standing in the posh hospitality room of the 64-story One Rincon Hill South Tower in downtown San Francisco, where residences sell anywhere from the $700,000s to more than $2 million, DOC Director Mark Nechodom reminded a horde of media members how remarkable and fragile it all is.
“If you were standing right here on Rincon Hill in 1906, you’d see a city in rubble,” he said, referring to the Great San Francisco Earthquake. “We are trying to improve our chances and the durability of the built environment the next time that happens. We’ve learned a lot in 100 years.”
The occasion was a news conference announcing that the seismic instrumentation of the landmark building had been completed, a first-of-its kind joint project by the California Geological Survey and the USGS. The data that the 72 seismic monitors – more properly known as accelerographs – collect ultimately may impact future building construction across the state and help protect public safety in earthquakes.
The federal survey bore the approximately $150,000 equipment cost, while CGS’ Strong Motion Instrumentation Program (SMIP) put the boots on the ground and the bolts in the wall, about a 50-50 split.
“This is a significant achievement for several reasons,” said State Geologist Dr. John Parrish, head of CGS. “First, this is the tallest residential structure in the U.S. with seismic instrumentation. Second, we believe we’re going to get some unprecedented data from this building because of its earthquake- resilient features, the concentration of the instrumentation, and its height. Third, this is the first time that USGS and a state survey have worked together on a project of this type and that cooperation has resulted in the densest array of instruments in any skyscraper in the U.S.”
Dr. William Leith, USGS Senior Science Advisor for Earthquake and Geologic Hazards, added: "I am delighted that the U.S. Geological Survey has collaborated with the California Geological Survey and the One Rincon Hill Association to install state-of-the science seismic instrumentation into this iconic building, which has a unique structural design to enhance its performance during earthquakes.”
So auspicious was the occasion that the Consul General of Japan, the Honorable Hiroshi Inomata (an acquaintance of both Director Nechodom and Parrish) was on hand to speak about the similar earthquake challenges faced by his country and California, and the importance of preparation.
There’s a 63 percent probability of a damaging earthquake magnitude 6.7 or greater in the next 30 years in the Bay Area. That’s the size of the devastating Northridge Earthquake of 1994 and just a tad weaker than the 1989 Loma Prieta quake that turned some parts of San Francisco to rubble.
The fact that downtown San Francisco is more or less equidistant from the dangerous San Andreas and Hayward faults was not lost on the One Rincon Hill South Tower’s designers.
At 641 feet high, the tower is not only among the tallest all-residential skyscrapers west of the Mississippi River but is the tallest building constructed using performance-based seismic design (PBSD) standards, which can improve design, cost less, and ease construction.
That technology “represents the future path of building design standards,” Parrish said.
The building’s thick concrete core is attached to “outriggers” -- tall columns of steel-reinforced concrete — by braces that act like shock absorbers during an earthquake. The braces are inside concrete and steel casings to ensure they maintain their strength during strong shaking. At the top of the building are four tanks capable of holding 50,000 gallons of water; the weight helps with stability both in strong winds and during seismic shaking. The foundation is designed to resist forces 2.5 times stronger than the building code requires.
“While this is an increasingly popular method of construction, it is still relatively unusual and thus we’re very interested to see the results from the monitoring instruments,” said Dr. Anthony Shakal, head of CGS’ Strong Motion Instrumentation Program (SMIP). “It’s important to see how a wide variety of buildings react to seismic shaking. We have a fairly robust collection of instruments on dams, bridges, low-rise buildings such as firehouses, and in the ground itself. We plan to instrument more high-rises and hospitals in the future.”
The seismic instruments, connected by more than two miles of cable, were placed inside the core “so as not to disturb the tenants and also to protect them from (activities in) the building,” Parrish noted, adding that the sensors “are already taking the building’s pulse.” Shakal, Moh Huang and Carl Petersen work on making arrangements to instrument buildings and structures around the state, including the Rincon Tower, and planning where the sensors will be placed. At Rincon, Rod Schoengarth led the actual installation, which also involved Don Leiser, Jeff Filak, and Adam Bollinger. The process of hooking up the tower took about five years, from inception to the news conference.
"It took us a while to get all of the pieces together," Shakal said, citing the need to coordinate with USGS, various parties involved with the building, and local authorities. “Once we did that, Rod and his folks did the instrumentation, and did a very nice job, by the way.”
The accelerographs measure the vertical and horizontal response of buildings, structures and soils to earthquake shaking. They produce a digital record from which the critical characteristics -- acceleration, velocity, displacement and frequency-- of the motion can be calculated. At the Rincon Tower, the instruments are clustered -- typically in groups of three – on 19 floors. There are six sensors at the base to capture data from the ground, but most of the sensors are in the upper stories, where the stress in the event of an earthquake is likely to be greatest.
The instruments at the One Rincon Hill South Tower are the latest high-resolution version – sensitive enough that the slight motion caused by a mild wind at the top of the building shows up on the monitors at CGS headquarters.
"It shows that at the roof, it's moving about nearly one thousandth of an inch, so you can see that's really high precision information we're getting," Shakal said, adding “What we would expect to see in a significant earthquake would be quite interesting. The tower is designed to sway up to three feet at the top.”
Ron Klemencic, president of Magnusson Klemencic Associates, the international structural and civil engineering firm behind the tower’s earthquake-resistant design, attended the event and praised the work of CGS and USGS.
“Our building is fortunate to be the first of its kind with such an extensive seismic monitoring system,” he said. “This is the next big step, collaborating with other professionals.”
Klemencic added that there is “tremendous value” in comparing and calibrating the mathematical models his company uses with the actual field data produced by the monitors.
“We’ve learned an awful lot, and we’ll put that knowledge to use in designing the next generation of buildings,” he said.
Construction is beginning soon on the second residential tower of the Rincon Hill complex – 52 stories and 541 feet tall – and the plan is to instrument that one as well.
Like Klemencic, Rincon complex developer Chris Collins took part in the news conference, which received widespread coverage in the Bay Area.
“This building is an engineering marvel,” Collins said. “It's also a place that 600 people call home. But I think what's amazing is it's now become an instrument to measure dynamic forces of nature … We’re thrilled to be part of it.”
SMIP has placed seismic monitors at a number of well-known structures in San Francisco, including City Hall, the Golden Gate Bridge, the 645-foot Millennium Tower on Mission Street, and the new Public Utilities Commission mid-rise on Golden Gate Avenue. Elsewhere in the Bay Area, instrumentation work was recently completed at the Eden Medical Center in Castro Valley and the Santa Clara Valley Hospital in San Jose. Work is ongoing at several locations in the region.
Within moments of a large earthquake, data from the seismic instruments are used to create a “ShakeMap.” Among other things, the ShakeMap helps emergency responders determine where the highest levels of shaking have occurred and thus where critical infrastructure – such as transportation corridors and water lines – is most likely to be damaged. The data also is disseminated to seismologists, engineers, building officials, and local governments. It has verified the performance of new types of earthquake-resilient construction and has contributed to improved formulas in the California Building Code for calculating building vibration periods, which is vital in earthquake- resilient design.
“California has the most stringent building standards in the world, thanks in part to the data collected by these instruments,” Parrish said. “Earthquakes that kill hundreds in other parts of the world cause relatively few casualties here. But when it comes to protecting public safety and property, there’s always room to improve.”
Director Nechodom reached back to 1986 for an analogy about the importance of planning and groundwork in general and SMIP in particular while addressing the media, later joking that he hoped he hadn’t alarmed some members of the audience. His father worked at the Hanford nuclear power plant in eastern Washington, and when the news broke about the Chernobyl disaster in the Ukraine, the senior Nechodom didn’t need to be told the details.
“They were doing some of the same experiments at Hanford that they were doing at Chernobyl,” Nechodom said. “The difference is that the people at Hanford were better prepared to handle an accident. And while earthquakes are much different than nuclear accidents, preparation is the key. Our investment in seismic monitors is significant. But a few million dollars spent here and there can save billions down the road.”
Back to Top of Page
CSMIP Receives Award from Applied Technology Council
The California Geological Survey’s Strong Motion Instrumentation Program (SMIP), which studies the effect of earthquake shaking on structures and soil to help guide engineering practices and protect public safety, has been honored as one of the top seismic programs of the 20th century by the Applied Technology Council.
“This award comes from an organization whose members use the data we produce, so this is a tremendous honor,” said State Geologist John Parrish, head of CGS. “We’re very pleased with and grateful for this recognition,” said Supervising Geologist Anthony Shakal, who heads SMIP. “The fact that the engineering community, which is the target of our work, recognizes the value of what we do tells us that we’re successful.”
The Applied Technology Council (ATC) is a nonprofit corporation headquartered in Redwood City. It was established in 1973 through the efforts of the Structural Engineers Association of California. ATC develops and promotes state-of-the-art, user-friendly engineering resources and applications for use in mitigating the effects of natural and other hazards on construction. ATC also identifies and encourages needed research and develops consensus opinions on structural engineering issues.
ATC’s board of directors includes representatives appointed by the American Society of Civil Engineers, the National Council of Structural Engineers Associations, the Structural Engineers Association of California, the Western Council of Structural Engineers Associations, and four at-large representatives involved in the field of structural engineering.
An ATC-commissioned jury selected award recipients. SMIP and the other winners were honored at a joint ATC-Engineering News Record event April 17 – the eve of the centennial anniversary of the Great San Francisco Earthquake -- at the Westin St. Francs Hotel in San Francisco.
Strong Motion Instrumentation Program colleagues (from left) Moh Huang, Supervising Geologist Tony Shakal, Carl Petersen and Hamid Haddadi celebrate an award from the Applied Technology Council.
SMIP – recently renamed the Earthquake Engineering Program -- was established in 1971 after the devastating San Fernando earthquake. It was tasked with obtaining vital data for the engineering and scientific communities through a statewide network of instruments. When activated by earthquake shaking, these “accelerographs” produce a record from which the critical characteristics of ground motion -- acceleration, velocity and displacement -- can be calculated.
The information is processed and disseminated to seismologists, engineers, building officials, local governments and emergency response personnel throughout the state. The data is used primarily to recommend changes to building codes, and assist local governments in their general plan process. SMIP also partners with the USGS, California Institute of Technology and UC Berkeley in the California Integrated Seismic Network. Real-time data collected by the network is used to produce a “ShakeMap” within minutes of a strong earthquake to help guide emergency response efforts.
SMIP has installed and maintains recording instruments at more than 1,000 locations statewide. The devices are housed in a variety of structures, including major bridges, high-rise buildings, dams, hospitals and industrial facilities. Among the instrumented sites are the city halls of Los Angeles, San Francisco and Oakland, and the state capitol. Accelerographs also are placed in open land to measure the motion of the ground and the effects of earthquake shaking on different types of soils. An advisory committee of engineers and scientists representing industry, government and universities help select SMIP’s station locations.
“I have a high regard for the work that SMIP does,’ said Christopher Rojahn, executive director of the ATC and a former research engineer involved in USGS’ strong motion program. “The program is very well organized. They’ve sought out the best advice in designing their program and provide a great service. The data SMIP got from its instrumentation in Parkfield is fundamentally important to our understanding of ground shaking.”
More than two decades of patience paid off for SMIP on September 28, 2004 when a magnitude 6.0 earthquake struck in Parkfield, a hamlet of 18 people located in rural southern Monterey County about midway between highways 5 and 101. The quake was centered almost directly underneath an array of 44 CGS and 10 USGS instruments. As a result, an unprecedented amount of information about how earthquakes work has been collected.
SMIP began placing instruments around Parkfield in 1982. Why there? Parkfield had experienced earthquakes in the magnitude 5.5 -6 range every couple of decades going back to 1857. The 2004 event was a late arrival: the previous significant quake in the self-proclaimed “Earthquake Capital of the World” occurred in 1966.
Among the most interesting findings out of Parkfield: an oddity noted in the measured peak acceleration, or movement. Shaking occurred at about a third the force of gravity in Parkfield, which is about six miles northwest of the epicenter and within a half-mile of the main branch of the San Andreas fault. However, both northwest and southeast of the village, SMIP instruments measured shaking that was three times as intense as the shaking in Parkfield.
“We were stunned with how much the ground shaking varied over a relatively short distance,” Shakal said.
That knowledge has called into question whether one of SMIP’s goals – at least one seismic instrument in every California zip code – is adequate. But as Shakal noted, the data gathered at Parkfield showed the benefits of sticking with a plan.
“Our greatest success so far probably has been staying the course,” Shakal said. “Thanks in no small part to our advisory committee, our stations have been well-placed and we’ve done a good job of maintaining them in the long haul. Those two things go hand-in-hand. The excellent performance we received from our 20-year-old instruments at Parkfield is a tribute to our field technicians.
Among SMIP’s current projects are the instrumentation of the new San Francisco Bay Bridge, several hospitals around the state, and wharfs at the Oakland, Long Beach and Los Angeles harbors. SMIP is also updating its older instruments, which capture ground shaking on film that has to be manually retrieved, with digital devices that report in real time to a central computer.
Back to Top of Page
SMIP Crew Reaches an Instrumental Milestone
CGS Has Installed 400 Seismic Monitors in Southern California
If a baseball player bats .400 for a season or slugs 400 home runs during his career, chances are he'll be in the hall of fame. Likewise, a quarterback who throws 400 touchdown passes during his career is destined for immortality.
If CGS's Strong Motion Instrumentation Program had a hall of fame Jim Agnew, Steve Fife and Ron Ayalaundoubtedly would be in it. And they probably wouldn't charge $10 for an autograph, either.
Those three recently reached a significant milestone, installing SMIP's 400th seismic instrument in Southern California as five years of work on the TriNet program concluded. Their work was recognized with Sustained Superior Accomplishment Awards at the recent DOC holiday party.
"There's a sense of accomplishment and pride throughout the whole SMIP team in getting 400 stations going," Fife said. "There was a lot of field time involved and a lot of coordination from headquarters. We were managing up to 60 ongoing projects at a time -- the instruments that were being installed, the ones that had just been installed and the next group to be installed."
Added Ayala: "The instruments will supply data that could help with emergency response if there's a major earthquake, so it's a good feeling to have contributed."
TriNet was one of the things to shake out of the 1994 Northridge earthquake. All 400 of SMIP's accelerographs are capable of dialing up a computer at CGS headquarters after recording strong shaking and transmitting their data over phone lines. With that information, CGS and its TriNet partners -- Caltech and the USGS -- can create a ShakeMap within minutes of a major quake. A ShakeMap pinpoints the location of greatest shaking intensity, which helps emergency response crews decide where to concentrate their efforts.
There were already some instruments in the field when the TriNet project began, but they were relatively low-tech. Someone had to retrieve the data from those instruments, a time-consuming process that was adequate for scientific research but not for emergency response.
"Our goal was to install 400 stations, either new ones or upgrades of the old analog ones, and Jim, Steve and Ron were the central people in getting that accomplished," said Tony Shakal, supervising geologist of SMIP.
The 400th SMIP instrument was placed in Los Angeles Fire Department Station 34 -- appropriate, since many of the accelerographs are housed in fire stations.
"We wanted to do things with a cost- and effort-minimizing approach, and we found that working through municipal agencies was a very effective way to go," Shakal explained. "Fire departments were the most receptive."
Initially, gaining permission to put in the instruments was challenging. The Los Angeles County Fire Department was the first to agree to installations. As the work continued, word got out about the potential benefit of ShakeMap to fire departments and other emergency workers, and more doors began to open.
"We like putting our monitors in fire departments because there's someone there 24 hours a day, so we don't have to worry about our $5,000 instruments disappearing," Agnew said.
SMIP has suffered its share of losses due to theft and/or vandalism over the years. Several years ago, instruments were stolen from a remote Mojave Desert location. So far, Agnew reports, no instruments placed in a fire department have been stolen. And none has caught fire.
Agnew's primary responsibility with TriNet was finding likely locales for instruments. When he spotted one-story structures of wood frame construction less than 4,000 square feet in size on a cement slab, Agnew had hit the jackpot. He was well-qualified for the job, having worked 18 years in private industry with a firm that installed seismic networks all over the country. He then worked at the Yucca Mountain nuclear waste storage facility in Nevada. Agnew wanted something a bit more challenging, and found it when he joined SMIP in March of 1998.
"Since the idea was to place one instrument per zip code, Jim had to work with a GIS map in his head," Shakal said. "He might come back from a field trip with 20 to 30 sites in mind, and maybe half of those survive our screening process."
In doing his scouting, Agnew flew into Los Angeles three or four times a month, hopped in a car and started fighting traffic in a frantic effort to see as many sites as quickly as possible.
"My record was 26 fire stations in one day," he said. "I didn't stop and talk to people, just drove by and took pictures. I got to know my way around Los Angeles to the point that I could probably get by without my Thomas Brothers map now, but I wouldn't want to try because the city's so big."
While Fife didn't tighten any nuts and bolts -- that was Ayala's role -- he was the nuts and bolts guy. A Senior Precision Electronic Specialist who has been with SMIP 11 1/2 years and on the TriNet project from the start, Fife took care of the details once Agnew did his scouting and made initial contact with the building's occupants. For example, Fife worked with fire chiefs to decide where the instrument would go in a station and where to put the GPS antenna.
"I made sure that Ron knew the project was doable before he went in to do his installations," Fife summarized.
Ayala, who estimates that he installed 280-300 of the 400 accelerographs, could probably mount an instrument and battery box in his sleep at this stage. But that was only half the battle. The other half was more complicated.
"In order to install an instrument, you need to get a phone line to it and hook it up to the antenna," he said. "Sometimes it got tricky -- for example, maybe the phone line I needed to tap into was in another building. Plus, when you're working in a fire station, you try to do your job while staying out of the way as much as possible."
The instruments often were placed under stairs or workbenches, places unlikely to trip up a hurried firefighter. Ayala discovered that gaining access to an installed accelerograph isn't always easy, even when it was placed in the perfect spot. One fire station put ductwork all around the instrument. "I have to do some crawling to get to that one," said Ayala, who celebrated his 10th year with SMIP on December 23.
SMIP's work in Southern California has wrapped up, at least for now. For the first time, however, there is money in the state budget to start installing instruments in Northern California, where there is, Shakal said, "a big vacuum." TriNet has become the California Integrated Seismic Network with the addition of UC Berkeley and the Menlo Park USGS network to the CGS-USGS-Caltech partnership. SMIP will install 150 instruments over the next five years from Bakersfield to Crescent City. But SMIP's work won't stop there.
"The goal remains one per zip code throughout the entire state, and there are 3,000 zip codes in the state," Shakal noted. "There are about 1,000 instruments running right now, and about half the Southern California zip codes are instrumented. But about 500 of those instruments are the old type that require someone to go out and retrieve the data. Those need to be replaced eventually. So there's a lot of work ahead of us."
Back to Top of Page
FOR IMMEDIATE RELEASE
GOVERNOR DAVIS ANNOUNCES NEW STATEWIDE SEISMIC MONITORING NETWORK 4/23/2002
New System Includes Online "ShakeMaps" for Emergency Responders
Governor Gray Davis today announced the creation of the California Integrated Seismic Network (CISN). The Governor's $2.9 million allocation will allow for the integration and expansion of existing regional earthquake monitoring networks and production of data for online "ShakeMaps" and other rapid information that will enhance the timeliness and efficiency of emergency response to devastating earthquakes. "It's imperative that first responders have the best tools available to them to get to the victims of devastating earthquakes," Governor Davis said. "CISN will create the system for generating real-time information for real-time response. "The Governor's Office of Emergency Services, which will provide overall leadership for CISN, has had a long-term interest in coordinated earthquake monitoring. The historical separation between seismic network operations in northern and southern California and between strong-motion and weak-motion networks statewide resulted in fragmentation and delays in providing information for earthquake response. Among the benefits of CISN will be the production of "ShakeMaps," that use a color scheme to map the shaking intensity surrounding the epicenter of an earthquake. Data for the maps are generated from seismic monitoring stations located throughout the state. CISN will also provide rapid and accurate information on the magnitude, location and suspected fault for any significant earthquake in California and deliver that information to OES via robust and redundant communication links from across the state. "In the past, it has taken too long to locate where the most severe damage has occurred following a major quake," Office of Emergency Services Director Dallas Jones said. "CISN's "ShakeMaps" and other resources show us immediately where the most serious shaking has occurred and allows us to quickly dispatch crews to where they are needed most." Recent advances in technology have made it possible to integrate existing, separate earthquake monitoring networks in California into a single seismic monitoring system. Participating agencies and organizations in CISN include the Department of Conservation's California Geological Survey, the Caltech Seismological Laboratory, the Berkeley Seismological Laboratory, and the United States Geological Survey's offices in Menlo Park and Pasadena. CISN will also serve as a model for the nation and be part of the Advanced National Seismic System, a federally funded initiative to modernize and coordinate earthquake monitoring nationwide. "The ability to gather vital seismic information quickly will not only help immediate response and recovery efforts, the data will also help us build stronger, safer structures in the future," Department of Conservation Director Darryl Young said. "We are proud to be partners in this important work. "For more information on CISN, go online at www.cisn.org.
Back to Top of Page
Pictures taken on April 23 at a press conference at the headquarters of Office of Emergency Services in Rancho Cordova in the State Operation Center
OES Director Dallas Jones addresses the audience from the State Operation Center.
Department of Conservation Director Darryl Young discusses the seismic monitors used throughout the state.
The gathering to view the press conference from the balcony overlooking the State Operations Center.
Director Jones discusses CISN with several of the state's leading seismologists prior to the press conference.
Back to Top of Page
Quake Response in Two Shakes
(from “Wired News”) 2:00 a.m. April 29, 2002 PDT
Although modern instruments have increased response times, technology has yet to be developed that will predict earthquakes before they occur.
"We can't predict earthquakes, but we do know how to locate them once they occur," Gee said. "Once an earthquake occurs, we can tell you about it."
"Prediction has been a Holy Grail for a number of years," Gee said. "Unfortunately, we haven't developed that capability yet. At this point, there are no clear-cut tools, no clear-cut mechanisms that we fully understand (to make predictions)."
The CISN will establish two processing centers, which will each locate earthquakes across the state. So if a major temblor hits the Hayward fault and UC Berkeley's facility is damaged, seismologists at Caltech will be able to provide the same ShakeMap data.
This robust "T1 ring" will allow the monitoring centers to be able to function independently even if the Internet goes down.
"Our efforts are very vulnerable to a damaging event in our own backyard," Gee said. "We don't want to be dependent on a single point of failure."
CISN's data will likely help engineers build safer, stronger structures, seismologists agree.
"The more data we record, the more projects (will be developed) to improve building codes and structural design," Gee said.
While scientists have been measuring seismic activity for decades, only recently have modern instruments been introduced that can help speed response times.
"We can still use data (after an earthquake occurs) to improve building codes, but the real step forward is that we can also use this data to improve emergency response," said Tony Shakal, of the California Geological Survey.
These new instruments have dynamic range and resolution so seismologists can measure even low levels of shaking and calculate frequencies shortly after earthquakes occur.
"Now we can convert raw measured data into useable information about shaking to understand the impact for a structure," Shakal said. "Five years ago it was not possible to do this."
CISN will likely serve as a model and will be part of the Advanced National Seismic System, a federal effort to modernize instruments and coordinate earthquake monitoring across the nation.
"California has been on the leading edge of seismic monitoring," Gee said. "We have the earthquakes and we have the population."
But California isn't alone in its earthquake risk. Just two weeks ago, a 5.0 earthquake shook New York.
"While California has the leading risk, earthquake hazard exists in any state," Gee said.
Back to Top of Page
Earthquake Monitoring to Be Expanded to All Parts of State
(from San Francisco Chronicle) Tuesday, April 23, 2002
(04-23) 23:28 PDT SACRAMENTO (AP) --
California's network of earthquake monitoring stations will cover the entire state under a new appropriation announced Tuesday.
After the federal government announced last year it would cut funding for the monitoring stations, the state stepped up with a $2.9-million program that will add 600 stations in Northern California and help Caltech operate its network of 600 stations in Southern California, Dallas Jones, director of the state Office of Emergency Services, told a news conference.
When complete, officials say, the system will enable state scientific and emergency authorities to pinpoint the precise location and damage pattern of any sizable quake within minutes of its occurrence anywhere in California.
Gov. Gray Davis said the California Integrated Seismic Network, a new umbrella group that incorporates the efforts of the Geological Survey, Caltech, University of California, Berkeley, and the California Geological Survey, has been created to coordinate quake monitoring in the state.
In both of California's most damaging quakes of recent years -- the 1989 Loma Prieta temblor in the Bay Area and the 1994 Northridge quake -- authorities were unsure for up to two days just where all the most severely damaged areas were.
That problem could be ameliorated by the new setup.
A vital feature of the Southern California network has been so-called shake maps, which depict the shaking in sizable quakes not only near the epicenter but in all areas where the quake is felt. Officials said these maps also notify authorities within the hour where emergency teams are needed.
Back to Top of Page
Ready to Rock
DMG Installs Seismic Instrumentation
Throughout New Cal/EPA Building in Sacramento
DOC had planned to move its headquarters to the Cal/EPA building in downtown Sacramento. But the 950,000 square feet of space in the new 25-story structure filled up quickly, leaving the department in the "Darth Vader" building a few blocks away.
However, there's still a bit of DOC in the core of the latest addition to the city's skyline.
As the Cal/EPA building was going up, technicians from DMG's Strong Motion Instrumentation Program (SMIP) were installing seismic monitors that will help engineers and the scientific community better understand how tall buildings react to strong seismic waves.
SMIP has installed monitors in about 170 buildings around the state, including 25 hospitals. The Cal/EPA building has by far the most modern monitoring system of the three instrumented structures in Sacramento; the Capitol and Office Building 8 (the "Twin Towers") are the others.
Most Sacramentans probably worry more about potential flooding than earthquakes. So why invest $50,000 or more to place seismic recorders on buildings in a city so far removed from major known faults? Moh Huang, a structural engineer who is deputy program manager of SMIP, explained the logic.
"Back in 1985, there was a large earthquake in Mexico that was centered about 250 miles from Mexico City, yet the tall buildings in Mexico City swayed back and forth," Huang said during a March 22 tour of the Cal/EPA building. "When the Loma Prieta earthquake occurred in 1989, the Renaissance Tower (DOC headquarters) was just being completed and didn't have
any tenants, but the building manager reported feeling the shaking. A strong earthquake can be felt far away from the epicenter. Downtown Sacramento is less than 100 miles from San Francisco, so we need to know how our buildings react, too."
There are 15 sensors, which cost about $1,000 apiece and are made by a Pasadena company, in the Cal/EPA building: four on the ninth floor, three each in the basement and on the roof, two on floors four and 20, and one on the first floor. The sensors are arranged to measure three types of motion in the event of strong ground shaking: East to West, North to South and torsion (whether the building twists).
"We don’t have any data from this building so far -- and that's OK, too," said Carl Petersen, SMIP's network operations manager. "That means there hasn't been any significant shaking."
Construction techniques used in the Cal/EPA buildings to minimize potential damage from shaking include heavy steel braces -- some four feet wide -- around the elevator shafts. And the welds holding the structural steel together are stronger than those used in the last generation of steel-frame buildings; the 6.7 Northridge Earthquake of 1994 broke the welds in some buildings. The building is designed to sway up to a foot and a half in the event of a large earthquake.
"The structural engineer that worked on this building also did a 73-story building in Los Angeles and he assured us that we're in good hands," Huang said.
"Dynamic analysis" of the Cal/EPA building from the structural engineer helped SMIP, with input from its advisory committee, decide where to place their sensors, small black instruments contained in locked gray boxes marked "Do not open -- scientific equipment."
Someone pounding on the wall or a stiff wind can't fool the sensors; it would take an earthquake in the magnitude-6 range in the Bay Area to awaken the three devices in the basement, which in turn trigger the other sensors. All 15 monitors are wired into a recording device on the first floor that is connected by phone lines to a computer in SMIP's office. In the event of a substantial reading, the computer automatically pages SMIP personnel.
"We don't need a lot of access to the sensors," Petersen said. "Our recorders automatically dial up our computers if there's an earthquake and they are automatically dialed up weekly to check
on their health. We only send someone to look at them is something's wrong, and the batteries only need to be changed every three to four years."
Petersen oversees a staff of 18 technicians who work all over the state -- primarily in the greater Los Angeles area and Bay Area -- installing and maintaining instruments. At any given time, DMG personnel are in various stages of perhaps a dozen projects. SMIP data is used to recommend changes to building codes, assist local governments in their general plan process and aid emergency response personnel in the event of a disaster.
"The idea behind all this work is to have safer buildings sooner," Huang said.
Back to Top of Page
Media Members Find Out What's Shaking
With DMG's SMIP Program in San Mateo
On April 18, the 94th anniversary of the San Francisco Earthquake, the Division of Mines and Geology's Strong Motion Instrumentation Program made a small rumble in the Bay Area.
At a well-attended news conference and demonstration at the western approach of the San Mateo Bridge, DOC Director Darryl Young and SMIP Supervising Geologist Tony Shakal introduced media members to an ongoing program of instrumentation on Caltrans toll bridges.
SMIP's work at San Mateo is nearly done after about four years, with the
Carquinez and Benicia-Martinez bridges next on the agenda. The instrumentation will, in the event of a magnitude 4 or greater earthquake, help demonstrate whether Caltrans' retrofitting work has been effective. Information provided by the SMIP accelerometers also will help engineers make a proposed new bridge from San Francisco to Oakland more earthquake-resistant.
About 20 technical staff members are either installing or doing maintenance on instruments at any given time. SMIP instruments are placed on buildings, dams, bridges and other structures, in open fields and "downhole" (as deep as 300 feet underground).
On the San Mateo Bridge, some of the sensors are inside the steel box girders, some are on the base of the columns at the water level and some are on the concrete piers below the road base to measure an earthquake's effect on different parts of the bridge. There also is a "downhole" array at the approach to the bridge.
Installing instruments on a bridge is an adventure -- and a workout. At San Mateo, there were two ways to get to the base of the pillars. The first involved boarding a barge and going out over the water on a "man lift" similar to what linemen use. The second involved climbing down -- and back up -- a ladder inside the pillar. The highest pillar on the San Mateo Bridge is 160 feet.
The Strong Motion Instrumentation Program came into being after the 1971 San Fernando earthquake. The damage done to the Bay Bridge by the 1989 Loma Prieta earthquake (magnitude 6.9) provided the impetus for the extensive instrumentation of the Golden Gate Bridge as well as Caltrans' 20 toll bridges.
The first fully instrumented bridge was near San Bernardino at the I-10/I-215 interchange. It produced data from the 7.3 Landers quake of 1992 and the 7.1 Hector Mine quake of last year.
Shakal likened the ongoing instrumentation to "setting the trap" for an earthquake. "Now all we need is the critter to come. The best data from the bridge instruments is yet to come, because we've had few earthquakes to get data from. The ideal would be to learn from an event that isn't traumatic and then make adjustments to the designs."
Back to Top of Page
Earthquake Monitors Installed at San Francisco City Hall
Sensors Will Provide Emergency Data, Determine Effectiveness of Retrofitting
SAN FRANCISCO -- It has beauty and a brain. Inside beautiful San Francisco City Hall, an electronic brain with an army of sensors is ready to respond to the next Bay Area earthquake.
State officials today demonstrated the new seismic monitoring system at the historic structure as part of an extensive earthquake retrofitting project.
The California Department of Conservation has installed 18 sensors. Divided among the four levels and dome of City Hall, the devices measure seismic waves shaking the building. During an earthquake, these "accelerometers" report to a central computer the shaking that occurs at several key points in the structure from the foundation to the top of the dome. The instruments provide valuable data about earthquake shaking and the building's response.
"We can't stop earthquakes from happening, but we can better prepare ourselves by improving the way we build new structures and retrofit older ones," said Darryl Young, director of the Department of Conservation. "These strong-motion sensors provide the latest technology to help us do that."
The installation project conducted by DOC's Strong Motion Instrumentation Program (SMIP) began in 1999 as part of the mammoth earthquake retrofit of City Hall.
The sensors also serve as watchdogs, automatically phoning an alert to computers at SMIP headquarters in Sacramento when strong ground motion occurs (generally magnitude 3.5 or greater in the San Francisco Bay Area.)
In addition to City Hall, accelerometers have been installed on other structures in the San Francisco area, such as the Golden Gate Bridge and San Mateo Bridge. In the event of a large earthquake, information gathered by the sensors can be analyzed by DOC computers and seismologists and help emergency crews determine the hardest-hit areas within minutes after the quake. During the 1989 Loma Prieta earthquake, the City Hall dome twisted like a bottle cap, moving two inches. Walls and concrete floor slabs cracked on all levels.
In 1995 engineers began a "base isolation" retrofit of the entire building. Base isolation helps buffer a building from seismic waves. There are 590 rubber cylinders at the base of City Hall's support columns that dampen the effect of the seismic waves. Base isolation also allows the building to move more than two feet in any direction during an earthquake, further minimizing quake damage.
Data gathered by SMIP sensors on how structures react to temblors is being applied by engineers to create stronger, safer building plans for new construction and retrofits.
The Strong Motion Instrumentation Program is part of the DOC's Division of Mines and Geology, which is California's State Geological Survey. SMIP instruments, in combination with sensors from the U.S. Geological Survey, California Institute of Technology and UC Berkeley, are the backbone of a developing integrated seismic network that will cover most of the state's earthquake-prone areas. This consortium of institutions will jointly produce maps of the shaking to help guide emergency response. With more than 800 stations in place, the state's Strong Motion Instrument Program, established in 1971 following the San Fernando earthquake, is one of the largest of its kind in the world.
In addition to studying and mapping earthquakes and other geologic phenomena, the Department of Conservation maps and classifies areas containing mineral deposits; ensures reclamation of land used for mining; regulates oil, gas and geothermal wells; administers agricultural and open-space land conservation programs; and promotes beverage container recycling. More information on DOC programs is available online at www.conservation.ca.gov
Back to Top of Page