The City of San Diego has a website (www.sannet.gov/development-services/industry/pdf/urmpn.pdf) that contains a list of 706 local buildings supposedly built out of unreinforced masonry -- that is, bricks held in place with mortar but not tied together by steel reinforcing. On this list, you'll find such prominent structures as the La Jolla Arcade, the venerable complex that lends charm to the intersection of Girard Avenue and Prospect Street. There's the building at 3325 Adams Avenue that once housed a movie theater (and now contains a discount fabric store). In Ocean Beach, Hodad's restaurant and The Black inhabit buildings on this list. Dozens of downtown buildings are listed. Although the Little Pig outwitted the Big Bad Wolf by building his house out of brick, one assumes he didn't live in earthquake country. In seismically active areas, unreinforced masonry is considered one of the most dangerous building materials. Its lethal potential was demonstrated in December of 2003 when a magnitude 6.5 earthquake racked a large section of the Central California coast near San Simeon for four long seconds. Amidst the chaos, two women working in a clothing store in the historic center of Paso Robles tried to make their way outdoors. They died when the second story of the unreinforced masonry building in which they worked slid off the first story and collapsed, crushing them as it fell to the sidewalk.
Don't Stand in the Doorway
If you have the bad luck to find yourself inside an unreinforced masonry building when an earthquake occurs, where's the safest place to be? Not under a doorway, advises Doug Copp.
Copp is the rescue chief and disaster manager of the San Francisco-based American Rescue Team International. He claims to have crawled inside close to 900 collapsed buildings over the past 20 years while working with rescue teams in 60 countries. "Everybody who gets under a doorway when buildings collapse is killed," Copp stated in a recent interview. "How? If you stand under a doorway and the doorjamb falls forward or backward, you'll be crushed by the ceiling. If the doorjamb falls sideways, you'll be cut in half by the doorway. In either case, you'll be dead!"
Based on his rubble-crawling experiences, Copp has concluded that "when buildings collapse, the weight of the ceiling's falling upon the objects or furniture inside crushes these objects, leaving a space or void next to them." Inside such "triangles of life," as Copp calls them, individuals can find shelter. He thus advises, "If you are in bed during the night and an earthquake occurs, simply roll off the bed" and into the safe void surrounding it. If watching television, "Lie down and curl up in the fetal position next to a sofa or large chair." Avoid stairs at all costs, he urges.
Kimberly Shoaf, assistant director of the Center for Public Health and Disasters at UCLA, concurs that doorways are a bad choice for refuge. "A lot of people still think that's what you should do," she says. "When I moved to California, that's what I thought we were supposed to do." This notion arose, she says, "because in old adobe buildings that are not wood-frame buildings, they have a wood-frame doorway. And from the 1933 Long Beach earthquake, there were some significant pictures of old adobe buildings that had fallen and were all collapsed, except for the wood-frame doorway. So that became the norm."
For the last 15 years or so, Shoaf says, schoolchildren in California have been taught another response: namely, to drop, cover, and hold. But she points out that no research has proven "that drop, cover, and hold is the appropriate thing. It makes sense. It's logical. But it's not based on data."
Shoaf says she and some colleagues have surveyed survivors of three fairly recent earthquakes (the 1987 Whittier Narrows quake, the 1989 Loma Prieta quake, and the 1994 Northridge quake), and their findings do suggest that staying put leads to fewer injuries. "The Northridge earthquake is the one for which we have the most data, so it's the easiest to be able to make extrapolations from." The researchers found, "People who stayed in bed were less likely to be injured than those who got out of bed. That was a significant finding. It was the middle of the night. Everyone was disoriented. It was hard for a lot of people to get up, so when they tried, they fell. Falls were a significant injury in that earthquake. Or if they were able to move, they ran into things that had fallen over or moved out of place, or they walked over glass."
The survey data also showed that "men were just as likely or more likely to be injured than women." Also, elderly people were the ones most likely to sustain an injury requiring hospitalization. However, it was the younger adults who had the highest likelihood of being injured. (Shoaf speculates that's "because they do stupid things -- like catching their television sets. They're more likely to take those kinds of actions to protect things.")
Shoaf says her "dream research project" would be to try to validate the drop, cover, and hold strategy using some experimental design. Shake tables, for example, could be used to study "at what level of shaking people can successfully move and at what level it is really detrimental to even try moving." Shoaf says she also would love to use crash dummies to determine "what kinds of positions are the most appropriate to take."
One person who has tried something like this is Marla Petal, director of community mitigation programs for Geohazards International in Palo Alto. Petal extensively studied the deaths and injuries in the Kocaeli, Turkey, earthquake, which killed 20,000 people on August 17, 1999. "We're all trying to put together the mysterious pieces and see how they fit," she says. "Particularly in terms of what to advise people."
"We've shaken buildings to see what happens, but we haven't shaken people," she says. However, Petal and some colleagues who had a shake table did take an informal look at human responses to shaking on one occasion when she was in Turkey. "Our public-education trainers came in one day and saw us shaking stuff on the shake table, and they said, 'Gee, could we try drop, cover, and hold?' 'Cause they were out there teaching that."
Petal continues, "I have seen numerous pictures of drop, cover, and hold illustrated with people squatting. And I can tell you for sure, when we tried that, you just fall over. It's a stupid position. Squatting is inherently unstable." She says the trainers also tried getting into a fetal position, something that was being advocated at that time in Turkey. "But when we got into a fetal position, we found that, depending on the angle you were lying at, you were just being rolled back and forth like a little ball."
Instead, "What we found was that the most stable position was to get down on your knees, but as close to the ground as possible and make yourself as small as possible. You want to be a small target, because things are going to fall, and the smaller you are, the less area there is to hit. The other thing we know absolutely from the death and injury studies is that the most vulnerable part of the body connected with death is the head, neck, and chest. So that's the part that needs the most protection."
Once they were folded up over their knees, "What people wanted to do -- when they had a chance to try it, again and again -- was to go into a kind of military-style crawl on the front of their arms," Petal says. "That gave them the most power of mobility. They could actually scoot to a safer place -- like to crawl under a table or away from something hazardous."
Petal points out that additional study would be necessary to confirm these observations. In the meantime, she mentions a "very interesting thing that was suggested to me as I was doing my study, by somebody who's an architect who's studied this for years. Basically, it's that people need to imagine scenarios for the places they live and work. They need to think about what they would do in the settings where they would most often be found. And frankly, those are different in every place. Maybe it is a doorway. Maybe it's staying in bed sometimes. It's really very, very difficult to hone in on the advice."
As for running outside of an unreinforced masonry building, some people argue that's a prudent thing to do, Petal says, "but all I can say is, I'm not one of them. If you're on a particular floor, there may only be bricks from one floor falling on you. But as you go outside, you may have bricks from multiple floors coming at you."
Structural engineers began to realize almost 100 years ago the disastrous impacts that shaking has on unreinforced masonry, according to Frieder Seible, dean of UCSD's Jacobs School of Engineering. "Starting with the 1906 San Francisco earthquake, we had ample evidence that these buildings have problems." Nonetheless, chambers of commerce, politicians, and other civic boosters for years resisted instituting building codes that would restrict the use of unreinforced masonry, arguing that such regulation would cost too much and dull California's golden reputation. This attitude persisted even after a large quake struck Santa Barbara in 1925.
It took the Long Beach earthquake to shatter that complacency. The magnitude 6.4 temblor struck at 5:55 on the evening of March 10, 1933, destroying 70 brick schoolhouses and inflicting major damage on another 120. Only the quake's occurrence after school hours prevented thousands of children from dying. (Even so, at least 115 individuals perished.)
Within just one month, the state legislature reacted by passing a law that became known as the Field Act. Intended to ensure the safety of all public schools in California, it dictated that only structural engineers who were knowledgeable about earthquake engineering could design schools, and they had to follow rules that exceeded those for other buildings. Plans had to be checked and construction inspected. In 1935, the state's Uniform Building Code was amended to make all buildings more earthquake resistant, and in the years that followed, local jurisdictions brought their own regulations into line. San Diego's ban on unreinforced masonry buildings was adopted on March 24, 1939.
Buildings constructed after that year were safer. But a large stock of buildings remained from the preceding, less enlightened era. In 1986 the California state government finally recognized the danger that these structures posed, when legislators enacted a law that required local governments in the most active seismic regions -- Zone 4 -- to inventory their unreinforced masonry buildings. This law didn't affect San Diegans because most of the county was then classified as Zone 3. Although damage in both Zones 3 and 4 can include the collapse of buildings and other structures not designed to seismic standards, the Zone 4 regions include high-risk, active faults, and major earthquakes are assumed to occur more frequently in Zone 4 regions. In the wake of the 1986 law, approximately 25,400 structures were identified in the Zone 4 regions. More than half (14,225) fell within Los Angeles County; San Francisco counted another 2014.
Even as jurisdictions elsewhere throughout the state scurried to assess how many unreinforced masonry buildings remained in their domains, some individuals were suggesting that San Diego ought to be doing the same thing. It deserved to be classified Zone 4 also, they argued, because it did contain a highly active earthquake fault -- namely, the one that runs through Rose Canyon. An extension of a fault that goes northward toward Los Angeles, this fracture line crosses into San Diego from offshore at La Jolla Shores, runs east for a bit, then bends south and, after passing through Rose Canyon, proceeds along the eastern side of Mission Bay, through Old Town, and under eastern downtown San Diego, before splitting into a number of more southerly branches. Although conventional wisdom decreed that no movement had occurred along the Rose Canyon Fault for at least 10,000 years, making it inactive, some geologists were disputing that by the 1980s.
Conclusive evidence that they were right came in 1989, when a San Diego State University geologist named Tom Rockwell and one of his former students dug into an SDG&E parking lot off Santa Fe Street in eastern Pacific Beach. The researchers knew that the ground there consisted of sediments laid down a mere 8000 years ago. Their excavation revealed that the two sides of the Rose Canyon Fault had slid by each other a total of 8.78 meters -- close to 30 feet -- over the past 8000 years, and Rockwell's subsequent work demonstrated that at least three earthquakes in the range of magnitude 7 to 7.3 have probably caused that movement. That's a lot of shaking -- more than enough to topple any weak structures should the Rose Canyon Fault move that much again.
When Rockwell's findings emerged, San Diego's seismic status didn't immediately change to Zone 4. (That didn't happen until February 7, 1996, when the state's 1994 Uniform Building Code became effective.) San Diego also never became subject to the state's Unreinforced Masonry Building Law, because the law was not written to apply retroactively to areas whose seismic status became upgraded. As a result, attention to San Diego's unreinforced masonry building has lagged behind that paid to those in other Zone 4 areas. Since 1986 approximately 85 percent of L.A.'s unreinforced masonry buildings have been either torn down or retrofitted to better withstand the impact of earthquakes. San Francisco in 2003 reported that 75 percent of its unreinforced masonry buildings had been either demolished or retrofitted to some extent. Statewide, the number of demolished or retrofitted buildings had reached 13,303 by 2003, according to the California Seismic Safety Commission. But San Diego's unreinforced masonry buildings have never been included in the building totals compiled by the state.
Rockwell's research did spur the San Diego city manager in 1990 to form a committee charged with drafting an ordinance to address the hazards of local unreinforced masonry buildings. According to Tony Court, a local structural engineer who was a member of the committee, "The options we considered ranged from 'do nothing' to 'do a full retrofit.' "
Court, who has studied older buildings for almost 20 years, has a dispassionate manner that remains understated as he enumerates the terrible ways in which unreinforced masonry structures react to being shaken by earthquakes. Parapets (the extension of the wall above the roof level) pose the biggest hazard, he says. Typically the parapets in these older buildings consist of unbraced freestanding walls. "And the freestanding elements are the ones that fall over first," the engineer says. "If you look at the Northridge earthquake or anything similar, even in areas where they did not have unreinforced masonry buildings, some of the first things that fell over were the six-foot-high freestanding screen walls between properties." Parapets are vulnerable in the same way. Moreover, buildings typically experience more severe shaking at their tops than at their bottoms, Court adds. "So you get the highest forces at the top -- where you often have the weakest element."
After parapets, Court says, the walls of unreinforced masonry structures pose the next most severe hazard. "The wall as a mass can pull away from the floor and roof." Walls may buckle and fall down "if the buckle goes too far." In a wall that contains a lot of windows, shear cracks also may develop between the windows, "and eventually, if the forces are great enough, the wall can collapse."
Finally, the first stories of some unreinforced masonry buildings tend to be weak, he says, explaining, "The first floor on a commercial building is often left open as a storefront. And that makes a very weak point in the system." Apply sufficient force to such a structure, and the upper stories can break free of the base and collapse like that historic building in Paso Robles that killed the two clothing-store workers.
The mortar in the older buildings can also be problematic, according to Court. "The mortar between the brick is supposed to hold it together. And it does, to a degree." However, in some unreinforced masonry buildings, "You find that the mortar has eroded to the point where it needs to be repaired. When that's the case, you can 'repoint' the mortar. That's the term for pulling out the weak outer portions and putting in new, stronger mortar." Court points to a large photograph on the wall of the conference room of his Mission Valley office. It shows the Christ Episcopal Church in Coronado, built in 1895. When Court's firm, Curry Price Court, took on the job of retrofitting it in the early 1990s, they found that the mortar was composed of beach sand mixed with lime, a common choice of materials in the past. "What happens over 100 years is that the lime interacts with the salts in the beach sand and loses its strength. So you're left with potentially a pile of rubble." In the church's case, Court says four-inch-diameter center cores were drilled through the 50- and 60-foot-tall church walls. Steel reinforcing was placed into the cores and secured with a polyester-resin grout. Before that was done, however, "We repointed the masonry, which entailed removing the outer inch and a half of weak mortar and replacing it" with a stronger material.
As with the mortar, engineers have devised a variety of ways to beef up the parapets and walls of unreinforced masonry buildings. Court says, "Parapets can be stabilized by adding bracing." That typically consists of adding diagonal steel braces, spaced four to six feet apart, behind the parapet. Although it's the cheapest solution, builders must be sure to waterproof the holes created in fastening the braces. Court says it's better (though more expensive) to add "a continuous 'cricket' " -- that is, to build a plywood frame behind the parapet and around the perimeter of the building within which parapet anchors and braces can be secured. And there are other ways to achieve the same end. "You can core down through the wall and insert reinforcing. That gives you a clean, unseen retrofit of the parapet." Yet another option is to remove the parapet altogether, though "that sometimes is not permitted if you're dealing with a historic building. Or the parapet might be providing a fire-separation function," Court says. "Typically you need a 30-inch-high noncombustible parapet on property lines, and sometimes the existing masonry parapet provides that function."
Retrofitting parapets is "pretty effective, if it's well done," Court declares. "I think any moderate earthquake -- say a 5.5 to 6 on the Rose Canyon -- can knock the parapets off [an unreinforced masonry building] if they're not retrofitted. But once you retrofit the parapets, they'll probably be good up to the 6.5 to 7 range. And usually by that time, if the rest of the retrofit has not taken place, some other parts of the building will have problems."
A wide variety of other measures can be taken to fortify the rest of the building. Court says the typical building pattern in San Diego before 1939 was to use unreinforced masonry walls in combination with wood floors and roofs. For engineers who are concerned about preventing the walls and roofs from separating, "The wood gives you something to tie into," the engineer says. "You might put a six-inch-square plate on the exterior of the wall, and you put a bolt back into the roof system and anchor it off the roof structure. If you drive down through the Gaslamp, you'll see a lot of those." Another approach is to tie the floors or ceiling to a steel rod embedded in the walls. To embed it, Court explains, "The contractor would first drill a 7/8-inch-diameter hole in the wall from the inside. Typically the walls are 9 to 13 inches thick, and you drill almost all the way through. You then insert a screen-tube into the hole, inject it full of epoxy, and push a 3/4-inch steel rod into the hole." (The drawback of this approach is that it's not as strong as and may be more expensive than using through-bolts and plates.)
Still further steps that can be taken to strengthen brick structures, according to Court, include upgrading the horizontal wooden floor and roof systems to make them better resist seismic loads. This can be done, he says, by adding new plywood to these "diaphragms," as they're known, to make them stronger. To upgrade old walls, concrete or other materials are sometimes added to their interior faces. Steel columns and bracing can also be installed, anchored to the roof, floor, and walls. "Those stiffen the walls and add some bracing," Court explains. "And if [the old building has] the open-storefront problem, you put bracing at the open storefront. It usually takes the form of diagonal steel bracing, but it can also take the form of a shear wall, a solid wall, or some kind of a rigid rectangular frame. If you look as you walk around downtown, you'll see some diagonal steel bracing. It can either be an X-form or a chevron -- two diagonals coming together in the middle of a beam between two columns."
Charged in 1990 with deciding which -- if any -- of these retrofitting measures to require, the city manager's committee took a middle course. For one thing, the committee recommended that no owners of single-family unreinforced masonry residences or multifamily buildings containing fewer than five units be required to do any earthquake retrofitting. Most residential buildings are smaller, Court explains. "Though you could certainly argue that a three-story apartment building with residents in it on a full-time basis and sleeping for a third of the time presents a higher overall risk than a low-use commercial building. But in general terms, residential involves smaller buildings that are less at risk than large buildings. Also, the walls are closer together, which tends to make them self-bracing to a greater extent than a large unreinforced masonry building.... Then, of course, there's a political side," Court adds. "The broader the net they cast, the more resistance they would get. And that played a role in limiting [the retrofit requirements] to commercial buildings."
According to Ali Fattah in the city's Division of Building and Safety, the city ordinance that ultimately passed in November 1992 had two parts: one voluntary and one mandatory. The mandatory requirements dictated that property owners had to do certain things to strengthen their commercial buildings by January 1, 2006. "You have to provide roof-to-wall ties, and you have to brace, stabilize, or remove your parapets if they exceed a certain height-to-thickness ratio," says Fattah, who served as coordinator of the unreinforced masonry program until recently. "And also, if you have any falling hazards or appendages on the building, like if you have a marquee or architectural appendages on the parapets or walls, you have to either remove or stabilize them."
The voluntary part of the ordinance is much more complex. Fattah explains, "If you choose to do work to your building, that may trigger certain requirements. So if you choose to do remodel work, and the accumulated value of the remodel over a five-year period is more than 50 percent of the value of the building, then you have to tie the floors to the walls. If the accumulated value of the remodel over a five-year period exceeds 100 percent of the value of the building, then you have to do a full seismic upgrade. If you have a change of occupancy to a higher-hazard category, say going from retail to restaurant or going from office to residential, and that change of occupancy involves more than a third of the building, then you have to do a full upgrade."
"The seismic risk is such that the smaller earthquakes are much more likely to occur than the larger earthquakes, so it's those high-probability earthquake events that you're addressing when you secure the parapet and tie the roofs to the walls," says Court, who adds, "That's really why the ordinance was written the way that it is -- to address that highest-risk element first."
Court points out that the city didn't have to require as much as it did. In fact, even the 1986 state law didn't force the municipalities that were in Zone 4 at that time to do very much about their unreinforced masonry buildings. They had to make a list of them and come up with some kind of a "mitigation plan." But they didn't have to require the property owners to strengthen their buildings. The mitigation plan could include as little as writing letters to the building owners and stating that their building type was known to perform poorly in earthquakes. ("This is typically the least effective type of program," the California State Seismic Safety Commission reported to the state legislature in 2003.) Or they could ask owners of unreinforced masonry buildings to post warnings that occupants and passersby might be at risk. ("In general, placarding has not proven to be an effective motivation for owners to retrofit," the Seismic Safety Commission also has concluded.)
In some cases, municipalities have adopted retrofitting requirements but set deadlines for accomplishing them far into the future. That's what happened in Paso Robles. Although the city in 1992 declared that all unreinforced masonry parapets had to be retrofitted by 1995, with the other parts of the affected buildings to be strengthened by 2007, business and building owners protested about the financial hardship this timetable placed on them. So in 1998, as the city's downtown area was beginning to experience a resurgence, the Paso Robles City Council pushed the building-retrofit deadline back still further, to 2018.
When the December 2003 earthquake struck, 9 of Paso Robles' downtown property owners had nonetheless already retrofitted their unreinforced masonry buildings, according to Paso Robles building official Doug Monn. After the dust had settled, seismic authorities looked with interest at those structures. They found that none of the 9, even those that had received only basic retrofits, had suffered any major damage. In contrast, 6 of the 44 unretrofitted commercial buildings sustained enough damage to require demolition. Among the conclusions drawn by one group of 15 scientists who reviewed the Paso Robles damage patterns was that "buildings on street corners performed poorly compared to other buildings." Having windows on the two street sides and solid walls without openings on the other two sides created an asymmetry that caused the building to twist as the ground shook, "leading to much larger damage." This group found that even unreinforced masonry buildings that had had no retrofitting didn't experience catastrophic failures when they were located midblock. "It seems that adjacent buildings provided confinement to each other and prevented collapse." However, both midblock and corner unreinforced masonry parapets and façades "were damaged due to out-of-plane motion...imposing hazard to adjacent buildings and pedestrians."
"Compared to new construction, even the best retrofit won't be as good," says Court, the San Diego structural engineer. But Court says the committee that developed San Diego's retrofitting requirements felt confident that requiring full retrofitting here could limit potential disaster down the road and requiring partial retrofitting could at least significantly lessen the risks. Fattah says by the time the ordinance was passed in 1992, the City of San Diego had conducted an inventory of the unreinforced masonry buildings in the city limits. Fattah says San Diego followed the methodology that Los Angeles used. First a team was hired to pore over Sanborn maps of San Diego. These are documents originally produced for fire-insurance underwriters who used them to calculate risks and establish premiums. Created at scales of 50 or 100 feet to the inch, they show not only the footprints of all the buildings in an area but also such other details as what each was made of, its height and number of stories, what it was used for, and even such minutiae as the location of doors, windows, chimneys, and elevators.
A preliminary list of about 1900 buildings thought to be built of unreinforced masonry was compiled, Fattah says. Then drive-by surveys were conducted "to see if the buildings were still standing." This process pared the list further, and Fattah says what resulted "was in the 800-something range."
Late in 2001, the City of San Diego finally sent notices to 813 building owners, telling them they had to take certain steps to make their unreinforced masonry buildings safer by January 1, 2006. That was almost nine years after the city's adoption of the ordinance in late 1992. Why the long lag? "Well, I think it was partly a staffing issue," Fattah says. "As I recall, the ordinance had a quiet period. I think it was about a year, when it wasn't going to go into effect...or something like that. And then there were some issues with the noticing. We sort of had a false start with the noticing. And then we had staff turnover, and then we had the recession. And we sort of lost staff, and we came roaring back after the recession. But ultimately I think now we're getting to be fully staffed."
One person who has some insight into the reaction of property owners to these notices -- when they arrived at last -- is Larry Figueroa, a marketing manager at Adamo Construction in Lakeside. "Ongoing facility modification is our specialty," Figueroa explained. "We've been in business for 43 years." To develop the retrofitting side of the business, Figueroa has spent some time visiting buildings on the city's list and getting in touch with their owners. "This is not something that these property owners are budgeting for," he said. "And we understand that. We felt bad for them. But at the same time, it's something they have to do. It's not us making them do it. We're trying to help them accomplish what they have to do."
Figueroa said he sometimes likens the retrofit requirements to "having to put a new roof on your house. It's something that doesn't add maybe a tremendous amount of value. It's not something you get to look at and say, 'Oh, it's really nice and pretty!' -- like a pool or a new kitchen or a new bathroom, where you're going to look at it every day and use it. It's just a roof. It's the same with [the retrofits]. It's money that the property owners don't necessarily feel like they're going to see. But it is a safety issue."
Figueroa said his company has done jobs ranging from just under $100,000 up to a little more than $500,000 (in that case, for "an enormous structure"). The cost depends "on a million factors," he said. "Buildings that are bordered by other buildings and share common walls can be very difficult. Parapet heights are a big issue. If your parapet is small enough, it won't need reinforcing. And if you don't have to reinforce the parapet, there's a good chance you won't have to tear up the roof. And the roofing is one thing that can make these projects so expensive."
Figueroa recalled two bids that his employers produced for two brothers who both owned property downtown. The one brother's building "was half the size, if not less, than the other's. But it cost more money because the amount of work that was involved was dramatically more. The access to the roof and ceiling in the bigger building was very good and easy. The access to the other one was horrible." If retrofit work must be done without disrupting commercial or other operations, that can add to the complexity and expense of the job. "We just did Our Lady of the Rosary Catholic Church in Little Italy," Figueroa said. "They have beautiful paintings on their ceiling, and we were working above that. So it took a lot of great, great care not to damage any painting or hurt anything." Furthermore, "We had to work all kind of crazy hours, split shifts, because they have Mass every day. So we'd work in the morning, then take a couple hours off and not work until Mass was over, and then we'd go back. That went on for four months."
In visiting buildings that were on the city's list, Figueroa commented that he'd had a lot of surprises. "Some of the buildings on that list are not brick or block. They're concrete or wood." In other cases, he'd found that the property had already been retrofitted.
Indeed, before the current list was last revised (on October 21) it included the building at 910 Prospect Street in La Jolla. That's the Grande Colonial Hotel, a massive structure that looks as if it would kill a lot of people if it collapsed. But Terrence Underwood, the general manager, says a thorough inspection by a structural engineer confirmed that the hotel was never built of unreinforced masonry. Rather, its framework consists of steel-reinforced concrete -- "really cutting-edge construction technology back in 1928, when it was built." Underwood adds that the hotel submitted this information to the city on January 18, 2002.
A block away from the hotel, the Athenaeum Music and Arts Library did for a long time occupy structures built of unreinforced masonry. "We have three separate buildings," explains director Erika Torre. "One was built after 1957, so that one did not fall under these regulations. But the other two buildings needed to be done. And it mostly had to do with securing the roof to the walls." Torre says this work was carried out in the fall of 2003 and cost between $250,000 and $300,000 (including all the engineering and design fees, permits, and so forth). Torre says that although the Athenaeum informed the City of San Diego that the work was completed around the end of 2003, the library is still included on the list, with the cryptic notation "Partial Retrofit."
In other parts of the city, it's not hard to find similar examples. The large Wilkinson Building at 3402 Adams Avenue in Normal Heights is made of brick and bears signs announcing its establishment in 1928. But it was extensively remodeled and retrofitted for earthquakes early in 2002. In Ocean Beach, the site of the old Strand Theater at 4948 Newport Avenue now contains the Wings surf shop. When that use-conversion took place, the required retrofitting was also accomplished -- and yet the property continues to be on the city's list of unreinforced masonry buildings.
It's thus unclear how many of the older buildings in San Diego continue to be death traps. "We were short-staffed for a while," Ali Fattah replied when asked how long it takes for retrofitted buildings to be removed from the list. "So we didn't have people to do the data entry. So that list was static. That list now has been updated to reflect demolitions, and it's been updated to reflect non-URM buildings." When informed that buildings such as the Wilkinson Building have been retrofitted but still remain on the list, Fattah suggested that the building owners "should probably be contacting" the city's new coordinator for the unreinforced masonry program.
Asked how many buildings he thought were on the list that shouldn't be, Fattah exclaimed, "You know, talk about a hip shot! Nobody agrees with me, but my sort of gut estimate is I'd say for 60 to 70 percent [of the buildings on the list] something has happened with it. Meaning, someone called and complained or they did a retrofit or they filed a letter saying, 'I'm demolished.' Something has happened." He guessed that maybe 50 to 60 percent (of the total) had already gotten some kind of retrofit, partial or complete. "But again, what do I have to base this on? I don't go down to the barrio, so I don't know what's going on there. I work downtown. From time to time, I walk around the Gaslamp. I've walked around La Jolla a little bit. But some of it is concealed. So I don't know."
The consequences for property owners who fail to meet the January 1, 2006, deadline sound murky also. "That's a very complicated question," Fattah responded when asked what those consequences will be. "Because, as you know, we're a city that prides ourselves on customer service. And we'll work with people to sort of get compliance. So the range of what could happen could vary. If you look at the literal wording in the municipal code, the building could be boarded up and vacated. That would be one extreme." But Fattah sounded dubious this would happen. "It would seem like it would have to be something pretty bad to go to that." Another possibility is for the city to levy fines and civil penalties on noncompliers, he said. Even milder would be "something called a retrofit guideline document, where the municipal code does allow phasing of work under certain cases. In one case, it's over a ten-year period. They'd have to show a hardship, I would think, and they would have to sort of have a time-certain schedule for how they intended to accomplish [the retrofit]." Fattah reiterated, "Our goal is customer service. We're here to sort of help people comply. Our goal is not to prosecute people."
Should the day come when every unreinforced masonry building in San Diego has been retrofitted or torn down, that still won't mean no building will ever fall down or hurt people when subjected to severe enough shaking. "There are other buildings that pose significant risks that have not been addressed on any wholesale level," says Court, the structural engineer. One category, built primarily from 1900 through about 1930, is known as nonductile concrete frame with hollow-clay-tile infills. These are reinforced concrete buildings that lack "the modern detailing that enables them to resist seismic forces," Court says. "The earthquake imposes a deformation on the building, and a well-detailed ductile concrete system will ride out" those forces, whereas nonductile buildings "tend to fail brittlely," he says. Insult is added to (potential) injury when such buildings contain in-fill walls made of 12-inch-square hollow, brick-looking units, as is the case in many old buildings downtown, according to Court. (The Balboa Theater, which Court's firm is currently retrofitting, is built of such materials.)
Although the use of hollow-clay-tile in-fill walls largely stopped after 1930, nonductile or semiductile concrete-frame buildings continued to be built into the 1970s, Court points out, and they can be dangerous too. In the 1979 El Centro earthquake, the Imperial County Services building was brand-new at the time, but its semiductile concrete columns failed. "Likewise, in the 1971 Sylmar earthquake. The Olive View Hospital had semiductile detailing in the concrete columns, and that led to its failure," Court says, adding that most of the concrete buildings erected in San Diego before 1970 used this vulnerable connection detailing.
Even wood-frame buildings can kill people if they're not designed well. Court says, the collapse that killed the most people in the 1994 Northridge earthquake involved a building that was made of wood but had a "tuck under" parking level that made the whole structure flexible and weak. "Every earthquake reveals something new, so you never have all the answers," Court says.
Earthquakes also can offer reassurance, though, a case in point being the magnitude 6.5 Paso Robles temblor. Even though two people died in it, that can be compared to the outcome four days later when a magnitude 6.6 quake killed 30,000 people in Bam, Iran. The Iranian deaths were "mostly due to the collapse of unreinforced masonry buildings," according to one group of earthquake scientists who studied both events. "Part of the difference is that the strongest shaking from the San Simeon earthquake probably occurred in the sparsely populated epicentral region, while the fault in the Bam earthquake ran directly through a sizable city." But "California was also more prepared."
Asked whether he hesitates before entering one of the city's unreinforced masonry buildings, Court reflected. "I'd say my risk is much higher on the highway than it is going into an unreinforced masonry building. The chances of an earthquake occurring in any given year, month, day, or hour are remote," he said. "So I go into them. But I wouldn't buy an unreinforced masonry building without doing something to it. I wouldn't work in one."