Deseret Morning News, Monday, April 17, 2006
Shaken to pieces
Unreinforced masonry buildings take biggest hit from the 'big one'
By Lee Davidson
Deseret Morning News
Over the decades, Wasatch Front residents built, sold and resold tens of thousands of pretty brick homes. Unfortunately, such houses — at least those that lacked seismic upgrades — turned out to be death traps in Utah's great 7.0 earthquake of 2008.
It was not just homes. It was all masonry buildings without reinforcing steel. Too many of the brittle structures could not flex well with strong ground shaking on the wintry afternoon of Feb. 1, so many buildings snapped like chalk and fully or partially collapsed. That included many schools, where casualty numbers were staggering; churches; government buildings and businesses — but mostly houses.
Some such buildings — as well as many of other construction types — dodged damage because of recent seismic upgrades to them, including such landmarks as the state Capitol, Salt Lake City-County Building and the Tabernacle.
Also, for example, a few school districts that had spent hundreds of millions of dollars on seismic upgrades fared well, but those that did not saw scores of schools severely damaged. Sadly, as had been predicted back in 2006, more than 700 students and teachers were killed in schools, and another 13,000 were injured.
Many hospitals paid for being too near faults and landslide areas.
Recent rebuilding of many bridges allowed them to survive, but a high number of older ones — built mainly in the 1960s and '70s as interstate freeways were constructed — were damaged or failed.
But the worst news of all for structures still came from those "unreinforced masonry" buildings.
Unreinforced masonry
Warnings had been given about unreinforced masonry buildings for years. Steve Bartlett, a University of Utah assistant professor of civil and environmental design, said during a 2006 community meeting on quakes that they are "the single largest threat to loss of human life" in an earthquake.
He was right, and their failures contributed greatly to the 6,200 deaths and 90,000 injuries in the 2008 quake — numbers close to those predicted in 2006 by Bob Carey, earthquake specialist for the state Office of Emergency Services, using computer modeling.
Barry Welliver, a structural engineer and chairman of the Utah Seismic Safety Commission, had also warned in 2006 that such structures "are the single worst performers in an earthquake" — and many could suffer severe damage in earthquakes as small as 5.0 on the Richter scale, let alone the 7.0 that hit in 2008.
Utah accumulated more than an estimated 200,000 such buildings through the years, including 65,000 to 85,000 in Salt Lake County alone, most of which were homes.
Welliver said they were "a building type that worked well for a number of years because of the ability to be constructed handily" and at low cost. But that was before their quake danger was known. Building codes eventually would ban new construction using this method, but laws did not force upgrades of existing homes.
Unfortunately for Utahns, they had far more such buildings than other earthquake-prone areas such as California.
"California only has 25,000 URMs (unreinforced masonry buildings) in the whole state," Welliver said in 2006; Salt Lake County alone had three times as many.
Welliver said, "That shows we haven't been shaken here (in Utah) enough to appreciate the potential damage from those buildings."
The earthquake of 2008 changed that.
In large part because of so many unreinforced masonry buildings, the quake at least moderately damaged 42 percent of all buildings along the Wasatch Front, contributing greatly to the estimated $40 billion economic loss from the quake.
That included damaging 120,000 buildings beyond repair, as had been predicted in 2006 by Carey. Not surprisingly, 65 percent of them — 77,200 — were unreinforced masonry.
Amid the destruction in 2008, nearly 200,000 single-family homes sustained at least moderate damage — about 40 percent of the total. And 99,000, or one of every five, were damaged beyond repair.
Among other types of buildings damaged beyond repair, close to what was predicted in 2006, were 14,200 other residential buildings, such as apartments; 4,500 commercial buildings; 160 government buildings; 79 churches; and 1,600 industrial buildings.
In the quake, again close to what had been predicted in 2006, about 850 people died in homes, apartments and condos, and another 13,000 were injured.
Limiting damage
Damage and carnage — at least from unreinforced masonry buildings — could have been reduced. Seismic upgrades, even relatively simple ones, could have greatly increased their chances of survival. The state for years had included some how-to information about such upgrades on its Web sites.
That includes, for example, better anchoring roofs to walls, and walls to each other. Roofs can act like the top of a box, holding sides together during the twisting of shear forces. Without the top, sides of the box (or building) would more easily collapse. And in many unreinforced masonry buildings, walls and roofs are not tied together well.
"But most people don't do it because it is expensive," Welliver said in 2006.
He said upgrade costs are more manageable if people do retrofits at the same time they do other renovations, such as when replacing a roof. Many public school districts and Brigham Young University, for example, said they programmed seismic retrofits any time they renovated older buildings.
Some landmarks that were originally largely unreinforced masonry survived the 2008 quake because of seismic retrofits they received earlier, including the state Capitol, the Salt Lake City-County Building and the Tabernacle. Such buildings were essentially put on a system of shock absorbers to help them survive quakes.
Retrofits of other types of buildings also helped avoid some disasters. The University of Utah's Marriott Library was built on rigid welded columns that engineers figured would snap in a strong quake, resulting in the roof and walls pancaking down on students. Retrofits in 2006 added flexibility and survivability.
Such retrofits likely saved hundreds to thousands of lives during the 2008 quake and saved money in the long run. "Our feeling is that for every $1 you spend before (earthquakes for retrofits), it is worth $4 or $5 afterward," Carey said in 2006.
Bartlett and Welliver said in 2006 that if homeowners then wanted to know how safe their homes likely would be in earthquakes and whether they likely needed seismic updates, they could simply look at when they were built.
Building codes essentially did not have seismic considerations before 1975, so homes older than that likely did not have them either. Codes steadily improved through the 1980s and '90s with lessons learned from earthquakes elsewhere, so structures built then were considered progressively safer. The strictest and best codes were enacted in 2003, so buildings constructed after that were considered the safest.
Few Utahns insured
Most people who lost their homes in the 2008 quake were not insured for earthquake damage, and many are now financially ruined. Regular homeowners insurance does not cover quake damage, unless additional earthquake riders are purchased.
Most insurance companies estimated back in 2005 that only between 10 percent and 15 percent of their Utah clients then had earthquake insurance — though it varied from below 5 percent to 20 percent, depending on the location and company.
"It's expensive. It's not required by lending institutions, so people don't buy it," Stuart Young, managing director of Acordia Mountain West Insurance, said in 2005.
Renters with renters' insurance are lucky: The quake damage to their possessions is usually included in regular policies, but too many renters did not bother to buy it.
John Henry, spokesman for United Services Auto Association insurance, said in 2006, "Renters insurance is often overlooked. Yes, apartment owners have insurance, but that only covers damage to the structure, not the possessions of renters. Renters insurance covers their possessions. It represents a good value."
Damaged schools
Schools, in part because many were old unreinforced masonry buildings, suffered severe damage and casualties. But it could have been much worse. Some districts in recent years had spent hundreds of millions to seismically upgrade or replace old schools, which helped them and their students largely avoid the destruction that hit others.
Still, close to what Carey had predicted in 2006, about 740 students and teachers were killed as the 2008 quake hit during the school day. About another 13,000 were injured in the large quake area from Brigham City to Santaquin, and from Tooele to Coalville.
Also close to Carey's 2006 predictions, a staggering 205 school buildings suffered at least moderate damage — a fourth of the total. About 38 are considered damaged beyond repair.
Another complication came because the 2008 earthquake hit on a cold, snowy day. Children in damaged schools were evacuated outside into freezing weather, where most emergency plans called for holding them there until parents could come retrieve them, unless buildings were declared safe to re-enter. Many were not safe.
The overall damage is not nearly as bad in the Salt Lake City School District, where voters approved a $136 million bond issue in 1999 largely to replace or retrofit schools for seismic safety.
"Currently most of our schools have been retrofitted or rebuilt," Jason Olsen, spokesman for the district, said in 2006. "Schools that are now completed actually meet stricter seismic codes than are required by state law. So hopefully they are very safe buildings in the event of an earthquake."
He added then, "We are making the buildings as safe as we can because we think schools will actually be a gathering point for our communities during emergencies. So we want them to withstand as much as humanly possible."
Indeed as predicted, neighborhoods are using the schools as shelters, emergency kitchens, coordination centers for emergency work and gathering points.
Damage also was not bad in Jordan School District in southern Salt Lake County. It assessed all its schools in 1990 to predict how they would do in an earthquake, according to Herb Jensen, the district facilities manager. It then began a program to replace or retrofit schools, usually when other remodeling projects were also done.
By 2006, work was completed at all but six of Jordan district's 100 buildings. Even at the ones that still lacked upgrades, Jensen said they were generally designed "to hold together long enough to allow evacuation after an earthquake."
The large Granite School District in the central portion of Salt Lake County did not do as much to prepare.
Of its 89 schools, about 35 had received "some earthquake enhancements over the years during a major remodeling, such as when a new roof was installed, to help tie the roof to the walls" to help survive ground shaking, Randy Ripplinger, spokesman for the district, said in 2006. A state study in 2006 said only 15 schools were considered up to current seismic code.
With so few schools considered truly safe seismically, a state study in 2006 said Granite would have needed $253 million to seismically upgrade its schools then.
With such problems, sixth-grade students at Granite's Hillsdale Elementary in West Valley City proceeded to make a surprising discovery in 2005 as they did exercises with Geographic Information Systems software and maps.
They found that their school sits on top of a fault.
It is part of the Granger fault. Geologists had predicted correctly in 2006 that a big quake on the Wasatch fault would make the smaller Granger fault also shake "in sympathy," and that it would leave a 3-foot scarp, or ledge, along much of its length. Sitting on that fault did not exactly help Hillsdale when the 2008 quake hit.
According to a state survey in 2006 among selected school districts, Alpine School District in Utah County had about two-thirds of its schools meet or "somewhat meet" seismic safety codes then.
Provo School District in 2006 sought a $35 million bond to improve and build some new schools, which voters debated and would eventually pass (but much of the construction did not come before the 2008 quake). Also, Davis School District (where 37 schools needed attention to seismic code) held a $230 million bond election in June 2006, which voters approved.
A group called SAFE — Save All From Earthquakes — had tried lobbying legislators back in 2006 to spend more to seismically upgrade schools but said it found little support.
In a letter to legislators then, SAFE said, "We could lose a generation of children if we stay in denial about the seismic vulnerability of Utah school buildings." It added, "We do not know how long we have, so we need to act now before it is too late."
Gary Wallace, a leader of SAFE, also complained in 2006, "It is interesting that legislators are willing to spend $200 million to retrofit their own offices in the state Capitol. In California, after they even further strengthened their schools, then they did their Capitol building."
Vulnerable hospitals
Emergency planners back in 2006 were surprised at how much damage computer models predicted for hospitals and were reviewing then whether it was actually correct. But damage was serious when the 2008 quake hit.
The 2006 projections had said that of 38 hospitals in the region, 15 would suffer at least moderate damage — and four would be damaged beyond repair.
Carey had said in 2006 that as the computer model was being reviewed, it suggested that some hospitals were close to landslide areas and faults, and they suffered more damage than officials earlier figured they would.
As the model had predicted, only about a third of the hospital beds that had been available before the quake were also usable immediately afterward for patients already in the hospital along with the tens of thousands of people injured in the quake.
Projections estimated that after one week, 58 percent of the hospital beds would be back in service and that after 30 days, about 79 percent would be operational.
Falling bridges
Close to what computer models and Carey predicted in 2006, more than 450 highway bridges were at least moderately damaged in the 2008 quake area. That includes 140 that collapsed or were damaged beyond repair.
The old 2006 projections said that about 120 of those damaged bridges would be functional again within seven days.
David Eixenberger, deputy state bridge engineer, said in 2006 that the state had numerous emergency contracts in place before emergencies to allow needed repair work to begin almost immediately. He said the state had also practiced emergency procedures to identify damage quickly and prioritize recovery work.
Adding a special complication was that many bridges over the Jordan River failed because of "liquefaction" that made soils beneath them act like quicksand during the earthquake. Damage to them tended to cut Salt Lake County in half, making it difficult for the east and west halves to help each other.
Eixenberger in 2006, however, predicted that because the Jordan is so relatively narrow and shallow, engineers would quickly find creative ways to span it or fix bridges to allow emergency transportation.
The damage, again, could have been much worse. But the state had upgraded many of its bridges in recent years. For example, the reconstruction of I-15 before the 2002 Olympics replaced many older, less-safe bridges with structures of modern design considered much more earthquake resistant.
But Eixenberger noted in 2006 that about half of the state's bridges still were built in the 1960s and '70s, well before seismic considerations were developed and added to building codes. They were built mostly as part of the interstate freeway system.
The state could not afford to replace or upgrade all of them at the same time, especially when growing areas were also pushing for other new and wider roads. Eixenberger said the state did seismic upgrades when possible with other widening and renovation projects.
He said projects such as the new Legacy Parkway added redundancy to the transportation system, to offer detours around problems from the quake on I-15. The state also hoped it would have allowed work to replace more older I-15 bridges by making a detour available to speed such work.
Of course, the earthquake hit before all such hoped-for work could be completed.