Passing trucks shook the six-story office building constantly in the months after a magnitude 7.0 earthquake in September 2010.
“There were quite big cracks, you could see daylight from some offices with outside walls,” said receptionist Maryanne Jackson. But, she added, “there was a green sticker on the door that said it was fine.”
The Canterbury Television building collapsed into a smoldering heap when a second major quake struck the New Zealand city of Christchurch five months later. The 115 who died in that building alone accounted for nearly two-thirds of the 181 victims.
The Feb. 22 tragedy has exposed shortcomings in a rapid assessment system that was pioneered in California and is used around the world to determine whether buildings can be reoccupied after major earthquakes.
Inspection reports obtained by The Associated Press under New Zealand public records laws show just how cursory the checks can be. They don’t take into account what predictably follows any major earthquake: aftershocks. Christchurch was hit repeatedly, as was northern Japan after its devastating earthquake and tsunami in March.
The problem is that people place more faith in the inspections than they should. A green sticker is no indication a building will withstand future quakes, nor does it require a robust analysis of a building’s structural health – something that was misunderstood by both building occupants and public officials in Christchurch.
The experience may serve as a wake-up call for cities from Tokyo to Athens that rely on the system. California officials have told the AP they plan to make improvements after reviewing what happened in Christchurch, and those changes will likely set the tone for the rest of the world.
The rapid-assessment placard system was developed in the 1970s and first used after the 1989 Loma Prieta earthquake in the San Francisco Bay Area. Officials quickly inspect buildings and assign a red, yellow or green tag to indicate whether people are banned from the building, can gain restricted access or are able to go back to work.
The father of the system, Oakland-based structural engineer Ron Gallagher, said it’s often about triage, and officials sometimes make judgment calls based on instinct while trying to juggle assessments of hundreds of buildings. The responsibility for a full inspection, he added, lies with building owners.
On a visit to Christchurch after the February quake, Gallagher found problems.
“We heard from a number of people that when the public viewed a green tag, they thought it meant the building was safe from future earthquakes,” he said. “That’s not the way the placard system is used, or is meant to be used.”
Green stickers were issued to two buildings – Canterbury Television and Pyne Gould Corporation – after the September quake based on limited examinations, according to the inspection reports obtained by the AP.
At the Pyne Gould building, where 18 died in February, inspectors came by the day after the earlier quake, but never went inside. Time stamps on the records indicate the examination may have lasted as little as two minutes. The report consisted only of a few checked boxes and a one-word summary: “OK.”
Inspectors did go inside the CTV building, as Canterbury Television was commonly known. But they didn’t tear back walls to assess the damage, commission engineering reports or look at building plans.
The inspection lasted 69 minutes and generated a brief summary: “Looked at by 3 CCC (Christchurch City Council) senior officials. Interviewed manager – no issues (signaled) by users of building.”
Officials ticked a box indicating they estimated damage to the building at between zero and 1 percent. They placed the green sticker on the front door. And they moved on to the next building.
Comments made after the February disaster indicate how much trust was placed in these rapid assessments. For instance, Christchurch Deputy Mayor Ngaire Button told The Australian newspaper that the CTV building had been “inspected by our engineers and declared safe.”
Representatives from both buildings told the AP that after the first quake, they commissioned engineering examinations, which concluded the buildings were sound. They wouldn’t let the AP review copies of the reports.
The owners of the CTV building said minor repairs were recommended, and they weren’t complete at the time the disaster struck.
Survivors of the collapse said they think the building was noticeably shakier after the first quake.
“All the girls lived in fear of that building,” Jackson said.
One colleague took to leaving open the fire escape door, even on cold days, in hopes she would be able to get out quickly in another quake, Jackson said. The woman – and most others – didn’t.
Jackson was lucky. She was standing near her desk when she felt the floor beneath her roll and saw the windows flexing. She ran out the front door and across the street, all the time hearing what she recalls as a “terrible” crashing noise. When she turned around, everything but the elevator shaft had collapsed.
Another survivor, Ron Godkin, said he felt intense shaking when a neighboring building was demolished following the September quake. “We all had concerns about it,” he said. “You couldn’t distinguish between the shudders and the earthquakes.”
The New Zealand government has launched several probes into the disaster, including one on the CTV collapse.
Christchurch officials declined to comment. In a letter to the AP, a lawyer for the city said Christchurch doesn’t want to pre-empt the official investigations “and for this reason does not intend to provide any interpretation or explanation of the material” in its inspection reports.
The attorney added that any records provided by the city may not be complete, because the disaster has left some records inaccessible.
Gallagher said the problems described by survivors – exterior cracks and excessive shaking – are indications that something was wrong with the CTV building after September.
He has his own theory about why the building collapsed. He said it likely didn’t have enough steel reinforcement in the concrete columns and column ties, and that a poor configuration allowed torsion on one side of the building but not the other. In the February quake, that would have led to joint failure and the building falling under its own weight, he said.
Jim Barnes, who oversees the placard system for the California Emergency Management Agency, also visited Christchurch after the disaster. He said his agency is planning changes based on what was learned in Christchurch.
“We have not noticed this sort of misunderstanding with the ‘Inspected’ tag before, but now that it has come to light, we can see how it could happen,” he wrote in an email.
Gallagher is writing a report, due out in January, on what Americans can learn from Christchurch.
He said one major finding will be the need to get information to building owners and occupants, in the form of printed literature, about what a red tag or a green tag means and the next steps they will need to take.
Dr. Maysoon Abbas, who died in the CTV collapse, was so worried about the building that she was looking for a medical job elsewhere, said her husband Maan Alkaisi.
“Sometimes it’s instinct. Something was telling her ‘Don’t stay in that place.’ That makes me really very sad,” he said. “She was feeling that something was wrong. But obviously, she’s not an engineer.”
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