Final Day of Inspections Still Highly Hazardous
David T. Biggs, P.E., S.E., Dist.M.ASCE, HTMS, a consultant and former principal of Ryan-Biggs Associates, a structural engineering firm in Troy, N.Y., continues his diary of experiences surrounding the 6.3 magnitude earthquake that struck Christchurch, New Zealand. Biggs happened to be delivering a seminar lecture on structural engineering and seismic forensics when the earthquake hit on Tuesday, Feb. 22, and he immediately went to work assisting New Zealand engineers in the assessment of buildings for safety.
Read Biggs' diary entries in sequence if you have not already -- Day One and Two, Day Three, and Day Four.
This (Saturday, Feb. 26) was to be our last day in Christchurch. We had to return to Auckland to continue our seminar series and Jason had classes to start teaching at the university.
At the morning briefing, the coordinators reported that approximately 900 buildings in the Central Business District had been inspected thus far. Some 23 percent were red tagged (slated for demolition), 18 percent were yellow, and 59 percent were green. Follow-up inspections of the red-tagged buildings according to Level 2 would begin next week.
Search and rescue was beginning a room-by-room re-survey of every building. Teams of red-suited rescue teams roamed the CBD, some with dogs. They came from New Zealand, Japan, Singapore, Taiwan, and Australia, and more were coming.
The previous day, our team included Jason Ingham of the University of Auckland and myself performing inspections, with Lisa Moon of the University of Adelaide, Australia, and Philip Herot, a Christchurch City Council plan reviewer, as our assistants, to record our comments and complete the inspections forms, and fill out the placards we placed on each entryway to every building we inspected. Lisa and Philip were essential to the operation and provided more assistance than just filing forms -- they observed many useful conditions.
We also had Steve, our “guardian” rescue volunteer. He was a volunteer medic that came to Christchurch to help. He was at my side for every building entry, provided another set of eyes for hazards, and posted all placards once an inspection was complete. He began the day nervous and rose to the challenge. I appreciated his help! With each building we entered, he felt better when I told him where to run if the shaking started. For some buildings, I had to tell him there was no safe place; we just had to get our inspections done and get out as fast as possible.
On his day, Jason was asked to have our team develop a list of “indicator” buildings. Our team seemed to have accumulated more experience in the CBD than any other, and our advice was valued. The “indicator” buildings were to be representative buildings of all construction types -- steel, concrete, precast, timber, unreinforced masonry and reinforced masonry. The coordinators wanted a limited number of specific buildings to watch. If those buildings experienced noticeable changes in subsequent aftershocks or ground movement, they would trigger re-evaluations of all the buildings of that structural type that were previously tagged green or yellow. Jason did this work and provided the list and photos of recommended buildings to the coordinators.
For the fourth day we had John and Willi as our rescue assistants. John was a builder by trade and Willi was a special lady. They came from Auckland as volunteer fire rescuers and became integral team members. Jason and I inspected another block of the CBD. Including the day before and this day, we ended up inspecting both blocks northwest and southwest of the cathedral. It was painful to continually pass the site of the cathedral.
Daily, we would be subject to questioning by police before entering the cordoned area of the CBD. We each had red sheets. These sheets were entry passes to enter the damage zone for inspections. The team also had duty sheets with warrants that listed the specific blocks we were to inspect. These warrants were issued because some looters had been found -- some posing as inspectors.
On this day, we found a group of four Japanese media wandering through our area of the CBD. It amazed us to find them there and also that they were photographing away like tourists and quite oblivious of the hazards around and over them; they had no safety gear. With some effort, we turned them around and pointed them out of the zone. I alerted a passing policeman that we’d found them and he set off to see that they indeed did leave.
Shortly after that, I was stopped while separated from my team and questioned intensely. It surprised them to meet an American. My pass saved me and another policemen recognized me as the one that alerted them to the Japanese media wanderers. That was the first I’d learned of the presence of looters in the CBD; we never saw any in four days. TV reported the first arrests that night.
We ended our work by early afternoon to catch a cab to the airport to return to Auckland. We signed out at command center, turned in our gear, and said our good-byes to the staff we’d gotten to know over the previous four days. This had been a bonding experience.
I thanked the cafeteria volunteers. They had fed us three meals a day. That was essential; we never had to forage for food and we could spend all our time working. I also thanked our volunteer guard at command center. I never knew his name but he kept unauthorized personnel out of command center, guided over-ambitious media away to their own staging area, reminded us to sign in and out always, and offered sanitizing gel for our hands with each entry. Each day was easier to enter as he became familiar with each of us.
I enjoyed my conversations with Philip. He was a wealth of information on Christchurch and guided us to the right people for advice. He had an intuition about people that I found very perceptive. He was old-school and believed in face-to-face meetings versus texts and voicemail. He was an excellent representative of the Christchurch City Council.
Willi thanked me for being there to help her country.
The route out of the cordoned area changed every day because the hazards changed every day. Daily concerns over additional building collapses created changes to roadblocks and sidewalk closures. On the final day, sinkholes had opened in streets near the Avon River and some buildings began to show new signs of building settlement.
We left Christchurch and the 28 aftershocks they had that day. We still have numerous papers and articles to write over the coming weeks. We’ve gathered an amazing amount of data that will be useful in Jason’s quest to update the New Zealand seismic assessment and retrofit guidelines.
Read on for David Biggs' postscript from Auckland.