Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Wednesday, February 23, 2011

Major Damage in Christchurch NZ from 6.3 Temblor

Brief note on the emergency response to this week's 6.3 temblor in New Zealand, which according to some experts could be a long delayed aftershock from the September quake (a very important question to insurers). The quake on Tuesday wasn't as powerful as the one four months ago, but the September quake's epicenter was deeper and more distant from major population centers, and therefore wasn't as destructive as this week's shake.

One of the international urban search and rescue teams dispatched to Christchurch is CATF-2, housed out of the Los Angeles County Fire Department

Five years ago I had the chance to shadow a deployment exercise by sister team CATF-7, housed out of the Menlo Park (CA) Fire Department. These are elite groups that train constantly and are set up to launch as fast as possible, which can be as little as six to eight hours from the incident. They bring everything they need by way of portable equipment, food, and supplies onto an Air Force transport. Local authorities only need to provide heavy equipment such as cranes and tracked excavators with hydraulic concrete breakers. 

FYI, here's a link to standard search markings used by the US&R task forces, which might help make sense of images you see on TV or on the Net. Photos on are here. Collapse-rescue video posted by the Associated Press is here.

All eyes are on the Grand Chancellor Hotel in downtown Christchurch, which is gravely damaged, is noticeably leaning, still settling, and could come down at any moment. Thankfully, no survivors are stranded inside the hotel. 

The Grand Chancellor if it falls -- when it falls -- will be one of the tallest structures ever to succumb to an earthquake. Mexico City lost a 22-story building in 1985. News accounts for the Grand Chancellor give its height as somewhere between 22 stories and 27 stories, so I'm guessing it's more than 300 feet tall.

When it comes to high rises, the most vulnerable tend to be unreinforced ones 10 to 15 stories in height, particularly when their resonance frequencies are matched to the ground motions. (Update: I'm advised overnight that the cause of the damage to the Grand Chancellor could not have been due to resonance because the ground motion on Tuesday was a significantly higher frequency than the building's tendency to sway.)

Here's an article I wrote on lessons in earthquake engineering from the Mexico City quake and earlier ones.

Because the hotel's collapse could bring down nearby buildings with debris or even a ground shock, the collapse danger is interfering with searches of buildings as much as four blocks away. Among these is the CTV Building, where much of the death toll occurred. 

My article on the social and technological history of collapse rescue can be found here. Once while writing a feature on firefighting I had the opportunity to put on some bunker gear and crawl through the nooks and crannies of a collapsed-building training facility in Los Angeles: claustrophobia city!

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