I took a tour of the Red Zone today. That’s the part of the downtown area that’s still cordoned off. It’s like touring a war zone or a scene from some post-apocalypse movie where everyone’s vanished. The city and the owners are deciding which buildings can be saved, which have to be destroyed, and how to demolish buildings safely. (A few days ago they found asbestos in one of the bank buildings.) Some buildings have concrete-filled shipping containers in front of them to keep them from falling over.
One problem is liquefaction. The whole area is an alluvial plain. During an earthquake (and during each of the hundreds of aftershocks), liquefied ooze shoots to the surface, causing foundations to shift and generally wreaking havoc. Some buildings that were found to be stable after the main earthquakes had to be demolished after smaller aftershocks made them unsalvageable.
I had to sign an assortment of waivers to take this tour, and they gave us a safety briefing on the bus full of dire warnings, then offered people a chance to leave. As far as I could tell, it wasn’t any more risky than walking around next to damaged buildings outside the Red Zone.