14 January 2010


Quake risks

Haiti earthquake damageFive years ago I wrote a long series of posts about the Indian Ocean earthquake and tsunami, compiling information from around the Web and using my training in marine biology and oceanography to help explain what happened. Nearly 230,000 people died in that event.

Tuesday's magnitude-7 quake in Haiti looks to be a catastrophe of similar scale. I first learned of it through Twitter, which seems to be a key breaking-news technology now. Hearing that it was 7.0 on the Richter scale and was centred on land, only 25 kilometres from Port-au-Prince, I immediately thought, "Oh man, this is bad."

And it is. Some 50,000 are dead already, and more will die among the hundreds of thousands injured or missing. Haiti is, of course, one of the world's poorest countries, which makes things worse. Learning from aid efforts around the Indian Ocean in 2005 and from other disasters, the Canadian government is offering to match donations from Canadians for relief in Haiti.

This is a reminder that we live on a shifting, active planet, one with no opinions or cares about us creatures who cling like a film on its thin surface. We have learned, recently, to forecast weather, and to know where dangers from earthquakes, volcanoes, floods, storms, and other natural risks might lie. But we cannot predict them precisely, and some of the places people most like to live—flat river valleys, rich volcanic soils, fault-riddled landscapes, monsoon coastlines, tornado-prone plains, steep hillsides—are also dangerous.

Worse yet, the danger may not express itself over one or two or three human lifetimes. My city of Vancouver is in an earthquake zone, and also sits not far from at least a couple of substantial volcanoes. Yet it has been a city for less than 125 years. Quakes and eruptions happen in this region all the time—on a geological timescale. That still means that there has been no large earthquake or volcanic activity here since before Europeans arrived.

We would, I hope, do better than Port-au-Prince in a similar earthquake, but such chaos is not purely a problem of the developing world. The Earth, nature, and the Universe don't take any of our needs into account (no matter what foolishness people like Pat Robertson might say). We are at risk all over the world, and when the worst happens, we need to help each other.

Labels: , , ,


My younger daughter was living in Seattle at the time of the magnitude 6.8 quake in 2001, and I arrived three days later for a (planned) visit. One person died of an apparent heart attack, and there was some damage - but driving around Seattle, I would not have known there had been an earthquake if they hadn't been talking about it on TV. Some people even started calling it a "miracle earthquake." The small amount of damage had to do with the type of earthquake, and the fact that Seattle had spent a lot of money retrofitting buildings; still it seemed strange that there was so little damage.
I felt that Nisqually quake in my basement office here in Vancouver, which is a almost 300 km north. However, remember that the earthquake magnitude scale is logarithmic: a 7.0 quake releases something like twice the energy of a 6.8.

The Haiti quake epicentre was much closer to the surface than the Seattle one, which is more dangerous too. Both were close to heavily populated areas, but of course the construction infrastructure in Port-au-Prince is less robust than in Seattle and Olympia. In 2001 it seemed like the worst damage was in the historic Pioneer Square area, where the buildings were old, brick, and unreinforced. Probably that's the kinds of buildings (or worse) that sit all over Port-au-Prince, and have now collapsed.

The 2004 earthquake that set off the Indian Ocean tsunami was magnitude 9.1 (or maybe 9.3)—at least 1300 times the energy of this week's Haiti quake, and over 2600 times that of the Seattle 2001 event. It was offshore, farther from a major city (Bada Aceh), and yet entirely aside from the horrific carnage wreaked by the tsunami it generated, that quake directly flattened much of Banda Aceh before the tsunami came to finish the job.

So far, we have been very, very lucky here in the Pacific Northwest. There have been numerous quakes of magnitude 8.6 or greater in this general region—from California to Alaska—recorded, including one in 1700 with an accompanying tsunami that reached Japan, and more recent ones in 1957, 1964, and 1965. There have been dozens of magnitude 7 to 8.5 quakes in that time, including the big ones in San Francisco and Los Angeles.