A major urban earthquake: planning for Armageddon

摘要

Two million people will die in earthquakes in the twenty-first century assuming no increase in the average annual rate of deaths from the twentieth century. The economic result is a financial loss of five trillion dollars to the world's economy in current dollar terms, and probably a comparable but lower financial figure for the building losses. This human economic loss represents six quarters of US government consumption on defense and non-defense spending, or about twenty-times the period in Australian gross domestic product terms. The probable largest fatal earthquake, defined as the probable century event with a one percent probability in the century, will have a death toll in the range of three-hundred-thousand to one million people, coupled with a significant loss of dwellings, factories, and production capacity for the city that bears this disaster. The death toll will be as high as thirty percent of the population in the peak felt intensity region of the earthquake zone. Two to three earthquakes in this century will have death tolls in the range of one hundred to three- hundred-thousand people. There are one-hundred and twenty-five urban areas that have sufficient population and population density to sustain a loss of the one million people. The bulk of these one-hundred and twenty-five urban areas are located in the intraplate regions of the world including the Central and Eastern United States (twenty five), Australia (two), Europe, China, and India. Interplate earthquakes occur on the edges of the major tectonic plates, whilst intraplate earthquakes occur within the tectonic plates. This distinct geologic feature between interplate and intraplate means that an earthquake with a Richter magnitude of six in an interplate region, such as Kobe, has about the equivalent destructive power as a Richter 5.2 in an intraplate region, such as Sydney or New York. Three significant issues arise for planning for a city, such as Sydney, Australia or New York, to deal with this fatal event. The first issue is that the probability of the major event occurring in each one of the one- hundred and twenty-five urban areas is poorly understood. The historical earthquake and geologic data does not support reducing the probability of each of the one-hundred and twenty-five urban area of suffering from this major event from the average of 0.8 percent without investigating the probability distribution of deaths of the preceding two millennia. The second issue is how to develop the key components of an interdisciplinary planning strategy for a compact major urban area to mitigate the losses in a probable century event. The third issue is to equitably deal with this loss from the world insurance perspective. This paper outlines the preliminary research into these three issues from a town planning perspective using Sydney, Australia as the city example.