Trends in Global Urban Earthquake Risk: A Call to the International Earth Science and Earthquake Engineering Communities

Abstract

There is a new “seismic gap” that we—members of the international Earth science and earthquake engineering communities, including members of the Seismological Society of America (SSA) and the Earthquake Engineering Research Institute (EERI)—need to know about: the large and growing gap between the seismic risk of rich countries and that of poor countries. We need to know about it because it threatens rich and poor countries alike, because what is being done about it is not enough, and because we are in a unique position to narrow it. In the next 20 years,... the urban population of developing countries will increase... by 2 billion people... Urban earthquake risk in poor countries is large and rapidly growing. Fifty years ago, the population of the world's largest earthquake-threatened cities was equally divided between rich and poor countries. Today, there are five times as many people in poor as in rich earthquake-threatened cities. Fifty years ago, the earthquake resistance of buildings in rich countries was better than that of buildings in poor countries, and since then it has steadily improved, while that in poor countries has steadily worsened. Data of the U.S. Office of Foreign Disaster Assistance indicate that the average number of deaths resulting from fatal earthquakes in rich countries decreased by about a factor of 10 between the first half of the 20th century and the last half. This improvement in seismic safety is presumably the result of, among other things, better building and land-use codes and better enforcement of those codes. By contrast, there are indications that earthquakes in developing countries will increase their lethality in the future. At last year's SSA conference, Roger Bilham described how we should expect in this century an earthquake that will kill as many as one million people in a developing country. We can …