Global Seismic Risk and Looming Megacity Catastrophes: Megacities, Megarisks

Abstract: According to the UN, in 2008, for the first time, more people live in cities than in rural areas. An estimated 1 billion of these urban dwellers currently live in shanty-towns.  By 2030 more than 60% of global population will be urban, with more than 2 Billion slum dwellers.  The global trend toward urbanization concentrates millions into dense megacities.

More than half of the 25 current largest megacities globally are subject to significant earthquake hazards; a similar number are situated on river floodplains and are subject to frequent flooding. Add in the changes expected from climate change — increasing frequency and severity of weather-related events from droughts to storms to heat waves, as well as rising sea levels — and you get a recipe for disaster, especially given that 10% of the global population, and one out of every eight urban dwellers, lives in coastal areas with elevations below 10 meters above sea level. The problem is intensified by the fact that many of the world’s largest cities are hot spots of extreme poverty, where millions of people live in informal and substandard housing. 

Natural hazards become disasters when they interact with humans and our built environment.  Risk is the convolution of the inherent hazard acting on the “exposure” (people, buildings, ecosystems), through their respective vulnerabilities.  Many new urban dwellers, particularly in developing countries, are settling in high-hazard zones, frequently on previously “unbuildable land” (e.g., steep slopes surrounding major urban centers, or filled-in swamps). Seismic risk, being the product of exposure and vulnerability, is thus increasing exponentially, because of the rapid proliferation of substandard and self-built construction, particularly housing for new urban residents.

Recent large earthquakes and other disasters have illustrated the extent of the destruction that extreme geohazards can inflict on a modern, interconnected society, particularly through cascading effects and chains of failure.

The talk will examine the nature of natural hazard risk, how scientists quantify seismic risk, the impact of future catastrophes, and will conclude with some risk reduction options.

About the Speaker: Mary Lou Zoback is a seismologist and Consulting Professor in the Geophysics Department at Stanford University. From 2006-2011 she was Vice President for Earthquake Risk Applications with Risk Management Solutions, a private catastrophe modeling firm serving the insurance industry. In that role she utilized the company’s commercial risk models to explore the societal role of earthquake insurance, and to quantify the costs and benefits of disaster management and risk reduction activities.

Zoback previously was a senior research scientist at the USGS in Menlo Park, CA where she served as Chief Scientist of the Western Earthquake Hazards team. Her research interests include the relationship between active faulting, deformation and state of stress in the earth’s crust, quantifying earthquake likelihood, and characterizing natural hazard risk.

Dr. Zoback has served on numerous national committees and panels on topics ranging from increasing the Nation’s resilience to disasters, defining the next generation of Earth observations from space, storage of high-level radioactive waste, facilitating interdisciplinary research, and science education. From 1997-2000 she was a member of the National Research Council’s Board on Radioactive Waste Management. In 2012 she was appointed to the U. S. Nuclear Waste Technical Review Board by President Obama.

In 1995 she was elected a member of the U. S. National Academy of Sciences. She is a member of the American Geophysical Union, the Seismological Society of American, and is a past President of the Geological Society of America. Zoback is also past chair of the Advisory Committee for San Francisco’s Community Action Plan for Seismic Safety (CAPSS) program. She is currently a member of the National Academies' Resilient America Roundtable and the Board on Energy and Environmental Systems.