Beginning with an analysis of the problems facing the world’s population and those trying to mitigate the impacts of earthquakes, Musson draws attention to the key factors in the level of damage caused by seismic events. The book is full of examples, and one that is particularly enlightening is the contrast between the 316,000 death toll of the 2010 Haiti Earthquake, which had a magnitude of 7.0Mw, and the 8.8Mw earthquake that occurred in Chile just a few weeks later. The reasons for this disparity in impact are multiple. Chile is more economically developed than Haiti and hence buildings there were able to be constructed to a higher standard with consideration of seismic hazard, Haiti is one of the poorest countries in the world and the 97,294 houses which collapsed due to the earthquake were built simply with the intention of minimising cost rather than maximising safety.
Musson then provides a succinct explanation of the principal factors that differentiate earthquake impact, focussing on four key terms: risk, the chance that loss will occur; hazard, the chance and likely strength of shaking in an area; exposure, the level of population and property that could be affected by shaking; vulnerability, how susceptible that population and its buildings are to damage from shaking, given education levels and the quality of building codes.
Having looked at how earthquakes occur and the reasons for their level of impact in different cases, Musson addresses the key issue of the book: how to prevent the “million death quake” that is expected within our lifetimes. I found the section on prediction particularly fascinating, both in the difficulty in determining between a small earthquake and the foreshock for a larger earthquake to come, but most of all in the unforeseen impacts of seismologists trying to predict earthquakes in certain cases. In particular, I was struck by the example of Brian Brady, a theoretical theorist who applied his theory of rock bursts to earthquakes and determined that there would be an earthquake on June 28, 1981 of over 9Mw off the coast of Peru on the basis of the 1974, 8.1Mw Lima Earthquake. He estimated a death toll of hundreds of thousands and complete destruction of Lima, the capital city of Peru. Understandably, this caused widespread alarm in Peru and despite the attempts of a panel of American seismologists to discredit Brady’s methodology, the prediction had a major impact on the economy of Peru – tourism slumped; workers quit their jobs to be with their families; and property prices plummeted. No major earthquake occurred in the summer of 1981 in Peru and soon after Brady withdrew his predictions, but real and significant damage had already been done to the Peruvian economy.
Overall, the book is very optimistic in tone – Musson strongly believes that through education programs and scientific development a seismic catastrophe can be avoided. His work is an enjoyable read, providing a strong grounding in the principles governing earthquakes whilst remaining accessible for readers of any level of geological knowledge, and is therefore definitely worth reading.
Written by Ben Williamson