2007), which can provide between seconds and tens of seconds of advance warning that can allow life-saving actions to be taken. More recently, there has been a focus on earthquake early warning systems (e.g., Gasparini et al.
There have been some remarkable successes, most notably the prediction of the February 1975 Haicheng earthquake in China (Adams 1976) however, the following year, the Tangshan earthquake on 28 July occurred without warning and took the lives of several hundreds of thousands of people. A great deal of effort has been invested in developing predictions of earthquakes, since with sufficient prior warning, evacuations could prevent loss of life and injury.
The most compelling reason to study earthquakes, however, must now be to mitigate their devastating impacts on people and on societies. As well as such advances in science, the development of seismology has also brought very tangible societal benefits, one of the most laudable being to distinguish the signals generated by underground tests of nuclear weapons from those generated by earthquakes, which made a comprehensive test ban treaty possible (Bolt 1976). The study of seismicity was instrumental in understanding plate tectonics and the analysis of seismic waves recorded on sensitive instruments all over the world has revealed, like global X-rays, the interior structure of our planet. The discipline of seismology has advanced enormously during the last century or so, and our understanding of earthquakes continues to grow. While it is easy for us to look on these worldviews as quaint or pitifully ignorant, our modern understanding of earthquakes and their origins is very recent (when my own father studied geology as part of his civil engineering education, the framework of plate tectonics for understanding geological events had yet to be formulated and published). Throughout history, peoples living in seismically active regions have formulated explanations for earthquakes, attributing their occurrence to the actions to disgruntled deities, mythical creatures or, later on, the Aristotelian view that earthquakes are caused by winds trapped and heated within a cavernous Earth (which is echoed in Shakespeare’s Henry IV, Part 1). The study of earthquakes serves many noble purposes, starting with humankind’s need to understand the planet on which we live and the causes of these calamitous events that challenge the very idea of residing on terra firma. While such practices may provide an impartial starting point for decision making regarding risk mitigation measures, the most promising avenue to achieve broad societal acceptance of the risks associated with induced earthquakes is through effective regulation, which needs to be transparent, independent, and informed by risk considerations based on both sound seismological science and reliable earthquake engineering. A more rational evaluation of seismic hazard and risk due to induced earthquakes may be facilitated by adopting, with appropriate adaptations, the advances in risk quantification and risk mitigation developed for natural seismicity. The challenge of achieving impartial acceptance of seismic hazard and risk estimates becomes even more acute in the case of earthquakes attributed to human activities.
Despite these advances in the practice of seismic hazard analysis, it is not uncommon for the acceptance of seismic hazard estimates to be hindered by invalid comparisons, resistance to new information that challenges prevailing views, and attachment to previous estimates of the hazard. The next major evolutionary step was the identification of epistemic uncertainties related to incomplete knowledge, and the formulation of frameworks for both their quantification and their incorporation into hazard assessments. Over the last several decades, the practice of seismic hazard analysis has evolved enormously, firstly with the introduction of a rational framework for handling the apparent randomness in earthquake processes, which also enabled risk assessments to consider both the severity and likelihood of earthquake effects. Directly or indirectly, this generally requires quantification of the risk, for which quantification of the seismic hazard is required as a basic input. The fundamental objective of earthquake engineering is to protect lives and livelihoods through the reduction of seismic risk.
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