Tuesday, June 19, 2018


The final major topic of this course is earthquakes, with a particular focus on how earthquake science intersects with society's current environmental challenges. This topic was chosen for several reasons:

First, this enables me to move from topics that I have general knowledge of to a topic that I have direct basic research and public policy experience with. Second, this is a topic that illustrates how our relationship with the Earth is unavoidable; we can't run away from earthquakes. Earthquakes teach us humility in the face of the power of nature, and are (I believe) one of the most obvious signs of our evolving environmental consciousness. Finally, earthquakes (and the science of seismology in general) are one more example of a topic that matters to people and requires a good understanding of basic science concepts to engage in informed discussion about what we really know and don't know.

When I first began to teach this course, most of the focus for this part of the course was on earthquake prediction, specifically: Will it ever be possible to predict earthquakes? This is still part of the course, and we analyze examples of the rich, and sometimes quite strange, history of predicted earthquakes and the public policy responses to those predictions. In some cases, the earthquakes were predicted by seismologists, but in other cases earthquakes were predicted by "outsiders" (such as non-scientists or scientists from other fields). For each of these case studies, we explore the responses of seismologists, government officials, the mass media, and citizens who were affected by the predicted earthquake. This topic, being presented by someone who has had first-hand experience with both its basic science and its the public policy aspects, provides a way to convey that there are usually no single final answers to scientific questions. My own opinion on this issue, which I make clear to the students is my (well-informed, I believe) opinion, is that: given the current state of knowledge in seismology, most (probably all?) specific predictions that are publicly announced are misleading and are often scientifically irresponsible. However, I have come to the conclusion that longer-term earthquake forecasting (at some level of detail) is possible, and can be scientifically responsible. Students are, of course, encouraged to think through this, and other course issues, by themselves, and not just accept my opinion as "fact", even on a topic that I do know a lot about.

More recently, I have modified this part of the course to include a more general discussion of "earthquakes and the environment." This addition to the course was motivated by my coming to believe that our attempts at accurate assessment of earthquake hazards is one of the most obvious examples of our evolving environmental consciousness, and of our coming to a true understanding of humans' relationship to planet Earth. We build things in earthquake prone regions, and over time earthquakes shake them down. The lifespan of a building is maybe 100 years, maybe hundreds of years, maybe in some cases even thousands of years. But, over geological time, earthquakes (and other natural events) will demolish them. All of our buildings and human-constructed environments are temporary. As Will Durant said, “Civilization exists by geologic consent, subject to change without notice.”

This is admittedly a rather bleak assessment of the situation; it is "the dark side" of earthquakes and the environment (and of the relationship between humans and geoscience, in general). But there is a brighter side that illustrates the importance of science and technology in (at least temporarily) mitigating such dark conclusions. There are things we can do to mitigate the effects of earthquakes, and hopefully make ourselves less vulnerable to their powerful effects. What can we do about earthquakes? We can learn about:

  • Where they are most likely to occur.
  • How large they can be, and where the largest earthquakes are likely to occur.
  • (maybe?) When they are likely to occur (earthquake prediction). Although this is very difficult, if possible at all.
  • How often a certain amount of earthquake-generated ground shaking is likely to occur in a region (earthquake hazard analysis). This is somewhat less difficult than earthquake prediction.
  • The ground shaking they are likely to generate once they do occur.
  • How to build buildings such that they will have a good chance of withstanding earthquakes.
And we can also:
  • Develop earthquake warning systems. Once earthquakes do occur, we can give people seconds to minutes of warning that strong ground shaking will soon be occurring.
  • Recognize that we probably do have at least some effect on the occurrence of earthquakes. This is the realm of "human induced earthquakes" (e.g., earthquakes related to hydraulic fracturing, or “fracking”).

The course ends with a few lectures on my own research on earthquakes in the Eastern United States, and how that research touches upon the other ideas covered in the course. This provides a summary both in terms of the specific earthquake "dark and brighter sides" discussed above, and also in terms the more general themes of certainty and uncertainty in science-based public policy.