Review of Predicting Disasters: Earthquakes, Scientists, and Uncertainty

 Predicting Disasters provides a comprehensive history of attempts by Japanese seismologists to identify regions likely to experience major earthquakes. Depending on one’s perspective, earthquake prediction can be considered a noble cause or a fool’s errand. Smith’s narrative represents both perspectives, as Japanese scientists discovered repeated cycles of earthquakes in certain locations, used technological advances to monitor and identify potential precursory seismic activity that, in some cases, preceded major earthquakes, and felt compelled to disclose these observations publicly. Against the backdrop of confidence that short-term earthquake prediction might be possible are the skeptics, who to date consider seismological understandings of the earthquake rupture process to be either inadequate to support accurate predictions or impossible due to the inherent uncertainties of nature.

According to Smith, Japanese earthquake prediction efforts began at the dawn of the 20th century. In 1905, Akitsune Imamura (1870–1948), an adjunct professor at Tokyo Imperial University, set earthquake prediction in motion by arguing that historic patterns of earthquakes in the Tokyo region suggested a major event would likely occur within the next 50 years. With this claim, Imamura not only established earthquake prediction as a scientific endeavor, he also connected scientific attempts to identify the location, size, and impact of future earthquakes to the social actions that could mitigate their effects. Early in his career, Imamura worked under the critical eye of Tokyo Imperial University’s distinguished seismologist, Kusakichi Omori. Omori was unenthusiastic about Imamura’s embrace of earthquake prediction and argued against the junior scientist’s claims about the timing and impact of a major Tokyo earthquake.

The Great Kantō Earthquake, which struck Tokyo in 1923, sparked concerns about the seismic vulnerability of population centers throughout Japan. Buoyed by confidence that prediction was possible, Imamura called for the construction of an extensive earthquake monitoring network. Imamura’s argument was rejected in favor of scientific proposals that emphasized basic research. During and after World War II, major earthquakes in the Nankai region in 1944 and 1946 rekindled the scientific pursuit of earthquake prediction. In 1960, flaws in Japan’s emergency response capabilities were exposed by Typhoon Vera and a tsunami generated by a magnitude 9.5 earthquake off the coast of Chile. This development prompted the passage of the 1961 Disaster Countermeasures Basic Act, which established a network of disaster preparedness councils and mandated disaster planning at every level of Japanese society. Taking advantage of this new emphasis on preparedness, scientists developed an earthquake prediction blueprint. This blueprint documented earthquake prediction progress through 1962, identified potential earthquake precursors, and set legislative priorities for measures that would lead to the prediction of future earthquakes.

The possibility of a major earthquake in the Nankai Trough near Suruga Bay had always been a major concern among prediction-oriented scientists. That concern, combined with efforts to advocate for additional legislation, culminated in passage of the Large-Scale Earthquake Countermeasures Act in 1978. This legislation endorsed the expectation that scientists could assess potential earthquake precursors in the Tokai region and would be able to issue short-term earthquake warnings. Such warnings would lead to community actions such as evacuation, the cessation of business activity and the closing of schools, the movement of the Self-Defense Army to the region, and the activation of local government response plans. As of April 2025, however, the Tokai prediction has not been fulfilled, prompting skeptics like seismologist Robert Geller to argue that prediction attempts should be abandoned and the Large-Scale Earthquake Countermeasures Act repealed (Geller 2011).

After the adoption of the Large-Scale Earthquake Countermeasures Act, failures to identify the location of several large earthquakes undermined trust in earthquake prediction efforts. Consequently, and as Smith points out, legislation such as the Special Measures Law on Earthquake Disaster Countermeasures, adopted in 1995, downplayed short-term earthquake prediction in favor of mid- to long-range forecasts, the mapping of earthquake faults, and studies that investigated the earthquake rupture process. Further, earthquake research institutions were reorganized and updated. For example, the mid-1970s era Headquarters for the Promotion of Earthquake Prediction was renamed the Headquarters for Earthquake Research Promotion.

Despite these developments, years of scientific and monetary investment in short-term earthquake prediction were not easily erased. Smith identifies three reasons for the persistence of earthquake prediction in Japan. First, no single institution or professional organization could declare an end to the pursuit of prediction because both scientific advocacy and funding sources were widely dispersed. Second, public perceptions influenced by media coverage and the imagery associated with prediction were periodically bolstered by developments such as the establishment of a nationwide earthquake early warning system in 2007 and the publication of probabilistic seismic hazard maps that seemed to indicate that scientists were getting closer in their quest to predict earthquakes. Finally, there was never a scientific resolution that unequivocally declared that one side of the prediction debate had prevailed. Advocates continued to claim that epistemic uncertainty could be reduced, which they believed would facilitate prediction. Skeptics continued to stress the salience of aleatory uncertainty, which they believed doomed earthquake prediction efforts.

An additional reason for the persistence of earthquake prediction in Japan was the subtle shift from the more strident claims associated with the prediction of earthquakes in the Tokai region to the short-term forecasts that focused on the Nankai Trough. Following the Great East Japan Earthquake and Tsunami of March 11, 2011, attention shifted to the southern portions of the subduction zone that produced the massive 𝑀W  9.1 earthquake and the probable impacts in this heavily populated region. While Smith notes that the warning protocol for the Tokai region was abandoned, the focus shifted to sending “special alerts” to local jurisdictions and the public if seismic activity in the Nankai region was judged by a committee of scientists and the Japan Meteorological Agency to warrant an advisory or warning.

Smith does not delve into the particulars of the subtle change from earthquake prediction to what has become known as operational earthquake forecasting (OEF). OEF is based on the observation that the probability of an earthquake in a region known to have experienced large damaging earthquakes in the past is not constant, but varies over days, weeks, and months based on seismic activity in that region (Jordan et al. 2011, 2014). Unlike an earthquake prediction, OEF special alerts issued for the Nankai region are short-term notifications that potential precursors (earthquakes of magnitude 7 or greater and/or slow slip events) have increased the short-term probability of a significant earthquake. These special alerts (an advisory or a warning) do not suggest that an earthquake is certain to occur. In fact, the probability of a major follow-on earthquake will be 10% or less over the few days that a special alert is in place. A great majority of the 736 municipalities in the Nankai region have developed plans for receipt of these special alerts. These plans outline limited and reasonable response measures for a low probability–high consequence hazard (Goltz et al. 2024). Since the implementation of the OEF program in 2018, there has been one advisory based on the occurrence of a 𝑀W  7.1 earthquake on August 8, 2024, off the Pacific coast of Miyagi City (Kyushu Island). There was no follow-on larger earthquake.

Predicting Disasters should be of interest to seismologists, earthquake engineers, students of natural hazard public policy, and historians of science. Smith’s highly readable and engaging history of earthquake prediction in Japan would be an excellent text for a class in seismology because it exemplifies the evolution of scientific understanding in the social and historic context of a nation contending with the uncertainties imposed by a quixotic natural environment.

References

Geller, R. J. 2011. “Shake-up time for Japanese seismology.” Nature 472 (7344): 407–409. https://doi.org/10.1038/nature10105.

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Goltz, J. D., K. Yamori, K. Nakayachi, H. Shiroshita, T. Sugiyama, and Y. Matsubara. 2024. “Operational earthquake forecasting in Japan: A study of municipal government planning for an earthquake advisory or warning in the Nankai region.” Seismol. Res. Lett. 95 (4): 2251–2265. https://doi.org/10.1785/0220230304.