Magnitude,moment, and measurement: The seismic mechanism controversy and its resolution

This paper examines the history of two related problems concerning earthquakes, and the way in which a theoretical advance was involved in their resolution. The first problem is the development of a physical, as opposed to empirical, scale for measuring the size of earthquakes. The second problem is that of understanding what happens at the source of an earthquake. There was a controversy about what the proper model for the seismic source mechanism is, which was finally resolved through advances in the theory of elastic dislocations. These two problems are linked, because the development of a physically-based magnitude scale requires an understanding of what goes on at the seismic source. I will show how the theoretical advances allowed seismologists to re-frame the questions they were trying to answer, so that the data they gathered could be brought to bear on the problem of seismic sources in new ways.     

Can animals predict earthquakes?: Bio-sentinels as seismic sensors in communist China and beyond

This paper examines the international research on abnormal animal behavior prior to earthquakes, with a focus on Chinese seismology during the Cultural Revolution. China experienced a series of powerful earthquakes in the 1960s and 1970s; in response, its scientists developed approaches to earthquake prediction, including the use of bio-sentinels. The paper demonstrates that Chinese seismology did not treat an earthquake simply as a geophysical event, but rather as an amalgam of environmental phenomena, including sensory experiences. Hence, distributive experience and sensory networks of humans and bio-sentinels constituted an important component of studying the environment. This historical case suggests insights into bio-monitoring of the global environment.     

Crustal layering, simplicity, and the oil industry: The alteration of an epistemic paradigm by a commercial environment

This paper proposes that the gradual alteration of the predominant epistemic paradigm in crustal seismology in the interwar period—namely, simplicity—came about because of the strong influence of a particular commercial environment, i.e. the oil industry. I begin by demonstrating the interwar predominance of Jeffreys’ ‘simplicity postulate’ and his probabilistic epistemology, highlighting the espousal by several seismologists (Bullen, Stoneley, Byerly), whose crustal models drew on mathematical idealisations. Next, I demonstrate that the renunciation of simplicity in the 1930s came about too quickly, and, above all, too heterodoxically to have been the result of new geological evidence. Rather, I argue, the paradigm shift among seismologists was a result of the significant rise in seismic exploration generated by the oil industry. Driven by market demands, American petroleum companies pioneered new technologies, organised research initiatives, and trained young geophysicists who, through the fusion of experimentalism and field experience, brought about fundamental progress in earthquake seismology. Remarkably, historians of science have almost entirely failed to recognise the interwar primacy of the simplicity paradigm as well as its subsequent renunciation. More importantly, they have failed to acknowledge the role the oil industry played in contributing to this renunciation and to the development of new paradigms in seismology.