THE CATASTROPHIC EARTHQUAKE, tsunami, and fire that destroyed Lisbon in 1755 and provoked Voltaire to write his coruscating attack on optimism and Catholicism, Candide, also marked the beginning of seismology as a science. As a direct result of monitoring this earthquake’s effects, enlightened thinkers, such as some fellows of Britain’s Royal Society, came to accept that earthquakes in general were caused by rocks shifting their position miles underground — not by God on high. Today, even the most unscientifically minded person is aware that every earthquake can be classified by its magnitude, a measure originally introduced by the Californian seismologist Charles Richter in 1935.
“The history of seismology since 1755 is traditionally seen as a progressive liberation of natural knowledge from the subjective impressions of earthquake victims,” notes Barnard College historian Deborah Coen early in The Earthquake Observers, accurately enough. But this will not do, she strongly argues. “Standardizing the measurement of disaster […] was nothing like standardizing mass, length, or electrical resistance.”
An old saw of seismology is that earthquakes don’t kill people; buildings do. Earthquake disasters are therefore extremely complex phenomena. They require seismologists to take into account both eyewitness reports by untrained individuals and a variety of physical effects dependent on the observer’s distance from the epicenter and on the differing construction quality of buildings, none of which can be captured by a single magnitude number or even by a range of numbers on an earthquake intensity scale. There is no such thing as the “true measure” of an earthquake, which would allow one “to conclude what damage occurred to buildings in the region without inspecting them,” wrote a Californian seismologist, Perry Byerly, in the 1960s. Recognizing this, the US Geological Survey runs a project, “Did You Feel It?” which invites members of the public worldwide to report their personal experience of an earthquake through a detailed questionnaire. Although Coen does not make the point, the inability of many seismologists to perceive the full complexity of earthquakes accounts for their overconfident promotion of the possibility of earthquake prediction in the second half of the 20th century.
The Earthquake Observers is a forceful, well written, and on the whole persuasive — dare I say it, groundbreaking — attempt to inject the importance of eyewitness reports into the history of seismology, chiefly during the 19th and early 20th centuries, concluding with the invention of Richter’s magnitude scale. To do this, the book concentrates on the reporting by all and sundry of earthquakes from the village of Comrie in the Scottish Highlands (which boasts the world’s first purpose-built seismic observatory, completed by the British Association for the Advancement of Science in 1874), from Switzerland, from the Austro-Hungarian Empire and, of course, from California. There is, however, almost nothing in the book on Japanese earthquake observing and culture, such as the popular outpouring of art after the great Ansei earthquake of 1855 in the form of entertaining and satirical “catfish” prints (namazu-e).
Throughout, the book draws both on unfamiliar archives, such as those of the Swiss Earthquake Commission. It also draws on the comments of the famous including scientist-explorers like Alexander von Humboldt and Charles Darwin, who experienced earthquakes in South America but whose chief interests were not in seismology, or writers like Mark Twain in California and Charles Dickens in London, who experienced an earthquake there in 1863 and was fascinated by the subject, arraying it alongside newly discovered phenomena such as electromagnetism. (Surprisingly, Coen does not quote Dickens’s fervid references to the great 1755 earthquake during his visit to Lisbon in 1858, published in his magazine Household Words.) Among seismologists, it is good to see plenty of attention devoted to Charles Davison, an English mathematics master at King Edward’s School, Birmingham, who experienced his first earthquake in 1896, became hooked on the subject during his lunch breaks, and eventually published an unrivaled history of British earthquakes in 1924.
Twain, as we might expect, was an acute observer of earthquakes. As a young journalist in San Francisco, he witnessed the city’s 1865 earthquake, its most violent since its founding. “Thousands of people were made so sea-sick by the rolling and pitching of floors and streets that they were weak and bed-ridden for hours, and some few for even days afterward,” he reported. But Twain also appreciated that ordinary people’s personal experience of earthquakes was not necessarily conducive to understanding when an earthquake would strike in the future. Soon after the 1865 quake, he published a parody, based on weather forecasting, of “the bombastic earthquake forecasting that infuriated nineteenth-century scientists” (Coen’s words), which is still amusing. Here is a brief extract:
Oct. 23. — Mild, balmy earthquakes.
Oct. 24. — Shaky.
Oct. 25. — Occasional shakes, followed by light showers of bricks and plastering. N.B. — Stand from under.
Oct. 26. — Considerable phenomenal atmospheric foolishness. About this time expect more earthquakes, but do not look out for them, on account of the bricks.
Oct. 27. — Universal despondency, indicative of approaching disaster. Abstain from smiling, or indulging in humorous conversation, or exasperating jokes.
But as Darwin frankly acknowledged after circumnavigating the world in the HMS Beagle from 1831 to 1836, there was no reason to assume that a trained scientist was a better observer of earthquakes than a local “savage.” Among the most sensitive observers were women, notes Coen, without overstressing the point: “A quiet, housebound lifestyle and close attention to the arrangement of domestic objects put many bourgeois women in an excellent position to detect tremors.” The Italian seismologist Giuseppe Mercalli agreed. While revising the Rossi-Forel intensity scale in 1902, Mercalli admitted: “Very sensitive and nervous people, especially women, feel earthquakes much better than I do.”
Today, the Modified Mercalli intensity scale is the best-known seismic intensity scale. Even so, after reading the complex history of intensity captured in The Earthquake Observers, one is not surprised that at least three different intensity scales — not just a single scale — are in international use.