Litigation Associate San Francisco
litigation associate san francisco
Earthquake control?
During the Cold War a geophysicist at UC Los Angeles, Gordon MacDonald, speculated about the use of earthquakes as a weapon. It would operate by the explosion of bombs in small faults, intended to trigger movement in a major fault. ‘For example,’ he explained, ‘the San Andreas fault zone, passing near Los Angeles and San Francisco, is part of the great earthquake belt surrounding the Pacific. Good knowledge of the strain within this belt might permit the setting off of the San Andreas zone by timed explosions in the China Sea and the Philippines Sea.’
In 1969, soon after MacDonald wrote those words, Canada and Japan lodged protests against a US series of nuclear weapons tests at Amchitka in the Aleutian Islands, on the grounds that they might trigger a major natural earthquake. They didn’t, and the question of whether a natural earthquake or an explosion, volcanic or man-made, can provoke another earthquake far away is still debated. If there is any such effect it is probably not quick, in the sense envisaged here.
MacDonald’s idea nevertheless drew on his knowledge of actual man-made earthquakes that happened by accident. An underground H-bomb test in Nevada in 1968 caused many small earthquakes over a period of three weeks, along an ancient fault nearby. And there was a longer history of earthquakes associated with the creation of lakes behind high dams, in various parts of the world.
Most thought provoking was a series of small earthquakes in Denver, from 1963 to 1968, which were traced to an operation at the nearby Rocky Mountain Arsenal. Water contaminated with nerve gas was disposed of by pumping it down a borehole 3 kilometres deep. The first earthquake occurred six weeks after the pumping began, and activity more or less ceased two years after the operation ended.
Evidently human beings could switch earthquakes on or off by using water under pressure to reactivate and lubricate faults within reach of a borehole. This was confirmed by experiments in 1970-71 at an oilfield at Rangely, Colorado. They were conducted by scientists from the US National Center for Earthquake Research, where laboratory tests on dry and wet rocks under pressure showed that jerks along fractures become more frequent but much weaker in the presence of water.
From this research emerged a formal proposal to save San Francisco from its next big earthquake by stage-managing a lot of small ones. These would gently relieve the strain that had built up since 1906, when the last big one happened. About 500 boreholes 4000 metres deep, distributed along California’s fault lines, would be needed. Everything was to be done in a controlled fashion, by pumping water out of two wells to lock the fault on either side of a third well where the quake-provoking water would be pumped in.
The idea was politically impossible. Since every earthquake in California would be blamed on the manipulators, whether they were really responsible or not, litigation against the government would continue for centuries. And it was all too credible that a small man-made earthquake might trigger exactly the major event that the scheme was intended to prevent. By the end of the century Kanamori’s conclusion, that the growth of a small earthquake into a big one might be inherently unpredictable, carried the additional message: you’d better not pull the tiger’s tail.
