In its first evaluation of an earthquake forecast, the U.S. National Earthquake Prediction Evaluation Council denounced the prediction by two geophysicists that a series of major quakes will occur in Peru this summer. Brian Brady of the U.S. Bureau of Mines made the prediction on the basis of a model of rock fracture. William Spence of the U.S. Geological Survey worked with Brady on the investigation of the tectonics near Peru. Despite the council's ruling, Brady maintains his prediction.
Meeting at the request of the Peruvian government, the council evaluated the predictions that seismic activity (magnitude 4.5 or greater) off Peru's coast will increase by mid-May. This increased activity will signal the start of a sequence of three earthquakes: a magnitude 7.5–8.0 event on or about June 28, a magnitude 9.2 event on or about August 10, and a magnitude 9.9 event on or about September 16. Brady and Spence used the Kanamoori scale, which is equivalent to the Richter scale below 8.0 but is more accurate above magnitude 8 because it accounts for low-frequency tremors. The Peruvian government made the request to the U.S. council in response to public apprehension on learning of the forecast.