’Quake forecast a ‘dilemma’

Press, 3 February 1981, Page 7

’Quake forecast a ‘dilemma’

A p/diction of an earthouakeh New Zealand would created major dilemma fot relieffgencies and the Govemrrim* according to the direct of the Ministry of Civ/Defence (Major-General r /. F. Holloway). il a paper presented at ftjier to the Conference on Lfge' Earthquakes, General jplloway said the dilemma Jis to decide whether a frediction presented “an Acceptable risk.” I “The dilemma would be (whether to act on. the prediction- or whether to .take drastic action or irreversible measures which may be costly in . both social and economic terms,” General Holloway said.' Earthquake prediction was unlikely to be in the clear and unequi vocable terms which the authorities needed to approve disaster planning and precautionary measures,

he said. , '■Rather, it seems -that a prediction will be uncertain in one or all of its elements of time, -place, and magni tude., It, will also be subject to continuing refinement, or even reversal.” . An earthquake prediction that could not be dismissed on scientific grounds would call for someone to make a difficult decision.. “The social and economic consequences of acting on a prediction-that proves to‘be false .are hardly to be preferred to the consequences of rejecting a prediction that seems improvable but which turns out .to be correct,” he said., . ■ "The decision must hinge on what is an acceptable risk'.’’ • * ’

However, in some cases, the need for extraordinary precautions would be unlikely. General Holloway cited the instance of a predicted earthquake, likely to be below a magnitude of six on the Richter scale, or one expected to shake populated areas with an intensity below six on the Modified Mercali scalein the last three years, there have been an average of six earthquakes a year with a Richter magnitude between five and six. But a predicted earthquake with an intensity of nine or more on the Modified Mercali scale in any populated or vulnerable area could hardly be ignored, even if it was regarded as relatively improbable.