’Quake Forecasting Methods Discussed

Gisborne Herald, Volume LXXV, Issue 22808, 1 December 1948, Page 2

’Quake Forecasting Methods Discussed

A common notion that earthquakes are caused by volcanoes has been quashed by C A Cotton, Professor of Geology, Victoria University College, Wellington. “The explanation of the fact that volcanoes and earthquakes are associated as related phenomena,” he says, “is not to be found in a theory that volcanoes cause earthquakes. The vast majority of the earthquakes felt in the Wellington district are of nonvolcanic origin. "The truth of the matter is that both volcanoes and earthquakes originate in the mobile belts of the earth's crust and notably in the Pacific rim. Actually the volcanic and earthquake districts in New Zealand, though they are side by side and overlap to some extent, are not the same. Earthquake activity is strong only in our middle district, and is strongest in those parts of it that are remote from volcanoes, active or extinct.” The question of the possibility of earthquake forecasting was a fascinating one, continued Dr Cotton. It might be possible in the future to determine to some extent the distribution of stress ii- crustal rocks; and, when all the main lines of weakness made by failure under former stress conditions were known and mapped, indications of accumulating stress near any one of these might justify a warning that an earthquake was imminent. In California the most promising approach to the problem of accumulating stress was made by observation of slow movements that were in progress some distance back from a major fault ling. Whether this method would prove fruitful in New Zealand was still in doubt. Here earthquake-mak-ing movements, in contrast with those of California, were in the main vertical, and it was- by no means certain that slow movements had here preceded shocks.