Recent Earthquakes

Abstract

DURING the period June 1-September 30 there were about forty major earthquakes, 140 moderate ones and some minor activity. The two greatest shocks during the period were probably those on July 10 in eastern Turkestan and on August 22 off British Columbia. Both reached instrumental magnitude 8. The former took place at 03h. 53m. 36s., G.M.T., from a focus with epicentre near lat. 39° N., long. 71° E., and was followed on the same day by four strong aftershocks and two moderate ones. The latter, at 04h. Olm. 12s., G.M.T., on August 22, took place from a focus with epicentre near lat. 54° N., long. 133° W., and was felt over a wide area in British Columbia. Minor damage was done. The earthquake caused a seismic sea-wave ortsunami which attained a height of two feet at Ketchican, Alaska, and for this earthquake the Hawaiian seismic sea-wave warning service was brought into operation (see Nature, October 1, p. 560). The shock of deepest focus for the month happened on June 12 from a focus 600 km. deep with epicentre near lat. 27° 8., long. 64° W., in northern Argentina. An aftershock the next day with the same epicentre took place from the same depth of focus.