The International Seismological Summary

Abstract

THE International Seismological Summary for October, November and December 1933 has just been received. It deals with 123 epicentres for earthquakes which occurred during that quarter, of which 47 were new epicentres and 76 repetitions of earthquakes from old epicentres, thus again confirming the knowledge ‘that earthquakes tend to recur from the same epicentres. The five earthquakes with abnormal focus during the quarter all had deep foci. The first was on October 25, with epicentre in the Andes north-west of Jujuy (Argentine) with focus 0·03 of the earth's radius below normal. The second was on November 14 with epicentre north-east of Santiago on the borders of Chile and the Argentino with focal depth 0·02 of the earth's radius below normal. The third was on Novomber 19 in the Pacific Ocean off the Japanese coast nearly south of Tokyo with focal depth 0·035 of the earth's radius below normal. The fourth and deepest was on December 1 with epicentre in the Pacific Ocean immediately to the south of the island of Aneityum (Loyalty Islands, Melanesia) with focus 0·09 of the earth's radius below normal. The fifth was on December 4 with epicentre in the Sea of Okhotsk to the east of Odomari with focus 0·040 of the earth's radius below normal. In continuation of the “Catalogue of Earthquakes 1925–1930”, by Miss E. F. Bellamy, it has been decided to publish annually indexes to the International Seismological Summary. The first three of these for the years 1931, 1932 and 1933 arrived with the International Seismological Summary for the last quarter of 1933 and they form a very valuable addition to the summary for quick reference, The indexes are on a time basis, whereas Miss Bellamy's Catalogue 1913–1930 was on a geographical basis. The geographical basis is in many respects the better owing to the tendency mentioned above for earthquake shocks to recur from the same epicentre.