Summary

The epicenter of the South Atlantic earthquake of August 28, 1933, was located at 58° 56′ S, 24° 54′ W, and the time of occurrence fixed as 22h 19m 38s U.T.

A study was made of the first motion of P. On the assumption that the earthquake was caused by a fault movement, the strike of the fault was determined as between N 33° W and N 1° E, and the dip as between 63° E and 76° E.

By integration of the seismograms the earth motion during the G phase was determined at 17 stations. This wave was found to agree with the theoretical surface wave of Love.

A study of the dispersion of G yielded the following conclusions. The crustal structure of the Atlantic Ocean region is very similar to that of the Indian and Pacific regions, and is characterized by having material with a high velocity for shear waves much nearer the surface than is observed in the continental regions. The thickness of the crustal structure in continental regions is about 30 to 40 km.

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