Abstract
THE periodicity of the aftershocks ee of the great Indian earthquake of June 12, 1897, is treated by Mr. R. D. Oldham in vol. xxxv. of the Memoirs of the Geological Survey of India. The principal conclusions, drawn from the records of the Shillong seismograph, have already been published in the Journal of the Asiatic Society of Bengal, vol. xxxi., and the present paper contains particulars of the discussion of other records, of varying completeness, and shows that they confirm the conclusion already arrived at, that there is a tendency to a slight increase of frequency about the time when the horizontal tide-producing forces are varying-most rapidly in amount and direction. The paper is illustrated by a number of curves of frequency, among which we may specially refer to one showing the semidiurnal frequency of shocks during the half days in which the variation of tidal stress is greatest and least; the curves are striking as they stand, but would have been even more instructive had the relative frequency been calculated to the mean of the whole year instead of to that of each period. The very marked diurnal variation in frequency is shown to have no relation to the variations of barometric pressure.
Article PDF
Rights and permissions
About this article
Cite this article
Seismological Notes . Nature 69, 571 (1904). https://doi.org/10.1038/069571b0
Issue Date:
DOI: https://doi.org/10.1038/069571b0