ON THE EARTH TIDES OBSERVED ON THE ASIAN CONTINENT AND IN THE PACIFIC AREA

Abstract

A great many observations of earth tides are being made by means of gravimeters, tiltmeters and extensometers at many stations in the world since the International Geophysical Year. But the values of three characteristic numbers on the earth tides h, k and l, related to the elastic behaviour of the earth, obtained at many stations are not always identical and regional differences are clearly recognized in the values of the characteristic numbers. A considerable divergency in their values, far in excess of observational error is also observed with time, even at one station. Results of earth tidal observations made with gravimeters at some stations on the Asian Continent and in the Pacific Area since the beginning of the IGY, are described in the present article. Data have been analyzed by the method of least squares, the Fourier transform or the usual harmonic analysis for obtaining the gravimetric factor G=1-3k/2+h and the phase lag. The most reliable value of the gravimetric factor G for continental stations in Asia is 1.14 but that for oceanic ones is slightly larger. The value of the phase lag is very small for both the continental and the oceanic stations. A regional difference between Asia and Europe is clearly found in various values related with the earth tides. It could be due to a regional heterogeneity in the elastic properties of the Upper Mantle for both continents.