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The free oscillations of the earth have been experimentally verified from an analysis of strain seismograph and pendulum seismograph recordings made in California and Peru from the great Chilean earthquake of May 1960. Both spheroidal and torsional oscillations were revealed by a power spectral analysis of the seismograms. The gravest spheroidal mode shows a split spectral peak with periods of 54.7 and 53.1 minutes. The theoretical prediction for the Bullen B model according to Alterman, Perkeris, and Jarosch is 53.7 min. The oscillations were observed for all modes up to 38 with corresponding periods as short as 3.7 minutes. For the higher modes, agreement in the observed period is found between the Chilian earthquake and the Kamchatka earthquake of 1952. In almost all cases agreement between experimental and theoretical predictions is close. Differences which occur should make it possible to discriminate between the several earth models which have been proposed. From the width of the spectral peak, values of the dissipation function Q−1 for the earth could be determined with an accuracy greater than was previously possible. For the spheroidal mode S3(T = 35.5 min), Q = 380, and for the mode S18(T = 6.2 min), Q = 170. On the assumption that Q is independent of frequency, this implies a higher Q in the core than in the mantle. A method is described for deducing the fault length and rupture velocity from analysis of phase difference between components of ground motion. Preliminary results indicate a fault length for the Chilean earthquake of about 1000 km and rupture velocities in the range 3 to 4 km/sec.

The dislocation theory representation of faulting of Vvedenskaya, Steketee, Chinnery, and Maruyama is used to compute the residual displacement, strain, and tilt fields at intermediate and large distances from major earthquakes. It is shown that the distant fields are large enough to be detected by modern instruments. The vertical displacement field from the Alaskan earthquake of March 27, 1964, indicates that the primary fault extended to a depth of 150 to 200 km and that it probably came to within 15 km of the surface. The residual strain observed at Hawaii amounted to 10−8, a value which is reasonably consistent with the extent of faulting and the displacements near the source. The elastic strain energy release was about 1025 ergs. Other observations of residual strains and tilts are examined. In some cases nonfaulting sources are probably involved. In other cases the observations may be a spurious manifestation of instrumental hysteresis. The Mindlin‐Cheng catalog of fields from various nuclei of strain in a half‐space offers a convenient way to derive residual displacements from diverse sources, including those of Chinnery and Maruyama.

Abstract. ]Komogeneous wave guide theory is used to derive dispersion curves, vertical pressure distributions, and synthetic baregrams for atmospheric waves. A complicated mode structure is found involving both gravity and acoustic waves. Various models of the atmosphere are studied to explore seasonal and geographic effects on pulse propagation. The influence of different zones in the atmosphere on the character of the baregrams is studied. It is found that the first arriving waves are controlled by the properties of the lower atmospheric channel. Comparison of theoretical results and experimental data from large thermonuclear explosions is made in the time an,d frequency domains, and the following conclusions are reached: (1) The major features on baregrams are due to dispersion; (2) superposition of severM modes is needed to explain observed features; (3) scatter of d•t• outside the range permitted by extreme atmospheric models shows the influence of winds for Ax; wind effects and higher modes are less important for A• waves. A discussion is included on atmospheric terminations and how these affect dispersion curves.