The Alaska earthquake, which occurred at 5:36 P.M. local time on Friday March 27, 1964 (0336, March 28, 1964 UT), initiated a large traveling ionospheric disturbance. This disturbance undoubtedly affected many different types of ionospheric sensors; however, the data reported here are limited to ionosondes operating at College, Alaska; Adak, Alaska; Palo Alto, California; and Maui, Hawaii. The ionosonde data show indications of the perturbation in two different forms. The form depends on the distance between the observing station and the epicenter of the earthquake.

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Analysis of data collected by five auroral radars in Alaska shows the distribution of of ionospheric disturbances as a function of time and location. The radars, operated during the IGY, were in a nearly straight line running magnetically north‐south across Alaska; these locations made it possible to observe disturbances continuously in the range from 60° to 80° geomagnetic latitude, which includes the visual auroral zone. An apparent radar auroral zone with a maximum at 67° geomagnetic latitude is shown. The decrease in occurrence to the south of this maximum is verified, but the decrease to the north cannot be accurately defined, as the role of aspect sensitivity is not fully understood. The radar auroral zone spreads to the south during increased magnetic disturbance, and some indication is found of a lessening of activity well north of the visual auroral zone. Further evidence is given to support the observation that the layer causing radio wave absorption during auroras is not uniform but contains ‘holes’ or regions of low absorption. The diurnal occurrence curves indicate two principal maxima. One is observed at all stations at times near local midnight. The time of the other maximum depends on the latitude of observations; it is later in the morning at the more northern locations. These two echoes exhibit different degrees of aspect sensitivity, the morning echoes having a narrower scattering polar diagram.

Several methods have been proposed for calculating the magnitude and direction of the earth's magnetic field at locations above the earth's surface. During the 1962 Johnston Island explosions, observations were made of the man‐made aurora caused by β particles guided into the southern conjugate region by the earth's magnetic field. The measured location of the initial disturbance was compared with the location calculated by several different models of the earth's magnetic field; the average differences between the observed and calculated points are tabulated. The Jensen and Cain coefficient set is found to give the smallest average difference in the region studied.