Standing waves on the moon

American scientists L. Chadderton, F. Krajigenbridge, R. Katz and A. Pouved suggested that the natural oscillations of the moon, caused by the fall of giant meteorites, can play a large role in creating large-scale features of the lunar surface.

The observed natural oscillations of the Earth, the largest of which had a period of about an hour, were excited by large earthquakes, in particular, Kamchatka 1952, Chilean 1960, Alaska 1964.

The oscillations of the Earth form on the surface of the globe two systems perpendicular to each other of the nodal lines, where the displacements are equal to zero; these lines are similar to the circles of longitude and latitude. Two types of natural oscillations are possible: torsional, when displacements occur tangentially to the sphere, and spheroidal, at which displacements also take place along the radius.

Dr. Chadderton and his colleagues came to the conclusion that the sudden release of energy on the lunar surface - during volcanic events or large meteorite falls - can initiate free oscillations of the Moon with the greatest periods of 16 minutes for torsional vibrations and 14 minutes for spheroidal ones. As a result of torsional vibrations, giant shear bands will appear, stretching in the directions northeast – southwest and northwest – southeast. For spheroidal vibrations, the picture will be similar, but compression and tension are also added.

This system of displacements, which covers the entire moon globe, is well linked to the system of preferential directions on the moon, described by Sparre in the 1940s. The predominant areas are primarily the linear formations on the continents of the Moon - the ramparts of craters, mountain ranges, valleys and fissures. Many old lunar craters have a markedly polygonal shape, and the directions of the sides often correspond to the global system of preferred directions. Thus, it seems that the natural oscillations of the moon are an important tectonic force on our satellite.

Under certain conditions, a local standing wave system may occur. In this case, the nodal lines will be a system of concentric circles. Perhaps it was the formation of such a system that played a role in the formation of the basin of the Eastern Sea, which is surrounded by several giant concentric ring shafts. For spheroidal vibrations, the picture will be similar, but compression and tension are also added.