Moonmoto

The moonquakes or moonquakes are lunar seismic movements that are generated at a depth of between 600 and 1000 kilometers, and their number is around 3000 per year.

Three different classes of moonquakes have been classified: fireball impacts, natural and artificially induced.

Of the first, we can highlight the one that occurred in July 1972, and was produced by an object weighing approximately 1000 kilograms.

The lunar seismometers, left behind by the Apollo missions, have recorded signs that show meteorite impacts of the order of 70 to 150 per year, with variable masses between 100 grams and one ton in weight.

Artificial or induced moonquakes have been caused by man in his study of the origin and lunar genesis. They are generated by the explosion of charges on the surface of our satellite, or by the impact of objects on the Moon such as the controlled launch of probes or useless phases of space vehicles against the ground.

The natural ones are those produced by the lunar geology itself, caused by the internal rearrangement of the Moon due to the fact that its orbit is not a perfect circle, since it presents an eccentricity, distinguishing the deep ones, generated by the tides, and the superficial ones whose origin is the expansion and contraction of the superficial rocks produced by the heating of the Sun.

Natural moonquakes have their origin inside the lunar globe, having been detected in the order of 4 weeks, although none of them have exceeded 2 degrees on the Richter scale, practically imperceptible by man.

The foci of a third of these earthquakes are located in a dozen points on the lunar globe, half of them having a common focus located 800 meters deep, under a small mountainous massif that separates the Nubium and Humorum.

The epicenters located so far are located along two lines about 2000 kilometers long, one of which is located approximately at the height of the 30ºW meridian, and the other oriented in the SW-NE direction.

Another curious peculiarity of moonquakes is that they occur especially during the week that corresponds to the passage of the Moon through its perigee, thus evidencing that these movements are favored by the tide that causes the terrestrial attraction, and that in that closest approach phase results in a wave of approximately 50 cm amplitude that propagates through the lunar crust.

Moonquakes have a maximum magnitude of 5 on the Richter scale and of this kind only occur about once a year.