Scientists have found that the Moon is shrinking and this can cause moonquakes.
The scientists at Center for Earth and Planetary Studies, Washington say that the Moon's surface crust is brittle so it breaks as the Moon shrinks causing quakes where one section of crust is pushed up over a neighboring part.
It is pertinent to mention that the Moon is not the only world in our solar system experiencing shrinkage. Mercury and ither planets also experienced similar shrinkage.
Source: Radio Pakistan