Small moonquakes, originating several kilometers below the surface, are thought to be caused by the gravitational pull of Earth.

发源自月球表面以下几英里的轻微月震据估计是由地球引力的牵引造成的。

This paper deals with the relation between the internal structure of the moon and the radial distribution of the focuses of moonquakes.

本文讨论月球的内部构造与月震震源径向分布的关系。

The moon has shrunk in the past billion years, and may still be shrinking today, triggering moonquakes and making the moon a more active body than previously thought.

月球在过去数十亿年中一直在收缩，并且今天可能还在收缩。它的收缩可能引发了月球地震，并说明它比我们过去认为的更加活跃。