The volcanic landforms, eruptive sites and longevity of activity on Mercury and the Moon contrast substantially with those of Earth, Venus and Mars. Here, I synthesize global maps of volcanic and tectonic features for these five worlds and, from the collective records of volcanic activity in the inner Solar System, draw conclusions about the long-term behaviour of terrestrial planets in general. Mercury and the Moon differ from the larger planetary bodies in terms of not only size and composition (and so shorter periods of melt production) but also by their being affected by a horizontally compressive stress state arising from a reduction in planetary volume as they cooled. The phenomenon of global contraction also readily accounts for the dearth of widespread extensional tectonic structures on Mercury and the Moon. From this comparative analysis, the most promising extrasolar planets on which to focus future searches for evidence of active, radiogenically driven volcanism are probably the larger rocky bodies in a mature planetary system or those worlds in relatively young systems.

水星和月球上的火山地貌，喷发点和活动寿命与地球，金星和火星形成鲜明对比。在这里，我综合了这五个世界的火山和构造特征的全球地图，并根据内部太阳系中火山活动的集体记录，得出了关于总体上地球行星的长期行为的结论。水星和月球与大行星体的不同之处不仅在于其尺寸和组成（以及较短的熔体生成时间），还在于它们受到水平压缩应力状态的影响，这些应力是由于冷却时行星体积的减小而产生的。全球收缩现象也很容易解释了水星和月球上广泛的伸展构造结构的缺乏。根据比较分析，