Active eruptions from the south polar region of Saturn’s ~500-km-diameter moon Enceladus are concentrated along a series of lineaments known as the ‘tiger stripes’^1,2, thought to be partially open fissures that connect to the liquid water ocean beneath the ice shell^3,4. To date, no study simultaneously explains why the tiger stripes should be located only at the south pole, why there are multiple approximately parallel and regularly spaced fractures, what accounts for their spacing of about 35 km, and why similarly active fissures have not been observed on other icy bodies. Here we propose that secular cooling, which leads to a thickening of the ice shell and building of global tensile stresses^5,6, causes the first fracture to form at one of the poles, where the ice shell is thinnest owing to tidal heating⁷. The tensile stresses are thereby relieved, preventing a similar failure at the opposite pole. The steadily erupting water ice loads the flanks of the open fissure, causing bending in the surrounding elastic plate and further tensile failure in bands parallel to the first fracture—a process that may be unique to Enceladus, where the gravity is too weak for compressive stresses to prevent fracture propagation through the thin ice shell. The sequence of fissures then cascades outwards until the loading becomes too weak or the background shell thickness becomes too great to permit through-going fractures.

来自土星直径约500公里的土卫二的南极地区的活跃喷发集中在一系列被称为“老虎条纹”的线^1,2上，这些线被认为是部分开放的裂隙，连接至海底下方的液态水海洋。冰壳^3,4。迄今为止，尚无任何研究同时解释为什么老虎条纹仅应位于南极，为什么存在多个近似平行且规则间隔的裂缝，占其约35 km间距的原因，以及为何未观察到类似的活动裂缝在其他冰冷的身体上。在这里，我们建议长期冷却，这会导致冰壳变厚并形成整体拉应力^5,6导致第一裂缝在其中一个极点形成，在极点处，由于潮汐加热⁷使冰壳最薄。由此减轻了张应力，从而防止了在相反的极处发生类似的故障。不断喷出的水冰将张开的裂缝的侧面加载，导致周围的弹性板弯曲，并在平行于第一次断裂的带中进一步拉伸破坏-这可能是土卫二的独特之处，因为重力太弱而无法承受压应力防止裂缝通过薄冰壳传播。裂缝的顺序然后向外层叠，直到载荷变得太弱或背景壳的厚度变得太大而无法穿透。