At Saturn’s moon Enceladus, jets along four distinct fractures called ‘tiger stripes’ erupt ice crystals into a broad plume above the South Pole. The tiger stripes experience variations in tidally driven shear and normal traction as Enceladus orbits Saturn. Here, we use numerical finite-element modelling of a spherical ice shell subjected to tidal forces to show that this traction may produce quasi-periodic strike-slip motion in the Enceladus crust with two peaks in activity during each orbit. We suggest that friction modulates the response of tiger stripes to driving stresses, such that tidal traction on the faults results in a difference in the magnitudes of peak strike slip and delays the first peak in fault motion following peak tidal stress. The simulated double-peaked and asymmetric strike-slip motion of the tiger stripes is consistent with diurnal variations in jet activity inferred from Cassini spacecraft images of plume brightness. The spatial distribution of strike-slip motion also matches Cassini infrared observations of heat flow. We hypothesize that strike-slip motion can extend transtensional bends (for example, pull-apart structures) along geometric irregularities over the tiger stripes and thus modulate jet activity. Tidally driven fault motion may also influence longer term tectonic evolution near the South Pole of the satellite.

在土星的卫星土卫二上，喷射流沿着四个被称为“虎纹”的明显裂缝，将冰晶喷发成南极上空的宽阔羽流。当土卫二绕土星运行时，虎纹会经历潮汐驱动的剪切力和正常牵引力的变化。在这里，我们使用受到潮汐力作用的球形冰壳的数值有限元模型来表明，这种牵引力可能会在土卫二地壳中产生准周期性走滑运动，并且在每个轨道上都有两个活动峰值。我们认为，摩擦调节了虎纹对驱动应力的响应，使得断层上的潮汐牵引力导致峰值走滑幅度的差异，并延迟了峰值潮汐应力之后断层运动的第一个峰值。模拟的虎纹双峰和不对称走滑运动与卡西尼号航天器羽流亮度图像推断出的喷流活动的日变化一致。走滑运动的空间分布也与卡西尼号红外热流观测结果相符。我们假设走滑运动可以沿着虎纹上的几何不规则性延伸张拉弯曲（例如，拉开结构），从而调节喷流活动。潮汐驱动的断层运动也可能影响卫星南极附近的长期构造演化。