土卫二上的喷流活动与潮汐驱动的沿虎纹走滑运动有关，这一成果由美国加州理工学院Berne, Alexander团队经过不懈努力而取得。相关论文发表在2024年4月29日出版的《自然—地球科学》杂志上。
据了解，在土星的卫星土卫二上，沿着被称为“虎纹”的独特裂缝的喷射流在南极上空喷出冰晶，形成广阔的羽流。当土卫二绕土星运行时，虎纹经历了潮汐驱动的剪切力和正常牵引力的变化。
研究使用受潮汐力作用的球形冰壳的数值有限元模型，以探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，在每个轨道上都有两个活动峰。研究人员认为，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导致峰值走滑幅度的差异，并延迟了潮汐应力峰值后断层运动的第一个峰值。
模拟虎纹的双峰和不对称走滑运动，与从卡西尼号宇宙飞船的羽流亮度图像推断的，喷流活动的日变化是一致的。走滑运动的空间分布也与卡西尼号对热流的红外观测相吻合。研究团队假设走滑运动可以沿着虎纹上的几何不规则性扩展张性弯曲(例如，拉分构造)，并调节喷流活动。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。
附：英文原文
Title: Jet activity on Enceladus linked to tidally driven strike-slip motion along tiger stripes
Author: Berne, Alexander, Simons, Mark, Keane, James T., Leonard, Erin J., Park, Ryan S.
Issue&Volume: 2024-04-29
Abstract: 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.
DOI: 10.1038/s41561-024-01418-0
Source: https://www.nature.com/articles/s41561-024-01418-0