Abstract Under gravitational loading, a volcanic edifice deforms, and the underlying lithosphere downflexes. This has been observed on Earth, but is equally true on other planets. We use finite element models to simulate this gravity-driven deformation at Olympus Mons on Mars. Eleven model parameters, including the geometry and material properties of the edifice, lithosphere and underlying asthenosphere, are varied to establish which parameters have the greatest effect on deformation. Values for parameters that affect deformation at Olympus Mons, Mars, are constrained by minimising misfit between modelled and observed measurements of edifice height, edifice radius, and flexural moat width. Our inferred value for the Young's modulus of the Martian lithosphere, 17.8 GPa, is significantly lower than values used previously, suggesting that the Martian lithosphere is more porous than generally assumed. The best-fitting values for other parameters: edifice density (2111 – 2389 kg.m–3) and lithosphere thickness (83.3 km) are within ranges proposed hitherto. The best-fitting values of model parameters are interdependent; a decrease in lithosphere Young's modulus must be accompanied by a decrease in edifice density and/or an increase in lithosphere thickness. Our results identify the parameters that should be considered within all models of gravity-driven volcano deformation; highlight the importance of the often-overlooked Young's modulus; and provide further constraints on the properties of the Martian lithosphere, namely its porosity, which have implications for the transport and storage of fluid throughout Mars' history.

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关于火星岩石圈，奥林匹斯山能告诉我们什么？

摘要 在重力载荷作用下，火山结构发生变形，下伏岩石圈向下弯曲。这已在地球上观察到，但在其他行星上也同样如此。我们使用有限元模型来模拟火星奥林帕斯山的这种重力驱动变形。改变了 11 个模型参数，包括建筑物、岩石圈和下伏软流圈的几何形状和材料特性，以确定哪些参数对变形影响最大。影响火星 Olympus Mons 变形的参数值通过最小化建模和观察到的建筑物高度、建筑物半径和弯曲护城河宽度测量值之间的失配来限制。我们对火星岩石圈杨氏模量的推断值为 17.8 GPa，明显低于之前使用的值，表明火星岩石圈比通常假设的更多孔。其他参数的最佳拟合值：建筑物密度 (2111 – 2389 kg.m–3) 和岩石圈厚度 (83.3 km) 在迄今为止建议的范围内。模型参数的最佳拟合值是相互依赖的；岩石圈杨氏模量的降低必然伴随着建筑物密度的降低和/或岩石圈厚度的增加。我们的结果确定了所有重力驱动火山变形模型中应考虑的参数；强调经常被忽视的杨氏模量的重要性；并提供对火星岩石圈特性的进一步限制，即其孔隙度，这对整个火星历史上流体的运输和储存都有影响。