Institute of Geophysics, ETH Zürich, Zürich, Switzerland.
Department of Geology, University of Maryland, College Park, MD, USA.
Science. 2022 Oct 28;378(6618):417-421. doi: 10.1126/science.abq7157. Epub 2022 Oct 27.
We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.
我们探测到了火星上两次陨石撞击产生的表面波。通过测量沿撞击着陆器路径的群速度频散，我们获得了远离洞察着陆器的地壳结构的直接约束。赤道二分体以北的地壳在 5 至 30 公里的深度范围内具有约 3.2 公里/秒的剪切波速度，深度变化很小。这意味着地壳密度高于着陆器下方推断的密度，表明在表面波穿过的火山区域存在成分差异或孔隙度降低。在着陆点下方至 10 公里深度处观察到的较低速度和地壳分层并不是全球特征。表面波揭示的结构变化对火星地壳形成和厚度的模型具有重要意义。
