Hobiger M, Hallo M, Schmelzbach C, Stähler S C, Fäh D, Giardini D, Golombek M, Clinton J, Dahmen N, Zenhäusern G, Knapmeyer-Endrun B, Carrasco S, Charalambous C, Hurst K, Kedar S, Banerdt W B
Swiss Seismological Service (SED), ETH Zurich, Zurich, Switzerland.
Federal Institute for Geosciences and Natural Resources (BGR), Hanover, Germany.
Nat Commun. 2021 Nov 23;12(1):6756. doi: 10.1038/s41467-021-26957-7.
Orbital and surface observations can shed light on the internal structure of Mars. NASA's InSight mission allows mapping the shallow subsurface of Elysium Planitia using seismic data. In this work, we apply a classical seismological technique of inverting Rayleigh wave ellipticity curves extracted from ambient seismic vibrations to resolve, for the first time on Mars, the shallow subsurface to around 200 m depth. While our seismic velocity model is largely consistent with the expected layered subsurface consisting of a thin regolith layer above stacks of lava flows, we find a seismic low-velocity zone at about 30 to 75 m depth that we interpret as a sedimentary layer sandwiched somewhere within the underlying Hesperian and Amazonian aged basalt layers. A prominent amplitude peak observed in the seismic data at 2.4 Hz is interpreted as an Airy phase related to surface wave energy trapped in this local low-velocity channel.
轨道观测和地面观测有助于揭示火星的内部结构。美国国家航空航天局（NASA）的“洞察号”任务能够利用地震数据绘制埃律西昂平原的浅层地下结构。在这项研究中，我们应用了一种经典的地震学技术，即对从背景地震振动中提取的瑞利波椭圆率曲线进行反演，从而首次在火星上解析出约200米深度以内的浅层地下结构。虽然我们的地震波速度模型在很大程度上与预期的分层地下结构一致，即由熔岩流堆叠之上的一层薄风化层组成，但我们在大约30至75米深度处发现了一个地震低速带，我们将其解释为夹在下层晚赫斯珀利亚纪和亚马逊纪玄武岩层之间某处的沉积层。在地震数据中观测到的2.4赫兹处的一个显著振幅峰值被解释为与被困在这个局部低速通道中的面波能量相关的艾里相。
