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- Title
Strong Heterogeneity in Shallow Lunar Subsurface Detected by Apollo Seismic Data.
- Authors
Zhang, Xiang; Zhang, Lei; Zhang, Jinhai; Mitchell, Ross N.
- Abstract
Experiencing heavy impacting, the Moon preserves a megaregolith in its shallow subsurface with physical properties that carry implications for lunar history. A strong scattering of seismic waves associated with the heterogeneous lunar megaregolith appears to be systematic, but deriving a statistical law of the random heterogeneities has remained elusive. Apollo seismic data are characterized by ultra‐long coda waves with weak amplitude decay that provide an opportunity to explore the extent of heterogeneity in the lunar crust. We obtain by numerical simulation the appropriate parameters for seismic velocity and density perturbation of the shallow lunar crust that match Apollo seismic data. The perturbations of the shallow lunar crust identified here, which are at least 50%, are much larger than previously thought. This physical behavior thus both confirms a strongly heterogeneous surface layer as well as provides a new constraint on the structural characteristics of the megaregolith. Plain Language Summary: The Moon experienced heavy impacting, thus the shallow crust should retain many cracks and boulders. Exploring the degree of complexity of the shallow crustal structure could reveal critical insights into the lunar evolutionary history. We compare the Apollo moonquake waveforms with numerous simulations and obtain better constraints on the structural characteristics of the shallow lunar crust. Our results confirm that the Moon has exceptionally strong heterogeneity in the crust, especially close to the surface, and it is much larger than reported in previous studies. This significant refinement could help better understand the structural characteristics of the shallow lunar crust. Key Points: We simulate lunar seismic data with ultra‐long coda waves and weak amplitude decay by applying strong scattering in shallow lunar crustWe detect the heterogeneity of the lunar crust by testing different possible types of models using a large number of numerical simulationsBoth deep and shallow moonquakes reveal that the heterogeneity in the shallow lunar crust is much greater than previously expected
- Subjects
SEISMIC waves; SEISMIC wave scattering; HETEROGENEITY; SEISMIC wave velocity
- Publication
Journal of Geophysical Research. Planets, 2022, Vol 127, Issue 11, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2022JE007222