| タイトル | Shallow Lunar Seismic Activity and the Current Stress State of the Moon |
| 本文（外部サイト） | http://hdl.handle.net/2060/20170002696 |
| 著者（英） | Johnson, Catherine L.; Weber, Renee C.; Watters, Thomas R.; Collins, Geoffrey C. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 2017-03-20 |
| 言語 | eng |
| 内容記述 | A vast, global network of more than 3200 lobate thrust fault scarps has been revealed in high resolution Lunar Reconnaissance Orbiter Camera (LROC) images. The fault scarps are very young, less than 50 Ma, based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben and may be actively forming today. The population of young thrust fault scarps provides a window into the recent stress state of the Moon and offers insight into the origin of global lunar stresses. The distribution of orientations of the fault scarps is non-random, inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress. Modeling shows that tidal stresses contribute significantly to the current stress state of the lunar crust. Tidal stresses (orbital recession and diurnal tides) superimposed on stresses from global contraction result in non-isotropic compressional stress and may produce thrust faults consistent with lobate scarp orientations. At any particular point on the lunar surface, peak compressive stress will be reached at a certain time in the diurnal cycle. Coseismic slip events on currently active thrust faults are expected to be triggered when peak stresses are reached. Analysis of the timing of the 28 the shallow moonquakes recorded by the Apollo seismic network shows that 19 indeed occur when the Moon is closer to apogee, while only 9 shallow events occur when the Moon is closer to perigee. Here we report efforts to refine the model for the current stress state of the Moon by investigating the contribution of polar wander. Progress on relocating the epicentral locations of the shallow moonquakes using an algorithm designed for sparse networks is also reported. |
| NASA分類 | Lunar and Planetary Science and Exploration |
| レポートNO | MSFC-E-DAA-TN40249 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
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