Shallow seismic activity and young thrust faults on the Moon

Abstract

The discovery of young thrust faults on the Moon is evidence of recent tectonic activity, but how recent is unknown. Seismometers at four Apollo landing sites recorded 28 shallow moonquakes between 1969 and 1977. Some of these shallow quakes could be associated with activity on the young faults. However, the epicentre locations of these quakes are poorly constrained. Here we present more-accurate estimates of the epicentre locations, based on an algorithm for sparse seismic networks. We found that the epicentres of eight near-surface quakes fall within 30 km of a fault scarp, the distance of the expected strong ground shaking. From an analysis of the timing of these eight events, we found that six occurred when the Moon was less than 15,000 km from the apogee distance. Analytical modelling of tidal forces that contribute to the current lunar stress state indicates that seven near-apogee events within 60 km of a fault scarp occur at or near the time of peak compressional stresses, when fault slip events are most likely. We conclude that the proximity of moonquakes to the young thrust faults together with evidence of regolith disturbance and boulder movements on and near the fault scarps strongly suggest the Moon is tectonically active.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: A prominent lobate thrust fault scarp in the Mandel’shtam cluster located in the far-side highlands (6.9° N, 161° E) is one of thousands discovered in the LROC images.
Fig. 2: Maps that show the locations of young lobate thrust fault scarps and shallow moonquakes.
Fig. 3: Seismic shakemaps and expected ground motion for a slip event on a thrust fault in the Mandel’shtam cluster.
Fig. 4: EMD over the course of the Apollo seismic experiment.
Fig. 5: Current near-surface stress state of the Moon.
Fig. 6: Possible evidence of recent activity on fault scarps near relocated shallow moonquakes.

Data availability

The images and data used in this study are available on the Smithsonian’s National Air and Space Museum Data Repository website (https://airandspace.si.edu/research/data-repository). The raw and calibrated image data that support the findings of this study are available from Planetary Data System Cartography and Imaging Sciences Node, LROC Data Archive at the LROC Data Node http://wms.lroc.asu.edu/lroc/rdr_product_select.

References

  1. 1.

    Watters, T. R. et al. Evidence of recent thrust faulting on the Moon revealed by the Lunar Reconnaissance Orbiter Camera. Science 329, 936–940 (2010).

  2. 2.

    Watters, T. R. et al. Global thrust faulting on the Moon and the influence of tidal stresses. Geology 43, 851–854 (2015).

  3. 3.

    Watters, T. R. & Johnson, C. L. in Planetary Tectonics (eds Watters, T. R. & Schultz, R. A.) 121–182 (Cambridge Univ. Press, New York, 2010).

  4. 4.

    Banks, M. E. et al. Morphological analysis of lobate scarps on the Moon using data from the Lunar Reconnaissance Orbiter. J. Geophys. Res. 117, E00H11 (2012).

  5. 5.

    Williams, N. R. Fault dislocation modeled structure of lobate scarps from Lunar Reconnaissance Orbiter Camera digital terrain models. J. Geophys. Res. 118, 224–233 (2013).

  6. 6.

    van der Bogert, C. H. et al. How old are lunar lobate scarps? 1. Seismic resetting of the crater size-frequency distribution. Icarus 306, 225–242 (2018).

  7. 7.

    Watters, T. R. et al. Recent extensional tectonics on the Moon revealed by the Lunar Reconnaissance Orbiter Camera. Nat. Geosci. 5, 181–185 (2012).

  8. 8.

    Nakamura, Y. et al. Shallow moonquakes: depth, distribution and implications as to the present state of the lunar interior. In Proc. Tenth Lunar Sci. Conf. (ed. Merrill, R. B.) 2299–2309 (Pergamon, New York, 1979).

  9. 9.

    Nakamura, Y. et al. Passive Seismic Experiment Long-Period Event Catalog Technical Report No. 118 (Institute for Geophysics, Univ. of Texas, 1981).

  10. 10.

    Nakamura, Y., Latham, G. V. & Dorman, H. J. Apollo lunar seismic experiment—final summary. J. Geophys. Res. 87, A117–A123 (1982).

  11. 11.

    Oberst, J. Unusually high stress drops associated with shallow moonquakes. J. Geophys. Res. 92, 1397–1405 (1987).

  12. 12.

    Binder, A. B. & Oberst, J. High stress shallow moonquakes: evidence for an initially totally molten Moon. Earth Planet. Sci. Lett 74, 149–154 (1985).

  13. 13.

    Lognonné, P., Gagnepain-Beyneix, J. & Chenet, H. A new seismic model of the Moon: implication in terms of structure, thermal evolution and formation of the Moon. Earth Planet. Sci. Lett. 211, 27–44 (2003).

  14. 14.

    Gillet, K., Magerin, L., Calvet, M. & Monnereau, M. Scattering attenuation profile of the Moon: implications for shallow moonquakes and the structure of the megaregolith. Phys. Earth Planet. Inter. 262, 28–40 (2017).

  15. 15.

    Knapmeyer, M. Location of seismic events using inaccurate data from very sparse networks. Geophys. J. Int. 175, 975–991 (2008).

  16. 16.

    Weber, R. C., Knapmeyer, M., Panning, M. & Schmerr, N. in Extraterrestrial Seismology (eds Tong, V. C. H. & Garcia, R. A.) 140–158 (Cambridge Univ. Press, New York, 2015).

  17. 17.

    Blanchette-Guertin, J.-F., Johnson, C. L. & Lawrence, J. F. Investigation of scattering in lunar seismic coda. J. Geophys. Res. 117, E06003 (2012).

  18. 18.

    Nakamura, Y. & Koyama, J. Seismic Q of the lunar upper mantle. J. Geophys. Res. 87, 4855–4861 (1982).

  19. 19.

    Oberst, J. & Nakamura, Y. in The Second Conference on Lunar Bases and Space Activities of the 21st Century Vol. 1 (ed. Mendell, W. W.) 231–233 (NASA, 1985).

  20. 20.

    Mahanti, P., Robinson, M. S., Thompson, T. J. & Henriksen, M. R. Small lunar craters at the Apollo 16 and 17 landing sites—morphology and degradation. Icarus 299, 475–501 (2018).

  21. 21.

    Worden, C. B., Gerstenberger, M. C., Rhoades, D. A. & Wald, D. J. Probabilistic relationships between ground–motion parameters and modified Mercalli intensity in California. Bull. Seism. Soc. Am. 102, 204–221 (2012).

  22. 22.

    Matsuyama, I. & Nimmo, F. Tectonic patterns on reoriented and despun planetary bodies. Icarus 195, 459–473 (2008).

  23. 23.

    Collins, G. C., et al. in Planetary Tectonics (eds Watters, T. R. & Schultz, R. A.) 264–350 (Cambridge Univ. Press, New York, 2010).

  24. 24.

    Siegler, M. A. et al. Lunar true polar wander inferred from polar hydrogen. Nature 531, 480–484 (2016).

  25. 25.

    Kumar, P. S. et al. Recent shallow moonquake and impact-triggered boulder falls on the Moon: new insights from the Schrödinger basin. J. Geophys. Res. 121, 147–179 (2016).

  26. 26.

    Arvidson, R., Drozd, R. J., Hohenberg, C. M., Morgan, C. J. & Poupeau, G. Horizontal transport of the regolith, modification of features, and erosion rates on the lunar surface. Moon 13, 67–79 (1975).

  27. 27.

    Schmitt, H. H. et al. Revisiting the field geology of Taurus–Littrow. Icarus 298, 2–33 (2017).

  28. 28.

    van der Bogert, C. H. et al. Derivation of absolute model ages for lunar lobate scarps. In 43rd Lunar Plant. Sci. Conf. abstr. 1847 (2012).

Download references

Acknowledgements

We thank A. Nahm and T. Kawamura for their thoughtful comments and suggestions that improved the manuscript, and we also thank M. S. Robinson and the LROC team. We gratefully acknowledge the LRO engineers and technical support personnel. This work was supported by the LRO Project and an ASU LROC Contract (T.R.W.). C.L.J. acknowledges support from the Natural Sciences and Engineering Research Council of Canada.

Author information

T.R.W. drafted the manuscript. R.C.W. and I.J.H. relocated the shallow moonquakes and R.C.W. analysed the timing and EMD, G.C.C. modelled the stress magnitudes and orientations, N.C.S. generated the seismic shake maps and C.L.J. and R.C.W. assisted with the statistical analysis. All the authors contributed to the interpretation and analysis.

Correspondence to Thomas R. Watters.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary text, Supplementary Figs. 1–6, Supplementary Tables 1–3, relocated epicentres table and Supplementary references.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark