Classifying Thermal Moonquakes Recorded in Apollo 17 Lunar Seismic Data Using Cross-Correlation and Diurnal Temperature Variations
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1.
California Institute of Technology
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2.
Goddard Space Flight Center
Abstract
We refine the newly developed seismicity catalog of the Apollo 17 Lunar Seismic Profiling Experiment, containing over 12,000 thermal events, using quality control algorithms and classify these events by possible source using cross‐correlation, azimuth calculation, and periodicity analysis. We first sort these events into two types—"repeating" or "isolated"—based on whether or not they share similar waveforms with at least one other event. Repeating events are characterized by minimal time between signal onset and maximum, a prevalence during early sunrise, a period consistent with the diurnal cycle, and a preferential direction to the east, coincident with the location of the Lunar Module. Isolated events, on the other hand, are distributed throughout the lunar day, originate from a wide variety of directions, and are characterized by a more gradual increase in amplitude. Many repeating events are likely caused by thermal expansion of the Lunar Module or of enclosed volatiles, while most isolated events may be caused by thermal fracturing of rock or sliding of regolith along crater slopes. In particular, we pinpoint several boulders at the Apollo 17 site whose thermally induced fractures may be the source of 45 moonquakes. Future lunar missions, such as deployments of seismic instruments or gravitational wave detectors, should be aware of thermally induced, repeating seismic signals caused by nearby boulders and structures.
Copyright and License
© 2025 American Geophysical Union. All Rights Reserved. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
Acknowledgement
We thank Yosio Nakamura, Zhongwen Zhan, Jamie Molaro, Nicholas Schmerr, Aisha Khatib, Mark Panning, Ceri Nunn, and Keisuke Onodera for their helpful discussion and comments. Y.T. acknowledges funding from the NSF Graduate Research Fellowship Program (National Science Foundation Grant 2139433), the Caltech Center for Comparative Planetary Evolution Graduate Fellowship, and the Lunar Data Analysis Program (NASA Grant 23-LDAP23_2-0066). We credit the use of images and online resources supplied by the Lunar Reconnaissance Orbiter Camera (LROC). We also acknowledge our use of generative artificial intelligence (AI) tools, namely ChatGPT and Google's AI Overview, to assist with our usage of Python libraries and functions, as well as debugging issues in Python and in Overleaf. Finally, we thank Renee Weber and two anonymous reviewers for their thorough feedback and suggestions.
Data Availability
The data can be found at Civilini (2023). We have also published the codes and catalogs used in our analyses in the Zenodo repository, Tamama et al. (2025).
Supplemental Material
Supporting Information S1 (PDF)
Files
JGR Planets - 2025 - Tamama - Classifying Thermal Moonquakes Recorded in Apollo 17 Lunar Seismic Data Using.pdf
Additional details
Related works
- Is supplemented by
- Dataset: 10.22002/gc871-q2a25 (DOI)
- Software: 10.5281/zenodo.15707792 (DOI)
Funding
- National Science Foundation Graduate Research Fellowship Program
- 2139433
- California Institute of Technology
- Caltech Center for Comparative Planetary Evolution Graduate Fellowship -
- National Aeronautics and Space Administration
- Lunar Data Analysis Program 23-LDAP23_2-0066
Dates
- Accepted
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2025-08-31
- Available
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2025-09-25Version of record online
- Available
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2025-09-25Issue online