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arxiv: 2601.16567 · v2 · pith:IBZIRPIBnew · submitted 2026-01-23 · 🌀 gr-qc · astro-ph.EP· astro-ph.HE· physics.geo-ph

Thick Lunar Crust Amplifies Deci-Hertz Gravitational-Wave Signal

Pith reviewed 2026-05-22 11:41 UTC · model grok-4.3

classification 🌀 gr-qc astro-ph.EPastro-ph.HEphysics.geo-ph
keywords gravitational waveslunar crustdeci-hertz bandmode couplingnormal-mode perturbationspectral-element simulationresonant detectorlateral heterogeneity
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The pith

Thick lunar crust amplifies deci-hertz gravitational-wave signals up to tenfold via mode coupling in heterogeneous interior.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper establishes that a high-resolution two-dimensional model of the Moon's response to gravitational waves reveals systematic signal amplification in thick-crust regions. By combining spectral-element simulations with normal-mode perturbation theory, the authors trace the effect to a mode-coupling process in which the quadrupolar oscillation induced by the wave transfers energy into higher-order hybridized eigenmodes of a laterally heterogeneous Moon. A sympathetic reader would care because this makes the Moon a viable resonant detector for gravitational waves in the hard-to-reach 0.01 to 1 Hz band and supplies concrete maps for choosing detector sites. The work shows that topographical and interior heterogeneity, long viewed as obstacles, can instead enhance the response in narrow frequency windows.

Core claim

The central claim is that the thick lunar crust amplifies the deci-hertz GW signal through a mode-coupling process. In the model, the passing gravitational wave induces a predominant quadrupole oscillation that distributes energy into a series of higher-order hybridized eigenmodes due to lateral heterogeneity. This results in up to tenfold amplification in certain narrow frequency ranges, as resolved by the dual approach of high-fidelity spectral-element simulations at 2 km grid spacing and analytical normal-mode perturbation theory.

What carries the argument

Hybridized eigenmodes produced by mode coupling between the original quadrupolar oscillation and higher-order modes in a laterally heterogeneous Moon.

If this is right

  • The Moon functions as an effective resonant gravitational-wave detector despite its complex topography and interior heterogeneity.
  • Quantitative amplification maps from the model directly inform optimal landing-site selection for future lunar detectors.
  • Up to tenfold signal boost extends into the deci-hertz band, opening narrow frequency windows for observation of early-universe and compact-object signals.
  • The dual numerical-analytical method resolves structurally fine-tuned features that simpler models miss.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • If verified, the amplification would allow lunar instruments to reach useful sensitivity with less demanding hardware than uniform-crust assumptions require.
  • The same mode-coupling mechanism could appear on other bodies with thick heterogeneous crusts, broadening the search for natural resonant detectors.
  • Three-dimensional extensions of the model would test whether azimuthal variations add further site-dependent effects beyond the two-dimensional results.

Load-bearing premise

The two-dimensional high-resolution model at 2 km grid spacing together with normal-mode perturbation theory accurately captures global free-oscillation patterns and energy transfer into hybridized eigenmodes without large contributions from three-dimensional effects, damping, or unmodeled heterogeneity.

What would settle it

Comparison of actual signal amplitudes recorded by lunar-based sensors placed in thick-crust versus thin-crust regions against the model's predicted amplification factors in the 0.01-1 Hz band would confirm or refute the tenfold enhancement.

Figures

Figures reproduced from arXiv: 2601.16567 by Han Yan, Jinhai Zhang, Lei Zhang, Xian Chen.

Figure 1
Figure 1. Figure 1: FIG. 1. Lunar model with topography and crustal-thickness variations. (a) Lunar crustal thickness model. The yellow triangles [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Comparison between layered and heterogeneous models and the simulated location-frequency distribution of amplifi [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Amplification according to the normal-mode pertur [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
read the original abstract

Gravitational waves (GWs) in the $0.01\sim1$ Hz band encode unique signatures of the early universe and merging compact objects, but they are beyond the reach of existing observatories. Theoretical models suggest that the Moon could act as a resonant detector, but the unknown influence of its rugged surface and heterogeneous interior poses a challenge to the accurate modeling of its response. Here, we address this long-standing uncertainty by constructing the first high-resolution, two-dimensional model of the lunar GW response, more realistic than previous ones. We achieve this by combining high-fidelity spectral-element simulations with the analytical power of normal-mode perturbation theory, thereby resolving topographical effects down to 2 km grid spacing while maintaining the capacity to discern global free-oscillation patterns. This dual-methodology approach not only recovers the expected predominant quadrupole ($l=2$) oscillation mode, but also exposes a systematic signal amplification in thick-crust regions. This enhancement is traced by our normal-mode analysis to a mode-coupling process, in which the original quadrupolar oscillation induced by the passing GW distributes energy into a series of higher-order modes, the hybridized eigenmodes of a laterally heterogeneous Moon. In certain narrow frequency ranges, we observe up to tenfold amplification spanning into the deci-hertz band, highlighting the power of numerical simulations in resolving these structurally fine-tuned features for designing future detectors. Our work establishes the Moon as a resonant GW detector albeit its complex topographical structures, and the resulting amplification maps provide quantitative guide for the optimal landing site selection.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper constructs a high-resolution two-dimensional spectral-element model of the Moon's gravitational-wave response, combined with normal-mode perturbation theory, to show that thick-crust regions produce up to tenfold amplification of deci-hertz signals through mode coupling that transfers energy from the dominant l=2 quadrupolar oscillation into hybridized higher-order eigenmodes of a laterally heterogeneous Moon. This is presented as enabling the Moon to serve as a resonant detector despite its complex topography, with amplification maps offered for landing-site selection.

Significance. If the reported amplification and its attribution to mode coupling survive validation, the work would be significant for deci-hertz gravitational-wave astronomy by identifying the Moon as a potentially sensitive resonant detector and supplying quantitative guidance for optimal instrument placement. The dual use of high-fidelity numerics and analytic perturbation theory is a methodological strength that could be extended to other planetary bodies.

major comments (3)
  1. [Abstract and Methods] Abstract and Methods: The central claim of up to tenfold amplification in narrow deci-hertz bands rests on a 2D high-resolution (2 km grid) spectral-element simulation plus normal-mode perturbation theory. No explicit verification is provided that this 2D reduction preserves the global free-oscillation spectrum or the perturbative coupling coefficients when lateral heterogeneity is strong enough to produce the reported amplification; 3D spherical geometry, azimuthal coupling, and out-of-plane scattering could alter the hybridization and resulting gain.
  2. [Abstract] Abstract: The tenfold amplification factor is stated without accompanying quantitative uncertainty estimates, convergence tests with respect to grid spacing, or direct comparison against independent benchmarks or 3D reference calculations, leaving the robustness of the numerical result unclear.
  3. [Results (normal-mode analysis)] Results (normal-mode analysis section): The tracing of energy transfer to hybridized eigenmodes via perturbation theory is load-bearing for the amplification interpretation, yet the manuscript does not demonstrate that the 2D slice captures the dominant coupling pathways that would exist in the full spherical-harmonic basis of a 3D Moon.
minor comments (2)
  1. [Abstract] The abstract refers to 'the first high-resolution, two-dimensional model' without citing prior 1D or low-resolution lunar GW-response calculations for context.
  2. [Methods] Notation for the hybridized eigenmodes and the precise definition of the amplification ratio should be introduced with an equation or explicit formula rather than described only qualitatively.

Simulated Author's Rebuttal

3 responses · 2 unresolved

We thank the referee for the thoughtful and constructive report. The comments highlight important limitations of our two-dimensional approach, which we address below. We maintain that the 2D high-resolution model combined with perturbation theory provides new and useful insights into lunar mode coupling, while agreeing that explicit discussion of three-dimensional effects is warranted.

read point-by-point responses
  1. Referee: [Abstract and Methods] Abstract and Methods: The central claim of up to tenfold amplification in narrow deci-hertz bands rests on a 2D high-resolution (2 km grid) spectral-element simulation plus normal-mode perturbation theory. No explicit verification is provided that this 2D reduction preserves the global free-oscillation spectrum or the perturbative coupling coefficients when lateral heterogeneity is strong enough to produce the reported amplification; 3D spherical geometry, azimuthal coupling, and out-of-plane scattering could alter the hybridization and resulting gain.

    Authors: We chose the two-dimensional equatorial slice to resolve topographic and crustal-thickness variations at 2 km scale while remaining computationally tractable. Within this geometry the dominant quadrupolar response is recovered and the perturbation theory is applied to the resulting eigenmodes. We acknowledge that azimuthal coupling and out-of-plane scattering are absent; a full three-dimensional treatment would be required to quantify their influence on the hybridization. In the revision we will add an explicit statement of this limitation together with a brief comparison to existing lower-resolution three-dimensional lunar models. revision: partial

  2. Referee: [Abstract] Abstract: The tenfold amplification factor is stated without accompanying quantitative uncertainty estimates, convergence tests with respect to grid spacing, or direct comparison against independent benchmarks or 3D reference calculations, leaving the robustness of the numerical result unclear.

    Authors: Convergence with respect to grid spacing was examined during code development; we will report these tests and associated uncertainty estimates in a revised Methods section. Direct three-dimensional reference calculations at comparable resolution remain prohibitive, but we will include a short comparison against published lower-resolution three-dimensional results to place the reported gain in context. revision: yes

  3. Referee: [Results (normal-mode analysis)] Results (normal-mode analysis section): The tracing of energy transfer to hybridized eigenmodes via perturbation theory is load-bearing for the amplification interpretation, yet the manuscript does not demonstrate that the 2D slice captures the dominant coupling pathways that would exist in the full spherical-harmonic basis of a 3D Moon.

    Authors: The normal-mode analysis is performed on the eigenmodes extracted from the two-dimensional spectral-element mesh, which already incorporates the lateral heterogeneity of the chosen slice. The dominant energy transfer from the l=2 mode to higher-order hybridized modes is therefore captured within that basis. We agree that the full three-dimensional spherical-harmonic coupling matrix is not reproduced and will add a clarifying paragraph on the assumptions and scope of the two-dimensional perturbation treatment. revision: partial

standing simulated objections not resolved
  • Explicit verification that the 2D reduction preserves the global free-oscillation spectrum and perturbative coupling coefficients under strong lateral heterogeneity
  • Demonstration that the 2D slice captures all dominant coupling pathways present in the full 3D spherical-harmonic basis

Circularity Check

0 steps flagged

No circularity: amplification derived from forward spectral-element simulation plus normal-mode perturbation

full rationale

The paper constructs a 2D high-resolution spectral-element model of the Moon and applies normal-mode perturbation theory to compute the gravitational-wave response. The reported up to tenfold amplification in narrow deci-hertz bands is obtained directly from the forward simulation of energy transfer from the l=2 quadrupolar mode into hybridized higher-order modes; the amplification factor is an output of the numerical solution, not an input parameter or a quantity fitted to the same data used to claim the result. No equation in the abstract or methods reduces the gain to a self-defined quantity, and the derivation relies on standard numerical methods rather than self-citation chains or imported uniqueness theorems. The central claim therefore remains independent of its own outputs.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claim depends on several modeling choices whose independent support is not supplied in the abstract. The 2D reduction, the specific lunar interior model, and the validity of linear perturbation theory for the heterogeneous case are taken as given.

free parameters (2)
  • crust thickness distribution
    The amplification is reported specifically for thick-crust regions; the exact thickness profile and its lateral variation are inputs to the model whose values are not derived from first principles in the abstract.
  • grid spacing of 2 km
    Chosen resolution for resolving topography; this numerical parameter directly controls which small-scale features enter the mode-coupling calculation.
axioms (2)
  • domain assumption Linear normal-mode perturbation theory remains accurate for the Moon's lateral heterogeneity at deci-hertz frequencies.
    Invoked to interpret the energy transfer from the l=2 mode into higher-order hybridized modes.
  • domain assumption The 2D spectral-element mesh with 2 km spacing faithfully represents the global free-oscillation response.
    Required to claim that the recovered quadrupole mode and the subsequent amplification are physically meaningful.

pith-pipeline@v0.9.0 · 5821 in / 1644 out tokens · 36011 ms · 2026-05-22T11:41:46.900867+00:00 · methodology

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Reference graph

Works this paper leans on

51 extracted references · 51 canonical work pages · 8 internal anchors

  1. [1]

    B. P. Abbott, R. Abbott, T. D. Abbott, et al., Ob- servation of Gravitational Waves from a Binary Black Hole Merger, Phys. Rev. Lett.116, 061102 (2016), arXiv:1602.03837 [gr-qc]

  2. [2]

    Abramovici, W

    A. Abramovici, W. E. Althouse, et al., LIGO: The Laser Interferometer Gravitational-Wave Observatory, Science 256, 325 (1992)

  3. [3]

    Advanced Virgo: a 2nd generation interferometric gravitational wave detector

    F. Acernese, M. Agathos, et al., Advanced Virgo: a second-generation interferometric gravitational wave detector, Classical and Quantum Gravity32, 024001 (2015), arXiv:1408.3978 [gr-qc]

  4. [4]

    Akutsu et al

    Kagra Collaboration, T. Akutsu, M. Ando, et al., KAGRA: 2.5 generation interferometric gravitational wave detector, Nature Astronomy3, 35 (2019), 6 arXiv:1811.08079 [gr-qc]

  5. [5]

    H. Xu, S. Chen, Y. Guo, et al., Searching for the Nano- Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I, Re- search in Astronomy and Astrophysics23, 075024 (2023), arXiv:2306.16216 [astro-ph.HE]

  6. [6]

    EPTA Collaboration, InPTA Collaboration, et al., The second data release from the European Pulsar Timing Array. III. Search for gravitational wave signals, Astron- omy & Astrophysics678, A50 (2023), arXiv:2306.16214 [astro-ph.HE]

  7. [7]

    Agazie et al

    G. Agazie, M. F. Alam, A. Anumarlapudi, et al., The NANOGrav 15 yr Data Set: Observations and Timing of 68 Millisecond Pulsars, The Astrophysical Journal Let- ters951, L9 (2023), arXiv:2306.16217 [astro-ph.HE]

  8. [8]

    D. J. Reardon, A. Zic, R. M. Shannon, et al., Search for an Isotropic Gravitational-wave Background with the Parkes Pulsar Timing Array, The Astrophysical Journal Letters951, L6 (2023), arXiv:2306.16215 [astro-ph.HE]

  9. [9]

    Arca Sedda, C

    M. Arca Sedda, C. P. L. Berry, K. Jani, et al., The missing link in gravitational-wave astronomy: discover- ies waiting in the decihertz range, Classical and Quantum Gravity37, 215011 (2020), arXiv:1908.11375 [gr-qc]

  10. [10]

    LISA Definition Study Report

    M. Colpi, K. Danzmann, et al., LISA Definition Study Report, arXiv e-prints , arXiv:2402.07571 (2024), arXiv:2402.07571 [astro-ph.CO]

  11. [11]

    TianQin: a space-borne gravitational wave detector

    J. Luo, L.-S. Chen, H.-Z. Duan, et al., TianQin: a space- borne gravitational wave detector, Classical and Quan- tum Gravity33, 035010 (2016), arXiv:1512.02076 [astro- ph.IM]

  12. [12]

    Z. Luo, Y. Wang, Y. Wu, W. Hu, and G. Jin, The Taiji program: A concise overview, Progress of Theoretical and Experimental Physics2021, 05A108 (2021)

  13. [13]

    Kawamura, M

    S. Kawamura, M. Ando, N. Seto, et al., The Japanese space gravitational wave antenna: DECIGO, Classical and Quantum Gravity28, 094011 (2011)

  14. [14]

    Ni, Core noise and GW sensitivities of AMIGO, International Journal of Modern Physics D31, 2250039 (2022), arXiv:2106.12432 [gr-qc]

    W.-T. Ni, Core noise and GW sensitivities of AMIGO, International Journal of Modern Physics D31, 2250039 (2022), arXiv:2106.12432 [gr-qc]

  15. [15]

    Weber, Detection and Generation of Gravitational Waves, Physical Review117, 306 (1960)

    J. Weber, Detection and Generation of Gravitational Waves, Physical Review117, 306 (1960)

  16. [16]

    Weber, Gravitational Waves, Physics Today21, 34 (1968)

    J. Weber, Gravitational Waves, Physics Today21, 34 (1968)

  17. [17]

    F. J. Dyson, Seismic Response of the Earth to a Gravi- tational Wave in the 1-Hz Band, Astrophys. J.156, 529 (1969)

  18. [18]

    Lognonn´ e, M

    P. Lognonn´ e, M. Le Feuvre, C. L. Johnson, and R. C. Weber, Moon meteoritic seismic hum: Steady state pre- diction, Journal of Geophysical Research (Planets)114, E12003 (2009)

  19. [19]

    Ben-Menahem, Excitation of the earth’s eigenvi- brations by gravitational radiation from astrophysical sources., Nuovo Cimento C Geophysics Space Physics C 6, 49 (1983)

    A. Ben-Menahem, Excitation of the earth’s eigenvi- brations by gravitational radiation from astrophysical sources., Nuovo Cimento C Geophysics Space Physics C 6, 49 (1983)

  20. [20]

    Testing Theories of Gravity with a Spherical Gravitational Wave Detector

    M. Bianchi, E. Coccia, C. N. Colacino, V. Fafone, and F. Fucito, Testing theories of gravity with a spheri- cal gravitational wave detector, Classical and Quantum Gravity13, 2865 (1996), arXiv:gr-qc/9604026 [gr-qc]

  21. [21]

    Majstorovi´ c, S

    J. Majstorovi´ c, S. Rosat, and Y. Rogister, Earth’s spheroidal motion induced by a gravitational wave in flat spacetime, Phys. Rev. D100, 044048 (2019)

  22. [22]

    H. Yan, X. Chen, J. Zhang, F. Zhang, M. Wang, and L. Shao, Toward a consistent calculation of the lunar re- sponse to gravitational waves, Phys. Rev. D109, 064092 (2024)

  23. [23]

    Majstorovi´ c, L

    J. Majstorovi´ c, L. Vidal, and P. Lognonn´ e, Modeling lu- nar response to gravitational waves using normal-mode approach and tidal forcing, Phys. Rev. D111, 044061 (2025), arXiv:2411.09559 [gr-qc]

  24. [24]

    Bi and J

    X. Bi and J. Harms, Response of the Moon to grav- itational waves, Phys. Rev. D110, 064025 (2024), arXiv:2403.05118 [gr-qc]

  25. [25]

    D. E. Smith, M. T. Zuber, et al., Initial observations from the Lunar Orbiter Laser Altimeter (LOLA), Geophysical Research Letters37, L18204 (2010)

  26. [26]

    M. A. Wieczorek, G. A. Neumann, F. Nimmo, et al., The Crust of the Moon as Seen by GRAIL, Science339, 671 (2013)

  27. [27]

    Y. H. Huang, J. M. Soderblom, D. A. Minton, M. Hirabayashi, and H. J. Melosh, Bombardment his- tory of the moon constrained by crustal porosity, Nature Geoscience15, 531 (2022)

  28. [28]

    M. A. Wieczorek and R. J. Phillips, Potential anoma- lies on a sphere: Applications to the thickness of the lu- nar crust, Journal of Geophysical Research: Planets103, 1715 (1998)

  29. [29]

    J. H. Woodhouse, The coupling and attenuation of nearly resonant multiplets in the Earth’s free oscillation spec- trum, Geophysical Journal61, 261 (1980)

  30. [30]

    F. A. Dahlen and J. Tromp, Theoretical Global Seismology (Princeton University Press, 1999)

  31. [31]

    J. H. Woodhouse and F. A. Dahlen, The effect of a gen- eral aspherical perturbation on the free oscillations of the earth., Geophysical Journal International53, 335 (1978)

  32. [32]

    Masters, J

    G. Masters, J. Park, and F. Gilbert, Observations of cou- pled spheroidal and toroidal modes, Journal of Geophys- ical Research88, 10285 (1983)

  33. [33]

    Deuss and J

    A. Deuss and J. H. Woodhouse, Theoretical free- oscillation spectra: the importance of wide band cou- pling, Geophysical Journal International146, 833 (2001)

  34. [34]

    Chen, The moon as a gateway to discovery: how lu- nar gravitational-wave detection advances science across disciplines, npj Space Exploration2(2026)

    X. Chen, The moon as a gateway to discovery: how lu- nar gravitational-wave detection advances science across disciplines, npj Space Exploration2(2026)

  35. [35]

    Harms, F

    J. Harms, F. Ambrosino, L. Angelini, et al., Lu- nar Gravitational-wave Antenna, Astrophys. J.910, 1 (2021), arXiv:2010.13726 [gr-qc]

  36. [36]

    Branchesi, M

    M. Branchesi, M. Falanga, J. Harms, et al., Lunar Gravitational-Wave Detection, Space Science Reviews 219, 67 (2023)

  37. [37]

    Jani and A

    K. Jani and A. Loeb, Gravitational-wave lunar observa- tory for cosmology, Journal of Cosmology and Astropar- ticle Physics2021(06), 044

  38. [38]

    K. Jani, M. Abernathy, E. Berti, et al., Laser Interfer- ometer Lunar Antenna (LILA): Advancing the U.S. Pri- orities in Gravitational-wave and Lunar Science, arXiv e-prints , arXiv:2508.11631 (2025), arXiv:2508.11631 [gr- qc]

  39. [39]

    H. J. Paik and K. Y. Venkateswara, Gravitational wave detection on the Moon and the moons of Mars, Advances in Space Research43, 167 (2009)

  40. [40]

    Amaro-Seoane, L

    P. Amaro-Seoane, L. Bischof, J. J. Carter, M.-S. Hartig, and D. Wilken, LION: laser interferometer on the moon, Classical and Quantum Gravity38, 125008 (2021), arXiv:2012.10443 [astro-ph.IM]

  41. [41]

    J. Li, F. Liu, Y. Pan, Z. Wang, M. Cao, M. Wang, F. Zhang, J. Zhang, and Z.-H. Zhu, Detecting gravita- tional wave with an interferometric seismometer array 7 on lunar nearside, Science China Physics, Mechanics, and Astronomy66, 109513 (2023)

  42. [42]

    Zhang, H

    L. Zhang, H. Yan, X. Chen, and J. Zhang, 2D numerical simulation of lunar response to gravitational waves using finite element method, Phys. Rev. D111, 063014 (2025), arXiv:2412.17898 [astro-ph.EP]

  43. [44]

    Komatitsch, S

    D. Komatitsch, S. Tsuboi, J. Tromp, A. Levander, and G. Nolet, The spectral-element method in seismology, Geophysical Monograph-American Geophysical Union 157, 205 (2005)

  44. [45]

    Zhang, J

    L. Zhang, J. Wang, Y. Xu, C. He, and C. Zhang, A proce- dure for 3D seismic simulation from rupture to structures by coupling SEM and FEM, Bulletin of the Seismological Society of America110, 1134 (2020)

  45. [46]

    Zhang, H

    L. Zhang, H. Yan, J. Zhang, and X. Chen, Nu- merical simulation of lunar response to gravitational waves and its 3D topographic effect using the spectral- element method, arXiv e-prints , arXiv:2512.21667 (2025), arXiv:2512.21667 [astro-ph.EP]

  46. [47]

    SeeCrustalAmplifyfolder in https://github.com/StrelitziaHY/LunarResponse (2025)

  47. [48]

    Masters, J

    G. Masters, J. H. Woodhouse, and G. Freeman, Mineos v1.0.2 [software], Computational Infrastructure for Geo- dynamics (2011),https://geodynamics.org/cig

  48. [49]

    H. Yan, X. Chen, J. Zhang, F. Zhang, L. Shao, and M. Wang, Constraining the stochastic gravitational wave background using the future lunar seismometers, Phys. Rev. D110, 043009 (2024), arXiv:2405.12640 [gr-qc]

  49. [50]

    Komatitsch and J

    D. Komatitsch and J. Tromp, Spectral-element simula- tions of global seismic wave propagation—i. validation, Geophysical Journal International149, 390 (2002)

  50. [51]

    Komatitsch, J

    D. Komatitsch, J. Ritsema, and J. Tromp, The spectral- element method, beowulf computing, and global seismol- ogy, Science298, 1737 (2002)

  51. [52]

    polarization average,

    L. Zhang, J. Zhang, and R. N. Mitchell, Dichotomy in crustal melting on early mars inferred from antipodal ef- fect, The Innovation3(2022). 8 SUPPLEMENTAL MATERIAL A. Numerical simulation using the spectral-element method We use a finite-element SEM based on the code SPECFEM2D [50, 51] to calculate the lunar response to GWs. This method was originally pro...