AIR – Airborne Inversion of Rayleigh waves

• Brissaud, Quentin; Kong, Chenxi; Froment, Marouchka; Wilding, John; Gülcher, Anna J. P. & Jackson, Jennifer M. [Show all 10 contributors for this article] (2026). Aerial and Space-borne Seismology on Venus: Viability and Design Implications for Future Missions. Earth and Space Science. 13(6). doi: 10.1029/2025EA004541. Full text in Research Archive Show summary

  Venus' evolution remains a mystery because of the lack of in situ geophysical data to constrain its interior structure. Recently-selected planetary missions VERITAS (NASA), DAVINCI+ (NASA), and EnVision (ESA) will investigate the planet's interior, surface, and atmospheric chemistry. However, none of these missions includes sensors capable of accurately probing Venus' crustal and mantle properties. Seismometer deployments are challenging on Venus due to high surface temperature and pressure. Acoustic balloon measurements and airglow observations—that monitor Venus' upper atmosphere glow caused by chemical and radiative processes—have been suggested as alternatives to surface deployments. However, it is critical to assess the potential of such missions under realistic conditions of geology, atmospheric states, network geometry, and seismicity using physics-based modeling. We employ a probabilistic framework to investigate detection probabilities as a function of Signal-to-Noise Ratio (SNR) for airglow and acoustic balloon missions using wave simulations, thermodynamically-consistent seismic velocity models, and realistic seismicity estimates. Our results demonstrate that the probability of detecting a single venusquake at SNR > 1 over 6 months is around 65% across an entire 3-balloon network of about 5,000 km extent. Probabilities using dayglow imager data are below 60% and below 10% using nightglow data. Seismo-volcanic sequences enhance detectability but only if high seismic activity occurs at multiple volcanoes. Long-duration missions with both airglow and balloon-borne sensors could allow seismic wave measurements over a broad range of frequencies. Our results are highly dependent on seismic velocities, attenuation, seismicity, noise levels, mission duration, and airglow-coupling efficiency which should be the focus of future studies.

• Xiao, Wanbo; Carrasco, Sebastián; Xu, Zongbo; Wang, Yanbin; Froment, Marouchka & Kawamura, Taichi [Show all 7 contributors for this article] (2025). Subsurface fluvial sediments beneath InSight on Mars from geophysical constraints. Communications Earth & Environment. 6(1). doi: 10.1038/s43247-025-02777-1. Full text in Research Archive Show summary

  Subsurface structure investigation on Mars is crucial for understanding its geological evolution and past hydrological conditions. Elysium Planitia (EP), located near the hypothesized ancient ocean shorelines, could contain clues for past water activity and paleoclimate. Here we present better-constrained subsurface models beneath InSight extending to ~800 m depth, obtained from joint inversion of seismic and seismoacoustic coupling data, and use the well-resolved subsurface structure to explore the lithological profile through rock physics models. The derived subsurface lithology agrees well with local geological context and exhibits a shallow 60-m-thick low-rigidity layer consistent with hydrated sedimentary materials. Despite possible contributions of aeolian and volcanic deposits, we favor the interpretation that the low-rigidity layer originated from fluvial activity in EP during the Hesperian or Hesperian-to-Amazonian epoch, as supported by adjacent paleo-shoreline morphology observations. These results hint at a period of warmer paleoclimate at low latitudes, possibly during high-obliquity phases of Mars’ rotational axis.

• Zhang, Xiang; Lognonné, Philippe; Kawamura, Taichi; Xu, Zongbo; Samuel, Henri & Sainton, Grégory [Show all 9 contributors for this article] (2025). Methods for Cleaning Apollo Passive Seismic Data. Earth and Space Science. 12(12). doi: 10.1029/2025ea004710. Full text in Research Archive Show summary

  Apollo passive seismic data provide a unique resource for studying the lunar interior structure. However, the raw data are frequently contaminated by various artifacts, either related to the seismic sensors and the acquisition system or to issues during data transmission to the Earth. Understanding and exploiting the data set as a whole for seismic analyses remains therefore challenging. In this article, we present different artifacts observed in Apollo passive seismic data. This includes a systematic acquisition error at the Apollo 14 station, which was not investigated in previous studies but could affect most of the records of this station. We describe methods for the removal of this acquisition error as well as the numerous glitches. We conclude by illustrating the efficiency of these cleaning techniques on the collection of major lunar impacts and provide the associated data for future research.

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter & Schweitzer, Johannes (2025). Balloon seismology enables subsurface inversion without ground stations. Communications Earth & Environment. 6, p. 1–12. doi: 10.1038/s43247-025-02917-7. Full text in Research Archive Show summary

  Earth’s interior structure is derived primarily from data recorded by ground-based seismometers. Such instruments would provide essential insight into the composition and evolution of Venus, but harsh surface conditions hinder their deployment. Balloon-borne seismology offers an alternative by capturing upper-atmospheric infrasonic signatures of seismic waves. We show that subsurface seismic velocities and earthquake source location can be jointly inverted from balloon observations. We demonstrate this method using infrasound signals recorded by four stratospheric balloons following a major earthquake in the Flores Sea, Indonesia. A Bayesian inversion using Markov chain Monte Carlo sampling is implemented to account for trade-offs in the joint location and subsurface velocity estimation. The inverted seismic parameters are consistent with results obtained using ground-based seismometers. This demonstration of the ability to estimate source and velocity parameters without ground deployments motivates further development of seismo-acoustic mission concepts to Venus, and provides new opportunities for seismic exploration in remote Earth regions.

• Cameijo, A. Janela; Pichon, A. Le; Sklab, Y.; Arib, S.; Brissaud, Quentin & Näsholm, S. P. [Show all 8 contributors for this article] (2025). Toward Real‐Time Assessment of Infrasound Event Detection Capability Using Deep Learning‐Based Transmission Loss Estimation. Journal of Geophysical Research (JGR): Atmospheres. ISSN 2169-897X. 130(19). doi: 10.1029/2025jd043577. Full text in Research Archive Show summary

  Accurate modeling of infrasound transmission loss is crucial for assessing the performance of the International Monitoring System, which monitors compliance with the Comprehensive Nuclear‐Test‐Ban Treaty by detecting atmospheric explosions. This modeling supports the design and maintenance of the operating monitoring network. State‐of‐the‐art propagation modeling tools enable transmission loss to be finely simulated using atmospheric models. However, the computational cost prohibits the exploration of a large parameter space in operational monitoring applications. To address this, recent studies made use of a deep learning algorithm capable of making transmission loss predictions almost instantaneously. However, the use of nudged atmospheric models leads to an incomplete representation of the medium, and the absence of temperature as an input makes the algorithm incompatible with long‐range propagation. In this study, we address these limitations by using both wind and temperature fields as inputs to a neural network, simulated up to 130 km altitude and 4,000 km distance. We exploit convolutional and recurrent layers to capture spatially and range‐dependent features embedded in realistic atmospheric models, improving the overall performance. The neural network reaches an average error of 4 dB compared to full parabolic equation simulations and provides epistemic and data‐related uncertainty estimates. Its evaluation on the 2022 Hunga Tonga‐Hunga Ha'apai volcanic eruption demonstrates its prediction capability using atmospheric conditions and frequencies not included in the training. This represents a significant step toward near real‐time assessment of International Monitoring System detection thresholds of explosive sources.

• Maia, Julia S.; Plesa, Ana-Catalina; Zelst, Iris Van; Ghail, Richard; Gülcher, Anna J. P. & Panning, Mark P [Show all 13 contributors for this article] (2025). The Seismogenic Thickness of Venus. Journal of Geophysical Research (JGR): Planets. ISSN 2169-9097. 130(7). doi: 10.1029/2025JE009065. Full text in Research Archive Show summary

  Growing evidence that volcanism is currently ongoing on Venus suggests that the sister planet of the Earth may also be seismically active. Given the success of seismic measurements on Mars and the Moon to reveal the interior structure of these bodies, seismic investigations on Venus are a natural next step. The potential for seismic activity is closely linked to the thickness of the so-called seismogenic layer, that is, the region where rocks behave in a brittle manner and quakes can nucleate. On Earth, the seismogenic thickness is correlated with the thermal structure of the lithosphere, and is typically associated with the depth of the 600°C isotherm. Here, we combine geophysical constraints with thermal evolution models to estimate the thermal structure of Venus' lithosphere and determine the corresponding seismogenic thickness. Taking all estimates into account, our results show that the seismogenic thickness overall varies from 2 to 35 km. The lowest values are associated with areas that probably correspond to local thermal anomalies associated with magmatic processes. This interpretation is corroborated by geodynamic models, which show that intrusive magmatism can largely increase the temperature within the lithosphere at local scales. The seismogenic layer is thickest at volcanic plains which are commonly associated with regions of mantle downwellings. In these regions, the seismogenic layer likely reaches Venus' mantle, while in areas with a thick crust or anomalously high thermal gradients, quakes might be limited to the crust. Our study provides evidence that Venus has a substantial seismic potential.

• Garcia, Raphaël; Zelst, Iris Van; Kawamura, Taichi; Näsholm, Sven Peter; Horleston, Anna & Klaasen, Sara [Show all 18 contributors for this article] (2024). Seismic Wave Detectability on Venus Using Ground Deformation Sensors, Infrasound Sensors on Balloons and Airglow Imagers. Earth and Space Science. 11. doi: 10.1029/2024EA003670. Full text in Research Archive Show summary

  The relatively unconstrained internal structure of Venus is a missing piece in our understanding of the formation and evolution of the Solar System. Detection of seismic waves generated by venusquakes is crucial to determine the seismic structure of Venus' interior, as recently shown by the new seismic and geodetic constraints on Mars' interior obtained by the InSight mission. In the next decade multiple missions will fly to Venus to explore its tectonic and volcanic activity, but they will not be able to conclusively detect seismic waves, despite their potential to detect fault movements. Looking toward the next fleet of Venus missions after the ones already decided, various concepts to measure seismic waves have been proposed. These detection methods include typical geophysical ground sensors already deployed on Earth, the Moon, and Mars; pressure sensors on balloons; and imagers of high altitude emissions (airglow) on orbiters. The latter two methods target the detection of the infrasound signals generated by seismic waves and amplified during their upward propagation. Here, we provide a first comparison between the detection capabilities of these different measurement techniques and recent estimates of Venus' seismic activity. In addition, we discuss the performance requirements and measurement durations required to detect seismic waves with the various detection methods. Our study clearly presents the advantages and limitations of the different seismic wave detection techniques and can be used to drive the design of future mission concepts aiming to study the seismicity of Venus.

• Turquet, Antoine Leo; Brissaud, Quentin; Alvizuri, Celso; Näsholm, Sven Peter; Pichon, Alexis Le & Kero, Johan (2024). Retrieving Seismic Source Characteristics Using Seismic and Infrasound Data: The 2020 M<inf>L</inf> 4.1 Kiruna Minequake, Sweden. Geophysical Research Letters. ISSN 0094-8276. 51(12), p. e2024GL109276–e2024GL109276. doi: 10.1029/2024GL109276. Full text in Research Archive Show summary

  A minequake of magnitude ML 4.1 occurred on 18 May 2020 early in the morning at the LKAB underground iron ore mine in Kiruna, Sweden. This is the largest mining-induced earthquake in Scandinavia. It generated acoustic signals observed at three infrasound arrays at 9.3 (KRIS, Sweden), 155 (IS37, Norway), and 286 km (ARCI, Norway) distance. We perform full-waveform focal mechanism inversion based on regional seismic data and local infrasound data. These independently highlight that this event was dominated by a shallow-depth collapse in agreement with in-mine seismic station data. However, regional infrasound data cannot inform the inversion process without an accurate model of atmospheric winds and temperatures. Yet, our numerical simulations demonstrate a potential of using local and regional infrasound data to constrain an event's focal mechanism and depth.

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter; Solberg, Celine Marie; Kaschwich, Tina & Turquet, Antoine Leo (2024). Probing a planet from the subsurface to the atmosphere with infrasound data. INTER-NOISE and NOISE-CON Congress and Conference Proceedings. ISSN 0736-2935. 270(5), p. 6164–6175. doi: 10.3397/IN_2024_3692. Full text in Research Archive Show summary

  The analysis of infrasound waves has a significant potential for retrieving a range of geophysical parameters across various scales, such as atmospheric structures, characteristics of surface and buried sources, and seismic velocity structures. This potential was recently showcased in infrasound studies that illustrated the ability to retrieve Earth's shallow velocities and Mars' near-surface atmospheric winds from remote acoustic observations. Consequently, infrasound is becoming an essential component of planetary missions, providing insights into the interiors and atmospheres of other terrestrial planets in the solar system. However, utilizing infrasound data requires efficient forward wave simulation techniques and an accurate description of waveform sensitivity to source and medium parameters. Even under ideal conditions, many inverse problems associated with infrasound-based probing are inherently ill-posed, necessitating regularization or other approaches to ensure reliable results. In this contribution, we highlight recent seismo-acoustic research findings, addressing atmospheric probing at both smaller and global scales, as well as innovative methods to accelerate infrasonic wave propagation modeling.

• Cameijo, Alice Janela; Pichon, Alexis Le; Aknine, S.; Sklab, Youcef; Arib, S & Brissaud, Quentin [Show all 7 contributors for this article] (2024). Deep learning methods for modeling infrasound transmission loss in the middle atmosphere. INTER-NOISE and NOISE-CON Congress and Conference Proceedings. ISSN 0736-2935. doi: 10.3397/IN_2024_3565. Full text in Research Archive Show summary

  Accurate modeling of infrasound transmission losses (TLs) is essential to assess the performance of the global International Monitoring System infrasound network. Among existing propagation modeling tools, parabolic equation (PE) method enables TLs to be finely modeled, but its computational cost does not allow exploration of a large parameter space for operational monitoring applications. To reduce computation times, Brissaud et al. 2023 explored the potential of convolutional neural networks trained on a large set of regionally simulated wavefields (< 1000 km from the source) to predict TLs with negligible computation times compared to PE simulations. However, this method struggles in unfavorable initial wind conditions, especially at high frequencies, and causal issues with winds at large distances from the source affecting ground TLs close to the source. In this study, we have developed an optimized convolutional network designed to minimize prediction errors while predicting TLs from globally simulated combined temperature and wind fields spanning over propagation ranges of 4000 km. Our approach enhances the previously proposed one by implementing key optimizations that improve the overall architecture performance. The implemented model predicts TLs with an average error of 8.6 dB in the whole frequency band (0.1-3.2 Hz) and explored realistic atmospheric scenarios.

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• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter & Schweitzer, Johannes (2025). Behind the paper: Balloon seismology enables subsurface inversion without ground stations. Springer Nature Research Communities. doi: https:/communities.springernature.com/posts/balloon-seismology-enables-subsurface-inversion-without-ground-stations. Full text in Research Archive Show summary

  What if we can’t place a seismometer directly on the ground? Our team has just shown that infrasound waves, recorded by floating balloons, can reveal information about the seismic sources and subsurface. This finding supports the concept of using balloon missions to explore the interior of Venus.

• Gullbekk, Sophus Bredesen; Froment, Marouchka; Brissaud, Quentin & Näsholm, Sven Peter (2025). Modeling the characteristics of infrasound signals as detected from a balloon platform: Earth and Venus applications. Full text in Research Archive Show summary

  The Strateole2 campaign deployed superpressure balloons for several weeks in the southern stratosphere. On 15 January 2022, their pressure sensors detected infrasound signals (0.01 to 1 Hz) from the major eruption of the Hunga Tonga Hunga Ha'apai (HTHH) volcano. These signals present differences in amplitude and frequency content compared to recording of ground International Monitoring System stations. Using HTHH as a case study, we apply ray-tracing and normal mode modeling techniques, coupled with ERA5 atmospheric models, to understand the particularities of the infrasound wavefield at these elevated platforms. We also propose to generalize these results to different seasons and geographical source-receiver location combinations. A key objective for our future work is to apply such frameworks to assess the possibilities for balloon based seismoacoustic probing on Venus.

• Gullbekk, Sophus Bredesen; Näsholm, Sven Peter; Froment, Marouchka & Brissaud, Quentin (2025). Morphology of infrasound wave propagation from ground to atmospheric balloons. Full text in Research Archive
• Froment, Marouchka; Näsholm, Sven Peter & Brissaud, Quentin (2025). Seismology using infrasound: Exploring the subsurface of Earth and Venus with balloons. Full text in Research Archive
• Froment, Marouchka (2025). Spectrogram analysis with examples on geophysical data. Full text in Research Archive
• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter; Schweitzer, Johannes & Gullbekk, Sophus Bredesen (2025). Revealing the structure of Venus' interiors using planetary rumbles. Full text in Research Archive Show summary

  Seismology has been remarkably successful in probing the interior structure of the Earth, the Moon, and more recently Mars. Could it achieve the same on Venus, and reveal what hides beneath the surface of this mysterious and hellish twin of Earth ? Venus’ surface conditions make the deployments of ground-based seismometers challenging. Instead, several mission concepts have proposed to record venusquakes from above, leveraging the conversion of seismic waves into acoustic waves in the dense atmosphere. Could seismology be conducted from floating balloons, or through satellite imaging ? To explore this possibility, we gather insights from balloon campaigns on Earth and from modeling.

• Froment, Marouchka; Brissaud, Quentin & Näsholm, Sven Peter (2024). Balloon-Borne Seismology for Subsurface Exploration. Full text in Research Archive Show summary

  The deployment of ground-based seismic or infrasound instruments can be complex and costly in remote regions on Earth. Similarly on Venus, conventional seismology is a challenge due to the extreme pressure and temperature conditions at the surface. Recent studies have demonstrated that balloon platforms can be used to monitor seismic activity from the atmosphere instead, at a low operational cost. Such balloons carry pressure sensors and record the coupling of solid seismic waves into acoustic infrasound waves, a process that is expected to be sixty times more efficient on Venus than on Earth. Thus, the analysis of infrasound waves excited by seismic surface waves and recorded in the high altitude of Venus presents an enticing alternative to traditional ground-based seismology, and could help shed light on the planet’s origin and evolution. Seismic infrasound signals show similar dispersion properties as surface waves recorded at the ground, enabling the use of classical inversion techniques to retrieve source and subsurface properties. However, it remains unclear how acoustic and instrumental noise, path effects, and the lack of polarity information translate into posterior distributions of source and subsurface parameters. In this contribution, we explore different inversion scenarios based on the characteristics of synthetic Venus signals and actual Earth observations. We propose a Bayesian Markov Chain Monte Carlo inversion method to assess the sensitivity of inversion results to the prior knowledge of the subsurface, the quality of the data, the number of balloons and the types of acoustic arrivals.

• Näsholm, Sven Peter; Brissaud, Quentin; Turquet, Antoine Leo; Kaschwich, Tina & Froment, Marouchka (2024). Exploring a planet with infrasound: challenges in probing the subsurface and the atmosphere. Full text in Research Archive Show summary

  (Invited talk abstract) Infrasound waves have shown great potential to retrieve a range of geophysical parameters across scales, such as atmospheric structures, surface and buried source characteristics, and seismic velocity structures. In particular, infrasound generated by seismic waves coupling to the atmosphere can provide unique insights into a planet's interior. However, utilizing infrasound data requires efficient forward wave simulation techniques and an accurate description of waveform sensitivity to source and medium parameters. Even under idealized conditions, many of the inverse problems associated with infrasound-based probing are inherently ill-posed, requiring regularization or other approaches to yield reliable output. In this contribution, we highlight recent research results from our group and collaborators, tackling atmospheric probing at smaller and global scales, as well as innovative approaches to speed up infrasonic wave propagation modeling. We also call attention to the objectives and early results from a newly launched project focusing on the feasibility of exploring the interior of Venus using infrasound recorded from balloon platforms.

• Näsholm, Sven Peter; Brissaud, Quentin; Solberg, Celine Marie & Froment, Marouchka (2024). Exploring the feasibility of detecting seismically-generated infrasound waves on Venus using balloon platforms. Full text in Research Archive Show summary

  Seismic waves are a primary source of information for our understanding of Earth's internal structure and they provide important constraints on subsurface seismic-velocity properties. However, traditional inversion methods cannot be implemented in regions of limited seismic-station coverage, in particular on Venus due to its harsh surface conditions but also in remote Earth regions. This lack of seismic data greatly limits our understanding of Venus’ origin and evolution and Earth’s subsurface. A window of opportunity is offered by the mechanical coupling between the ground and its atmosphere, which enables the seismic energy to be transmitted into the atmosphere as low-frequency acoustic waves carrying information about the seismic source and the subsurface properties. While infrasound is traditionally recorded at ground-based stations, which suffers from the same in-situ deployment limitations as seismic stations, recent studies have demonstrated that balloon platforms can be used to monitor seismic activity from the atmosphere at a low operational cost. Balloon-borne seismology is a new dynamic field and this might be the only viable approach to investigate Venus’ interior. However, inversion methods for balloon-borne infrasound data are not well developed and the coupling between seismic and acoustic waves in realistic media is not fully understood. In this contribution, we will explore the feasibility of detecting seismically-generated infrasound waves on Venus and assess their potential for subsurface velocity inversions through full-waveform numerical simulations.

• Brissaud, Quentin; Näsholm, Sven Peter & Solberg, Celine Marie (2024). Assumptions and uncertainties when simulating seismo-acoustic wave propagation on Venus. Full text in Research Archive
• Solberg, Celine Marie; Brissaud, Quentin & Näsholm, Sven Peter (2024). Preliminary assessments of the global detectability of venusquakes from a balloon platform. Full text in Research Archive Show summary

  (presented on-site by Celine Marie Solberg)

• Brissaud, Quentin; Froment, Marouchka; Solberg, Celine Marie & Näsholm, Sven Peter (2024). Svært lange lydbølger kan avdekke Venus’ skjulte indre. geoforskning.no. Full text in Research Archive Show summary

  https://geoforskning.no/svaert-lange-lydbolger-kan-avdekke-venus-skjulte-indre/ Venus kalles jordens «onde tvilling». Til tross for ganske like utgangspunkt, har Venus utviklet et ekstremt fiendtlig miljø. Varmen og trykket gjør det også umulig å plassere måleinstrumenter på bakken. Derfor undersøker vi om data fra lydmålere båret av høytflyvende ballonger kan hjelpe oss å forstå vår naboplanet.

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter; Solberg, Celine Marie; Kaschwich, Tina & Turquet, Antoine Leo (2024). Probing a planet from the subsurface to the atmosphere with infrasound data (conference presentation). doi: https:/2024.internoise.org/. Full text in Research Archive
• Brissaud, Quentin; Gülcher, Anna; Jennifer, Jackson; M, Wilding J; Froment, Marouchka & Näsholm, Sven Peter [Show all 8 contributors for this article] (2024). Global detectability estimates of venusquakes and volcanic activity from a balloon network. Full text in Research Archive
• Brissaud, Quentin; Näsholm, Sven Peter; Turquet, Antoine; Kaschwich, Tina & Solberg, Celine Marie (2023). The AIR project: Leveraging balloon pressure data for planetary exploration. Full text in Research Archive Show summary

  Our understanding of Earth’s internal structure comes primarily from seismic waves that provide important constraints on subsurface seismic-velocity properties. However, traditional inversion methods cannot be implemented in regions of limited seismic-station coverage, in particular on Venus due to its harsh surface conditions but also in remote Earth regions. This lack of seismic data greatly limits our understanding of Venus’ origin and evolution and Earth’s subsurface. However, the mechanical coupling between the ground and its atmosphere enables the seismic energy to be transmitted into the atmosphere as low-frequency acoustic waves carrying information about the seismic source and the subsurface properties. While infrasound is traditionally recorded at ground-based stations, which suffers from the same in-situ deployment limitations as seismic stations, recent studies have demonstrated that balloon platforms can be used to monitor seismic activity from the atmosphere at a low operational cost. Balloon-borne seismology is a new dynamic field considered to be the only way to investigate Venus’ interior. However, inversion methods for balloon-borne infrasound data are lacking and the coupling between seismic and acoustic waves in realistic media is poorly understood. Taking advantage of historical balloon pressure data, the newly granted project Airborne Inversion of Rayleigh waves (AIR), will address these key theoretical and practical issues by analyzing and modeling these seismically-induced infrasound signatures to retrieve the source and subsurface properties. In this contribution, we will present the project objectives and recent progress in balloon seismology and infrasound modeling.

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