5. The Self-Potential Method for Environmental and Engineering Applications

This article presents a tutorial of the bases for, and problems encountered with, the resistivity and induced polarization methods in geotechnical and environmental applications. It commences with a discussion of aqueous electrolytic conduction in rocks including consideration of the effects of temperature, rock texture, rock type, geological processes, and of the presence of clay minerals. Both electrode and membrane polarization in soils and rocks are described. The elementary theory for the resistivity and induced polarization methods is introduced via formulas for electrodes on homogeneous and layered half-spaces. The notion of apparent resistivity is presented. Vertical electric sounding is described in relation to curve types, inversion, equivalence, anisotropy, and correlation. Profiling with resistivity is briefly treated while combined sounding-profiling is treated in more detail for both the resistivity and induced polarization methods. The parameters used to describe the induced polarization phenomena are introduced. A brief discourse follows on data acquisition and processing, including design considerations for transmitters and receivers, electrodes, and wire logistics. A section on arrays and the factors involved in selecting an array provokes the disclosure that while their application in geotechnical and environmental studies usually is straightforward much remains to be learned about the resistivity and induced polarization methods in general. Specific topics requiring study are comparative studies of various arrays in (a) depth of exploration in sounding and in profiling, (b) resolution of horizontal structures, (c) sensitivity to depth, (d) sensitivity to lateral effects, (e) sensitivity to buried and surface topography, and (f) the effectiveness of focused arrays. References to recent significant publications on one-, two-, and three-dimensional forward and inverse interpretation procedures follow. Problems encountered with these methods are initially treated under the section on arrays and are expanded with specific reference to geologic noise and negative induced polarization effects. The advantages of focused arrays are illustrated. The paper concludes with nine representative examples of applications.

Next No AccessJournal of Environmental and Engineering GeophysicsVolume 27, Issue 4Introduction to the Journal of Environmental and Engineering Geophysics Special Issue on the Application of Proximal and Remote Sensing Technologies to Soil InvestigationsAuthors: Barry AllredAsim BiswasCraig LobseyLaurie WhitesellBarry Allred*Corresponding Author – E-mail Address: [email protected] USDA Agricultural Research Service, Soil Drainage Research Unit, Columbus, Ohio, USA Search for more papers by this author, Asim Biswas University of Guelph, School of Environmental Sciences, Guelph, Ontario, Canada Search for more papers by this author, Craig Lobsey University of Southern Queensland, School of Mechanical and Electrical Engineering, Toowoomba, Queensland, Australia Search for more papers by this author, and Laurie Whitesell Society of Exploration Geophysicists, Near Surface Geophysics & Mining and Mineral Exploration, Tulsa, Oklahoma, USA Search for more papers by this authorhttps://doi.org/10.32389/JEEG22-080 SectionsAboutFull TextPDF PlusePUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InReddit "Introduction to the Journal of Environmental and Engineering Geophysics Special Issue on the Application of Proximal and Remote Sensing Technologies to Soil Investigations." Journal of Environmental and Engineering Geophysics, 27(4), pp. vi–viiFiguresReferencesRelatedDetails Volume 27Issue 4Dec 2022Pages: vi-244ISSN (print):1083-1363 ISSN (online):1943-2658 publication data© 2022 Publisher:Environmental & Engineering Geophysical Society HistoryPublished Online: 21 Apr 2023Published in print: 01 Dec 2022 CITATION INFORMATION Barry Allred, Asim Biswas, Craig Lobsey, and Laurie Whitesell, (2022), "Introduction to the Journal of Environmental and Engineering Geophysics Special Issue on the Application of Proximal and Remote Sensing Technologies to Soil Investigations," Journal of Environmental and Engineering Geophysics 27: vi-vii. https://doi.org/10.32389/JEEG22-080 Plain-Language Summary Loading ...

The recent publication in Eos of communications from P. J. Baum and A. J. Dessler (October 23, 1984, p. 770) and B. Ü. O. Sonnerup (December 25, 1984, p. 1242) about the peer review process has stimulated us to contribute to the discussion this statement of the editorial philosophy and practice of Geophysical Research Letters (GRL). GRL is, of course, a very different journal from the Journal of Geophysical Research (JGR), with different goals, function, and readership. Our contribution should not be understood as a statement of how JGR should work. The editorial goal of GRL is to provide prompt publication of urgent results of general geophysical interest.

Karl E. Butler is an Associate Professor in the Department of Geology and Director of the Geological Engineering Program at the University of New Brunswick. He holds a BSc (1987) from Queen’s University, as well as MSc (1991) and PhD (1996) degrees in Geophysics from the University of British Columbia. From 1987 to 1989 he was employed in oil exploration with Chevron Canada Resources. His postdoctoral experience, prior to joining UNB in 1999, included electromagnetic modelling research at Lamontagne Geophysics Ltd and a study of electromagnetic effects associated with seismicity in mines carried out as a NSERC Industrial Research Fellow at Engineering Seismology Group Inc. His research interests include seismoelectric and electrical methods and, more generally, novel applications of high-resolution geophysics in hydrogeology, engineering and geological exploration. Luigi Sambuelli is Associate Professor of Applied Geophysics at the Politecnico di Torino. He holds an MSc in Mining (1982) from the Politecnico di Torino. From 1992 to 1995 he was Associate Professor in Applied Geophysics at the Universita di Cagliari. He was the scientific leader of the research ‘Experiments in the High-Frequency Georadar Band (0.9–2.5 GHz) for the Analysis of Ancient Historical Buildings’ within the ‘Cultural Heritage’ project of CNR and scientifically responsible for the European project ‘Holographic Ground Probing Radar System’. He has been invited lecturer at the International School of Applied Geophysics at the ‘Ettore Majorana’ Centre in Erice (Sicily) at the 8th European Meeting of Environmental and Engineering Geophysics in Aveiro, Portugal and at the School of Civil and Environmental Engineering (Georgia Tech, Atlanta, USA). Since 1997 he has been a member of EEGS and since 1988 he has been on the Editorial Board of European Journal of Environmental and Engineering Geophysics. From 2007 he has been a member of SEG and he is associate editor of Near Surface Geophysics. He is owner of one Italian patent and co-owner of two international patents. His main interests are the applications of geophysics to very small scales (non-destructive testing), to archaeology, tunnelling, geotechnics, the environment and hydrogeology.

The 2018 Global Dust Storm (GDS) has been observed on Mars from the surface and from orbit. Here we focus on the surface temperatures measured locally by REMS/MSL in Gale crater and column dust IR opacities observed globally by Mars Climate Sounder on-board Mars Reconnaissance Orbiter  (MCS/MRO) (e.g. Montabone et al., 2020). Recent modeling efforts of the 2018 GDS highlight that climate models do not simultaneously capture both the evolution of surface temperatures and the decay rate of global column dust opacities, which suggests that significant changes in dust particle sizes may occur during the dust storm (e.g. Bertrand et al., 2020, Montabone et al., 2020). These models typically assume a constant lifted dust particle size—with size evolution occurring in the atmosphere but only because of gravitational sedimentation. For instance, simulations with sufficiently large particles sizes to yield reasonable decay/sedimentation rates also provide excessive radiation fluxes at the surface, with excessive surface temperatures during peak dust loading. One possible way to improve the agreement between the simulations and the observations is to allow the dust particle sizes to change more significantly in time and/or space during the simulated GDS.  Particle size evolution toward large radius during GDSs is supported by several observations (e.g. Elteto and Toon, 2010, Lemmon et al., 2019). Different mechanisms could take place during dust storms to shift the dust particle distribution towards a larger effective radius: (1) the lifted particle size at the surface could change due to different active reservoirs or due to depletion of small particles as the storm increases in intensity and (2) the particle size in the atmosphere could change more significantly due to Brownian coagulation (production of large particles by the collisions induced by Brownian motions of the particles in the gas and subsequent sticking together of small particles) and gravitational coagulation (accretion through sedimentation, Murphy et al., 1990, Jacobsen et al., 1999, Montmessin et al., 2002, Fedorova et al., 2014).  Previous studies have explored the impact of coagulation processes and concluded that coagulation only affects smaller particles (

The Wave Gradiometry Method(WGM) has emerged as a powerful multipurpose tool to  extract strain and rotation tensor, identify phases, and most importantly to image the near surface or deep structure. The WGM measures the spatial gradients of the wavefield within a subarray to extract 4 major attributes: phase velocity, wave directionality, geometrical spreading and radiation pattern. These attributes can be further used to extract strain and rotation tensor (Langston and Liang CT, 2008; Sollberger et al. 2016) and structural information. An azimuth-dependent dispersion curve inversion (ADDCI, Liang et al. 2020) is applied together with the WGM method to extract both 3D shear wave velocity and 3D azimuthal anisotropy. Additionally, the geometrical spreading extracted by the WGM is used to find the attenuation of the materials. In this study, we review the theoretical foundation, technical development, major applications of the WGM and compare the WGM with other major array-based imaging method. Similar with the Ambient Noise tomography, the WGM is also boiled down to dispersion curve inversion. Even though it can be applied to arrays with a wide range of scales, here we concentrate on the applications to large scale arrays such as the USARRAY (average spacing of 70km), CHINARRAY (average spacing of 40km). It may also be applied to any other dense regional array, such as the ALPARRAY and others. The imaging depth is only limited by the corner frequency of the seismometer. We will compare our results with that from other techniques to highlight its advantage and disadvantages.References：Cao F H, Liang C T. 2022, 3D velocity and anisotropy of the southeastern Tibetan plateau extracted by joint inversion of wave gradiometry, ambient noise, and receiver function, Tectonophysics, https://doi.org/10.1016/j.tecto.2022.229690Cao, F., Liang, C., Zhou, L., & Zhu, J. (2020). Seismic azimuthal anisotropy for the southeastern Tibetan Plateau extracted by Wave Gradiometry analysis. Journal of Geophysical Research: Solid Earth, 124, e2019JB018395.  https://doi.org/10.1029/2019JB018395Liang, C., Liu, Z., Hua, Q., Wang, L., Jiang, N., & Wu, J. (2020). The 3D seismic azimuthal anisotropies and velocities in the eastern Tibetan Plateau extracted by an azimuth‐dependent dispersion curve inversion method. Tectonics, 39, e2019TC005747. https://doi.org/10.1029/2019TC005747 Langston, C. A. (2007). Wave gradiometry in two dimensions. Bulletin of the Seismological Society of America, 97(2), 401–416. https://doi.org/10.1785/0120060138 Porter R, Liu YY, and Holt WE (2016). Lithospheric Records of Orogeny within the Continental U.S.. Geophysical Research Letters, 43(1), 144–153. https://doi.org/10.1002/2015GL066950Sollberger D Schmelzbach C, Manukyan E, Greenhalgh SA, Van Renterghem C and Robertsson JOA (2019). Accounting for receiver perturbations in seismic wavefield gradiometry. Geophysical Journal International, 218(3), 1748–1760. https://doi.org/10.1093/gji/ggz258.

The Martian planetary boundary layer (PBL) drives the surface-atmosphere exchange processes such as the Martian dust cycle, which leads to strong atmospheric variations from diurnal to seasonal and inter-annual time scales [1]. The amount of dust lifted into the atmosphere and the vertical winds that balance the gravitational settling for the aerosols are affected by the turbulent mixing within the boundary layer. Several studies focused on the dynamics of the Martian PBL during daytime conditions [2,3]. During daytime conditions, the strong buoyancy caused by the vertical thermal gradient can generate turbulent mixing and initiate turbulence. On the other hand, the nighttime boundary layer is suggested to form under very weak turbulent mixing conditions. However, recent observations by the InSight lander showed unexpected turbulent signatures during nighttime conditions [4]. Nevertheless, lacking the observational datasets revealing the vertical variation of temperature and winds within the first kilometer of the Martian atmosphere, we do not fully understand the dynamics of the Martian boundary layer. To complement the limited observations on the Martian boundary-layer meteorology, high-resolution limited area models, so called large-eddy simulations (LES), are used. Here, we use the LES module of MarsWRF [3,5] to investigate the time and length scales of nighttime turbulence and possible large-scale atmospheric phenomena that can affect the near-surface nighttime meteorology. We present possible implications related to the Martian dust cycle.[1] Senel, C.B., Temel, O., Lee, C., Newman, C.E., Mischna, M.A., Muñoz‐Esparza, D., Sert, H. and Karatekin, Ö., 2021. Interannual, Seasonal and Regional Variations in the Martian Convective Boundary Layer Derived From GCM Simulations With a Semi‐Interactive Dust Transport Model. Journal of Geophysical Research: Planets, 126(10), p.e2021JE006965.[2] Spiga, A., Forget, F., Lewis, S.R. and Hinson, D.P., 2010. Structure and dynamics of the convective boundary layer on Mars as inferred from large‐eddy simulations and remote‐sensing measurements. Quarterly Journal of the Royal Meteorological Society: A journal of the atmospheric sciences, applied meteorology and physical oceanography, 136(647), pp.414-428.[3] Temel, O., Senel, C.B., Porchetta, S., Muñoz-Esparza, D., Mischna, M.A., Van Hoolst, T., van Beeck, J. and Karatekin, Ö., 2021. Large eddy simulations of the Martian convective boundary layer: towards developing a new planetary boundary layer scheme. Atmospheric Research, 250, p.105381.[4] Temel, O., Senel, C.B., Spiga, A., Murdoch, N., Banfield, D. and Karatekin, O., 2022. Spectral analysis of the Martian atmospheric turbulence: InSight observations. Geophysical Research Letters, 49(15), p.e2022GL099388.[5] Wu, Z., Richardson, M.I., Zhang, X., Cui, J., Heavens, N.G., Lee, C., Li, T., Lian, Y., Newman, C.E., Soto, A. and Temel, O., 2021. Large eddy simulations of the dusty Martian convective boundary layer with MarsWRF. Journal of Geophysical Research: Planets, 126(9), p.e2020JE006752.

In recent years, an increase in the frequency and intensity of cyclones with tropical characteristics has been observed in areas of the Mediterranean Sea (De la Vara et al., 2021). The rise in this type of cyclones has triggered extreme weather conditions in many Mediterranean coastal regions (Romero & Emanuel, 2013). With the increasing focus on the study and characterisation of these types of cyclones (Gutiérrez-Fernández et al., 2024), numerous research efforts have employed different methodologies to investigate the favourable conditions for the development of cyclones with tropical characteristics in the Mediterranean (Romero & Emanuel, 2017). Among the methods used to study the favourable conditions for the development of tropical cyclones, one of the most widely applied is the Potential Intensity (PI; Holland, 1997). This index measures the theoretical maximum intensity a cyclone with tropical characteristics can achieve under specific atmospheric conditions. This method has been investigated in numerous studies on tropical cyclones and demonstrates that high values of this index are associated with a higher likelihood of intense tropical cyclone development (Emanuel, 2005; Wing & Camargo, 2007).Therefore, the main motivation for this study is to analyse the evolution of the Potential Intensity (PI) over the past 70 years in the Mediterranean region. For this purpose, ERA5 reanalysis data (Hersbach et al., 2023) covering the period from 1950 to 2023 over the Mediterranean basin were used. The results indicate an increase in the values of this index, particularly during the autumn months, when most cyclones with stronger tropical characteristics occur. Finally, an individual analysis of this index was conducted under pre-development conditions for recent cyclones with tropical characteristics in the Mediterranean.de la Vara, A., Gutiérrez‐Fernández, J., González‐Alemán, J. J., & Gaertner, M. A. (2021). Characterization of medicanes with a minimal number of geopotential levels. International Journal of Climatology, 41(5), 3300-3316.Emanuel, K. (2005). Genesis and maintenance of" Mediterranean hurricanes". Advances in Geosciences, 2, 217-220.Gutiérrez‐Fernández, J., Miglietta, M. M., González‐Alemán, J. J., & Gaertner, M. A. (2024). A new refinement of Mediterranean tropical‐like cyclones characteristics. Geophysical Research Letters, 51(8), e2023GL106429.Hersbach, H., Bell, B., Berrisford, P., Biavati, G., Horányi, A., Muñoz Sabater, J., Nicolas, J., Peubey, C., Radu, R., Rozum, I., Schepers, D., Simmons, A., Soci, C., Dee, D., Thépaut, J-N. (2023): ERA5 hourly data on pressure levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS), DOI: 10.24381/cds.bd0915c6 (Accessed on 29/10/2024)Holland, G. J. (1997). The maximum potential intensity of tropical cyclones. Journal of the atmospheric sciences, 54(21), 2519-2541.Romero, R., & Emanuel, K. (2013). Medicane risk in a changing climate. Journal of Geophysical Research: Atmospheres, 118(12), 5992-6001.Romero, R., & Emanuel, K. (2017). Climate change and hurricane-like extratropical cyclones: Projections for North Atlantic polar lows and medicanes based on CMIP5 models. Journal of Climate, 30(1), 279-299Wing, A. A., Sobel, A. H., & Camargo, S. J. (2007). Relationship between the potential and actual intensities of tropical cyclones on interannual time scales. Geophysical research letters, 34(8).

Coal seam fire and coal mine fire as well as fire in coal waste or storage piles are worldwide general phenomenon and pose a great threat to the national economy, environment, ecology and health of peoples living in its proximity. In 17th century the coal mining in India first started in Raniganj coalfield in an ill- planned way and some planned mining started in an about 1820. In early days, the collieries were owned by several small companies and owners. In 1971, the Indian coal industry was nationalized under Coal India (CIL) and Bharat Coking Coal Limited (BCCL) was formed as a subsidiary of CIL. The haphazard coal mining without suitable mine planning pose several paramount threats with environmental hazards. At present it is spread over more than 70 areas. The mapping and understanding of hidden subsurface coal fire is a challenging task. In view of this, the present study was attempted for Coal fire mapping and detection of previously burnt coal fire regions in East Basuria colliery, a part of the Jharia coal field, India. Magnetic and Self Potential (SP) methods of geophysical investigation have been used for coal fire mapping over parts of Jharia Coalfield, India mainly due to cost-effectiveness with good accuracy and faster data acquisition. SP study works based on redox potential generated by oxidation of coal and also on Thomson potential due to temperature gradient. Whereas, magnetic study allows to map the previously burned, currently burning and unburned locations based on the magnetic properties of the materials and their changes with temperatures above or below Curie temperature. SP data have been analysed using Particle Swarm Optimization (PSO) technique. Magnetic data have been corrected for diurnal variation followed by correction using reduced to magnetic pole (RTP). The corrected magnetic data further, enhanced using north-south and east-west horizontal derivatives, first vertical derivative, second vertical derivative, Total horizontal derivative, Analytical signal, Tilt Derivative and downward continuation techniques. Radially averaged power spectrum (RAPS) of magnetic data has been calculated to estimate the average depth to the top of different layers. Different sets of 3D Euler’s depth solutions have been estimated separately for each various source geometry (SI = 0, 0.5, 1.0, 1.5, 2, 2.5 and 3) to understand the possible source geometry of complex fire activities. PSO inversion of SP data reveals that the depth of the coal fire extends between 10 and 12 m below the surface. The study based on SP method over East Basuria reveals that the geometry of subsurface coal combustion is possibly similar to the inclined sheet with relatively large horizontal extension. The large variations in inclination angles of the causative sources may possibly indicate complex nature of fire propagation along different inclined fractured planes which are generated in multiphase coal seam combustion. It is observed that the total magnetic field intensity anomaly of the area varies approximately from 44,850 to 47,460 nT and the residual magnetic anomaly varies approximately from −1323 to 1253 nT. The range of the magnetic anomaly after RTP is approximately 1050–1450 nT. Twelve low (L1–L12) and nine high (H1–H9) RTP magnetic anomalies have been delineated from RTP of East Basuria Colliery for 2012. The average depth to the top of different layers estimated using radially averaged power spectrum (RAPS) over East Basuria colliery are (i) 10 m, (ii) 18 m and (iii) 38 m for 2012. It is observed that the average depth of the estimated Euler’s solution for different SI is varies from 10 to 26 m for 2012. Possible fire affected, non-fire and possible baked and cool areas have been delineated as (i) 21%, (ii) 36%, (iii) 42% for the years 2012 based on RTP anomaly distribution over East Basuria colliery. The results prove the efficacy of the SP and magnetic methods for characterization of causative sources associated with coal fires over East Basuria colliery, Jharia coalfield, India.

1540. Komatsu, G., Ori, G.G., Ciarcelluti, P., and Litasov, Y.D., 2004, Interior layered deposits of Valles Marineris, Mars— Analogous subice volcanism related to Baikal rifting, southern Siberia: Planetary and Space Science, v. 52, no. 1–3, p. 167–187. Lucchitta, B.K., 1990, Young volcanic deposits in the Valles Marineris, Mars?: Icarus, v. 86, no. 2, p. 476–509. Lucchitta, B.K., 1999, Geologic Map of Ophir and Central Candor Chasmata (MTM–5072) of Mars: U.S. Geological Survey Scientific Investigations Series I–2568, scale 1:500,000. Malin, M.C., Bell, J.F., III, Cantor, B.A., and 11 others, 2007, Context camera investigation on board the Mars Reconnaissance Orbiter: Journal of Geophysical Research, v. 112, no. E5, p. E05S04. Malin, M.C., Danielson, G.E., Ingersoll, A.P., and 4 others, 1992, Mars Observer Camera: Journal of Geophysical Research, v. 97, no. E5, p. 7699–7718. Mangold, N., Gendrin, A., Gondet, B., and 7 others, 2008, Spectral and geological study of the sulfate-rich region of West Candor Chasma, Mars: Icarus, v. 194, no. 2, p. 519–543. McEwen, A.S., Banks, M.E., Baugh, N.F., and 67 others, 2010, The high resolution imaging science experiment (HiRISE) during MRO’s primary science phase (PSP): Icarus, v. 205, no. 1, p. 2–37. Metz, J.M., Grotzinger, J.P., Mohrig, D., and 5 others, 2009, Sublacustrine depositional fans in southwest Melas Chasma: Journal of Geophysical Research, v. 114, no. E10, p. E10002. Michalski, J.M., and Niles, P.B., 2012, Atmospheric origin of Martian interior layered deposits—Links to climate change and the global sulfur cycle: Geology, v. 40, no. 5, p. 419–422. Murchie, S.L., Roach, L.H., Seelos, F.P., and 7 others, 2009a, Evidence for the origin of layered deposits in Candor Chasma, Mars, from mineral composition and hydrologic modeling: Journal of Geophysical Research, v. 114, p. E00D05. Murchie, S.L., Seelos, F.P., Hash, C.D., and 20 others, 2009b, Compact Reconnaissance Imaging Spectrometer for Mars investigation and data set from the Mars Reconnaissance Orbiter’s primary science phase: Journal of Geophysical Research, v. 114, p. E00D07. Nedell, S.S., Squyres, S.W., and Anderson, D.W., 1987, Origin and evolution of the layered deposits in the Valles Marineris, Mars: Icarus, v. 70, p. 409–414. Netoff, D.I., and Shroba, R.R., 2001, Conical sandstone landforms cored with clastic pipes in Glen Canyon National Recreation Area, southeastern Utah: Geomorphology, v. 39, no. 3–4, p. 99–110. Niles, P.B., and Michalski, J.M., 2009, Meridiani Planum sediments on Mars formed through weathering in massive ice deposits: Nature Geoscience, v. 2, no. 3, p. 215–220. Okubo, C.H., 2010, Structural geology of Amazonian-aged layered sedimentary deposits in southwest Candor Chasma, Mars: Icarus, v. 207, no. 1, p. 210–225. Okubo, C.H., 2013, High-resolution Geologic Mapping in West Candor Chasma, Mars—2013 Status Report, in 2013 Annual Planetary Geologic Mappers Meeting, Washington, DC, National Aeronautics and Space Administration. Okubo, C.H., Lewis, K.W., McEwen, A.S., and Kirk, R.L., 2008, Relative age of interior layered deposits in southwest Candor Chasma based on high-resolution structural mapping: Journal of Geophysical Research, v. 113, no. E12, p. E12002. Okubo, C.H., Schultz, R.A., Chan, M.A., Komatsu, G., and the High Resolution Imaging Science Experiment Team, 2009, Deformation band clusters on Mars and implications for subsurface fluid flow: Geological Society of America Bulletin, v. 121, no. 3–4, p. 474–482. Pelkey, S.M., Mustard, J.F., Murchie, S.L., and 9 others, 2007, CRISM multispectral summary products—Parameterizing mineral diversity on Mars from reflectance: Journal of Geophysical Research, v. 112, no. E8, p. E08S14. Scott, D.H., and Tanaka, K.L., 1986, Geologic map of the western equatorial region of Mars: U.S. Geological Survey Miscellaneous Investigations Series Map I–1802–A, scale 1:15,000,000. Witbeck, N.E., Tanaka, K.L., and Scott, D.H., 1991, Geologic map of the Valles Marineris region, Mars: U.S. Geological Survey Miscellaneous Investigations Series I–2010, scale 1:2,000,000. Zurek, R.W., and Smrekar, S.E., 2007, An overview of the Mars Reconnaissance Orbiter (MRO) science mission: Journal of Geophysical Research, v. 112, no. E5, p. 1–22.

Limestone covers about 4500 km2 in Romania, meaning about 2% from the country surface, being specific for the karst of the temperate zones due to its landforms, terrain diversity and the amplitude of the exo and endokarst particularities. Carbonate rocks are spread in the mountains and sub-mountains areas, with the most compact and the largest surface of this type of rocks in the Banat Mountains, more exactly in the Resiţa-Moldova Noua Synclinorium. The aim of this study to examine the use of the self-potential as geophysical method in detection of water flow and water resources in shallow karst depressions (sinkholes) in the Anina Karst Region, Banat Mountains, Romania. The self-potential (SP) method—also known as spontaneous potential—is founded on the measurements regarding the natural or spontaneous potentials that are forming in the ground. Our SP approach in several sinkholes in the Anina Karst Region shows that most of the anomalous zones with positive spontaneous electric potential are localized in the middle of the sinkholes, indicating the higher retention of water within the bottom part of the karst depressions. Also, the most of the values showing negative anomalies are situated in those parts where the karrens are developed. SP method applied in the Anina Karst Region, Banat Mountains, Romania, has shown the feasibility of this geophysical method in the study of water circulation in shallow karst environment. Since sinkholes are landforms that favor the fast circulation of the water from the surface into the underground, the SP approach could be a feasible method to study aquifers and the presence of contaminants in karst aquifers since water is a very important resource in karst areas. Moreover, SP method is reliable in characterization of shallow karst topography research and this geophysical method can be combined with other geophysical method in karst terrain analysis, methods like GPR and ERT.

Extreme midlatitude weather is often associated with pronounced Rossby waves. This has motivated interest in how the ‘waviness’ of the atmosphere is changing as Earth warms. Multiple summary metrics have been used to assess midlatitude waviness, which include both descriptions of the magnitudes of associated anomalies in geopotential height, and geometric measures of deviations of the jet from a more zonal state.Recent work illustrated that a) these metrics can respond differently to warming, and that the same metric can respond differently to warming applied in different ways (Geen et al. 2023), and b) that different metrics can link to rather different patterns of extreme temperature (Roocroft et al. 2025). It remains unclear what specific types of characteristic jet structures these various metrics capture, and how these dynamically link to surface weather extremes.Here, we first explore how different metrics relate to extreme winter weather events (cold, rain and wind) over Europe and North America, and how these relationships compare to known modes of climate variability such as the NAO. Next, to explore underlying jet structures driving these extremes, we apply a Self Organising Maps analysis to 500-hPa geopotential height anomalies. This allows us to map the values taken by different metrics and the likelihoods of extreme events for different jet configurations in a reduced dimensionality space. ReferencesGeen, R., Thomson, S. I., Screen, J. A., Blackport, R., Lewis, N. T., Mudhar, R., ... & Vallis, G. K. (2023). An explanation for the metric dependence of the midlatitude jet‐waviness change in response to polar warming. Geophysical Research Letters, 50(21), e2023GL105132.Roocroft, E., White, R. H., & Radić, V. (2025). Linking atmospheric waviness to extreme temperatures across the Northern Hemisphere: Comparison of different waviness metrics. Journal of Geophysical Research: Atmospheres, 130(20), e2024JD042631.

Traditionally, the ocean is treated as an incompressible fluid to simplify wave modeling. However, ocean compressibility—dictated by its density and bulk modulus—significantly impacts wave dynamics, particularly for long-period surface waves (>30 s) and compressional waves within the water column. Similarly, Earth's transition from rigid to elastic behavior under surface loads further influences wave propagation by altering phase speed and waveforms. These effects manifest as arrival time discrepancies and waveform modulation, as observed in tsunami and long-wave dynamics (Allgeyer & Cummins, 2014; Abdolali et al., 2017, 2019).This study explores the combined effects of ocean compressibility, Earth elasticity, and background density on wave characteristics across a wide frequency range, including infra-gravity (IG), storm surge, tidal waves, and compressional acoustic waves. Building on prior work, a dispersion relationship is derived, accounting for dynamic ocean compression under gravity interacting with a finite, multi-layered elastic Earth. By analyzing phase speed, group velocity, travel times, and pressure profiles, this research advances understanding of wave dynamics and offers a robust framework for improved modeling of tides and storm surges, coastal flooding, tsunamis, and acoustic wave propagation.Abdolali, A., & Kirby, J. T. (2017), Role of compressibility on tsunami propagation. Journal of Geophysical Research: Oceans, 122, 9780–9794.Abdolali, A., Kadri, U. & Kirby, J.T. (2019), Effect of Water Compressibility, Sea-floor Elasticity, and Field Gravitational Potential on Tsunami Phase Speed. Scientific Reports, 9, 16874Allgeyer, S., & Cummins, P. (2014). Numerical tsunami simulation including elastic loading and seawater density stratification. Geophysical Research Letters, 41(7), 2368-2375.

IntroductionThe horizontal distribution of sulfuric acid clouds in the Venusian atmosphere is an essential factor that influences the solar energy absorbed by the planet. The cloud layer reflects about 75% of the solar energy [1] and controls the amount of energy input to the planet. Understanding how sulfur dioxide, SO2, the precursor of sulfuric acid, is transported from the lower atmosphere to the cloud top, where the cloud particles are formed from SO2 photochemically, is one of the essential subjects for understanding the Venusian climate system. Japanese Venus orbiter Akatsuki [2] has been conducting new observations to understand the supply and consumption process of SO2. The ultraviolet imager onboard Akatsuki is equipped with two bandpass filters centered at 283 nm for observation of SO2 and 365 nm for the unidentified UV absorber, taking disk images every two hours at two wavelengths [3]. In recent analysises, the local time mean field of the temperature field obtained by mid-infrared observations of Akatsuki has confirmed that the wavenumber 2 component of thermal tides has a large amplitude at low latitudes, which can be one of the processes that explains the variation of SO2 at the cloud top altitude [4, 5]. In this study, we have developed a method to retrieve only the effect of absorption by SO2 from the 283 nm images by using additional images simultaneously taken through a 365 nm filter. We obtained the local time and latitudinal mean distribution of SO2 to analyze on the transport by thermal tides with large amplitude in the mean field. DatasetIn this study, we used over 15,000 pairs of 283 and 365 nm UV images taken by the Japanese Venus orbiter Akatsuki. The main absorbers around 283 nm are both SO2 and the unidentified UV absorber, while the absorption of SO2 is negligible and that of the unidentified UV absorber is dominant at 365 nm. The UV images are Level 3b data, which are 2880 by 1440 maps of calibrated radiance in the longitude-latitude coordinates expanded from 1024 by 1024 Venus disk images taken by the Akatsuki UV imager. We binned down to 120 by 60 to reduce computational cost. Retrieval of Sulfur DioxideWe used radiative transfer calculations to calculate reflectance under various amounts of SO2 and the unidentified UV absorber to create a look-up table. The calculations were performed under the same geometrical conditions as those of the observation of each pixel on the UV images by using our originally developed calculation code based on the adding-doubling method suitable for the calculation of multiple scattering under a divided icosahedral grid for spherical numerical integration to increase suitability for comparison with observations from orbital positions. The effect of the unidentified UV absorber was considered as the imaginary part, ni, of the complex refractive index of the sulfuric acid solution cloud droplets. First, ni is obtained from the 365 nm image under certain initial conditions. The ni has wavelength dependence, so it is converted to a value at 283 nm using the function of wavelength of ni estimated from the Venus Express UV spectroscopy observations. Next, the 283 nm image and the ni value are used to determine the amount of SO2. The obtained amount of SO2 is used again to obtain the value of ni from the 365 nm image. By performing this loop calculation until convergence, the SO2 and ni  values were simultaneously retrieved. We performed a sensitivity analysis to cloud altitude. Figure 1: An Example of retrieval from two UV images. Top two figures are observed reflectance at 283 and 365 nm. Left bottom is retrived amount of SO2 and right bottom is ni. Local Time Distribution of Sulfur DioxideUsing all of the horizontal distributions of SO2 retrieved from 15,000 pairs of UV images, we obtained the mean distribution of SO2 in local time-latitude coordinates shown in Fig. 2.Figure 2: Mean distribution of SO2 on local time and latitude coordinates. The left side of the figure is the afternoon side, and the right is the morning. There is an single maximum around 14-15 in the afternoon. The mean value of SO2 is 80 to 200 ppb, which is consistent with the previous study [6]. The distribution has a clear single peak, and the mixing ratio of SO2 monotonically increases from the morning to around 14:30 and decreases toward the terminator of the evening. In the latitudinal direction, it decreased from low to middle latitudes. The distributions can be explained by the vertical movement of air excited by thermal tides of wavenumber 2. Thermal tides have a structure that is warmer in the afternoon and cooler in the morning. When the background wind passes through this structure, the air is lifted most on the afternoon side. This causes SO2, which is abundant in the lower layers, to be lifted to the cloud-top region, resulting in a single maximum on the afternoon side. The distribution obtained by this study is qualitatively consistent with the result of a Venus GCM with photochemistry [7] and the wave structures reproduced by the Venus GCM by [8]. References [1] Taylor, F., and D. Grinspoon (2009), Climate evolution of Venus, J. Geophys. Res., 114, E00B40, doi:10.1029/2008JE003316. [2] Nakamura, M. et al. (2016), AKATSUKI returns to Venus, Earth Planets Space, 68, 75, doi:10.1186/s40623-016-0457-6. [3] Yamazaki, A., et al. (2018), Ultraviolet imager on Venus orbiter Akatsuki and its initial results, Earth Planets Space, 70, 23, doi:10.1186/s40623-017-0772-6. [4] Kouyama, T. et al. (2019), Global structure of thermal tides in the upper cloud layer of Venus revealed by LIR on board Akatsuki, Geophysical Research Letters, 46, 9457–9465, doi:10.1029/2019GL083820. [5] Fukuya, K. et al. (2021), The nightside cloud-top circulation of the atmosphere of Venus, Nature, 595, 511–515, doi:10.1038/s41586-021-03636-7. [6] Belyaev, D. et al. (2012), Vertical profiling of SO2 and SO above Venus’ clouds by SPICAV/SOIR solar occultations, Icarus, 217, 2, doi: 10.1016/j.icarus.2011.09.025. [7] Stolzenbach, A. et al. (2023), Three-dimensional modeling of Venus photochemistry and clouds, Icarus, 395, 115447, doi:10.1016/j.icarus.2023.115447. [8] Takagi, M. et al. (2018), Three-dimensional structures of thermal tides simulated by a Venus GCM, Journal of Geophysical Research: Planets, 123, 335–352, doi:10.1002/2017JE005449.

Fault zones play a fundamental role in controlling subsurface fluid circulation and mineralization. Their capacity to alternately behave as barriers or conduits—commonly conceptualized within the fault-valve model—results from complex interactions among multiphysical processes (thermal, hydraulic, mechanical, and chemical) acting across a wide range of spatial and temporal scales within the fault structure.Focusing on the gouge scale, we investigate the hydromechanical behavior of faults using a three-dimensional pore-scale modeling framework that couples a Discrete Element Method (DEM) with a pore-scale finite volume (PFV) scheme. Building on the approach of Nguyen et al. (2021), the DEM is used to model the gouge material as a granular assembly, while the PFV method is used to model fluid flow within the evolving pore space.Using this coupled approach, we simulate a sheared, fluid-saturated granular gouge subjected to hydromechanical loading through a controlled cyclic fluid injection protocol applied at constant shear stress. The DEM-PFV model captures emergent behaviors consistent with laboratory and in situ observations, and reveals pronounced cycle-to-cycle variability in both the onset of reactivation (Sarma et al., 2025) and the magnitude of slip under repeated pressurization and depressurization. In particular, some cycles produce large slip episodes whereas others exhibit comparatively small slip under similar loading conditions. To connect this macroscopic variability to micromechanics, we track the evolution of the force-chain population throughout the cycles using the characterization method proposed by Peters et al. (2005). The results provide grain-scale insights into how internal load-bearing structures reorganize across cycles and how these force-chain dynamics relate to the occurrence of large-slip events in fault-valving sequences.ReferencesNguyen, H. N. G., Scholtès, L., Guglielmi, Y., Donzé, F. V., Ouraga, Z., & Souley, M. (2021). Micromechanics of sheared granular layers activated by fluid pressurization. Geophysical Research Letters. https://doi.org/10.1029/2021GL093222Sarma, P., Aharonov, E., Toussaint, R., & Parez, S. (2025). Fault gouge failure induced by fluid injection: Hysteresis, delay and shear-strengthening. Journal of Geophysical Research: Solid Earth. https://doi.org/10.1029/2024JB030768Peters, J., Muthuswamy, M., Wibowo, J., & Tordesillas, A. (2005). Characterization of force chains in granular material. Physical Review E. https://doi.org/10.1103/PhysRevE.72.041307