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Situated between the petroliferous Cenozoic Zhujiang (Pearl) River Mouth Basin and the mud volcano-rich Mesozoic Dongsha Basin in the middle sector of the northern South China Sea, the Weitan Banks area has been previously mapped as a basement high that is composed of Mesozoic magmatic rocks. In this study, we present several favorable indicators for petroleum geology that were detected from geophysical profiling and benthic sampling in the area. A conspicuous hill was discovered, named "Zhongwei Hill", ∼80 m high above the ∼340 m deep seafloor and ∼1 km broad, in a depression with more than 7 km thick sedimentary strata. The Zhongwei Hill was seismically imaged with a mushroom-shaped structure and containing a cake-like crown, fluid flow pipes, and an ∼10 km broad anticline at depth. Thus, the hill represents a source-plumbing-eruption system. Shallow gas zones linked to deep fracture were found at or near the hill. Stratigraphic correlation indicates that the deep strata comprise the Jurassic and Paleogene strata, the major hosts of hydrocarbon source rocks. In addition to the hill, there are number of mounds from which three bottom water samples were collected and the samples are rich in dissolved methane with concentrations high up to ∼900 nmol/L, much higher than the background level (0.5–2 nmol/L). The benthic samples are rich in coarse sediment clastics, authigenic carbonate nodules, and deep-water habitats likely feeding on methanotrophic community. Given these observations and the context, we propose that the Zhongwei Hill represents a mud volcano, likely thermally driven, that seeps methane from Jurassic and Paleogene source layers, thus poses a favorable clue for significant hydrocarbon generation capacity in transitional zone of the Zhujiang River Mouth Basin and the Dongsha Basin. [ABSTRACT FROM AUTHOR]

Diversity of extremophilic microorganisms in mud volcanoes is largely unexplored. Here we report the isolation of a novel alkaliphilic, mesophilic, fermentative bacterium (strain FN5sucT) from a terrestrial mud volcano located at the Taman Peninsula, Russia. Cells of strain FN5sucT are gram-stain-positive, non-sporeforming, motile rods. The temperature range for growth is 10–37°C, with an optimum at 30°C. The pH range for growth is 7.5–10.0, with an optimum at pH 9.0. The isolate utilizes various organic polymeric substances, organic acids, carbohydrates, and proteinaceous compounds. The end products of carbohydrates fermentation are acetate, CO2 and trace amounts of H2 and formate. The major cellular fatty acid compounds are C16:0, C16:1 ω7c, and monounsaturated dimethyl acetal C14:1. Phylogenetic analysis reveals that strain FN5sucT is most closely related to Petrocella atlantisensis = DSM 105309T (98.4% 16S rRNA gene identity). The total size of the genome of strain FN5sucT is 3.35 Mb, and a genomic DNA G+C content is 37.0 mol %. The genome contains complete glycolisis/glyconeogenesis pathway. We propose to assign strain FN5sucT to the genus Petrocella, as a new species, Petrocella pelovolcani sp. nov. The type strain is FN5sucT (=DSM 113898T = UQM 41591T). [ABSTRACT FROM AUTHOR]

In spite of wide distribution, the phenomenon of mud volcanism is fragmentarily studied by geoscientists, saying nothing about the role of the mud volcanoes as the geopark components or the independent geoheritage objects. In Azerbaijan (the eastern part) and the adjacent water area of the South Caspian basin, the mud volcanism has its most development in comparison with the rest parts of world. The mentioned area is considered as the host for over 350 mud volcanoes onshore and offshore, differing in type, morphology, dimensions, eruption activity and intensity of fluids’ emitting and even possible risks for the environment. Here, the mud volcanoes, being the unique and noticeable units of the local landscape, claim the attention of not only the geoscientists but also the domestic and foreign tourists. Consequently, it represents a good enough potential for promoting the future geotourism development of the region not only as the geopark component, but also as independent geoheritage units. The study characterizes the provinces of mud volcanoes distribution, their specific features, definitions and classification. Seven remarkable mud volcanoes from various provinces in Azerbaijan had been selected in the present paper. They are described not only as geological objects but also as the landscape units, scenic attraction and local landmarks. The detailed description as well as the images of the volcanoes can give the comprehensive view about the target of research. The study concludes that following the example of the described mud volcanoes, these geological edifices have the good enough potential to gain the status of geoheritage. [ABSTRACT FROM AUTHOR]

Mud volcanoes are geological structures observed throughout the world that arise from the upwelling of deep fluids along discontinuities in the subsoil. The detection of mud fluid migration pathways can be challenging, even when using Electrical Resistivity Tomography (ERT) as detectability issues may arise from complex geological settings. This paper presents new results from 2D and 3D ERT synthetic modelling for the investigation of the shallow, internal structure of terrestrial mud volcanoes. This study revealed the internal structure of the 'Cenerone-Pineto' mud volcano (Central Italy) and provided further clues as to its internal structure. The main results of the study are: the presence of a mud chamber, which represents the last phase of mud accumulation before final emission, not located beneath the crater but laterally offset, as well as the presence of a narrow, shallow feeder channel; these findings represent evidence of a much more complex structure than one would expect. This means that the mud volcano is not supplied with mud fluids directly from below as would be the case with an uprising of deep fluid along a near-vertical open fracture and that the shallow mud fluid reservoir is not correlated to the distribution of any mud volcano observed on the surface. Findings from this study are consistent with the observed structural features already noted in ERT and seismic field data collected at the 'Cenerone-Pineto' mud volcano and may be helpful in explaining the mechanisms and processes involved in mud volcanism in similar geological settings. [ABSTRACT FROM AUTHOR]

An alkaliphilic, sulfate-reducing, anaerobic bacterium (strain H1T) was isolated from a terrestrial mud volcano at the Taman Peninsula, Russia. The cells of the isolate were gram-negative motile vibrios, 1 µm in diameter and 2.0–2.5 µm in length. Strain H1T grew at 14–42°C (optimum at 37°C), pH 8.5–10.5 (optimum at pH 9.5), and NaCl concentrations of 0.5–6% (wt/vol) (optimum at 0.5–1.5%); pyruvate, lactate, butyrate, caproate, or pelargonate were used as electron donors, and elemental sulfur, sulfite, or sulfate were used as electron acceptors. Pyruvate and lactate were fermented. No growth occurred in the presence of oxygen. Thiosulfate, DMSO, fumarate, nitrate, nitrite, arsenate, selenite, and Fe(III) were not used as electron acceptors. Elemental sulfur, thiosulfate, and sulfite were not disproportionated. Glucose, fructose, sucrose, trehalose, galactose, xylose, fumarate, citrate, yeast extract, and peptone were not fermented. Predominant fatty acids were C20:0 (54.2%), C22:0 (24.6%), and C18:0 (11.1%). The genome of strain H1T was 3.66 Mb in size and had G + C DNA content of 51.1%. The genome contained the genes encoding the enzymes of dissimilatory sulfate reduction and β-oxidation of fatty acids. According to the results of analysis of the 16S rRNA gene sequence, Desulfobotulus mexicanus was the organism most closely related to strain Н1Т (98.3% similarity). Based on its phenotypic characteristics and the data of phylogenetic analysis, affiliation of the isolate as member of a novel Desulfobotulus species, Desulfobotulus pelophilus sp. nov., is proposed, with the type strain H1T (=DSM 112796T = VKM B-3697Т =UQM 41590T). [ABSTRACT FROM AUTHOR]

A novel alkaliphilic sulfate-reducing bacterium, strain M08butT, was isolated from a salsa lake of terrestrial mud volcano (Taman Peninsula, Russia). Cells were rod-shaped, motile and Gram-stain-negative. The temperature range for growth was 15–42 °C (optimum at 30 °C). The pH range for growth was 7.0–11.0, with an optimum at pH 8.5–9.0 Strain M08butT used sulfate, thiosulfate, sulfite, dimethyl sulfoxide and arsenate as electron acceptors. Acetate, formate, butyrate, fumarate, succinate, glycerol and pyruvate were utilized as electron donors with sulfate. Fermentative growth was observed with fumarate, pyruvate, crotonate. Strain M08butT grew chemolithoautotrophically with H2 and CO2. The G + C content of the genomic DNA was 60.1%. The fatty acid profile of strain M08butT was characterized by the presence of anteiso-C15:0 as the major component (68.8%). The closest phylogenetic relative of strain M08butT was Desulfatitalea tepidiphila (the order Desulfobacterales) with 96.3% 16S rRNA gene sequence similarity. Based on the phenotypic, genotypic and phylogenetic characteristics of the isolate, strain M08butT is considered to represent a novel species of the genus Desulfatitalea, with proposed name Desulfatitalea alkaliphila sp. nov. The type strain of Desulfatitalea alkaliphila is M08butT (= KCTC 25382T = VKM B-3560T = DSM 113909T = JCM 39202T = UQM 41473T). [ABSTRACT FROM AUTHOR]

Many features indicative of natural gas and oil leakage are delineated in the deep-water Orange Basin offshore South Africa using 3D reflection seismic data. These features are influenced by the translational and compressional domains of an underlying Upper Cretaceous deep-water fold-and-thrust belt (DWFTB) system detaching Turonian shales. The origin of hydrocarbons is postulated to be from both: (a) thermogenic sources stemming from the speculative Turonian and proven Aptian source rocks at depth; and (b) biogenic sources from organic-rich sediments in the Cenozoic attributed to the Benguela Current upwelling system. The late Campanian surface has a dense population of > 950 pockmarks classified into three groups based on their variable shapes and diameter: giant (> 1500 m), crater (~ 700–900 m) and simple (< 500 m) pockmarks. A total of 85 simple pockmarks are observed on the present-day seafloor in the same area as those imaged on the late Campanian surface found together with mass wasting. A major slump scar in the north surrounds a ~ 4200 m long, tectonically controlled mud volcano. The vent of the elongated mud volcano is near-vertical and situated along the axis of a large anticline marking the intersection of the translational and compressional domains. Along the same fold further south, the greatest accumulation of hydrocarbons is indicated by a positive high amplitude anomaly (PHAA) within a late Campanian anticline. Vast economical hydrocarbon reservoirs have yet to be exploited from the deep-water Orange Basin, as evidenced by the widespread occurrence of natural gas/fluid escape features imaged in this study. [ABSTRACT FROM AUTHOR]

An alkaliphilic, facultatively anaerobic bacterium (strain T05bT) was isolated from a terrestrial mud volcano on the Taman Peninsula, Russia. The cells of the isolate were motile spirilla 0.5 µm in diameter and 1.5–2.5 µm long. Strain T05bT grew at 6–42°C (optimum at 30°C), pH 8.0–11.0 (optimum at 9.0), and 0–14% NaCl (wt/vol). Lactate, formate, malate, pyruvate, H2, elemental sulfur, sulfite, thiosulfate, and sulfide were used as electron donors; nitrate, fumarate, elemental sulfur, sulfite, thiosulfate, dimethyl sulfoxide, arsenate, and oxygen could be used as electron acceptors. Nitrate was reduced to ammonium. Malate, pyruvate, and fumarate were fermented. Microaerobic growth was possible at up to 3% О2 (vol/vol). Strain T05bT did not use sulfate and Fe(III) as electron acceptors, was unable of elemental sulfur, sulfite or thiosulfate disproportionation, and did not ferment glucose, fructose, sucrose, lactate, formate, maleate, yeast extract, or peptone. The predominant fatty acids were C16:1 ω7 (45.9%), C16:0 (25.8%), and C18:1 ω7 (20.9%). The genome of strain T05bT was 2.46 Mb in size and had the G + C DNA content of 45.5%. It contained the genes encoding the following enzymes of energy metabolism: Nap nitrate reductase periplasmic complex, Phs/Psr thiosulfate/polysulfide reductase, Sqr sulfide:quinone oxidoreductase, and Arr respiratory arsenate reductase. According to analysis of the 16S rRNA gene nucleotide sequence, strain T05bT exhibited 98.61% similarity to the type strain of Sulfurospirillum alkalitolerans (phylum "Campylobacterota"). Based on its phenotypic characteristics and the results of phylogenetic analysis, assignment of the isolate to a new Sulfurospirillum species, Sulfurospirillum tamanensis sp. nov., is proposed, with the type strain T05bT (=DSM 112596T = VKM B-3538T). [ABSTRACT FROM AUTHOR]

The upwelling of fluids, subject to overpressure, along with discontinuities in the subsoil, causes the formation of geological structures known as mud volcanoes. These structures, very widespread in the world and in some cases located near inhabited centers, can represent a considerable risk factor for the population, as they can give rise to paroxysmal eruptions, even very violent. The assessment of the characteristics and structure of the subsoil of the areas affected by this phenomenon can prove to be a useful tool for risk mitigation. Non-invasive geophysical surveys were carried out in the area of the active cone of the Santa Barbara mud volcano in order to obtain a 3D characterization of the subsoil. Through the processing and integration of data derived from active and passive seismic surveys was obtained, a 3D model showing the seismostratigraphic subsoil structure. The electrical resistivity tomography surveys provided results comparable to those obtained from seismic surveys and supplied information on the perimetral areas of the mud volcano. The information obtained is useful to study the boundary conditions that influence short-scale activity. Furthermore, this study seeks to evaluate the possibility of using the proposed methodological approach for monitoring the variations that occur over time in the areas affected by mud volcanoes phenomenon. [ABSTRACT FROM AUTHOR]

The Lower Kura Depression (LKD) in Azerbaijan is a unique place on Earth where enormous oil and oil–gas-condensate deposits coexist with mud volcanoes. Large mud volcanoes developed in this area as a result of favorable tectonic processes, depositional settings, and subsurface pressure conditions. Disequilibrium compaction leading to overpressurization of mudrocks, as well as gas generation, have been previously proposed as the main factors that cause overpressure and trigger mud volcanism. To assess the mechanisms contributing to mudrock overpressure, we conducted a 2D basin modeling work to simulate the burial, temperature, maturation, and pressure histories of the sedimentary pile along a 120-km-long geological cross-section in the ENE‒WSW direction perpendicular to major structures in the LKD. The results of the calibrated model suggest that the main petroleum source rocks of the LKD, namely the Oligocene–Middle Miocene Maykop and the Eocene Middle Koun mudrock formations, are still in the oil generation zone. Therefore, previously speculated gas generation effect on overpressurization is insignificant in the LKD. Modeling also predicts overpressure of varying magnitude in the potential hydrocarbon source rocks of dominantly mudstone lithology. We have verified that disequilibrium compaction caused by rapid sedimentation in the last 3 million years has led to mudrock overpressurization that exceeded rock strength. We take model-predicted fracturing as a proxy indicator of mud ascent and suggest that fracturing of the mudrocks enabled ascend of the mud via fault-associated weakness zones.Graphical abstract: The Lower Kura Depression (LKD) in Azerbaijan is a unique place on Earth where enormous oil and oil–gas-condensate deposits coexist with mud volcanoes. Large mud volcanoes developed in this area as a result of favorable tectonic processes, depositional settings, and subsurface pressure conditions. Disequilibrium compaction leading to overpressurization of mudrocks, as well as gas generation, have been previously proposed as the main factors that cause overpressure and trigger mud volcanism. To assess the mechanisms contributing to mudrock overpressure, we conducted a 2D basin modeling work to simulate the burial, temperature, maturation, and pressure histories of the sedimentary pile along a 120-km-long geological cross-section in the ENE‒WSW direction perpendicular to major structures in the LKD. The results of the calibrated model suggest that the main petroleum source rocks of the LKD, namely the Oligocene–Middle Miocene Maykop and the Eocene Middle Koun mudrock formations, are still in the oil generation zone. Therefore, previously speculated gas generation effect on overpressurization is insignificant in the LKD. Modeling also predicts overpressure of varying magnitude in the potential hydrocarbon source rocks of dominantly mudstone lithology. We have verified that disequilibrium compaction caused by rapid sedimentation in the last 3 million years has led to mudrock overpressurization that exceeded rock strength. We take model-predicted fracturing as a proxy indicator of mud ascent and suggest that fracturing of the mudrocks enabled ascend of the mud via fault-associated weakness zones. [ABSTRACT FROM AUTHOR]

The South Caspian Basin (SCB), located within the Alpine-Himalayan mobile belt, is known for its intensive modern fluid dynamics, a quantitative and qualitative analysis of which makes it possible to solve many problems of oil and gas ontogenesis, including the development of diapirism and mud volcanism. In this paper, using example of basic mud volcanoes (MVs) and gas condensate fields, the main features of modern fluid dynamics in the SCB are considered in order to quantify the volumetric velocity of their focused flows. These assessments are carried out using both conventional and new (based on the concept of renewable gas resources in the reservoir and in the focus of MVs) methodological approaches. The estimates made for the volumetric rate of periodic replenishment of the MV chamber with gas (0.44 × 103 m3/day) are in good agreement with the estimates of the rate of natural replenishment of the gas reservoir (0.42 × 103 m3/day) at the Lokbatan structure affected by the MV of the same name. The estimates of the volume of gas emitted into the atmosphere during an MV eruption are 1–2 orders of magnitude less than the earlier estimates. The forecast and analysis of the dynamics of fluid pressure in the MV chamber is recommended as an additional criterion for assessing the volume of explosive gas. [ABSTRACT FROM AUTHOR]

Despite its location in the "Arid Diagonal" of South America, the Valle de Iglesia contains a number of artesian springs, the most important of which are the Baños Pismanta thermal springs, which release water at ~ 45 °C. Despite the scarcity of water resources in the Valle de Iglesia, there have been few attempts to study these springs in any detail. In this study, > 50 springs are described, each characterised by small volcano-like mud structures up to 15 m tall. Hydrogeological and hydrochemical analyses of the groundwater system in the Valle de Iglesia were performed to improve our understanding of the subsurface water flow and of the connections between the subsurface water and the associated systems of faults and springs. Site measurements were made, and the concentrations of the main ions and trace elements were also determined by laboratory analysis of water samples. The samples obtained from the spring were rich in Na–HCO3–SO4 and Na–SO4–HCO3, but the surface water samples from the Agua Negra River were rich in Ca–SO4–HCO3. The temperature of the springs was in the range 20–45 °C. Both the temperatures and the ionic ratios are compatible with the presence of a deep hydraulic circulation system. The oxidation of sulphide minerals nearby the magmatic rocks and volcanic edifices causes the mobilisation of arsenic, which accumulates in the groundwater due to the low annual rainfall. The concentrations of arsenic in the spring water samples were therefore higher than the current limit set by the World Health Organisation, meaning that the water is not suitable for human consumption. [ABSTRACT FROM AUTHOR]

Mud volcanoes are geological phenomena characterized by a fluid structure occurring within specific geologic structures and hydrogeological environments and provide valuable information on the ground surface during eruptions. There are numerous mud volcanoes in the North Tianshan area in Xinjiang Province, NW China. The origins of water and gas from mud volcanoes in the Tianquan Area, Baiyanggou in Usu, Aiqigou in Usu, Dushanzi District in Karamay, and Khorgas in Shawan County of the North Tianshan area have been analyzed by investigating isotopic and compositional signatures of them. The water from mud volcanoes in the North Tianshan area may primarily originate from atmospheric precipitation stored in the anticline structure. The stored precipitation, coupled with the arid marine phase and river/lake phase sedimentary sandstones and mudstones (including evaporite rocks, such as rock salt, gypsum and carbonate) experienced a series of complex water–rock interactions and formed the hydrochemical characteristics of the mud volcano water. Through the analysis of the main gas compounds carried out using a gas chromatograph equipped with a thermal conductivity detector, the major component of the gases from the mud volcanoes in the North Tianshan area was determined to be methane, with a range of 85.6–94.6%. In addition, through mass spectrometry analysis, the 13C/12C ratios of CH4 and CO2 were tested. By combining relevant data from other studies, we found that the δ13C1 values of hydrocarbon gases from the North Tianshan mud volcanoes (– 45.8 to – 37.2‰) were consistent with values from oil-associated gases in the Junggar Basin, which indicated that the hydrocarbon gases might be from oil source-rock. The δ13 C CO 2 values of the mud volcano gases from the North Tianshan area (15.8–20.2‰) are abnormally enriched in 13C. This may be due to biochemical actions or the reaction of residual CO2 and H2. [ABSTRACT FROM AUTHOR]

The diversity of anaerobic microorganisms in terrestrial mud volcanoes is largely unexplored. Here we report the isolation of a novel sulfate-reducing alkaliphilic bacterium (strain F-1T) from a terrestrial mud volcano located at the Taman peninsula, Russia. Cells of strain F-1T were Gram-negative motile vibrios with a single polar flagellum; 2.0–4.0 µm in length and 0.5 µm in diameter. The temperature range for growth was 6–37 °C, with an optimum at 24 °C. The pH range for growth was 7.0–10.5, with an optimum at pH 9.5. Strain F-1T utilized lactate, pyruvate, and molecular hydrogen as electron donors and sulfate, sulfite, thiosulfate, elemental sulfur, fumarate or arsenate as electron acceptors. In the presence of sulfate, the end products of lactate oxidation were acetate, H2S and CO2. Lactate and pyruvate could also be fermented. The major product of lactate fermentation was acetate. The main cellular fatty acids were anteiso-C15:0, C16:0, C18:0, and iso-C17:1ω8. Phylogenetic analysis revealed that strain F-1T was most closely related to Pseudodesulfovibrio aespoeensis (98.05% similarity). The total size of the genome of the novel isolate was 3.23 Mb and the genomic DNA G + C content was 61.93 mol%. The genome contained all genes essential for dissimilatory sulfate reduction. We propose to assign strain F-1T to the genus Pseudodesulfovibrio, as a new species, Pseudodesulfovibrio alkaliphilus sp. nov. The type strain is F-1T (= KCTC 15918T = VKM B-3405T). [ABSTRACT FROM AUTHOR]

Diversity of extremophilic microorganisms in mud volcanoes is largely unexplored. Here, we report the isolation of a novel alkaliphilic, mesophilic, fermentative bacterium (strain F-3apT) from a terrestrial mud volcano located at the Taman peninsula, Russia. Cells of strain F-3apT are Gram-stain-positive non-motile rods. The formation of endospores is not observed. The temperature range for growth is 14–42 °C, with an optimum at 37 °C. The pH range for growth is 7.5–11.0, with an optimum at pH 9.0. The isolate utilizes various organic polymeric substances, organic acids, carbohydrates, and proteinaceous compounds. The end products of glucose fermentation are ethanol, CO2, and H2. The major cellular fatty acids of strain F-3apT are C16:0, C16:1, and C14:0. Phylogenetic analysis reveals that strain F-3apT belongs to the order Clostridiales, with less than 91% of 16S rRNA gene sequence similarity to any species with a validly published name. The total size of the genome of strain F-3apT is 2.98 Mb, and a genomic DNA G + C content is 56.78 mol%. The whole-genome phylogenetic analysis confirms that strain F-3apT forms a distinct lineage within Clostridia. We propose to assign strain F-3apT to a new species of a novel genus Anaerotalea alkaliphila gen. nov., sp. nov. The type strain is F-3apT (= KCTC 15917 T = VKM B-3406 T). [ABSTRACT FROM AUTHOR]

We investigated a mud volcano (MV) in a fault zone located at the southern edge of the Kumano Basin, the largest forearc basin along the Nankai Trough. Existing seismic sections show a truncated bottom-simulating reflection by a conduit below a topographic high, indicating the presence of an MV. New shipboard acoustic observations show that the fluid may be seeping through the seafloor, which in turn indicates that there are sufficient fluids for larger scale fluid migration in this area. Autonomous underwater vehicle-based high resolution acoustic observations and pH measurements indicate that soft sediment covers most of the MV and surrounding seafloor and that mud and small amounts of “high-backscattered materials” are sprinkled within the crater and around the MV. The MV type is different from those in the landward part of the Kumano Basin: the southern MV is smaller in size, has a steeper slope angle than the those in the northern Kumano Basin, and is located in a fault zone. The characteristics of this 14th Kumano Basin MV suggest that it is an expression of the larger scale fluid and sediment migration along the southern edge of the Kumano Basin, which may provide information regarding fluid and sediment migration along fault systems in the Nankai Trough accretionary prism. [ABSTRACT FROM AUTHOR]

The generation temperatures of gas-water fluids released from mud volcanoes in different provinces of the Caucasian region have been constrained using Mg/Li (TMg/Li) chemical geothermometry. Mud volcanic fluids in the Taman Peninsula (Kerch-Taman mud volcanic province) were generated at temperatures (TMg/Li) from 41°C to 137°C. The depths of the respective mud reservoirs estimated from TMg/Li values and local geothermal gradient are in a range of 1.0 to 3.4 km which spans the Maykop Formation of marine shale. For the South Caspian province, the TMg/Li values of waters vary from 18°C to 137°C and the respective root depths HMg/Li of mud volcanoes range from ∼ 0.85 to 6.5 km. The obtained TMg/Li values for the analyzed mud volcanic waters from Caucasian provinces are in positive correlation with HCO3− contents and water oxygen isotope compositions ( δ 18 O H 2 O and Δ δ 18 O H 2 O ) and in high negative correlation with Cl−. The increase of TMg/Li toward the Greater Caucasus Range, as well as the lateral TMg/Li patterns in the Taman and South Caspian mud volcanic provinces, support the idea that mud volcanic fluids generate at temperatures increasing progressively toward the Alpine orogenic belt. [ABSTRACT FROM AUTHOR]

Abstract—In 2014–2019, integrated geological and geophysical studies were carried out in the largest flexural-rupture and fold-and-fault zones of the Northwest Caucasus (the Anapa, Akhtyr, Moldavanovka, Karabetov, Fanagoria and Azov anticlinal ridges and the Pshekha–Adler, Kerch–Tuzla, and Kerch Strait faults). Microseismic sounding method (MSM) was the main geophysical approach. The MSM studies identified the deep structural features of the Earth's crust in the study region and made it possible to correlate them with the specific tectonic structures on the surface. The correlation was established by reconciling the results of the MSM studies, the parameters of sedimentary cover section, and crustal discontinuities revealed by drilling and previous studies of the converted waves from the earthquakes. It is found out that the Anapa flexure and longitudinal tectonic zones have the distinct deep roots beneath them. The trans-Caucasian Anapa flexural-rupture zone separates the pericline of the Northwest Caucasus from the region of the Taman Peninsula, whereas longitudinal flexures and fault structures divide the meganticlinorium from the subsided West Kuban and Azov blocks of the northern slope of the folded system and from the Kerch–Taman trough of the southern framing of the Northwest Caucasus. The faults in the study region are distinguished into deep faults penetrating into the lower crust and even reaching the upper mantle and near-surface faults localized within the sedimentary cover in the Earth's interior. The seismogenic role of these tectonic deformations in the studied seismic region is determined. [ABSTRACT FROM AUTHOR]

Based on 3D and 2D high-resolution multichannel seismic reflection data in the Western High-Sea of Marmara, this study reviews shallow gas occurrence and related structures and classifies gas conduit systems within the upper, few hundred meter-thick sediment layers below the seafloor. Acoustic anomalies including high amplitude-reverse polarity reflections (bright spots), low amplitude transparent zones, chaotic or discontinuous reflections, pull-down effects, and plumes in the water column are interpreted in terms of natural gas occurrence and fluid flow structures (e.g., mud volcanoes, pockmarks). The gas occurrence is thought to be mostly of thermogenic origin. Mud volcanoes are one of the primary gas conduits forming craters on the seabed due to overpressure of fluidized gassy sediment flows. Following the reach of the Northern Branch of the North Anatolian Fault (NAF-N) to the Western High, the thermogenic fluids are believed to migrate vertically and horizontally to shallow depths mainly through the faults. Natural gas most probably originates from the Thrace Basin Eocene source rock or the Eocene-Oligocene reservoir rock, which extends below the Western High. Shallow gas is distributed by minor faults and gas pipes. Gas, to some extent, emanates from the seafloor via pockmarks and mud volcanoes or is trapped by the crests of the anticlines coinciding with erosional surfaces, impermeable sediments, and gas hydrate-bearing layers. Shallow traps below the tectonized “Western High” structure are likely located in thin layers of sands imbedded with impermeable silty clay layers. However, there is no shallow reservoir in the usual sense within the upper layers imaged by the 3D seismic data (< 300 ms two-way travel time). The existence of gas is an indicator of hydrocarbon-rich layers at depth and of active tectonics, and it also impacts the global climate and marine life conditions. [ABSTRACT FROM AUTHOR]

In the present study, some mud volcanoes in Pingtung and Kaohsiung areas were selected. The selected mud volcanoes are located above the mud diaper system in southern Taiwan. Three different sampling techniques were used to collect samples in and around the said mud volcanoes. The results show that river water samples from different places fall on the meteoric line. Mud samples are found to be heavier in oxygen isotope while hydrogen isotope remains the same. Soil gas samples were also collected at the depth of 1 m and dissolved gases from the mud volcanic site (or nearby) were collected for gas chromatography analyses. Soil gas samples and dissolved gas from mud pool and groundwater were analyzed for radon concentration using RAD7 (solid-state nuclear track detector) bi-weekly. Long-term investigation will be needed to understand the relationship of mud volcanoes the eruption cycle with gas composition variations. It will also help to understand their relationship with tectonic activities in the region. [ABSTRACT FROM AUTHOR]

Shikhzarli is a typical active mud volcano (MV) in Azerbaijan with extremely high percentages of fire eruptions reaching 74%. The strong eruption of Shikhzarli MV on 13 March 2011 (Shamakhi-Gobustan region, central Azerbaijan, at 40°29′12.5′′N; 49°02′03.4′′E) was accompanied by gas ignition with a straight-flow vertical gas flare. A large (60 m height) short-living (30 min) gas flare and small (1.5 m height) gas spouts with longer lifetimes (5 h) were simulated in SigmaFlow, and the model was used to evaluate methane flux and the amount of combusted methane. Geological and mineralogical data, field observations, as well as eye witness reports and photographs in mass media were used to choose the boundary conditions for the gas fire simulation. This study provides the first quantitative evaluation for methane emission during an MV catastrophic eruption. As simulation predicts, 14,000 m of methane was consumed for the life time (30 min) of the main 60-m high flare, which is equivalent to nine tons of cold gas at ambient conditions; the volume of erupted methane for the 5-h lifetime of a small spout (1.5 m high) was 72.6 m (45 kg) of cold CH. The amount of methane emitted during a single strong flame eruption is commensurate with the annual output of permanently active individual MV vents or may be ten to hundred times as high. [ABSTRACT FROM AUTHOR]

A small mud volcano in Murono, Niigata Prefecture, north-central Japan, shows active ground surface displacements, not only when large earthquakes occur in the region but also during quiescent periods between earthquake events. The site recently underwent abrupt deformations due to strong regional earthquakes in 2004, 2007, 2011, and 2014, while gradual surface deformations were reported during quiescent periods between the earthquakes. To detect the spatial distribution of the changes in the mud volcano's ground surface elevation, we carried out multi-temporal terrestrial laser scanning. Point cloud datasets were registered at different times by minimizing the distance between the closest points in different clouds for stable ground features, which revealed centimeter- to decimeter-scale deformations around the domain of the conspicuous uplift. The spatial distribution of the deformation triggered by the earthquakes, including both central uplift and peripheral subsidence, exhibits an elliptical pattern, on which open crack fractures, associated with the earthquake-triggered uplift, were formed. The displacement and stress fields for the earthquakes were modeled numerically, and anomalously high pressure and/or weakening of the surficial materials was expected for the formation of fractures in the local domain. In contrast, continuous uplift was observed during the inter-seismic quiescent periods, the domain of which seems to have changed after the strong earthquake in 2014. In the coming years, further measurements will be necessary to unravel the physical subsurface mechanics of the mud volcano. [ABSTRACT FROM AUTHOR]

The results of hydrogeochemical observations on the Yuzhno-Sakhalinsk mud volcano in 2010-2014 are considered. The chemical analysis of samples of mud-volcanic waters was carried out at various analytical centers, which is similar to the common situation where hydrochemical data for a volcano are obtained by different researchers. It is shown that the chemical composition of the mud-volcanic waters is relatively stable in time and space (for different gryphons of the volcano). This allows us to determine the characteristic range of hydrogeochemical indicators. For each year of observations, the coefficients of variation for the concentrations of Na, Mg, Ca, K, and HCO mostly range from 10 to 30%. However, the concentrations analyzed in individual samples may differ significantly from each other. These natural variations are a likely source of errors in the interpretation of hydrochemical data. In addition, it is necessary to account for the specifics of mud-volcanic waters as an object of analytical chemical investigations. [ABSTRACT FROM AUTHOR]

A microtremor survey aiming to obtain information on subsoil structure was performed in the lower southwestern Etnean flank (Sicily, Italy). The area is characterized by emissions of muddy and salty water which create specific pseudo-volcanic edifices. Recording sites were both randomly selected in the area and along two profiles. Horizontal-to-vertical noise spectral ratio, polarization and surface wave prospecting techniques were used. The spectral ratios results set into evidence different frequency ranges that appear interesting to infer information on the subsoil structure. The depth of the hydrocarbon reservoir was inferred through 1D modeling, by using the information coming from the literature and experimental surveys. Moreover, a strongly directional effect suggests the existence of a NNW-SSE-oriented mud feeding dike. [ABSTRACT FROM AUTHOR]

Mud diapir and mud volcano have the same formation mechanism and similar development and evolution characteristics, but different geological features and forms. In this study, the development and characteristics of a mud diapir in Yinggehai Basin (northwestern South China Sea) and a mud volcano in Southwest Taiwan Basin (northeastern South China Sea) were investigated. The geochemical characteristics of their associated natural gases were also analyzed. The results indicated that the Yinggehai Basin mud diapir is mainly distributed in the deep and large depression of the central basin and presents five lines in echelon arrangement along a northwest direction. Its development and evolution characteristics are low density and speed, and abnormally high temperature and overpressure. In contrast, the Southwest Taiwan Basin mud volcano is mainly distributed in a deep water slope area of the south sag and Tainan-Kaohsiung. Onshore mud volcanoes are mainly distributed along the deep and large fault zone, and their morphological characteristics are similar to venting volcanoes. The seabed morphology of offshore mud volcano seems similar, but current research is still insufficient. There are many types of associated hydrocarbon gases in mud diapir and mud volcano, but the high maturity coal-type hydrocarbon gas is the main one. The associated non-hydrocarbon gas is rich in CO2 and N2, which is mainly derived from a CO2 source from inorganic crust. The source of both diapir and volcano is thick marine Miocene and Pliocene age mud with hydrocarbon-generating potential. The mature hydrocarbon generation, mud diapir/mud volcano migration and deposition into an appropriate reservoir, as well as diapir-associated structures, constitute a unique oil/gas migration and accumulation system, which thus adds to our understanding of the distribution of such “mud diapir/volcano-type oil/gas reservoir.” [ABSTRACT FROM AUTHOR]

We perform terrestrial laser scanning (TLS) to detect changes in surface morphology of a mud volcano in Murono, north-central Japan. The study site underwent significant deformation by a strong earthquake in 2011, and the surface deformation has continued in the following years. The point cloud datasets were obtained by TLS at three different times in 2011, 2013 and 2014. Those point clouds were aligned by cloud-based registration, which minimizes the closest point distance of point clouds of unchanged ground features, and the TLS-based point cloud data appear to be suitable for detecting centimeter-order deformations in the central domain of the mud volcano, as well as for measurements of topographic features including cracks of paved ground surface. The spatial patterns and accumulative amount of the vertical deformation during 2011-2014 captured by TLS correspond well with those previously reported based on point-based leveling surveys, supporting the validity of TLS survey. [ABSTRACT FROM AUTHOR]

For research of an opportunity forecasting of earthquakes and eruptions of mud volcanoes, monitoring of Rn, (and) Ra in the springs and gryphones of the mud volcanoes and Rn, Rn in the soil in the Taman Peninsula occasionally were carried out since 1995. Simultaneous measurements in two springs of the Western Caucasus and in the thermal spring of Southwest Turkey Rn were started also. Simultaneous changes of Rn concentration in water in Southwest Turkey and South Russia before regional earthquakes were obtained. Reduction of soil Rn concentration in territory of mud volcanoes before occurrence of new gryphon was observed. [ABSTRACT FROM AUTHOR]

Mud volcanism is a natural phenomenon well-known for on-shore and off-shore environments. Its major driving forces are deeply seated fluid accumulations and lithology and tectonism favorable for creating overpressure within deep strata with subsequent breakthrough of solid, liquid, and gaseous products of mud volcanism towards a ground surface. The mud breccia clasts provide information about the sedimentary section (up to several kilometers thick) through which the mud volcano erupted. Geochemical investigation of mud breccia clasts with characteristics of source rocks can help in understanding the petroleum potential of entire basin prior to expensive offshore exploration drilling. This is an especially important and useful method for initial estimation of petroleum potential of deep continental margin basins. The method of geochemical investigation of organic matter in the mud breccia clasts allowed to identify the Miocene and Upper Cretaceous clayey and carbonate deposits in the sedimentary sequence in the deep part of the Gulf of Cadiz as having the highest petroleum potential. [ABSTRACT FROM AUTHOR]

We consider the specific features of remote registration of sources of natural hydrocarbon gas seeps in Arctic water areas to substantiate the possibility of aerospace monitoring of shelf zones prospective for hydrocarbons. The main characteristics of degassing sources and their manifestations at the surface and in the water column have been determined. The areas of the Arctic shelf with potential natural gas shows that can be detected through remote sensing have been identified. We analyze promising aerospace methods for the registration of gas shows in the sea and give examples of hydrocarbon gas seeps observed from space. [ABSTRACT FROM AUTHOR]

The problem of seismic imaging in complex structures such as folded faulting areas, salt domes, or mud volcano-bearing areas cannot be properly solved by the conventional seismic processing methods. The reverse time migration, Gaussian beam migration, the extended search strategy in the optimized common reflection surface (CRS) stack, and the partial CRS stack methods are among the new methods introduced for seismic imaging in complex structures. Among them, the CRS stack method is frequently used for seismic imaging. However, besides its great advantage in enhancing the quality of seismic section, it faces with some problem in imaging of complex structures, especially in the existence of conflicting dips. The CRS method transforms pre-processed multi-coverage data into a zero-offset section by summing along stacking surfaces instead of only along a common reflection point trajectory. The extended parameter search strategy in the CRS method and the partial CRS stack method were introduced to solve the problem of conflicting dips in the CRS method. However, some examples showed that these methods could not completely solve the problem of conflicting dips. In this study, a new introduced method is used to completely solve the problem of conflicting dips in complex structures. The new stacking surface is the approximation of diffraction response of a diffraction point. The surface is made by well-known three CRS attributes, where the radius of normal and normal incidence point waves is equals. The third parameter is the emergence angle of the central ray that the stacking surface is built for each angle, thus making an operator volume. Therefore, the operator gathers more energy that might get lost by other stacking surfaces. The new method was applied on a seismic data from a complex geological structure from northeast of Iran. This area contains mud volcano, an indicator for gas reservoir. Mud also absorbs the seismic energy and deteriorates the quality of the seismic section. Therefore, imaging the boundary of the mud volcano is questionable. By applying post-stack time migration on the stacked section obtained by the new method, the advantage of the stacking operator has been evaluated for imaging in complex structures. These advantages were more highlighted in depth migration applied on the new introduced operator volume common diffraction surface (CDS)-stacked section. The results showed that not only the boundary of the mud but also the faults that were completely unclear in previous results were imaged well. [ABSTRACT FROM AUTHOR]

The Shenhu Area of the northern South China Sea (SCS) has been regarded as a promising area for gas hydrate exploration. In this research, the petrography and stable isotopic composition of authigenic carbonates within a core of shallow sediment from Site 08CF7 in the Shenhu area have been studied. Based on the results of grain sizes, magnetic susceptibility, carbonate contents, textural characteristics, the age constrains of the core and the tectonic setting of the study area, it can be inferred that the core may represent the subsurface sediment in a mud volcano area within the gas hydrate system. Core sediments below 188 cm in the core may be associated with the in situ mud volcano activity. The authigenic carbonates (calcite, aragonite and dolomite) in fine size fraction below 188 cm indicate the mud volcano-induced methane seepage and anaerobic oxidation of methane (AOM), and their carbon source was mainly biogenic methane. In addition, the variation in magnetic susceptibility corresponds with in situ mud volcano sediments and associated methane seepage. These signals provide new methods of identifying AOM and application prospect for the exploration of seepage gas hydrates in SCS. [ABSTRACT FROM AUTHOR]

Using Shen's method (Shen et al., 1996), deformations of the Earth's crust in Azerbaijan were studied based on GPS measurements. For estimating the rate of deformation, we used the field of velocity vectors for Azerbaijan, Iran, Georgia, and Armenia that were derived from GPS measurements during 1998-2012. It is established that compression is observable along the Greater Caucasus, in Gobustan, the Kura depression, Nakhchyvan Autonomous Republic, and adjacent areas of Iran. The axes of compression/contraction of the crust in the Greater Caucasus region are oriented in the S-NE direction. The maximum strain rate (approximately 200 × 10 per annum) is documented in the zone of mud volcanism at the SHIK site (Shykhlar), which is marked by a sharp change in the direction of the compression axes (SW-NE). It is revealed that the deformation field also includes the zones where strain rates are very low approximating 5 × 10 per annum. These zones include the Caspian-Guba and northern Gobustan areas, characterized by extensive development of mud volcanism. The extension zones are confined to the Lesser Caucasus and are revealed in the Gedabek (GEDA) and Shusha (SHOU) areas, as well as in the zone located between the DAMO and PIRM sites (Iran), where the deformation rate amounts to 100 × 10 per annum. It is concluded that the predominant factor responsible for the eruption of mud volcanoes is the intensity of gas-generation processes in the earth's interior, while deformation processes play the role of a trigger. The zone of the epicenters of strong earthquakes is correlated to the gradient zone in the crustal strain rates. [ABSTRACT FROM AUTHOR]

The Makran accretionary wedge has a much larger number of mud volcanoes then those reported earlier. Using high-resolution satellite images, over 70 active mud volcanoes were identified. These mud volcanoes occur within a well-defined zone; we call it the Makran zone of active mud volcanoes (MZAMV), which is parallel to the regional trend of the accretionary wedge. Mud volcanoes within the zone occur as clusters, which form linear belts parallel to the regional thrusts associated with anticlines. The MZAMV zone also includes the offshore mud volcanoes occurring in the shallow shelf area, including the recurrently emerging mud islands. Several occurrences of thick deposits of old mud volcanoes (Pleistocene or even older) are also present within this zone, which also display recognizable features that are characteristic of the fossil mud volcanoes. We propose that the MZAMV developed and evolved in response to the continued compression within the Makran accretionary wedge, which in turn, is a response of the subduction process. Mud diapirism has been an ongoing phenomena since Pleistocene or even earlier. The events of enhanced mud extrusion in mud volcanoes and/or emergence of island(s) have relevance with seismic phenomena and, therefore, may be closely monitored. [ABSTRACT FROM AUTHOR]

Although a relationship between the occurrence of large earthquakes and the eruptions of close mud volcanoes is well known, several uncertainties remain on understanding the triggering mechanisms. In the present study, we evaluate both the static and dynamic strains induced by earthquakes in the substratum of mud volcanoes. We studied the effects of two earthquakes of M 6.18 and 6.08 occurred in the Caspian Sea on 25 November 2000 close to Baku city, Azerbaijan. A total of 33 eruptions occurred at 24 mud volcanoes within a maximum distance of 108 km from the epicentres in the 5 years following the earthquakes. The overall eruption rate in the studied area of the 50 years before the 2000 earthquakes was 1.24 that is much smaller than the eruption rate of 6.6 of the 5 years following these earthquakes. The largest number of eruptions occurred within 2 years from the earthquakes with the highest frequency within 6 months. Our calculated earthquake-induced static effects show that crustal dilatation might have triggered only seven eruptions at a maximum distance of about 60 km from the epicentres and within 3 years. Based on our data, dynamic rather than static strain is likely to have been the dominating 'promoting' factor because it affected all the studied unrest volcanoes and its magnitude was much larger. [ABSTRACT FROM AUTHOR]

Sakhalin Island is the only region in the Russian Far East where mud volcanism is manifested on land. The South Sakhalin mud volcano is located in the south of the island in the zone of the Central Sakhalin Fault (upthrow-thrust). The horizontal and vertical displacements of the earth's surface after this mud volcano erupted in 2011 are revealed for the first time based on the GPS observation data. On the basis of the inversion of the measured displacements for the homogeneous elastic half-space, a model of the finite spherical eruption source is constructed. The coordinates, depth, and possible size of the source are defined and the volumes of the erupted clay rock, water, and gas are estimated. [ABSTRACT FROM AUTHOR]

The aim of this article is to describe two 'model' geosites of Torino province (Piedmont, NW Italy) in order to explain the state of the art of paleontological and stratigraphical geosite inventory and management in Piedmont. Collaboration between Torino University, local administrations, and industry resulted in the inauguration of the first geosite in Torino province, located in Verrua Savoia quarry, in October 2010. This site documents the geological record of the birth, life and death of a submerged mud volcano. Based on the success of this project, we propose the creation of another equipped area in Valle Ceppi, which constitutes an international point of reference for the study of Miocene molluscs. Piedmont is a region characterized by a heterogeneous patchwork of geological peculiarities that need to become public knowledge. Mismanagement of these areas may lead to their destruction, resulting in irreparable scientific and cultural damage. It should also be noted that the creation of equipped geosites plays an important role in the development of environmental awareness among the general public and local administrative entities and also increases the economic resources of the surrounding areas. [ABSTRACT FROM AUTHOR]

Fluid and mud samples were collected from Wushanting (WST), Hsiaokunshui (HKS), Yenshuikeng (YSK), Kuantzeling (KZL), and Kunshuiping (KSP) mud volcanoes of southwestern Taiwan. Concentrations of major ions and trace elements in mud volcanic fluids were analyzed to find the possible linkage to elevated arsenic (As) concentrations in the Chianan plain groundwater. The elevated Na, K, and Cl concentrations indicated possible marine origin of the fluids. The trace element concentrations in the mud volcanic fluids were generally low, but the As concentrations were up to 0.12 mg/L. High contents of As, Fe, and Mn were observed in the mud samples. Saturation index calculations indicated that both carbonate and oxide minerals acted as potential sinks for As in the mud volcanic fluids. Arsenic in the dewatering fluids and muds may be transported by the subsurface flow and surface streams as suspended solids and eventually deposited in the Chianan plain aquifers. Under reducing conditions, As may be released from the host minerals (such as Fe- and Mn-oxides/hydroxides), thereby causing widespread groundwater As pollution. [ABSTRACT FROM AUTHOR]

A number of mud volcanoes exist in the southern Junggar Basin. To date few systematic studies on natural gas geochemistry of mud volcanoes have been conducted in China. In June 1991 and August 2010, the authors investigated the mud volcanoes in the southern Junggar Basin twice, and the mud volcanism weakened gradually as seen from the variations such as the decrease of gas pressure and output, the downthrow and dry up of the mud pool. The volcanic intensity was significantly weaker than that in Taiwan. The natural gas from the mud volcanoes in the southern Junggar Basin has similar geochemical characteristics, indicating the same source or origin. The main component of the mud volcano gas is alkane gas with contents of 91.15%-97.49%, and the gas is high-quality commercial gas since methane dominates in the alkane. The δC values are −49.1‰-−40.6‰, which are in accordance with the peak δC frequency of mud volcano gas around the world, and the alkane gas displays positive carbon isotopic series, i.e., δC< δC< δC, suggesting typical thermogenic origin. The helium in the mud volcano gas is typically crust-derived due to the low R/Ra values of 0.011-0.054. The mud volcano gas is coal-derived since the δC values are all greater than −28‰, and C/C and δC values are in accordance with those of natural gas derived from the Lower-Middle Jurassic coal-measures. Therefore, alkane gas from mud volcanoes in the southern Junggar Basin is mainly sourced from the Lower-Middle Jurassic coal-measures. [ABSTRACT FROM AUTHOR]

Mud volcanism is a global phenomenon usually associated with compressional tectonics that favour extrusion of fluid- and clay mineral-rich sediment both on land and offshore. Methane, the dominant gas phase, is emitted at variable rates during and after emplacement of the mud domes. In case of continental mud volcanoes, the gas is directly released into the atmosphere, thereby contributing to global warming. Azerbaijan is one of the countries with one of the highest abundances of mud domes globally. One of the most prominent mud volcanoes, Dashgil, has been chosen for a case study because of its historic record of violent eruptions, continued activity, and well-documented regional geology in the Caucasus orogenic wedge adjacent to the Caspian Sea. Since 2003, gas flux has quantitatively measured at one of the two crater lakes and is characterized by valve-type behaviour and episodically violent degassing. In 2007, the large crater lake was additionally equipped with methane fluxmeters as well as an in situ pore-pressure probe into the conduit. Our data are complemented by regional seismicity, and exhibit the following results: (1) there seems to be a significant correlation between changes in pore pressure in the conduit feeding the main crater lake and the rate of gas escape; (2) changes in gas-flux rate appear to be independent of local seismicity, in particular since no larger EQs have been recorded since 2003; (3) despite discontinuous monitoring owing to technical failures, we observe an overall increase in methane emission with time; (4) nearby earthquake activity (

Global positioning system (GPS) and satellite-based InSAR (Interferometric Synthetic Aperture Radar) measurements of the subsidence and uplift of a populated area of Sidoarjo, East Java are due to the eruption of the Lusi mud volcano (2006–present). These data are the first direct quantitative measurements of deformation due to the growth of a mud volcano edifice. The GPS data were recorded over periods of a few hours to several months and show that between June 2006 and September 2007, the earth’s surface has been subsiding at rates of 0.1–4 cm/day. Maximum rates of subsidence occurred in an area 300–400 m to the northwest of the main mud volcano vent. Horizontal displacements were 0.03–0.9 cm/day and were also towards this area. In general uplifts of up to 0.09 cm/day were recorded in areas outside of the edifice. Changes in elevation measured using satellite imagery (InSAR technique) provide regional datasets of subsidence and uplift. They confirm that during the first year a roughly circular area was undergoing sag-like subsidence centered to the northwest of the main vent and that uplift was occurring 3–4 months after the initiation of the eruption due to the movement Watukosek fault system. Subsidence occurred due to the weight of mud and man-made dams and the collapse of the overburden due to removal of mud from the subsurface. Assuming constant rates of subsidence of 4 cm/day, then in the centre of the edifice there would be up to 44 m of subsidence in 3 years, and up to 16 m in 10 years. The mud volcano is now in a self-organizing state with new fluid conduits forming as a result of the collapse. [ABSTRACT FROM AUTHOR]

The paper presents the results of multidisciplinary seismic surveys carried out by refraction and reflection methods for compressional and shear waves on Yuzhno-Sakhalinsk mud volcano. A large extinct (approximately 60–70 years ago) volcano was identified near the active volcano, and its structure was studied. It was found that the recognized intermediate fluid-bearing chambers correlate with the distinguished tectonic dislocations. A supposition was made that the mud volcanism is sequentially developed in the northeastern direction and related to the modern tectonics of the Central Sakhalin Fault. [ABSTRACT FROM AUTHOR]

The examination of the Main Pugachevo gas-water-lithoclastic volcano during the summer of 2005 and GPS-controlled large-scale (1: 1000) mapping revealed its regular but rather peculiar eruption. It was the largest among the eruptions investigated since 1911 and produced a very unusual lithoclastic field with an area of about 100 000 m2 and a volume of about 100 000 m3. The eruption occurred from three distinct active centers and began with a vigorous explosion-like gas burst from one center followed by the noncontemporaneous discharge of a gas-and water-saturated liquid lithoclastic mass from the three centers, which produced a number of flows of different directions and sizes. The flows almost completely covered the smoothed flat open area of the volcano and even invaded the larch forest surrounding the volcano, where they bent, overturned, broke, and occasionally uprooted and dragged over some distance some large trees. The analysis and comparison with all the previously documented eruptions of the Main Pugachevo gas-water-lithoclastic volcano revealed their fairly diverse, sometimes strongly variable character with respect to many parameters: the amount of ejected lithoclastic material; the number of eruption centers; and the proportions of the erupted gaseous, liquid, and solid components. In general, the eruptions show a distinctly multirank periodic character: relatively minor or small low-rank eruptions take place once every 1–2 yr, and large eruptions of a higher rank are much less frequent (supposedly, once in 70 years). [ABSTRACT FROM AUTHOR]

The Håkon Mosby Mud Volcano is a natural laboratory to study geological, geochemical, and ecological processes related to deep-water mud volcanism. High resolution bathymetry of the Håkon Mosby Mud Volcano was recorded during RV Polarstern expedition ARK XIX/3 utilizing the multibeam system Hydrosweep DS-2. Dense spacing of the survey lines and slow ship speed (5 knots) provided necessary point density to generate a regular 10 m grid. Generalization was applied to preserve and represent morphological structures appropriately. Contour lines were derived showing detailed topography at the centre of the Håkon Mosby Mud Volcano and generalized contours in the vicinity. We provide a brief introduction to the Håkon Mosby Mud Volcano area and describe in detail data recording and processing methods, as well as the morphology of the area. Accuracy assessment was made to evaluate the reliability of a 10 m resolution terrain model. Multibeam sidescan data were recorded along with depth measurements and show reflectivity variations from light grey values at the centre of the Håkon Mosby Mud Volcano to dark grey values (less reflective) at the surrounding moat. [ABSTRACT FROM AUTHOR]

Many mud volcanoes are distributed along the tectonic sutures in southern Taiwan and can be divided into five zones based on their relative positions in different tectonic domains. Most active mud volcanoes are exhaling methane-dominated gases. Nevertheless, some gases show unusual carbon dioxide-dominated and/or nitrogen-excess compositions. This implies that there are multiple sources for the gas compositions of mud volcanoes in Taiwan.For better understanding the total amount of exhalation gases and its flux, the gas flow and compositions were continuously measured in the interval of two minutes at Chung-lun (CL) bubbling mud pool for a few months. The major compositions of gases exhaling from this site were 75~90% of CO2 and 5~12% of CH4. The amount of gases exhaling from the mud pool can be estimated to be about 1.4 ton/year for CH4 and 28 ton/year for CO2, respectively. The preliminary results of exhaling gas flux from the major vents of representative active mud volcanoes, yielded an estimated total CH4 output of the mud volcanoes in Taiwan of ca. 29 ton/year during quiescent period. [ABSTRACT FROM AUTHOR]

The South Caspian sedimentary basin is a unique area with thick Mesozoic-Cenozoic sediments (up to 30-32 km) characterized by an extremely high fluid generation potential. The large amount of active mud volcanoes and the volumes of their gas emissions prove the vast scale of fluid generation. Onshore and offshore mud volcanoes annually erupt more than 109 cubic meters of gases consisting of CH4 (79-98%), and a small admixture of C2H6, C3H8, C4H10, C5H12, CO2, N, H2S, Ar, He. Mud volcanism is closely connected to the processes occurring in the South Caspian depression, its seismicity, fluctuations of the Caspian Sea level, solar activity and hydrocarbon generation.The large accumulations of gas hydrates are confined to the bottom sediments of the Caspian Sea, mud volcanoes crater fields (interval 0-0.4 m, sea depth 480 m) and to the volcanoes body at the depth of 480-800 from the sea bottom. Resources of HC gases in hydrates saturated sediments up to a depth of 100 m and are estimated at 0.2×1015-8×1015 m3. The amount of HC gases concentrated in them is 1011-1012 m3.The Caspian Sea, being an inland closed basin is very sensitive to climatic and tectonic events expressed in sea level fluctuations. During regressive stages as a result of sea level fall and the reducing of hydrostatic pressure the decomposition of gas hydrates and the releasing of a great volume of HC gases consisting mainly of methane are observed.From the data of deep drilling, seismoacoustics, and deep seismic mud volcanic activity in the South Caspian Basin started in the Lower Miocene. Activity reached its highest intensity at the boundary between the Miocene and Pliocene and was associated with dramatic Caspian Sea level fall in the Lower Pliocene of up to 600 m, which led to the isolation of the PaleoCaspian from the Eastern ParaTethys. Catastrophic reduction of PaleoCaspian size combined with the increasing scale of mud volcanic activity caused the oversaturation and intoxication of water by methane and led to the mass extinction of mollusks, fishes and other groups of sea inhabitants. In the Upper Pliocene and Quaternary mud volcanism occurred under the conditions of a semi-closed sea periodically connected with the Pontian and Mediterranean Basins. Those stages of Caspian Sea history are characterized by the revival of the Caspian organic world.Monitoring of mud volcanoes onshore of the South Caspian demonstrated that any eruption is predicted by seismic activation in the region (South-Eastern Caucasus) and intensive fluid dynamics on the volcanoes. [ABSTRACT FROM AUTHOR]

Mud volcanoes, mud cones, and mud ridges have been identified on the inner portion of the crestal area, and possibly on the inner escarpment, of the Mediterranean Ridge accretionary complex. Four areas containing one or more mud diapirs have been investigated through bathymetric profiling, single channel seismic reflection profiling, heat flow measurements, and coring. A sequence of events is identified in the evolution of the mud diapirs: initially the expulsion on the seafloor of gasrich mud produces a seafloor depression outlined in the seismic record by downward dip of the host sediment reflectors towards the mud conduit; subsequent eruptions of fluid mud may create a flat topped mud volcano with step-like profile; finally, the intrusion of viscous mud produces a mud cone. The origin of the diapirs is deep within the Mediterranean Ridge. Although a minimum depth of about 400 m below the seafloor has been computed from the hydrostatic balance between the diapiric sediments and the host sediments, a maximum depth, suggested by geometric considerations, ranges between 5.3 and 7 km. The presence of thermogenic gas in the diapiric sediments suggests a better constrained origin depth of at least 2.2 km. The heat flow measured within the Olimpi mud diapir field and along a transect orthogonal to the diapiric field is low, ranging between 16 ± 5 and 41 ± 6 mW m. Due to the presence of gas, the thermal conductivity of the diapiric sediments is lower than that of the host hemipelagic oozes (0.6-0.9 and 1.0-1.15 W m K respectively). We consider the distribution of mud diapirs to be controlled by the presence of tectonic features such as reverse faults or thrusts (inner escarpment) that develop where the thickness of the Late Miocene evaporites appears to be minimum. An upward migration through time of the position of the décollement within the stratigraphic column from the Upper Oligocene (diapiric sediments) to the Upper Miocene (present position) is identified. [ABSTRACT FROM AUTHOR]

Data on the dioxin contents in landscapes of modern active volcanoes, buried volcanic ashes, and fresh ejecta of mud volcanoes are obtained. It is shown that endogenous sources of natural (nontechnogenic) dioxins exist in the areas of tectonomagmatic activation. It is suggested that extremely toxic chemical compounds (dioxins) were continuously supplied to the biosphere during the geological time. The environmental importance of this phenomenon for the biota is still difficult to estimate. [ABSTRACT FROM AUTHOR]

Mud volcanoes are often associated with large areas of CO2 and CH4 emission that are potentially dangerous due to sudden paroxysmal gas and mud eruptions. Despite the interest in understanding such natural environments, they have not yet been thoroughly investigated and a single interpretative framework remains to be elaborated. This lack of knowledge may be due to the difficulty in measuring in-plume CO2 as there is very little contrast with atmospheric CO2, coupled with the complex organizational strategies required for long-term monitoring. This work features three different methods that were used to evaluate the CO2 flux at the Salinelle mud volcano in the foothills of Mt Etna (Italy), carried out periodically from December 2013 to April 2018. We computed in-plume CO2 flux indirectly using a tunable laser and a portable MultiGAS and, directly, measuring the gas volumetric flux from bubbling pools. The morphological variations of the mud field were recorded using unmanned aerial vehicle (UAV) imagery, which provided information on the migration of vents in relation to the observed variations in measured gas output. Our analysis shows that the three methods gave comparable values, indicating the feasibility of this approach. Our findings suggest a pseudo-cyclical pattern in the bulk CO2 emitted at Salinelle, introducing a new interpretation of the processes involved in mud volcano dynamics. We theorize that the periodic variation of the gas emitted at the Salinelle may be attributed to a "geyser-like" mechanism that may be subject to interruption or changes in magnitude by volcanic or seismic events. [ABSTRACT FROM AUTHOR]