Mud Volcano Eruptions Research Articles

ANALYSIS OF HYDROCARBON GASES OF MUD VOLCANOES OF THE LOWER KURA TROUGH

Based on the detailed analysis of the existing geological-geophysical material, the distribution area of the mud volcanoes developed in the depression, and the geochemical characteristics of their eruption products were studied. The aim is to determine the gases contained in the wastes thrown by volcanoes onto the earth's surface and to study of distribution along the territory. For this reason, the capacity of methane gas, heavy hydrocarbons, nitrogen and carbon dioxide of erupted materials on the surface was studied. Based on the results obtained during the analysis, the composition of the gases of the mud volcanoes located in the depression consists mostly of methane. The content of methane in the eruptive materials of Agzibir volcano varies from 86.3% to 98.88% (Kalamaddin mud volcano). The average mark of methane gas ranges from 86.6% (Akhtarmaardi) to 91.3% (Harami). In addition, maps were drawn up to determine the distribution of gases in the eruptive materials along the study area. Besides, a map of the location of the Galmaz mud volcano, a geological profile passing through the mud volcano was created. The content of gases emitted into the atmosphere was determined based on the analysis of mud volcano eruptive wastes in the south-west and north-east parts of the Galmaz field. As a result of geological-geophysical studies was determined that the chemical composition of the eruption materials of the Galmaz mud volcano is different. The analysis show that, most of the gases emitted from the volcano to the atmosphere consist of methane (CH4) gas. Content of it is up to 97.42% and more. The content of other gases is relatively small, so heavy hydrocarbons is 0.04%, nitrogen is 0.48%, CO2 is 2.06%. The individual deposits related with mud volcano are mainly massive, structural and tectonically screened types. However, hydrocarbons accumulated within traps are formed oil-gas and gas individual deposits. Keywords: Galmaz field, mud volcano eruption, methane gas content, content of nitrogen, carbon dioxide, crushing zones, heavy hydrocarbons, oil and gas accumulations.

Substantiating of oil and gas prospects of Mesozoic sediments based on the geochemical model of mud volcanoes in the Shamakhi-Gobustan structural element of the South Caspian megadepression

There are up to 120 mud volcanoes in the Shamakhi-Gobustan region. During the process of mud volcano eruptions, a large amount of solid, liquid, and gaseous products are thrown to the Earth’s surface, which are widely used for the identification of oil and gas deposits and are considered the main indicator of the productivity of the basin. According to laboratory results from the analysis of solid, liquid, and gas products of mud volcanoes, it is possible to obtain detailed information about the oil-gas content of deep-lying sediments. Therefore, the study of the geochemical composition of the mud volcanoes in the Shamakhi-Gobustan trough plays a major role in the discovery of new oil-gas and gas-condensate deposits. To clarify the changes in the chemical and isotopic composition of gases from mud volcanoes in the Shamakhi-Gobustan trough and to evaluate the oil-bearing and gas-bearing potential of Mesozoic sediments, the characteristics of changes in the isotopic composition of methane gas, heavy hydrocarbons, carbon dioxide, ni- trogen, as well as CH4 and CO2, were studied. The amount of methane in the gas emissions released from mud volcanoes in the Azerbaijan region is more than 90%. The amount of CH4 in the mud volcanoes of the Shamakhi-Gobustan trough ranges from 78.5% to 97.56%. The minimum amount of methane is found in North Gobustan (Gizmeydan 86.8%, Malikchobanli 78.5%), while relatively high amounts are mainly noted in Central (Kushchu 97.55%) and South Gobustan (including Dashgil 97.57%, Goturdag 96.55%, Bahar 96.78%). Mud vol- canoes are less developed in the North Gobustan region and are small in size. In the Central zone, both the size and the number of volcanic cones increase significantly compared to North Gobustan. The largest and most active volcanoes have developed in the southern zone of the trough. Huge mud volcanoes such as Dashmerdan, Solakhay, Ayrantoken, Goturdag, Kirdag, and other volcanoes have developed along the Alat range. The mud volcanoes of North and Central Gobustan are mainly confined to Cretaceous and Paleogene sediments, and due to the low occurrence of plastic clay rocks in these sediment sections, mud volcanoes are rare and weakly active. On the contrary, to the south of these zones, that is, in South Gobustan, they are located in Pliocene sediments, and due to the presence of very thick plastic rocks in their section, mud volcanoes are widespread, and they are active volcanoes that are morphologically sharply reflected. It should be noted that in areas where plastic clay rocks with significant thickness and rheologically active properties are developed, large cones of mud volcanoes that erupt frequently are observed. The calculated gas production of mud volcanoes increases from the northern zone towards South Gobustan. Thus, while the calculated gas production of the Nabur volcano located in the Northern zone is 1500 m3/day, the calculated gas production of the Dashgil mud volcano located in South-Eastern Gobustan is 40,000 m3/day. In the central and south- ern zones of the Shamakhi-Gobustan trough, the presence of ancient rock fragments from the Oligocene-Miocene (Maykop) age rocks forming their roots in the solid waste of mud volcanoes (Cretaceous, Paleocene, Eocene), a large percentage of methane gas (97.57%), transverse elevations, and the presence of an intersection zone of longitudinal faults suggests that there is a tectonic rupture zone rich in natural gas below the base of the volcano. This is proven once again by the occurrence of gas flows in Anart (110,000 m3/day), Utalgi (50,000 m3/day), and the Touragay field (20,000 m3/day). The presence of oil films in the eruption products of mud volcanoes indicates the accumulation of oil alongside gas.

Some questions of the connection between mud volcanism and seismicity in Azerbaijan

The article discusses some issues of the genetic connection between mud volcanic activity in Azerbaijan and seismicity, the results of monitoring studies of mud volcanoes characterized by active gryphon-salsa activity between eruptions located in tectonic structures of different ages. For the first time, an anomalous change in Br and J, mainly associated with Paleogene-Miocene deposits, was established in the chemical composition of the studied waters based on hydrogeochemical indicators of volcanic activation. The established differences in the studied waters are associated with the location of mud volcanoes within different oil and gas bearing regions of Azerbaijan and the lithofacies features of terrigenous-carbonate rocks in mud volcanic breccia. The above measurements of the temperature of waters carried by mud volcanoes to the earth’s surface confirmed the previously obtained results: during quiet activity of volcanoes, fluids are carried out from Pliocene deposits, and when their gryphon-salsa activity is activated, they are diluted with fluids coming from the depths of the Paleogene-Miocene age. Analyzing various intervals of “rest” between eruptions of mud volcanoes, tracing changes occurring in small crater fields (cracks, subsidence, etc.), the seismogeological material we have accumulated allows us to make an estimated forecast (as a long-term one) of the eruption of a mud volcano within one year.

Myth busting: Was Pulau Tiga really first created by a mud volcano eruption in 1897?

Pulau Tiga is Malaysia’s largest mud volcano, and the entire island is famously reported to have suddenly appeared in September 1897. The story of Pulau Tiga’s “birth” following two large earthquakes in the Philippines is widespread, being found in scientific papers, media stories, Wikipedia, and thousands of websites. This study “fact checks” whether Pulau Tiga really first appeared in 1897. The event is described in detail in one 1986 scientific study, and the idea of Pulau Tiga’s sudden appearance is supported by instances of islands being created by large mud volcano eruptions, such as Pulau Batu Hairan offshore Malaysia in 1988. However, maps of Borneo published prior to 1897 indicate that Pulau Tiga is charted on maps dating back to 1554 and specifically named on more than 40 maps. These maps conclusively prove that Pulau Tiga does not suddenly appear in 1897 and also indicate that Pulau Tiga has had approximately the same shape for centuries, demonstrating that the island was also not partially formed in 1897. A review of the newspapers and scientific reports from 1897 to 1904 reveals that two new islands did emerge offshore northern Borneo on 21 September 1897, but neither of them is Pulau Tiga. New mud volcano islands temporarily appeared off the western Klias Peninsula near Bukit Tomboh and off the northern tip of Sabah at the approximate position of the Pulau Batu Hairan. The origin of Pulau Tiga’s 1897 birth “myth” is proposed to be a 1986 study by McManus and Tate, who appear to have confused reports of an island forming off the Klias Peninsula in 1897 with an eruption of Pulau Tiga. This study definitively “busts” the myth of Pulau Tiga’s 1897 birth and unearths details of Malaysia’s history of large mud volcano eruptions that have been largely forgotten by the geoscience community.

Modelling of geochemical properties of mud volcano eruption products and relationship with oil and gas prospects within the South Caspian megadepression of Lower Kura region

Modelling of geochemical properties of mud volcano eruption products and relationship with oil and gas prospects within the South Caspian megadepression of Lower Kura region

Identification of Precursors in InSAR Time Series Using Functional Data Analysis Post-Processing: Demonstration on Mud Volcano Eruptions

One of the most promising applications of satellite data is providing users in charge of land and emergency management with information and data to support decision making for geohazard mapping, monitoring and early warning. In this work, we consider ground displacement data obtained via interferometric processing of satellite radar imagery, and we provide a novel post-processing approach based on a Functional Data Analysis paradigm capable of detecting precursors in displacement time series. The proposed approach appropriately accounts for the spatial and temporal dependencies of the data and does not require prior assumptions on the deformation trend. As an illustrative case, we apply the developed method to the identification of precursors to a mud volcano eruption in the Santa Barbara village in Sicily, southern Italy, showing the advantages of using a Functional Data Analysis framework for anticipating the warning signal. Indeed, the proposed approach is able to detect precursors of the paroxysmal event in the time series of the locations close to the eruption vent and provides a warning signal months before a scalar approach would. The method presented can potentially be applied to a wide range of geological events, thus representing a valuable and far-reaching monitoring tool.

"NOVOSIBIRSK" MUD VOLCANO AND EVIDENCE OF ITS ACTIVATIONS (LAKE BAIKAL)

An integrated study of mud volcanoes in the World Ocean is important for making assessment of potential geological-ecological disasters caused by rapid large-volume gas discharge into the water column and mud volcano eruptions at the bottom. The study of mud-volcanic activity in the past and determination of its periodicity are pioneering for the Baikal. The mud volcanoes and other hydrate-bearing structures are largely concentrated in the Middle Baikal basin along the tectonic faults. The most representative example of these phenomena is the "Gydratny" fault, four of six structures along which are mud volcanoes. An integrated geological-geophysical study (seismoacoustic and hydroacoustic sounding and geological sampling) of the "Novosibirsk" mud volcano, the largest and well-pronounced feature of the lake bottom relief, confirmed its structural identity with classical submarine mud volcanoes. The "Novosibirsk" mud volcano possesses all major elements of other single hydrate-bearing mud volcanoes of the lake which include volcanic cone in the bottom relief, vertical acoustically not transparent feeding channel, mud-volcanic breccia, gas saturation, and gas hydrates. This makes it one of the reference hydrate-bearing mud volcanic-type structures of Lake Baikal.The analysis of the bottom hydroacoustic profiling yielded evidence of the Late Pleistocene mud-volcanic eruptions shaped as two layers-flows at sub-bottom depths of 15 and 26 m (30 and 50 kyr ago, respectively). The presence of mud-volcanic breccia beneath the thin Holocene diatomic silt deposits testifies to the Holocene mud volcano activation due to the warm fluid rising from the depths to the volcano roots along the active segment of the tectonic fault in accordance with the model of the "Baikal-type" mud volcanism. Using the "Novosibirsk" mud volcano and the "Gydratny" fault as an example, it can be shown that the past tectonic activity of the Baikal basin may be determined based on the knowledge of the structure and evolution of the mud volcanoes of the lake.

Underwater Sensing Technologies for Assessment of Marine Geological Hazards

In recent years, more and more countries are facing the threat of marine geological hazards. The huge losses caused by marine geological disasters have forced people to put on the agenda to develop technologies that can monitor marine geological hazards. There are currently multiple technologies available for monitoring marine geological hazards, the purpose of this article is to explore possibly the basic information of technologies used for marine geohazards assessment and their advantages for using various assessment technologies to monitor the occurrence of marine geological hazards. The technologies to be explored in this article include AUV, multibeam sonar mapping, and sub-bottom profiler. UAVs can take images of the seafloor, seamount, and sediments of the eruptions, and multiple sensors carried by the AUVs can collect related marine geological data including the temperature and salinity of the seawater. The data collected and the images produced can be used to assess the occurrence of marine geohazards. The multi-beam sonars with different working frequencies are used for different purposes, which means that sonars with different working frequencies are also attached to different platforms to fit their mission assigned. The sub-bottom profilers can be used for assessment of eruptions of mud volcanoes and the fluid mud produced during the eruptions.

Volumetric Changes of Mud on Mars: Evidence From Laboratory Simulations

AbstractSubtle mounds have been discovered in the source areas of Martian kilometer‐sized flows and on top of summit areas of domes. These features have been suggested to be related to subsurface sediment mobilization, opening questions regarding their formation mechanisms. Previous studies hypothesized that they mark the position of feeder vents through which mud was brought to the surface. Two theories have been proposed: (a) ascent of more viscous mud during the late stage of eruption and (b) expansion of mud within the conduit due to the instability of water under Martian conditions. Here, we present experiments performed inside a low‐pressure chamber designed to investigate whether the volume of mud changes when exposed to a Martian atmospheric pressure. Depending on the mud viscosity, we observe a volumetric increase of up to 30% at the Martian average pressure of ∼6 mbar. The reason is that the low pressure causes instability of the water within the mud, leading to the bubble formation that increases the volume of the mixture. This mechanism bears resemblance to the volumetric changes associated with the degassing of terrestrial lava or mud volcano eruptions caused by a rapid pressure drop. We conclude that the mounds associated with putative Martian sedimentary volcanoes might indeed be explained by volumetric changes in the mud. We also show that mud flows on Mars and elsewhere in the Solar System could behave differently to those found on Earth because mud dynamics are affected by the formation of bubbles in response to the different atmospheric pressures.

Genesis of ferromanganese nodules associated with mud volcanoes in the southeastern Dongsha waters of the northern South China Sea: Implications for regional deep Mesozoic hydrocarbon prospects

The Dongsha waters of the South China Sea are the location of thick Mesozoic deposits and many mud volcanoes that suggest hydrocarbon accumulation. Knowledge of the mechanism, fluid source and evolution of these mud volcanoes, however, remains inadequate. Ferromanganese nodules have been sampled from several deep-water mud volcanoes in waters around Southeast Dongsha island and provide a unique opportunity to study the fluid origin and evolution of the mud volcanoes in the area. In this contribution, the petrology, geochemistry and C–O isotopes of fluid inclusions in the nodules have been analyzed. The ferromanganese nodules are composed of distinct black Fe–Mn crust layers and light-yellow nucleus that contain quartz that hosts fluid inclusions. The outermost layers mainly consist of iron manganese minerals with high Mn/Fe ratios (0.9∼1.57), whereas the nucleus are dominated by siliceous debris. Positive Ce anomalies (δCe: 1.45∼2.13) and negative Y anomalies in growth layers indicate an anoxic environment, which is conducive to hydromanganite precipitation. In contrast, negative Ce anomalies (δCe: 0.27∼0.96) and positive Y anomalies in the nucleus suggest oxidized conditions. The absence of obvious Eu anomalies may be related to low-temperature hydrothermal conditions. The nucleus is enriched in δ13C (−2.59∼1.09‰) and weakly depleted in δ18O (−4.94∼0.89‰), whereas the growth layers are strongly depleted both in δ13C (−16.94∼–12.57‰) and δ18O (−23.05∼–17.48‰). These values indicate that carbon in the nucleus is mainly inorganic carbon from volcanism, whereas the carbon in the growth layers is related to the leakage of deep old hydrocarbon. The fluid inclusions in the quartz from the nucleus show records of at least two periods of CO2-rich hydrothermal activity and an origin from deep Mesozoic strata before release by mud volcanism. Given the widespread mud volcanism, the quartz from the nucleus may come from debris carried by mud volcano eruptions; the quartz also experienced diagenesis related with micro-organisms. The growth layers are considered to be hydrogenic and affected by the leakage of mature thermogenic hydrocarbons from deep old strata. These findings provide insights into deep mature hydrocarbon sources and thermogenic activity and improve understanding of mud volcanism and deep oil and gas resources in the southeastern Dongsha waters.

Assesment of the risk of degazation of the Black Sea: type of limnological disaster on lake Nyos reconsidered

The possibility of a repetition of the limnological catastrophe in the Black Sea is considered. It is shown that, in contrast to the volcanic lakes of Africa Nyos and Manun, where limnological catastrophes occurred in the 1980s, the concentration of dissolved gases in deep waters is significantly less than the saturation value. This eliminates the mechanism of so called “eruption” of carbon dioxide such as gas lift. However, on a smaller scale, significant methane releases are possible during strong eruptions of underwater mud volcanoes. The mechanism for the release of carbon dioxide from the lake into the atmosphere is so similar to a volcanic eruption that mathematical models developed for ordinary volcanoes are used to describe it. In both cases, the rise of erupted masses occurs due to an increase in the buoyancy of the gas-liquid mixture, which carries with it particles of the environment. The formation and growth of gas bubbles at intermediate depths occurs provided that the total partial pressure of all gases inside the bubble exceeds the hydrostatic pressure at a given depth. The article shows that the concentration of dissolved methane in the Black Sea is much less than the saturation level. Due to the relatively low solubility of methane in water, methane bubbles are able to overcome a significant depth range. And as additional components of the gas mixture, together with methane, carbon dioxide and hydrogen sulfide can thus enter the atmosphere. It was concluded that as the water temperature in the Black Sea increases due to climate change, the reserves of methane gas hydrate at the bottom of the sea will begin to decompose, which will also be accompanied by jet gas release. At the same time, methane can escape to the surface from depths of no more than 900 m.

The study of interrelation of mud volcanoes with oil fields based on geological-field data

The research surveys have been carried out based on the actual data obtained in the patches of Sangachal-deniz-Duvanny-deniz-Khara-Zira adasy field. The changing of dynamics of oil production as a result of the eruptions of mud volcanoes, reservoir properties of the samples, as well as the other characteristics of field development are reviewed. It was revealed that during volcano eruption, despite the distance from it, the flow rate of the wells changed and in those located near volcano, the flow rate remained unchanged. The reason for the increase and decrease of production was the geological-mountain surveys conducted in the wells, and by the technical reasons, repair works carried out in the wells and some other aspects as well.

Electric Discharge in Erupting Mud

AbstractSelf‐ignition during the explosive eruption of mud volcanoes can create flames that in some cases reach heights that exceed hundreds of meters. To study the controls on electrical discharge in natural mud, we performed laboratory experiments using a shock‐tube apparatus to simulate explosive eruptions of mud. We vary the water content of the mud and proportions of fine particles. We measure electric discharge within a Faraday cage and we use a high‐speed video camera to image the eruption of mud and some of the electric discharge events. We find that (a) decreasing the proportion of fine particles and (b) increasing water content each suppress the number and magnitude of electric discharge events. Experimentally observed mud volcano lightning occurs where particles exit from the vent and within the jet of erupting particles.

Assessment of natural radioactivity level before and after a mud-volcano eruption: A study from Piparo mud-volcano, Trinidad and Tobago

The present study was conducted in the Piparo mud-volcano, which is situated in the central part of the island of Trinidad, is geologically connected with the Central Fault Range Zone (CFRZ). This fault zone is a neotectonic (active) strike-slip fault system and an extension of the Andes Mountain chain. This study was aimed at detecting the possible gamma radiation level in Piparo MV after its eruption in September 2019 and finding the change in the ambient radiation level after that eruption. To achieve this aim, gamma radiation data were collected for 6 months (three times at 3 months interval) after this eruption. As a pilot study, gamma radiation measurements were measured with the help of a portable Geiger Muller counter from 32 locations. Radiation levels were nearly 2 times higher than the average background levels in the country indicating Piparo mud-volcano could have controlled the elevated radiation levels in the area. Good correlations were also found between elevated radiation in the northern and western sides of the main crater and presence of auxiliary craters in the same sides. Previous studies reported that the northern side of the crater was more active, and the present study also supported their observation. Good correlation (with coefficient >0.9) indicates that these radioactivity values might be syngenetic. Continuous release and slow reduction of radiation levels (only 13% over 6 months) may indicate a continuous activity in Piparo mud-volcano and may support CRFZ as a creep fault.

Engineering geomorphological reconnaissance of the December 2018 Waimata Valley mud volcano eruption, Gisborne, New Zealand

Gisborne (North Island, NZ) is affected by rainfall-induced landslides, earthquakes and tsunami, as well as mud volcanoes (MVs). The latter form via upward mobilization of Eocene–age sediments, and have not been studied from an engineering geological standpoint, so the 15 December 2018 Waimata Valley MV eruption provided a unique opportunity. The event erupted c. 16 900 m 3 of mud, forming an elevated vent area, and three mudflows propagating north, east and south. Scanning electron microscopy (SEM) identified smectite as the dominant clay in the Sr-rich mud, and Atterberg limits indicate high plasticity. In-situ testing using dynamic cone penetrometer and shear vane (3–168 kPa) revealed wide variability in strength properties with depth, while ring shear values are 11.3–13.5°. A fault extends NW beneath the Waimata Valley MV, coinciding with the pre-existing Arakihi Road MV. The Waimata Valley MV area was subject to uplift and cracking during the September 2016 Te Araroa earthquake ( M w 7.1), which caused increased activity at pre-existing mud volcanoes at that time. Geodetic data for the Gisborne district shows an uplift phase culminating around the December 15 2018 MV eruption, followed by the commencement of a Hikurangi subduction zone ‘slow slip event’. Nevertheless, relationships between tectonics and MV eruptions remain equivocal.

Mud volcano as a feature of emergence in Caspian Sea

An eruption occurred on Dashli Island, 75 km from Baku, on 4th of July 2021, at 21:51 local time. The island is known as the mud volcano and has a history of eruption. We suspected that mud volcano eruption causes emergence on this island. Thus, the effect of this 2021 eruption is investigated using a remote sensing technique. Processed Sentinel-1 and 2 images are employed for this aim. We considered pre- and post-eruption scenarios to evaluate the effect of this eruption on the island. Satellite image classification is used to calculate shoreline changes. Results show that Dashli Island with an area of about 8.55 ha before eruption is now expanded to about 21.8 ha (about 155% increase). The DInSAR method is used to estimate the ground displacement of the island. According to the results, a two-year-displacement before the eruption was between 0.18 and 0.2 m, while a five-month-displacement after the eruption is estimated to be between 0.32 and 0.4 m. Considering ground displacement pre- and post-eruption we estimated 62000 m3 land gaining, due to emergence. We concluded that mud volcano can be counted as a feature of emergence in Dashli Island.

Did socioeconomic status influence psychological preparedness for potential disaster of resident around lapindo mud disaster

Lumpur Sidoarjo or known as LUSI is geologicall disaster that has been going on for 14 years since 2006. It is consider as the world’s largest mud volcano eruption. It bring tremendous impact to the livelihood of the resident live around the site. People live around the site mostly relied on the ponds as a living thus LUSI bring a devastated impact to the local communities. The condition has bring negative impact not only to their economic condition but also to their mental health. Study found that there are growing number of people live around the site that experience psychological problem. Psychological preparedness for disaster is one of the factors that could help people in coping with stress after disaster strike. Previous study has found that most of the resident live around the LUSI site has average level of psychological preparedness. Research on psychological preparedness found that one of the factor that associated with psychological preparedness is socioeconomic status. It is said that people with low socioeconomic would also have a low level psychological preparedness. However, the relationship between socioeconomic status and the psychological preparedness in resident around lapindo mud disaster (LUSI) was unclear. Therefore, this study aimed to investigate the relationship between socioeconomic status and the psychological preparedness for potential disaster among resident around lapindo mud disaster. The study was conducted in Sidoarjo. Survey research was applied using a Psychological Preparedness for Potential Disaster scale as a mean to identify the psychological preparedness of the Sidoarjo people.

Explosive mud volcano eruptions and rafting of mud breccia blocks

Azerbaijan hosts the highest density of subaerial mud volcanoes on Earth. The morphologies characterizing these structures vary depending on their geological setting, frequency of eruption, and transport processes during the eruptions. Lokbatan is possibly the most active mud volcano on Earth exhibiting impressive bursting events every ∼5 years. These manifest with impressive gas flares that may reach more than 100 meters in height and the bursting of thousands of m3 of mud breccia resulting in spectacular mud flows that extend for more than 1.5 kilometres. Unlike other active mud volcanoes, to our knowledge Lokbatan never featured any visual evidence of enduring diffuse degassing (e.g., active pools and gryphons) at and near the central crater. Only a very small new-born gryphon was intermittently active in 2019 (with negligible flow). Gas flux measurements completed with a closed-chamber technique reveal extremely low values throughout the structure with average CH4=1.36 tonnesyr−1 and CO2=11.85 tonnesyr−1. We suggest that after eruptive events, the mud breccia is able to seal the structure preventing gas release and thereby promoting overpressure build-up in the subsurface. This self-sealing mechanism allows a fast recharge of Lokbatan resulting in more frequent and powerful explosive episodes. Our field observations reveal the presence of large (up to ∼50,000 m3) stratified blocks that were originally part of a large crater cone. These blocks were rafted >1 km from the vent on top of mud breccia flows. We use a model based on lubrication theory to show that it is reasonable to transport blocks this large and this far provided the underlying mud flow was thick enough and the blocks are large enough. The presence of large rafted blocks is not a unique phenomenon observed at Lokbatan mud volcano and is documented at other large-scale structures both onshore and offshore.

Analysis of the Surface Subsidence of Porong and Surrounding Area, East Java, Indonesia based on Interferometric Satellite Aperture Radar (InSAR) Data.

Since 2006, the mud volcano erupted in the Porong area due to wellbore failure triggered by an earthquake (2006) epicenter in the Jogjakarta area. The mud volcano buried several villages with mud and continued erupted until today. Based on the InSAR data, it can be seen that the subsidence is still happening near the dam area and another area that is not related to mud volcano eruption such as the production of two gas fields in the Porong area. Moreover, the Porong area is flat and low, less than 4 meters above sea level. The analysis shows that the subsidence rate in this area is up to 0.5 m/yr. If this subsidence is continuing, the city can be sinking and flooding during the rainy season. The prediction result from this method is about 10 years more and 36 years since in 2006 based on the mudflow rate method.

THE EFFECT OF HARMFUL AND FAVORABLE GAS AND CHEMICAL CONTENT EMITTED BY MUD VOLCANO TO ENVIRONMENT

The recent eruption of Kesongo mud volcano (MV) that occurred in 28August 2020 in Blora, Central Java was a common natural phenomenon.MV eruption occurred periodically depending on the recharge fluid systemthat interconnected to a geothermal system and hydrocarbon reservoir.During the eruption, methane and CO2 gas were emitted to theatmosphere together with rocks, muds and fluids flowing from the fractureand fault system of MV. The extruded materials could be harmful andbeneficial for the affected ecosystem. Aims: This study aimed to addressthe potential impact of the extruded mud volcano materials to theenvironment. Methodology and Results: An attempt was carried out byinvestigating gas and fluid content of every mud volcano morphology in theselected 11 areas of Kradenan, Central Java and Sidoarjo, East Java. The pristine fluids and gas of MV were sampled for chemical and toxiccompound observation. Gas composition and type was observed using gaschromatography. The result shows that methane gas content ranges from0.06 to 67.6 mol%., while the CO2 content ranges from 0.21 to 79.9 mol%.Methane gas exhibits thermogenic gas that associated with hydrocarbongeneration. Conclusion, significance and impact study: The chemicalcompound of fluids indicates high Boron (B) content above 0.5 ppm whichhas harmful effect for crops and human health, but some compounds ofCa, Na, K, Mg present as essential elements for soil nutrient. According tothe methane flux and chemical compound emitted by mud volcano, thisstudy contributes to a management practice to restore and conserve the global ecosystem.