Lusi Mud Research Articles

Autoclaved Aerated Concrete (AAC) made from Sidoarjo mud (Lusi mud)

This paper presents the results of an experimental study on Autoclaved Aerated Concrete (AAC) containing Sidoarjo Mud (Lusi) mud to utilize the mud. Autoclaved aerated concrete (AAC) made from fine Artificial Lightweight Aggregate from Lusi mud and Fly Ash as a filler, sintered Lusi mud as the binder, aluminium powder as the foaming agent. Autoclaving process was conducted at 14 bars for 6 hours. AAC prepared in 3 (three) compositions, based on the variation of filler. The filler used in the research were sands (M-sand), fine ALWA made from Lusi mud (M-0), and fine ALWA made from Lusi mud mixed by fly ash (M-50). The workability of AAC investigated in this research was compressive strength of the AAC after 14 days, density, and X-Ray Diffraction. Experimental data showing that the compressive strength of AAC depends on the filler that is used, AAC classified at AAC-3 and AAC-4. The density of all the AAC can’t be classified as lightweight concrete. Experiment data showed the density occurs at 1148,0 kg/m3 to 1206,4 kg/m3. Chemical compounds of AAC with fine ALWA filler consisted of quartz, hematite, tobermorite, calcite, anorthite, magnetite, lime, and forsterite.

Implementation of the Collaborative Principles on Marine Tourism: Lessons from Mud Island, Indonesia

This paper aims to examine marine tourism as an empirical phenomenon. To gain insight into the systemic conditions of the collaboration process, it is observed from the point of view of the principles of the collaboration process from Roberts, Van Wyk & Dhanpat. The authors identify the principles implemented in the collaborative process between the Community, Village-Owned Enterprises, and the Government in a collaborative network towards sustainable marine ecotourism. This analytical descriptive study used case survey methods in the partnership networks. The data is obtained through a qualitative approach, observation, semi-structured interviews, and documentation. The findings reveal that stakeholders involved in the collaboration contribute to realizing a common purpose and providing mutual benefits, but the quality of collaboration is not optimal because it is still informal. Lessons learned from the application of collaboration principles on marine tourism in the Lusi Mud Island, Sidoarjo Regency, Indonesia are: the importance of trust and enabling environmental factors that collaboration to be realized; the importance of the characteristics of community leaders who have a deep concern as leaders, and ensure the participation of local communities in the development and management stages of marine tourism towards marine ecotourism.

Multi-GPU based 3D numerical modeling of fluid migration and clay dehydration influence on Lusi hydrothermal activity (Java, Indonesia)

The Lusi mud eruption in East Java has been active since May 2006. Magma emplacement at depth, clay dehydration, and mud liquefaction during seismic wave propagation have been invoked as mechanisms fueling this eruption. However, the respective roles of these processes are still poorly constrained. In this focused study, we numerically investigate the influence of clay dehydration, mass and heat transport on fluid outflow at the Lusi site using a fully coupled 3D model for this active system. Using a multi-GPU parallel processing algorithm, we propose an estimate of the 3D time evolution of pressure, temperature, porosity, permeability and water liberation in a large-scale (9 km - 14 km - 5.5 km) deep hydrothermal system at high-resolution. Simulations indicate that high-pressure fluids generated by dehydration reactions are sufficient to induce hydro-fractures that would significantly influence the porosity and permeability structures. Dehydration is an essential component for understanding the Lusi system, because the fluids generated contribute to the outflow and may have a considerable impact for the maintenance of the infrastructure required to keep the Lusi site safe. High-Performance Computing (HPC) offers high-resolution simulations for studying time evolution of such natural systems, and potentially for geothermal resource development for the surrounding population.

Application of Different Coherence Threshold on PS-InSAR Technique for Monitoring Deformation on the LUSI Affected Area During 2017 and 2019

Difficulties encountered in the DInSAR technique is the temporal and geometric decorrelation. This method’s main objective is to identify a single-pixel called Permanent Scatter (PS) over a long-time-interval and for a wide-angle of view variation. In this study, we aim to use the PS-InSAR technique to monitor land surface changes in the LUSI mud volcano area with coherence threshold difference analysis using the Sentinel 1A data set using SARPROZ as a tool. The land surface change that is our focus is west and east of the LUSI. Sentinel 1A data processing with different coherence threshold, affecting the number of PS points formed. Based on Fisher’s test on each coherence threshold showed that cumulative displacement and velocity did not differ significantly. During the 3 years since 2017 - 2019, the West LUSI region experienced average cumulative subsidence of -47.95 mm with an average velocity decline of 19.20 mm/year. The East LUSI region experiences average cumulative subsidence of 60.86 mm in the year, with an average velocity decline of 24.37 mm/year. The results of subsidence and velocity in this study are still in the line of sight (LOS)

Eleven Years of Mangrove–Mudflat Dynamics on the Mud Volcano-Induced Prograding Delta in East Java, Indonesia: Integrating UAV and Satellite Imagery

This article presents a novel approach to explore mangrove dynamics on a prograding delta by integrating unmanned aerial vehicle (UAV) and satellite imagery. The Porong Delta in Indonesia has a unique geographical setting with rapid delta development and expansion of the mangrove belt. This is due to an unprecedented mud load from the LUSI mud volcanic eruption. The mangrove dynamics analysis combines UAV-based Structure from Motion (SfM) photogrammetry and 11 years (2009–2019) satellite imagery cloud computing analysis by Google Earth Engine (GEE). Our analysis shows unique, high-spatiotemporal-resolution mangrove extent maps. The SfM photogrammetry analysis leads to a 3D representation of the mangrove canopy and an estimate of mangrove biophysical properties with accurate height and individual position of the mangroves stand. GEE derived vegetation indices resulted in high (three-monthly) resolution mangrove coverage dynamics over 11 years (2009–2019), yielding a value of more than 98% for the overall, producer and consumer accuracy. Combining the satellite-derived age maps and the UAV-derived spatial tree structure allowed us to monitor the mangrove dynamics on a rapidly prograding delta along with its structural attributes. This analysis is of essential value to ecologists, coastal managers, and policymakers.

Tectonic insight and 3-D modelling of the Lusi (Java, Indonesia) mud edifice through gravity analyses

SUMMARY Lusi is a sediment-hosted hydrothermal system located near Sidoarjo in Central Java, Indonesia, and has erupted continuously since May 2006. This mud eruption extends over a surface of ∼7 km2, and is framed by high containment dams. The present study investigates the geometry of the subsurface structures using a detailed gravimetric model to visualize in 3-D the Lusi system and surrounding lithologies. The obtained residual Bouguer anomaly map, simulated through geostatistical interpolation methods, supports the results of previous deformation studies. The negative gravity anomaly zones identified at Lusi are interpreted as fractured areas through which fluids can ascend towards the surface. A 3-D detailed geological model of the area was constructed with Geomodeller™ to highlight the main features. This model relies on the structures’ density contrasts, the interpreted residual Bouguer anomaly map, and geological data from previous authors. 3-D algorithms were used to calculate the gravity response of the model and validate it by inverse methods. The final output is a gravity constrained 3-D geological model of the Lusi mud edifice. These results provide essential details on the Lusi subsurface and may be useful for possible future geothermal resource exploitation and for the risk mitigation plans related to the maintenance of the man-made framing embankment.

SIDOARJO MUD DRAINAGE SYSTEM

Sidoarjo or Lusi mud has an area of ​​640 ha and an average embankment height of 10 meters and submerges three sub-districts, namely Porong District, Jabon District and Tanggulangin District. In 2018, the Sidoarjo mud embankment has decreased or subsided by up to 8.5 meters at several points, which was caused by the condition of the embankment which was almost full and caused the soil condition of the embankment to become unstable. For this problem, it is necessary to build a drainage channel at the edge of the embankment to overcome the overflow of the embankment and flow it to the Porong river which is on the south side of the Sidoarjo mud embankment. From the calculation of the planned rain discharge, it is found that R2 = 72.95 mm after the planned rainfall is obtained, then the next is to look for the flood discharge plan which then plans the dimensions of the channel on the west and east sides of the embankment after obtaining the dimensions of the channel, then the next is planning the resistance pond and draining it to the porong river. with Siphon Network Pipe

The deep subsurface structure beneath Lusi and the adjacent volcanic chain inferred from local travel-time tomography

Since 2006, the Lusi mud eruption is ongoing in the northeast of Java Island, Indonesia. We perform a 3D seismic tomography of the area surrounding Lusi and the adjacent Arjuno-Welirang volcanic complex using P-wave arrivals of 797 local earthquakes recorded on 31 seismic stations for two years between 2015 and 2016. Resolution tests show that we can reasonably well constrain the subsurface velocity structure beneath Lusi down to a depth of 20 km. The results of our tomography reveal that Lusi has a shallow plumbing system that is interconnected with the neighboring Penanggungan volcano. Their joint system reaches down to a depth of 20 km. The Arjuno-Welirang volcanic complex has its own deep-rooted plumbing system that might be connected to Penanggungan volcano and Lusi along the Watukosek Fault zone. The connection of Lusi with this large reservoir volume elucidates the longevity of the Lusi eruption.

Mud gas play

The presence of methane gas seepage in the mud volcano proves the existence of gas associated with over pressured zone in the subsurface. The analysis of C isotope on samples of methane gas seepage of mud volcano show the gas is thermogenic methane at the level of thermal maturity that is equivalent to the peak of petroleum formation. The mud of mud volcano extruded from overpressures zone beneath is predicted to have high gas storage capacity. The objectives of this paper are to define capacity of the mud of mud volcano system as a potential reservoir gas and its role in petroleum system. Isothermal absorption test is performed to answer the storage capacity of the mud of Kesongo and Lusi mud volcanoes system. Seismic data and velocity data show over pressured mud zone as chaotic zone with low velocity anomaly distributed crossing the reflector layer as chamber. The gas storage capacity of the mud based on adsorption test at the temperature of 65-degree Celsius ranges from 812 scf/ton up to 3,217 scf/ton shows it has capacity of gas reservoir. The adsorbed gas in over pressured mud shows different mechanism with that of the conventional reservoir. Adsorbed gas in over pressured mud can be proposed as unconventional gas reservoirs with new alternative hydrocarbon play: mudgas-play (MGP). Mud-gas-play is defined as the accumulated gas trapped in over pressured zone. Gas accumulations tend to be concentrated in the upper part of over pressured zone.

Anatomy Of The ‘LuSi’ Mud Eruption, East Java

Early in the morning of the 29th of May 2006, hot mud started erupting from the ground in the densely populated Porong District of Sidoarjo, East Java. With initial flow rates of ~5000 cubic meters per day, the mud quickly inundated neighbouring villages. After almost four years, the ?Lusi? eruption has expelled over 73 million cubic meters of mud at an average rate of approximately 64000 cubic meters per day and at maximum rates of 170000m3/day. The mud flow has now covered over 700 hectares of land to depths of over 25 meters, engulfing a dozen villages and displacing approximately 40000 people. In addition to the inundated areas, other areas are also at risk from subsidence and distant eruptions of gas. However, efforts to stem the mud flow or monitor its evolution are hampered by an overall lack of knowledge and consensus on the subsurface anatomy of the Lusi mud volcanic system. In particular, the largest and most significant uncertainties are the source of the erupted water (shales versus deep carbonates), the fluid flow pathways (purely fractures versus mixed fracture and wellbore) and disputes over the subsurface geology (nature of deep carbonates, lithology of lithological unit between shales and carbonates). This study will present the first balanced overview of the anatomy of the Lusi mud volcanic system with particular emphasis on these critical uncertainties and their influence on the disaster.

The response of seedling growth of Rhizophora apiculuta to various concentrations of Sidoarjo mud

This study aims to determine the effect of some concentration of Lusi mud (Sidoarjo mud) as a medium to grow mangrove plants on the growth of Rhizophora apiculuta seedlings. A total of 24 experimental units arranged in a randomized block design with treatment were Lusi mud concentration on planting medium, ie: 10%, 20%, 30%, 40%, and 50%. The variables observed were plant height, stem diameter, long root leaf area and wet weight and dry weight of plant. Data obtained were analyzed statistically by an analysis of variance and HSD test were used to indicate the significant differences between the mean values (p<0.05). The results showed that the 10% Lusi mud concentration responded to the growth of canopy, root length, and wet weight and dry weight of R. apiculuta plants similar to those in the control treatment. At concentrations of 20%, 30%, 40%, up to 50% of Lusi mud, plants are able to grow well despite lower growth rates comparedwith no Lusi mud

The cause of the 2006 Lusi mud volcano (Indonesia): Please let's not rewrite history

The cause of the 2006 Lusi mud volcano (Indonesia): Please let's not rewrite history

Deep hydrothermal activity driving the Lusi mud eruption

The Lusi mud eruption in East Java continues unabated after more than a decade of activity as a pulsating geyser system bursting mud, clasts, water, and gas. The origin of the fluids and their properties at depth are not well constrained, thus hampering our understanding and modelling of the system. Previous geochemical and geophysical studies show that Lusi is a sediment-hosted hydrothermal system with two sources of mud at depths between 0.3–2 km and another between 3.5–4.75 km. Here, we present results of mineral thermometry using Raman spectroscopy and chlorite composition on clasts erupted at Lusi. The results show that some of these specimens originate from the two main fluid sources, and at depths consistent with the geochemical and geophysical interpretation. Two main clast lithotypes erupt at Lusi. The first lithotype is a light grey shale returned to the surface from the Upper Kalibeng Formation (the primary mud source) and equilibrated at temperatures below 200 °C. The second lithotype is a black shale, whose source is the Ngimbang Formation at >3800 m depth. Two distinct temperature clusters are recorded in these black shales: one at 179±17 °C, consistent with the temperature estimate at 3800 m depth with the pre-eruption geothermal gradient, while younger minerals in the same specimen recorded substantial anomalous heating at ∼250 °C. These high temperatures indicate interaction with a heat source associated with the eruption through mixing with hydrothermal fluids. This temperature jump suggests rapid heating at ∼4000 m depth, consistent with a scenario of a magmatic intrusion and hydrothermal fluids circulation. This rapid and significant temperature increase would initiate devolatilisation reactions of hydrous minerals within the deep sedimentary package and generate substantial (highly overpressured) fluids at depths significantly below the main source of erupted mud. We infer that reactive and thermal pressurisation led to a deep and metastable system susceptible to e.g. seismic activity ultimately opening fluid pathways towards the surface along the Watukosek fault system. The two temperatures clusters recorded in the clasts show that conductive heat flow was the dominant heat transport prior to the eruption, while the system is now driven by large-scale convection and advective heat transport. The Lusi eruption occurred in a highly populated area forcing the evacuation of several tens of thousands of people. This system appears unstoppable and poses a real and present hazard for the settlements still surrounding the eruption site. Continuous research is necessary to understand this spectacular phenomenon, both for its important scientific relevance, and the societal impact of this natural disaster.

An alternative review of facts, coincidences and past and future studies of the Lusi eruption

Abstract The cause of the Lusi mud eruption remains controversial. The review by Miller and Mazzini (2017) firmly dismisses a role of drilling operations at the adjacent Banjarpanji-1 well and argues that the eruption was triggered by the M6.3 Yogyakarta earthquake some 254 km away. We disagree with these conclusions. We review drilling data and the daily drilling reports, which clearly confirm that the wellbore was not intact and that there was a subsurface blowout. Downhole pressure data from Lusi directly witness the birth of Lusi at the surface on the 29th of May 2006, indicating a direct connection between the well and the eruption. Furthermore, the daily drilling reports specifically state that Lusi activity was visibly altered on three separate occasions by attempts to kill the eruption by pumping dense fluid down the BJP-1 well, providing further evidence of a connection between the wellbore and Lusi. By comparison with other examples of newly initiated mud eruptions elsewhere by other earthquakes, the Yogyakarta earthquake was far away given its magnitude. The seismic energy density of the Yogyakarta earthquake was only 0.0043 J/m3, which is less than a quarter of the minimum 0.019 J/m3 seismic energy density that has ever been inferred to trigger other mud eruptions. We show that the Lusi area had previously experienced other shallow earthquakes with similar frequencies and stronger ground shaking that did not trigger an eruption. Finally, the data from the BJP-1 well indicates that there was no prior hydrodynamic connection between deep overpressured hydrothermal fluids and the shallow Kalibeng clays, and that there was no evidence of any liquefaction or remobilization of the Kalibeng clays induced by the earthquake. We thus strongly favor initiation by drilling and not an earthquake.

Rare earth element contents of the Lusi mud: An attempt to identify the environmental origin of the hot mudflow in East Java – Indonesia

AbstractThe Sidoarjo mudflow in East Java, Indonesia, has been erupting since May 29

Drone high resolution infrared imaging of the Lusi mud eruption

The use of low-cost hand-held infrared (IR) thermal cameras based on uncooled micro-bolometer detector arrays became more widespread during the recent years. Thermal cameras have the ability to estimate temperature values without contact and therefore can be used in conditions where targets are difficult or dangerous to reach such as volcanic eruptions. Since May 2006 the Indonesian Lusi mud eruption continues to spew boiling mud, water, aqueous vapour, CO2, CH4 and covers a surface of nearly 7 km2. Here we performed surveys above and around the erupting crater using a specifically equipped remote-controlled aerial vehicle (drone). Despite the harsh logistics and the continuously varying gas concentrations, we managed to collect IR images composing mosaics to estimate the crater zone spatial and temporal thermal variations as well as that in the surrounding regions. In this manuscript we provide a) a description of the main processes that affect and control the acquisition of IR images; b) an overview of still non disclosed physical model used by the thermal camera employed during our survey (i.e. Flir I7 IR); c) a method for capturing high resolution infrared images over an erupting clastic system; d) analysis and interpretation of the acquired data and scientific results. The results show that it is possible to obtain good quality mosaics also in inaccessible areas such as erupting craters where fixed reference points are not constant, and where the presence of IR attenuation factors introduce errors in terms of temperature estimates. However the IR camera radiative transfer model (based on Lowtran model) allows the control of only some of the parameters that affect the attenuation of the IR spectrum. This results in obtained crater temperature estimates up to ∼20% lower than those measured with hand held thermometers, providing, however, very important information about the thermal gradient and the potential radioactive absorption factors. The imaged Lusi vent thermal pattern suggests the presence of shallow convective chambers inside the caldera zone; these are activated by the rise of boiling mud breccia that suddenly cools and sinks. The thermal survey conducted on the dry mud region to the NE of the crater reveals temperatures matching with those measured directly on the field with a hand held thermometer. Here the presence of hot spot anomalies and colder circular features is consistent with the migration of deeper warm fluids along a faulted and fractured area and with widespread pools distribution.

Radon and carbon gas anomalies along the Watukosek Fault System and Lusi mud eruption, Indonesia

An extensive survey was carried out in the Sidoarjo district (East Java, Indonesia) to investigate the gas leaking properties along fractured zones coinciding with a strike-slip system, the Watukosek Fault System (WFS) in NE Java. This structure has been the focus of attention since the beginning of the spectacular Lusi mud eruption on the 29th May 2006. The sinistral strike-slip WFS originates from the Arjuno-Welirang volcanic complex, intersects the active Lusi eruption site displaying a system of antithetic faults, and extends towards the NE of Java where mud volcanic structures reside.In the Lusi region we completed a geochemical survey along three profiles combining measurements of a) 220Rn and 222Rn activity, b) CO2 and CH4 soil gas content, c) CO2 and CH4 fluxes, and d) gas analyses. The profiles are up to ∼1.2 km long and intersect perpendicularly areas with intense fracturing and surface deformation along the WFS. The purpose was to investigate the presence and origin of soil degassing activity in potentially active fault zones.Results show that the peripheral sectors of the profiles have high 220Rn activity and reduced CO2 and CH4 fluxes and concentrations. This suggests low fluids migration that could be affected by shallow circulation. In contrast, the segments of profiles intersecting the fractured zones have the highest 222Rn activity, CO2 and CH4 flux and gas concentration values.The relationship existing among the measured parameters suggests that the WFS acts as a preferential pathway for active rise of deep fluids. The presence of such advective processes is suggested by the relatively high rate of migration needed to obtain anomalies of short-lived 222Rn in the soil pores. Gas molecular and isotopic composition reveals that all sampled localities have a mixed hydrocarbon origin implying the presence of shallow microbial and deeper thermogenic hydrocarbons. CO2 isotopic values (δ13C-CO2 ranges between −9.48‰ and 4.12‰ V-PDB) indicate the presence of mantle derived CO2 and thermo-metamorphic CO2 suggesting that elevated temperatures have a key role in this active system. The samples collected from fractured and faulted zones reveal to have gas composition similar to that obtained from Lusi crater, indicating deep origin fluids.

Genesis and evolution of the Watukosek fault system in the Lusi area (East Java)

Detailed analysis of two-dimensional seismic lines acquired in the NE Java basin has been performed to unravel the subsurface geology of the region around the Lusi mud eruption. This work revealed the existence of a system consisting of a complex set of faults, here called the Watukosek fault system, forming triangular deformation zones converging at the top of the early Miocene Carbonates. This system continues downwards with vertical individual fault segments, often bordering the steep margins of the carbonate platforms. The analysis of data includes the interpretation of seismic lines, regional structural data inferred from basement gravity maps and present-day main direction of stress. Results suggest that a possible rotation of stress direction from N40E-S40W to N-S occurred during the post-Miocene history of the Java back arc tectonic evolution. The Watukosek fault system was first generated as a tensional lineament during the E-W sinistral transpressive strain, which involved the basement. In this phase, synthetic and antithetic Riedel faults formed, the former controlling the NW-SE orientation of the structural highs represented by Oligo-Miocene carbonate platforms. As a consequence of the rotation of the main principal stress direction to a N-S direction, the Watukosek fault and similar parallel lineaments became sinistral Riedel shears, developing intense triangular deformation zones. Based on the stratigraphic position of gentle anticlinal deformations with axis corresponding to the N40E-S40W oriented triangular deformation zones, the transpressive strain linked to the N-S main stress compression occurred likely in the Late Pliocene-Early Pleistocene.The detailed examination of a) stratigraphy at the wells BJP-1 and Porong-1 as well as b) the seismo-stratigraphic architecture of the entire succession in the study area, allowed a new subsurface interpretation and revision of the stratigraphic units below Lusi. The thick Early Miocene Tuban Formation is found sandwiched between the coheval Upper Kalibeng Formation and the Early Miocene Carbonate of the Kujung Formation, which in turn overlain the older Ngimbang Formation.

Numerical modeling of the Lusi hydrothermal system: Initial results and future challenges

The Lusi mud eruption in East Java, Indonesia, is an active clastic-dominated geyser and a sedimentary hosted hydrothermal system that has generated wide interest across many disciplines. This moderate-to-high enthalpy system is driven by multiphase and multicomponent processes, fluid and rock mechanics, and heat transport processes, all which present challenges in developing realistic numerical models of the underlying physics. We develop a hydrogeological conceptual model for this deep and complex hydrothermal system, and construct an appropriate 3D geological model using the available data. This geological model then serves as the basis for numerically simulations that include some of the dominant processes driving Lusi. We adopt a flexible continuum approach with an efficient numerical simulator based on the 3D geological model representing the deep structures of this hydrothermal system and geothermal reservoir by incorporating borehole information and seismic data obtained in the framework of the LUSI Lab project. The geological model is transformed into a computational grid using binary space partitioning (BSP) of the input geometry and octree refinement on the grid to perform multi-physics simulations. Thermodynamic calculations using the equation of state for a CO2-bearing aqueous NaCl solution suggest that Lusi is a two-phase flow system (Water/CO2). Finally, we present initial results from a simple hydro-mechanical multiphase numerical model that simulates processes that likely contributed to the initiation of Lusi.

Modelling fluid flow in clastic eruptions: Application to the Lusi mud eruption

Clastic eruptions involve the rapid ascension of sedimentary clasts together with fluids, gas and/or liquid phases that may further deform and brecciate the host rocks. These fluids transport the resulting mixture, called mud breccia, to the surface. Such eruptions are often associated with geological structures such as mud volcanoes, hydrothermal vent complexes and, more generally, piercement structures. They involve various processes, acting over a wide range of scales, which makes them a complex and challenging multi-phase system to model. Although piercement structures have been widely studied and discussed, only a few attempts have been made to model the dynamics of such clastic eruptions. The ongoing Lusi mud eruption, in the East Java back-arc basin, which began in May 2006, is a spectacular large scale clastic eruption. The Lusi eruptive behaviour has been extensively studied over the past decade and thus represents a unique opportunity to better understand ongoing clastic eruptions and thus fossil clastic systems. We use both analytical formulations and numerical models to investigate simple relationships between the mud breccia properties (density, viscosity, gas and clast content) and the volumetric flow rate. Our results show that the conduit radius of such piercement systems cannot exceed a few metres at depth, and that clasts, if not densely packed, will not affect the flow rate when they are smaller than a fifth of the conduit size. Using published data for the annual gas fluxes at Lusi, we infer a maximal depth at which exsolution starts. This occurs between 1800 m and 3200 m depth for methane and between 750 m and 1000 m for carbon dioxide. Based on annual gas fluxes, we estimate that the conduit radius should be no larger than 1.5 m to match the maximal mud discharge, recorded at Lusi.