paleohydrology of the upper miocene bicorb lake eastern spain as inferred from stable isotopic data from inorganic carbonates abstract the hydrological evolution of the upper miocene bicorb lake eastern spain has been established based on sedimentology carbonate mineralogy and stable isotopic data from inorganic carbonates from the upper lacustrine unit three main subunits have been recognized in subunit a the sedimentological features suggest a hydrologically closed lake although the isotopic data are not conclusive the isotopic compositions of primary carbonates from subunit b display a distribution typical for a hydrologically closed lake and allow the differentiation of four developmental stages the first stage was defined by the deposition of gypsum lmc dolomite and aragonite indicating large variations in the water mg ca ratio during the second and third stages only lmc was deposited suggesting only minor mg ca fluctuations the 13c and 18o pattern of the second stage shows a well defined covariance r 0 8 while in the third stage the isotopic data display a negative covariant relationship r 0 8 changes in dissolved inorganic carbon composition are considered the main factor to explain the variations from positive to negative covariance in the fourth stage the lake waters underwent large mg ca fluctuations as indicated by the deposition of lmc hmc and aragonite the isotopic trend is also covariant finally subunit c is characterized by lmc and minor amounts of hmc suggesting minor changes in mg ca ratio the isotopic features of this subunit are more congruent with a hydrologically open lake the lowest 13c and 18o values are very similar in the three subunits reflecting the most dilute conditions of the lake water and a uniform isotopic composition of the local meteoric water during these periods the changes in water balance and solute inputs recorded in the mineralogy and isotopic signatures of carbonates were controlled by the diapiric evolution and changes in the e p balance

seismic fatigue failure may have triggered the 2014 mw7 9 rat islands earthquake seismic waves propagating from large earthquakes cause global transient stress changes capable of triggering other earthquakes at great distances the study of such remote and dynamic triggering phenomena provides a better understanding of the mechanisms that generate earthquakes i introduce an integrated seismicity model to stochastically evaluate the time intervals of consecutive earthquakes at global scales making it possible to detect a pair of earthquakes possibly related to each other i show a mw7 9 intermediate depth earthquake that occurred in the rat islands in 2014 is inferred to have been associated with a sequence of distant large mw 6 5 earthquakes originating from the kermadec islands the passage of seismic surface waves from the kermadec events that produced small stress changes varying within at most 10 pa at the hypocenter probably caused a reduction in the fault s strength by cyclic fatigue and eventually triggered its failure during their passage

fracture abundance and strain in folded cardium formation red deer river anticline alberta foothills canada abstract the folded and thrusted mesozoic clastic sequence of the canadian rocky mountain foothills forms important hydrocarbon reservoirs however the generation of fractures and their timing relative to folding and thrusting have remained unclear understanding the distribution and evolution of natural fractures especially their timing of formation relative to the evolution of the fold and thrust system could potentially improve exploration and development outcomes in these otherwise tight low permeability reservoirs we investigated the relation between folding and fracture formation in the upper cretaceous cardium formation by combining field structural observations and kinematic modeling of the fold and thrust belt evolution we evaluated the effects of structural position and strain on the formation of predominantly opening mode fractures by analyzing fracture intensity and aperture in the backlimb the shallow forelimb close to the crest and the steep forelimb away from the crest of a reservoir scale anticline the red deer river anticline fracture strain determined from both outcrop and microscanlines varies little across the three structural domains of the fold although somewhat lower fracture strain was measured in the forelimb close to the crest these fracture strain measurements are qualitatively consistent with calculated horizontal strain in the tectonic transport direction obtained from kinematic numerical models that simulate fold development associated with slip along the underlying burnt timber thrust the kinematic models predict similar magnitudes of horizontal extension in both the back and forelimbs and somewhat lower extension in the upper forelimb during early development of the red deer river anticline predicted early fracture formation during fold development is consistent with field structural observations of shear reactivation during later stages of folding this combined kinematic modeling and field structural study demonstrates that deforming fold and thrust belts can undergo a complex evolution of bed parallel extension in both space and time resulting in spatially variable fracture formation in structurally complex subsurface reservoirs

more than ten years of lusi a review of facts coincidences and past and future studies abstract the lusi mud eruption in east java indonesia has continued unabated for more than ten years with no end in sight this review summarizes what has been learned about this intriguing system from its inception to the current 2017 well established metastable geysering system that continuously erupts mud breccia gas steam and water we discuss the initiation of lusi highlighting discrepancies and evidence through the published data to build a comprehensive database that emphasizes how the results converge towards a natural scenario of this system we argue that attempts to understand constrain or predict the behaviour of this system that rely on a drilling trigger can not explain subsequent observations on the other hand we show that a well constrained conceptual model recognizing lusi as a volcanically linked hydrothermal system has provided important insights for the documented observations over the last eleven years the response of lusi to the yogykarta earthquake falls directly within the range of earthquake triggering phenomena globally of similar hydrothermal geothermal systems suggesting a natural trigger as the more likely culprit for the lusi phenomenon we also offer some future directions of additional scrutiny for understanding this newborn tectonic scale volcanic hydrothermal complex

ascent velocity and dynamics of the fiumicino mud eruption rome italy author s vona a giordano g de benedetti aa d ambrosio r romano c manga m abstract 2015 american geophysical union all rights reserved in august 2013 drilling triggered the eruption of mud near the international airport of fiumicino rome italy we monitored the evolution of the eruption and collected samples for laboratory characterization of physicochemical and rheological properties over time muds show a progressive dilution with water the rheology is typical of pseudoplastic fluids with a small yield stress that decreases as mud density decreases the eruption while not naturally triggered shares several similarities with natural mud volcanoes including mud componentry grain size distribution gas discharge and mud rheology we use the size of large ballistic fragments ejected from the vent along with mud rheology to compute a minimum ascent velocity of the mud computed values are consistent with in situ measurements of gas phase velocities confirming that the stratigraphic record of mud eruptions can be quantitatively used to infer eruption history and ascent rates and hence to assess or reassess mud eruption hazards

triggering and dynamic evolution of the lusi mud volcano indonesia abstract mud volcanoes are geologically important manifestations of vertical fluid flow and mud eruption in sedimentary basins worldwide their formation is predominantly ascribed to release of overpressure from clay and organic rich sediments leading to impressive build up of mud mountains in submarine and subaerial settings here we report on a newly born mud volcano appearing close to an active magmatic complex in a backarc sedimentary basin in indonesia the location of the mud volcano close to magmatic volcanoes results in a high background temperature gradient that triggers mineralogical transformations and geochemical reactions at shallow depth the eruption of 100 c mud and gas that started the 29th of may 2006 flooded a large area within the sidoarjo village in northeast java thousands of people have so far been evacuated due to the mud flood hazards from the eruption since the initial eruption the flow rate escalated from 5000 to 120 000 m 3 d during the first eleven weeks then the erupted volume started to pulsate between almost zero and 120 000 m 3 d in the period august 14 to september 10 whereas it increased dramatically following swarms of earthquakes in september before reaching almost 180 000 m 3 d in december 2006 sampling and observations were completed during two fieldwork campaigns on the site the eruption of boiling water is accompanied by mud aqueous vapour co 2 and ch 4 based on geochemical and field results we propose a mechanism where the eruptions started following the 27th of may earthquake due to fracturing and accompanied depressurization of 100 c pore fluids from 1700 m depth this resulted in the formation of a quasi hydrothermal system with a geyser like surface expression and with an activity influenced by the regional seismicity

upper crustal structure of an active volcano from refraction reflection tomography montserrat lesser antilles to better understand the volcanic phenomena acting on montserrat the sea calipso seis mic experiment seismic experiment with airgun source caribbean andesitic lava island precision seismo geodetic observatory was conducted in 2007 december with the aim of imaging the upper crust and the magmatic system feeding the active soufri ere hills volcano the 3 d survey covered an area of about 50 40 km and involved the deployment of 247 land stations and ocean bottom seismometers obss a subset of the data recorded by four obss and four land stations on a southeast to northwest line has been analysed and traveltimes have been inverted to obtain a 2 d seismic velocity model through the island inverted phases include crustal and sediment p waves and wide angle reflections the resulting velocity model reveals the presence of a high velocity body 3 5 5 5 km s 1 beneath the island with highest velocities beneath the soufri ere and centre hills cor responding primarily to the cores of these volcanic edifices built of a pile of andesite lava domes and subsequent intrusions in the off shore region velocities in the surficial sediment layer vary from 1 5 to 3 0 km s 1 consistent with a mainly calcareous and volcaniclastic composition a wide angle reflector is observed at a depth of 1200 m below the seabed and appears to deepen beneath the island the upper crust beneath this reflector has velocities of 4 0 6 0 km s 1 and is infer red to cor respond to plutonic and hypabyssal rocks and sedimentary material of the old arc the high velocity region beneath the island extends into the crust to a depth of at least 5 km and is believed to be caused by an intrusive complex possibly of intermediate composition a low velocity zone as would be expected in the presence of an active magma chamber was not observed perhaps due to the limited resolution beneath 5 km depth our results so far provide the first wide angle seismic constraints on the upper crustal structure of the island to a depth of 10 km and will help understanding the processes that drive volcanism at montserrat and other island arc volcanoes

corrigendum lusi mud eruption triggered by geometric focusing of seismic waves nature geoscience 6 642 646 2013 published online 21 july 2013 corrected after print 28 august 2014 in our 2013 article1 we adopted a published velocity profile2 described as check shot data which we used as an input constraint for our numerical simulations we were subsequently alerted to artefacts in that velocity profile so below we present revised simulation results based on additional data

natural hazards triggered mud eruption the indonesian government ruled that the lusi mud eruption was triggered by drilling and held an oil company responsible instead a curved rock layer capping the mud reservoir may have amplified passing seismic waves and the trigger may have been natural

seismic impedance inversion and interpretation of a gas carbonate reservoir in the alberta foothills western canada acoustic and simultaneous elastic impedance inversions of a 2d land seismic data set are performed to characterize a carbonate reservoir of mississippian age in the turner valley formation in the rocky mountain foothills of western canada the inversions produce p wave and s wave impedance sections ip and is respectively from which lame parameter density and sections are derived the ip data provide a separation between the clastics and carbonates the data provide an estimate of porosity distribution within the dolomitized limestone target deviations from baseline curves for water saturated carbonates of versus porosity versus porosity and is versus ip are interpreted as indicators of gas potential these indicators all provide similar spatial patterns of areas of high gas potential and are consistent with the gas occurence observed in a well

genesis and evolution of the watukosek fault system in the lusi area east java abstract 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

modeling study of growth and potential geohazard for lusi mud volcano east java indonesia abstract the mud volcano known as lusi first erupted in may 2006 in east java indonesia the eruption has continued for over two years and potentially will continue for many years to come impacting an ever larger area an obvious and significant question is how extensive the impacted area will become in the coming years the answer is important for planning scenarios for the relocation of people and infrastructure and for managing the environment and economy to make such a prediction an understanding of the geological processes controlling the mud volcanic evolution is needed a three dimensional simulation model was built to predict the area affected by the mudflow over a ten year period with a special focus on the period from december 2007 until june 2010 the primary model inputs are the mud debit rate the rate of subsidence and the topography the model prediction was validated at the december 2007 time step by comparing the results with satellite images from the same period the simulation was found to provide a good approximation for the mud overflow and growth the results indicate that the mudflow tends to spread to the west and particularly to the east and north from the currently inundated area the model predicts that in june 2010 the peak of the mud volcano will have risen 26 m above the original ground level and the maximum subsidence will have been 63 m below the original ground level the dynamic subsurface condition in the area creates geohazard risks and these are also discussed in this paper

influence of seismicity on the lusi mud eruption earthquakes trigger the eruption of mud and magmatic volcanoes and influence ongoing eruptive activity one mechanism that could trigger an eruption is clay liquefaction here we model the propagation of seismic waves beneath the lusi mud eruption east java indonesia using available seismic velocity and density models to assess the effect of subsurface structure on the amplification of incident seismic waves we find that using an updated subsurface density and velocity structure there is no significant amplification of incident seismic energy in the upper kalibeng formation the source of the erupting solids hence the hypothesis that the lusi eruption was triggered by clay liquefaction appears unlikely to be correct independent constraints from gas chemistry as well as analyses of drilling activities at the nearby banjar panji 1 gas exploration well and an analysis of the effects of other earthquakes all favor a drilling trigger

triggering of the lusi mud eruption earthquake versus drilling initiation abstractthe lusi mud volcano in east java has erupted unabated for almost 2 yr ooding an area of 7 km 2 and displacing more than 25 000 people despite its disastrous impact the mechanism for triggering the lusi eruption remains highly controversial two distinct mechanisms have been proposed one hypothesis suggests that the eruption was triggered by the m w 6 3 earth quake that struck yogyakarta 250 km from lusi two days before the eruption however an examination of static and dynamic stress changes and stress transfer mechanisms indicates that the yogyakarta earthquake was at least an order of magnitude too small to reactivate faults and open uid ow pathways under lusi an alternate theory suggests that lusi was triggered by a blowout following drilling problems in the nearby banjar panji 1 well blowouts result from an inability to control pore uid intakes into the borehole and typically occur when the drilling win dow fracture pressure minus pore pressure is approximately zero and when there is insuf cient protective casing of the well bore pore and fracture pressure data from banjar panji 1 indicate that the well had a narrow drilling window of only 0 2 3 mpa furthermore two planned casing points were skipped during drilling resulting in 1742 m of unprotected borehole the combina tion of hazardously narrow drilling window and long uncased borehole would have made drill ing problems in banjar panji 1 dif cult to control placing the well at high risk of blowing out furthermore well bore pressures following drilling problems in banjar panji 1 reached magni tudes in excess of the fracture pressure and thus were suf cient to create uid ow pathways in the subsurface therefore we suggest that no viable method is known by which the yogyakarta earthquake could have triggered the mud ow and that a blowout in the banjar panji 1 well was the most likely mechanism for triggering the lusi eruption keywords

subsurface fluid distribution and possible seismic precursory signal at the salse di nirano mud volcanic field italy mud volcanoes are geological systems often characterized by elevated fluid pressures at depth deviating from hydrostatic conditions this near critical state makes mud volcanoes particularly sensitive to external forcing induced by natural or man made perturbations we used the nirano mud volcanic field as a natural laboratory to test pre and post seismic effects generated by distant earthquakes we first characterized the subsurface structure of the nirano mud volcanic field with a geoelectrical study next we deployed a broad band seismic station in the area to understand the typical seismic signal generated by the mud volcano seismic records show a background noise below 2 s sometimes interrupted by pulses of drumbeat like high frequency signals lasting from several minutes to hours to date this is the first observation of drumbeat signal observed in mud volcanoes in 2013 june we recorded a m4 7 earthquake that occurred approximately 60 km far from our seismic station according to empirical estimations the nirano mud volcanic field should not have been affected by the m4 7 earthquake yet before the seismic event we recorded an increasing amplitude of the signal in the 10 20 hz frequency band the signal emerged approximately two hours before the earthquake and lasted for about three hours our statistical analysis suggests the presence of a possible precursory signal about 10 min before the earthquake

lusi hydrothermal structure inferred through ambient vibration measurements abstract the spectacular lusi mud eruption started in northeast java indonesia the 29th of may 2006 following a m6 3 strike slip seismic event after the earthquake several mud pools aligned along a ne sw direction appeared in the sidoarjo district the most prominent eruption site was named lusi lusi is located 10 km to the ne of the northernmost cone of the arjuno welirang volcanic complex with which it is connected by the watukosek fault system in this study we applied the hvsr method which is a common tool used for site effect investigations as well as to infer buried structures and reconstruct sub surface geology the method is based on the ratio of the horizontal to vertical components of ground motion and it generally exhibits a peak corresponding to the fundamental frequency of the site spectral ratio results highlight a fundamental frequency band between 0 4 and 1 0 hz in the lusi neighborhood we interpret these peaks as related to the velocity lithological contrast at depth between alluvial deposits and bluish grey clay our analysis also highlights the presence of a depocenter characterized by fundamental frequency up to 0 3 hz which is interpreted as the subsidence caused by withdrawal of mud and fluids from depth as also shown by the comparison of the hvsr results with gravimetry data moreover in the area of the lusi vent a broad band frequency range is related to the lusi conduit in this paper we show that detailed microtremor surveys could be used as a preliminary and fast approach to locate mud conduits with sufficient precision

the nevados de payachata volcanic region 18 s 69 w n chile subduction related volcanism in the nevados de payachata region of the central andes at 18 s comprises two temporally and geochemically distinct phases an older period of magmatism is represented by glaciated stratocones and ignimbrite sheets of late miocene age the pleistocene to recent phase 0 3 ma includes the twin stratovolcanoes volcan pomerape and volcan parinacota the nevados de payachata volcanic group and two small centers to the west i e caquena and vilacollo both stratovolcanoes consist of an older dome and flow series capped by an andesitic cone the younger cone i e v parinacota suffered a postglacial cone collapse producing a widespread debris avalanche deposit subsequently the cone reformed during a brief second volcanic episode a number of small relatively mafic satellitic cinder cones and associated flows were produced during the most recent activity at v parinacota at the older cone i e v pomerape an early dome sequence with an overlying isolated mafic spatter cone and the cone forming andesitic dacitic phase mostly flows have been recognized the two nevados de payachata stratovolcanoes display continuous major and trace element trends from high k2o basaltic andesites through rhyolites 53 76 sio2 that are well defined and distinct from those of the older volcanic centers petrography chemical composition and eruptive styles at v parinacota differ between pre and post debris avalanche lavas precollapse flows have abundant amphibole at sio2 59 wt and lower mg numbers than postcollapse lavas which are generally less silicic and more restricted in composition compositional variations indicate that the magmas of the nevados de payachata volcanic group evolved through a combination of fractional crystallization crustal assimilation and intratrend magma mixing isotope compositions exhibit only minor variations pb isotope ratios are relatively low 206pb 204pb 17 95 18 20 and208pb 204pb 38 2 38 5 87sr 86sr ratios range 0 70612 0 70707 143nd 144nd ratios range 0 51238 0 51230 and 18osmow values range from 6 8 o to 7 6 o smow a comparison with other central volcanic zone centers shows that the nevados de payachata magmas are unusually rich in ba up to 1800 ppm and sr up to 1700 ppm and thus represent an unusual chemical signature in the andean arc these chemical and isotope variations suggest a complex petrogenetic evolution involving at least three distinct components primary mantle derived melts which are similar to those generated by subduction processes throughout the andean arc are modified by deep crustal interactions to produce magmas that are parental to those erupted at the surface these magmas subsequently evolve at shallower levels through assimilation crystallization processes involving upper crust and intratrend magma mixing which in both cases were restricted to end members of low isotopic contrast

assessment of sidoarjo mud flow embankment stability using very low frequency electromagnetic method the earth on lusi embankment has a high failure potential due to several factors such as seepage leakage vertical and horizontal deformation cracking and fault discontinuity overtopping mud slide and swelling very low frequency electromagnetic method was carried out at lusi embankment in order to delineate fracture and potential pathway of seepage occurring through the subsurface structure the embankment body to reach these objectives several methods were carried out in the selected area such as direct current resistivity total station and rayleigh wave dispersion to provide information on the mechanical properties lusi embankment subsurface this study indicates that seepage and fracture through the lusi embankment is presented by a set of lines which are possibly caused by deformation in the lusi area furthermore based on the fracture and seepage positions and mud or fluid flow direction the unstable lusi embankment is determined as located around the northwest and northern parts of the area

gas isotope reversals in fractured gas reservoirs of the western canadian foothills mature shale gases in disguise isotopically reversed gases 13c methane 13c ethane 13c propane occur in fractured mixed clastic carbonate reservoirs of the permian and the triassic in the foothills at the western edge of the western canada sedimentary basin wcsb the 13c methane values 42 to 24 gas dryness and organic maturity ro 2 2 are indicative of mature gases and gas maturity generally increases with reservoir age and from the southeast to the northwest the 13c ethane values range from 44 to 25 with the less negative values in isotopically normal gases to the northeast of the gas fields we studied to explain the gas isotope reversals observed in the wcsb foothills we adopt the concept of a closed system shale in which simultaneous cooking of kerogen oil and gas yields gas with light 13c ethane and heavy 13c methane this gas was released from shales and trapped in fractured folds of brittle clastic carbonate rocks during deformation and thrust faulting of the laramide orogeny creating some of the most prolific gas pools these gases are actually mature shale gases local high abundances of h2s and co2 are most likely the products of thermochemical sulfate reduction tsr reactions in anhydrite rich interbeds and underbeds that admixed to the released shale gas during the tectonic event no evidence exists that tsr is responsible for the isotope reversals variations in 13c ethane are likely caused by local differences in thermal history the timing of gas release from shale and the timing of the fault and fold development less negative 13c ethane values resulting in isotopically normal gases to the northeast of the fields and in the underlying devonian carbonates likely reflect a more open shale system where the earliest generated gas was lost we suggest that isotopic reversals are restricted to closed system maturation and that their magnitude may be related to the relative volume of gas retained in shales

the future of natural gas exploration in the foothills of the western canadian rocky mountains the foothills of the western canadian sedimentary basin wcsb cover 40 000 miles2 in the fold and thrust belt of the canadian rocky mountains the topmost northwestern point lies just north of the northwest territories border at the town of fort liard the foothills also occupy part of the adjacent yukon territory run southeast through british columbia and alberta and terminate near the u s canadian border figure 1 the northwestern and southeastern limits are controlled by political boundaries and the extent of the natural gas gathering system

linking structures with the genesis and activity of mud volcanoes examples from emilia and marche northern apennines italy mud volcanism is known to be strictly linked to tectonic structures since they have the ability to trap hydrocarbon and other fluids and eventually induce them to migrate from a deep reservoir e g sited into an anticline core where large overpressures may be generated to the surface a central theme is how fluids can migrate upward and which is the role in this process of near structures i e structures directly controlling the mud volcano system and far structures i e faults located far away from the mud volcano system in this study we investigate the role of both types of structures in the genesis and evolution of mud volcanoes in particular we investigate six mud volcano case studies from the emilia romagna and marche pede apennine margin in italy through integration of fieldwork interpretation of available seismic reflection profiles and aerial photos the results of these analyses support an intimate link of the investigated mud volcanoes with anticline structures we discuss two different fluid migration settings particularly i mud volcanoes emplaced on outcropping anticlines and ii mud volcanoes located on top of buried structures discerning when fluids are likely to exploit anticline related fracture sets or secondary structures and porosity finally we speculate on how far structures via the seismic triggering may play a role in the occurrence of historical eruption of some of the investigated mud volcanoes

numerical modeling of the lusi hydrothermal system initial results and future challenges abstract 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 co 2 bearing aqueous nacl solution suggest that lusi is a two phase flow system water co 2 finally we present initial results from a simple hydro mechanical multiphase numerical model that simulates processes that likely contributed to the initiation of lusi

comment to more than ten years of lusi a review of facts coincidences and past and future studies by miller and mazzini 2018 taking the trigger debate above ground abstract since erupting in 2006 the lapindo mudflow or lusi as it is known by scientists has released a constant flow of mud that has devastated communities and environments in east java s sidoarjo regency the mudflow also has spawned countless formal and informal scientific reports that dispute what initiated the eruption drilling for gas or a distant earthquake a 2018 special issue in marine and petroleum geology by the lusi lab is devoted entirely to the mudflow which includes an article by miller and mazzini 2018 that presents one perspective of the current status of the trigger debate this discussion article draws attention to a series of inaccuracies and misrepresentations within miller and mazzini s 2018 article these concerns include 1 the promotion of erroneous drilling and geological data 2 the inaccurate and unprofessional characterization of scientists who posit opposing interpretations of drilling and geological data 3 the use of deceptive rhetoric 4 the dissemination of misleading and unsubstantiated claims about unnamed stakeholders and 5 the lack of knowledge of and sensitivity toward social contexts after providing an overview of these issues this article focuses on items 3 4 and 5 which tend to be overlooked in ongoing geological discussions on the disaster but have a significant impact on the production circulation and reception of geoscience in both professional and non professional arenas this commentary on miller and mazzini 2018 does not challenge the credibility or integrity of the authors or any scientist associated with the lusi lab but rather argues for a version of geoscience that stays above ground by being conscientious to the social dynamics that impact and are impacted by scientific inquiry without the appropriate care and scholarly caution even the most neutral scientist s work can be perceived as compromised to both scholarly and non scholarly audiences

mud volcanism an updated review abstract mud volcanism or sedimentary volcanism represents one of the most intriguing phenomena of the earth s crust with important implications in energy resource exploration seismicity geo hazard and atmospheric budget of greenhouse gases since the first review papers were issued at the beginning of 2000s a large amount of new geological geophysical and geochemical data has been acquired which clarified ambiguous concepts and significantly improved our knowledge of mud volcanism here we offer an updated review of the knowledge and implications of mud volcanoes with emphasis on the terminology used to describe different processes and structures the physical chemical and morphological characteristics of the several fluid emission structures the chemical properties of the released fluids in particular the molecular and isotopic composition of the gas the mud volcano formation dynamics and the several implications for petroleum exploration geo hazards and global atmospheric methane budget this review integrates new fluids data collected in azerbaijan and is complemented with field observations from various mud volcano provinces worldwide although the total number of mud volcanoes on earth is still uncertain 600 main onshore structures with a large variety in shapes and sizes are documented in recent global data sets and several thousand are assumed to exist in the oceans it is clear that a mud volcanoes are broadly distributed throughout the globe in active margins compressional zones of accretionary complexes thrust and overthrust belts passive margins deep sedimentary basins related to active plate boundaries as well as delta regions b they are specifically located in hydrocarbon bearing basins along anticline axes strike slips and normal faults and fault related folds in petroleum systems c they represent a specific category of natural gas oil seepage manifestation often related to deep and pressurised reservoirs d the main engine driving mud volcanism is given by a combination of gravitative instability of shales and fluid overpressure build up followed by hydrofracturing e hydrocarbons are generally of thermogenic origin while microbial gas is released in only a few cases mud volcanism on other planets e g mars and titan and microbial activity associated with gas seepage represent emerging issues and opportunities for future research

late neogene lacustrine record and palaeogeography in the quillagua llamara basin central andean fore arc northern chile abstract the cenozoic quillagua llamara basin northern chile central andes is an asymmetrical intramassif fore arc basin with a relatively wide northern sector separated from a narrower southward extension by a basement threshold the northern sector was characterised by a noticeable oligocene late neogene alluvial fan and lacustrine dominated deposition which resulted in sequences up to 900 m thick whereas the southern sector was often a bypass zone with thinner fluvial and lacustrine sediment accumulation the basin infill includes two third order alluvial lacustrine unconformity bounded units which include other higher frequency 4th to 5th order sequences the evolution of the late miocene pliocene lacustrine episodes in the quillagua llamara basin was not only controlled by the regional variations from arid to hyperarid palaeoclimate conditions due to the combined influence of the pacific high pressure cell the rain shadow effect exerted by the rising andes and the northward flowing cold oceanic currents but also by a the extensional tectonics and evolution and uplift of the fore arc region which defined the location and size of the depocentres b the resulting basement palaeorelief which affected sediment thickness and facies distribution during the late basin infill episodes and c the tectonic modifications of watersheds water divides and drainage networks in the precordillera which caused considerable changes of water income in the lacustrine systems understanding of this regional tectonosedimentary evolution is a necessary first step before analysing of the low to high order lacustrine sequence changes in the region lacustrine water supply was very sensitive to tectonics even gentle tectonic tilting and uplifting in critical water divide zones could result in changes in water balance in the lacustrine basins and trigger variations in the depositional record the very conspicuous lacustrine regime changes recorded in the quillagua llamara basin infill cannot be considered in themselves conclusive proof of an exclusive climatic forcing since they took place close to either major regional drainage changes or to gentle but noticeable tectonic reactivation in the fore arc region

a new hydrothermal scenario for the 2006 lusi eruption indonesia insights from gas geochemistry abstract the 29th of may 2006 gas and mud eruptions suddenly appeared along the watukosek fault in the north east of java indonesia within a few weeks several villages were submerged by boiling mud the most prominent eruption site was named lusi to date november 2011 lusi is still active and a 7 km2 area is covered by the burst mud breccia the mechanisms responsible for this devastating eruption remain elusive while there is consensus about the origin of the erupted mud the source of water is uncertain the origin of the gas is unknown and the trigger of the eruption is still debated in order to shed light on these unknowns we acquired a wide set of data of molecular and isotopic composition of gas sampled in several lusi vents in the surrounding mud volcanoes in the closest natural gas field wunut and in the hydrothermal vents at the neighbouring volcanic complex in the period 2006 2011 the boiling fluids erupted in the crater zone are apparently co2 dominated while colder ch4 dominated and c2 c3 bearing fluids are identified at several sites around the crater zone gas genetic diagrams maturity plots and gas generation modelling suggest that the hydrocarbons are thermogenic 13c1 up to 35 13c2 up to 20 deriving from marine kerogen with maturity of at least 1 5 ro for instance in the 4400 m deep ngimbang source rocks co2 released from the crater and surrounding seeps is also thermogenic 13c from 15 to 24 related to kerogen decarboxylation or thermal ch4 oxidation in deep rocks although three vents just outside the crater showed an apparent inorganic signature 7 5 4000 m magmatic intrusions and hydrothermal fluids responsible for the enhanced heat that altered source rocks and or gas reservoirs the neighbouring magmatic arjuno complex and its fluid pressure system combined with high seismic activity could have played a key role in the lusi genesis and evolution within this new model framework lusi is better understood as a sediment hosted hydrothermal system rather than a mud volcano

enhanced hydrothermal processes at the new born lusi eruptive system indonesia abstract little is known about the processes taking place in new born hydrothermal systems we investigate the eruptive activity of lusi a sediment hosted hydrothermal system active since 2006 in east java indonesia we show that superimposed on the regular geysering activity lusi features periods of enhanced hydrothermal processes during which boiling mud breccia is violently discharged from the eruptive vents this results in sudden flooding lasting from several minutes to several hours and featuring almost instantaneous temperature peaks i e from 35 c to more than 65 c in less than 2 min such activity here named hydrothermal waves is marked by high frequency seismic radiations and is distinguished by sharp peaks of ch4 and co2 concentrations in the erupted fluids this suggests fluids upwelling from at least tents of meters below the near surface the injection into the shallow plumbing system of ch4 and co2 rich batches of fluids may promote instabilities in the mud breccia column leading to the hydrothermal waves our findings provide key insights into the deep charging dynamics of a new born hydrothermal system and highlight the effects imposed by subtle variations in fluid chemistry changes at depth

the 11 april 2012 east indian ocean earthquake triggered large aftershocks worldwide although strong remote aftershocks are exceedingly rare their rate increased fivefold during the six days following the 2012 east indian ocean earthquake perhaps as a result of the strike slip nature of the 2012 event or a build up of close to failure nucleation sites

climatic and volcanic forcing revealed in a 50 000 year diatom record from lake massoko tanzania the interactions between climatic and volcanic forcing on diatom communities contained in a 50 000 year sedimentary sequence from lake massoko tanzania were examined at the century scale 19 discrete tephra inputs to the lake isolated the sedimentary nutrient supply and shifted the diatom communities to those tolerant of low phosphorus levels whereas at the millennial scale diatom inferred shifts in precipitation evaporation based on conductivity optima and diatom life form ratios were broadly similar to lake level reconstructions from lake rukwa lake malawi and others in the region some fluctuations of lake massoko are consistent with the precession driven changes in insolation but the major climate shifts do not relate directly to orbital forcing of summer insolation south of the equator and show more consistency with records from the equatorial and northern tropics that receive rainfall from the passing of the intertropical convergence zone sea surface temperatures are strongly correlated to multimillennial scale climate patterns over this region of africa

northridge earthquake damage caused by geologic focusing of seismic waves despite being located 21 kilometers from the epicenter of the 1994 northridge earthquake magnitude 6 7 the city of santa monica experienced anomalously concentrated damage with mercalli intensity ix an intensity as large as that experienced in the vicinity of the epicenter seismic records from aftershocks suggest that the damage resulted from the focusing of seismic waves by several underground acoustic lenses at depths of about 3 kilometers formed by the faults that bound the northwestern edge of the los angeles basin the amplification was greatest for high frequency waves and was less powerful at lower frequencies which is consistent with focusing theory and finite difference simulations

lacustrine sedimentation in active volcanic settings the late quaternary depositional evolution of lake chungara northern chile lake chungara 18 15 s 69 09 w 4520 m above sea level is the largest 22ae5 km2 and deepest 40 m lacustrine ecosystem in the chilean altiplano and its location in an active volcanic setting provides an opportunity to evaluate environmental volcanic vs climatic controls on lacustrine sedimentation the late quaternary depositional history of the lake is reconstructed by means of a multiproxy study of 15 kullenberg cores and seismic data the chronological framework is supported by 10 14c ams dates and one 230th 234u dates lake chungara was formed prior to 12ae8 cal kyr bp as a result of the partial collapse of the parinacota volcano that impounded the lauca river the sedimentary architecture of the lacustrine succession has been controlled by i the strong inherited palaeo relief and ii changes in the accommodation space caused by lake level fluctuations and tectonic subsidence the first factor determined the location of the depocentre in the nw of the central plain the second factor caused the area of deposition to extend towards the eastern and southern basin margins with accumulation of high stand sediments on the elevated marginal platforms synsedimentary normal faulting also increased accommodation and increased the rate of sedimentation in the northern part of the basin six sedimentary units were identified and correlated in the basin mainly using tephra keybeds unit 1 late pleistocene early holocene is made up of laminated diatomite with some carbonate rich calcite and aragonite laminae unit 2 mid holocene recent is composed of massive to bedded diatomite with abundant tephra lapilli and ash layers some carbonate rich layers calcite and aragonite occur unit 3 consists of macrophyte rich diatomite deposited in nearshore environments unit 4 is composed of littoral sediments dominated by alternating charophyterich and other aquatic macrophyte rich facies littoral carbonate productivity peaked when suitable shallow platforms were available for charophyte colonization clastic deposits in the lake are restricted to lake margins units 5 and 6 diatom productivity peaked during a lowstand period unit 1 and subunit 2a and was probably favoured by photic conditions affecting larger areas of the lake bottom offshore carbonate precipitation reached its maximum during the early to mid holocene ca 7ae8 and 6ae4 cal kyr bp this may have been favoured by increases in lake solute concentrations resulting from evaporation and calcium input because of the compositional changes in pyroclastic supply diatom and pollen data from offshore cores suggest a number of lake level fluctuations a late pleistocene deepening episode ca 12ae6 cal kyr bp four shallowing episodes during the early to mid holocene ca 10ae5 9ae8 7ae8 and 6ae7 cal kyr bp and higher lake levels since the mid holocene ca 5ae7 cal kyr bp until the present explosive activity at parinacota volcano was very limited between c 12ae8 and 7ae8 cal kyr bp mafic rich explosive eruptions from the ajata satellite cones increased after ca 5ae7 cal kyr bp until the present

insights on the structure of lusi mud edifice from land gravity data abstract since may 2006 the active lusi mud eruption has continuously erupted boiling mud during the early stages of the eruption in 2006 previous gravity studies showed that the piling up of the mud constructed a large edifice that subsides within the unconsolidated sediment especially around a large area over the active crater after ten years of continuous eruption the size of the edifice has grown significantly over a surface framed by 10 m tall containment embankments in 2015 and 2016 several land gravity surveys were carried out to investigate the structure of the mud edifice and the effect of local geological active features the new residual bouguer anomaly map calculated for a reference density of 2670 kg m 3 shows significant changes in the local gravity field in comparison to the previous 2006 gravity map survey the new data set shows that the gravity decrease is generally restricted along the faulted and fractured zones around erupting vents and in the southern part of the mud edifice maximum gravity variations reach 1 4 mgal in some areas of the mud edifice in the region outside the embankment the gravity reductions are 0 6 mgal e w and 1 0 mgal n s a second vertical derivative analysis of gravity data indicates that the mud edifice continues to pile up and subside mostly in the western and southern part of the edifice results of a 3d forward model of a vertical cylinder shape allowed characterising the extent of compacted material along the watukosek fault system that originates from the neighbouring volcanic arc and crosses the mud edifice our results support the hypothesis of local pinched volume of mud ongoing between the subsided and uplifted masses of mud the density of compacted mud breccia material increases between 16 and 27 gravity data also shows that the lusi mud edifice is built over an extended nw se gravity increase interpreted as a sediment density variation within the basin and which is parallel to the trend of the basin

the deep subsurface structure beneath lusi and the adjacent volcanic chain inferred from local travel time tomography abstract 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

seismic activity of the nevados de chillan volcanic complex after the 2010 mw8 8 maule chile earthquake abstract couplings between large magnitude subduction zone earthquakes and the subsequent response of their respective volcanic arcs are generally accepted but the mechanisms driving this coupling are not known the 2010 maule earthquake mw8 8 ruptured approximately 500 km along strike in the south central part of chile and provides an opportunity to investigate earthquake volcano interactions in an exploratory campaign we deployed four broadband seismometers atop and surrounding the nevados de chillan volcanic complex because it is located directly behind one of the two primary slip patches of the maule earthquake the data recorded from december 2011 to april 2012 shows significant seismic activity characterized by numerous volcano tectonic events and tremor episodes occurring within the volcanic complex we recorded two strong aftershocks of the maule earthquake mw 6 1 in january 2012 and mw 7 1 in april 2012 and investigated the response of the volcano to the incoming seismic energy we find that volcanic tremor increased significantly upon arrival of the seismic waves from the mw 6 1 event which was then followed a few hours later by a significant increase in volcano tectonic events when tremors subsided this delay between tremor and volcano tectonic events suggests that fluid and or magma migration manifested as tremor readjusted the local stress state that then induced the volcano tectonic events the increased activity persisted during the subsequent two weeks in contrast the mw 7 1 event which occurred at a similar epicentral distance from the volcano did not produce any significant seismic response of the volcanic complex analysis of the particle velocity records of the two events shows that the volcanic system was perturbed in different ways because of the incidence angle of the incoming energy inducing a back elliptical vertical and fault parallel motion for the mw 6 1 and no clear directional dependence for the mw 7 1 this suggests dilatation induced fluid migration within the complex and a kinematic mechanism of the perturbation rather than the perturbation amplitude our results demonstrate the importance for continued monitoring of the arc behind maule with an increased seismometer and gps array density to determine the style of deformation currently occurring in the arc

lusi mud eruption triggered by geometric focusing of seismic waves the lusi mud eruption in indonesia has been ongoing since 2006 numerical simulations show that a parabolic shaped layer in the rock surrounding the site of the lusi eruption could have amplified and focussed incoming seismic energy from an earthquake which then triggered the mud eruption

modelling of gas generation following emplacement of an igneous sill below lusi east java indonesia highlights we have tested a hypothesis where a sill intrusion is present at depth near lusi we have calculated the co2 generation following the emplacing a 150 m sill in an organic rich sequence at 4 5 km this scenario may provide the co2 currently emitted from lusi and are consistent with geological information abstract the lusi mud eruption started in 2006 and is located near the arjuno welirang volcanic complex in northeastern java lusi is characterized by the eruption of aqueous vapor co2 and ch4 in addition to mud breccia and boiling water however the ultimate driving force for the eruption remains unclear here we investigate if lusi could have been driven by the heat released from a deep seated igneous sill originating from the neighboring volcanic arc we have used a 1d thermal model to calculate the production of co2 from thermally matured organic matter in the contact aureole of a hypothetical 150 m thick sill the sill is tentatively emplaced at 1100 c at 4 5 km depth within the organic rich eocene ngimbang formation the carbon gas produced from the thermal perturbation reaches a peak of 1357 kg m2 y co2 equivalents shortly after sill emplacement stressing the efficiency of organic matter transformation in contact aureoles our simulations show that during the first 1000 years after emplacement 53 5 ton co2 m2 is produced in the contact aureole when scaled to a sill size of 150 m 25 km2 i e a sill volume of 3 75 km3 the aureole has the potential to generate a total of 1350 mt co2 during the first 1000 years with a peak generation of about 34 mt co2 y we conclude that contact metamorphism in our hypothetical geological scenario generates co2 in the gigaton range and represents a plausible source for the lusi gas

transient tectonic regimes imposed by megathrust earthquakes and the growth of nw trending volcanic systems in the southern andes abstract geophysical data show that megathrust earthquakes can promote transient tectonic regimes lasting up to several decades however such variations are not trivial to be recognises in the geological records of volcanic arcs to better understand the occurrence of transient tectonic regimes we study the inter and post seismic deformation in the upper crust of the andean volcanic arc affected by the m8 8 2010 maule earthquake we focus on the region around the nevados de chillan volcanic complex southern central chile where we compare geological and earthquakes data this nw oriented andean transverse volcanic complex faces one of the regions that slipped the most during the 2010 m8 8 maule earthquake field fault slip data from lithostratigraphic units forming the basement of nevados de chillan volcanic complex point out three tectonic regimes the principal is driven by a sub horizontal and ne oriented 1 transpressional kinematics this regime is compatible with today s gps data recorded during inter seismic periods the second and third tectonic regimes are less abundant and indicate transpression 1 sub horizontal and nw oriented and normal 1 sub vertical and e w oriented faulting respectively the geological record was also compared with seismic data acquired from 2010 to 2015 in the investigated region the moderate magnitude seismic activity occurred beneath the volcanic arc after the maule earthquake points out an enhanced crustal deformation if compared to inter seismic periods the inversion of focal mechanisms suggests that intra arc regions may experience a short lived post seismic transtensional regime with an e w oriented 1 with a dip of about 45 our work suggests that megathrust earthquakes impose transient stress variations in the volcanic arc possibly reactivating oligo miocene nw striking inherited crustal structures upon which volcanic edifices develop this may help explaining the occurrence of andean transverse volcanic complexes oriented sub perpendicular to the ne oriented 1 driving convergence in the southern andes

activation of gas bubble emissions indicated by the upward decreasing lead 210 activity at a submarine mud volcano ty1 offshore southwestern taiwan abstract a submarine mud volcano mv known as ty1 is one of the largest conical structures found offshore southwestern taiwan active gas bubble emissions at the flat crest of the mud volcano disperse sediment particles into the water column changes in the mud volcanism of ty1 were revealed by radiograph and grain size analysis of the sediment cores 210 pb geochronology was applied to the near seafloor sediments to reveal the detailed mud volcanism from the deposition rate in a 58 cm long sediment core taken from the northern margin of the crest known as ty1 n 170 the size and frequency of the mud clasts decrease upward the clasts are smaller than 8 mm above a sediment depth of 34 cm below the sea floor cmbsf sediments between 0 and 19 cmbsf are massive and particles larger than 2 mm are absent an enrichment of coarse silt sized particles in the massive sediment unit and the restricted distribution of the unit suggest that the massive unit was generated by re deposition of sediment particles that were dispersed into the water column by gas bubble emission these characteristics suggest that during the last mud volcanism of ty1 there was a decrease in mud eruption energy and gas bubble emission became the main activity in core ty1 s 440 taken from the southern slope a massive sediment unit enriched with coarse silt sized particles is intercalated between mud breccia structures this suggests repeated mud breccia flows caused by ty1 the excess 210 pb activity present in the massive sediment unit of ty1 n 170 suggests activation of gas bubble emission in the massive unit a decrease in excess 210 pb activity appears upward toward the seafloor the highest value is 3 1 dpm g at 19 8 cmbsf 26 4 g cm 2 in cumulative mass values lower than 1 0 dpm g are distributed 2 8 6 8 cmbsf 3 6 8 8 g cm 2 the upwardly decreasing trend is opposite that of the reference core from which a reasonable areal sedimentation rate was obtained using a constant flux constant sedimentation model the anomalous depth profile at the massive unit indicates an increasing rate of sediment deposition which originated from the activation of gas bubble emission

deep 3 d seismic reflection imaging of precambrian sills in southwestern alberta canada abstract a number of bright reflector sequences within the crystalline basement were imaged on 2 d multichannel crustal seismic reflection profiles collected by lithoprobe from 1991 to 1995 one such sequence in southern alberta the head smashed in hsi reflector spans a depth range of 6 21 km with an aerial extent of at least 6000 km2 this series of reflectors and similar sequences in central alberta and northern saskatchewan have been interpreted as packages of horizontal sheet like mafic sills that intruded the precambrian basement hundreds of millions of years after crustal formation in 1999 through our request to extend an exploration survey to longer travel times a partnership group from the canadian petroleum industry recorded a 9 by 6 km 3 d reflection dataset to 8 s two way traveltime twtt at a location southwest of the hsi reflector following processing which included a special procedure to remove strong ground roll that persisted at travel times of interest we identified a sequence of reflections between 4 and 5 s that we correlate with those associated with the hsi reflector however the reflections are not as bright or as continuous as those on the 2 d profiles based on these results and the characteristics of the sills on the lithoprobe data we infer that we imaged the feathering ends of the sill intrusions such sills represent a net addition of crustal material and may provide insight into the ancient stress field during emplacement and clues as to how cratons achieve their thickness and stability although the survey area is small this study represents the first attempt in north america and only the second in the world to examine upper middle crustal structure to depths of approximately 20 km using industry style 3 d seismic reflection data the results indicate that industry 3 d data with extended recording times could provide useful information for studying the crystalline crust below sedimentary basins

seismic triggering by rectified diffusion in geothermal systems widespread seismicity was triggered by the june 28 1992 landers california earthquake at a rate which was maximum immediately after passage of the exciting seismic waves rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake in a hydrothermal system modeled as a two component h 2o co 2 fluid in porous rock the pressure initially increases linearly with time the rate of pressure buildup depends sensitively on the mean bubble radius and is large for small bubbles the diffusion induced pressure is relaxed by percolation and resorption of vapor into the liquid solution the induced seismicity itself also relieves stress values of parameters used in the present calculations give results consistent with observations of triggered seismicity at long valley caldera after the landers earthquake for one representative condition at 250 c and 5 6 km depth oscillating strain acting on 10 m diameter bubbles increases pore pressure at the rate of 151 pa s resulting in a pressure increase of 12 kpa in the 80 s duration of the landers earthquake the elevated pressure induced by a single 26 m diameter cloud of bubbles in saturated rock relaxes by percolation through soil of 0 2 mdarcy permeability in 53 6 hours observations of earthquake swarms at other locations suggest that self induced buildup of pore pressure by rectified diffusion can provide a positive feedback mechanism for amplifying seismicity

the east java mud volcano 2006 to present an earthquake or drilling trigger abstract on may 29th 2006 a mud volcano later to be named lusi started to form in east java it is still active and has displaced 30 000 people the trigger mechanism for this the world s largest and best known active mud volcano is still the subject of debate trigger mechanisms considered here are a the may 27th 2006 yogyakarta earthquake b the drilling of the nearby banjar panji 1 gas exploration well 150 m away and c a combination of the earthquake and drilling operations we compare the distance and magnitude of the earthquake with the relationship between the distance and magnitude of historical earthquakes that have caused sediment liquefaction or triggered the eruption of mud volcanoes or caused other hydrological responses based on this comparison an earthquake trigger is not expected the static stress changes caused by the rupture of the fault that created the yogyakarta earthquake are a few tens of pascals much smaller than changes in stress caused by tides or variations in barometric pressure at least 22 earthquakes and possibly hundreds likely caused stronger ground shaking at the site of lusi in the past 30 years without causing an eruption the period immediately preceding the eruption was seismically quieter than average and thus there is no evidence that lusi was primed by previous earthquakes we thus rule out an earthquake only trigger the day before the eruption started may 28th 2006 as a result of pulling the drill bit and drill pipe out of the hole there was a significant influx of formation fluid and gas the monitored pressure after the influx in the drill pipe and annulus showed variations typical of the leakage of drilling fluid into the surrounding sedimentary rock strata furthermore we calculate that the pressure at a depth of 1091 m the shallowest depth without any protective steel casing exceeded a critical level after the influx occurred fractures formed due to the excess pressure allowing a fluid gas mud mix to flow to the surface with detailed data from the exploration well we can now identify the specific drilling induced phenomena that caused this man made disaster

the plumbing system feeding the lusi eruption revealed by ambient noise tomography lusi is a sediment hosted hydrothermal system featuring clastic dominated geyser like eruption behavior in east java indonesia we use 10 months of ambient seismic noise cross correlations from 30 temporary seismic stations to obtain a 3 d model of shear wave velocity anomalies beneath lusi the neighboring arjuno welirang volcanic complex and the watukosek fault system connecting the two our work reveals a hydrothermal plume rooted at a minimum 6 km depth that reaches the surface at the lusi site furthermore the inversion shows that this vertical anomaly is connected to the adjacent volcanic complex through a narrow 3 km wide low velocity corridor slicing the survey area at a depth of 4 6 km the ne sw direction of this elongated zone matches the strike of the watukosek fault system distinct magmatic chambers are also inferred below the active volcanoes the large scale tomography features an exceptional example of a subsurface connection between a volcanic complex and a solitary erupting hydrothermal system hosted in a hydrocarbon rich back arc sedimentary basin these results are consistent with a scenario where deep seated fluids e g magmas and released hydrothermal fluids flow along a region of enhanced transmissivity i e the watukosek fault system damage zone from the volcanic arc toward the back arc basin where lusi resides the triggered metamorphic reactions occurring at depth in the organic rich sediments generated significant overpressure and fluid upwelling that is today released at the spectacular lusi eruption site

strike slip faulting as a trigger mechanism for overpressure release through piercement structures implications for the lusi mud volcano indonesia piercement structures such as hydrothermal vent complexes pockmarks and mud volcanoes are found in various geological settings but are often associated with faults or other fluid focussing features this article aims to investigate and understand the mechanisms responsible for the formation of piercement structures in sedimentary basins and the role of strike slip faulting as a triggering mechanism for fluidization for this purpose four different approaches were combined fieldwork analogue experiments and math

regional earthquake as a trigger for enhanced volcanic activity evidence from modis thermal data 1 the magnitude 6 4 earthquake that occurred in java on 26 may 2006 provided us with data capable of revealing an immediate eruptive response at two javanese volcanoes merapi and semeru the availability of pre processed thermal data for volcanic hot spots detected by the moderate resolution imaging spectrometer modis and provided on http hotspot higp hawaii edu allowed us to produce heat and volume flux time series for these two erupting volcanoes covering a 35 day period spanning the earthquake our results revealed a coupled response by the volcanoes to the earthquake both experiencing increases in heat and volume flux beginning 3 days after the earthquake with the response lasting 9 days the response was felt at both volcanoes as a factor of two to three increase in the rate of volumetric output after which output returned to the pre response rates this implies that the earthquake triggered enhanced output at two erupting volcanoes 50 and 300 km distant from the earthquake epicenter and separated from each other by 260 km

the lusi mud volcano triggering controversy was it caused by drilling abstract following the yogyakarta earthquake on may 27th 2006 the subsequent eruption of a mud volcano has been closely observed and analyzed by the geological community the mud volcano known as lusi began erupting near the banjarpanji 1 exploration well in sidoarjo east java indonesia lusi offers a unique opportunity to study the genesis and development of a mud volcano for the first time this paper presents all raw and interpreted drilling data so any interested party can perform their own assessment our study suggests that lusi mud volcano was a naturally occurring mud volcano in an area prone for its mud volcanism pressure analysis done on the banjarpanji well shows that the pressure exerted at the well is lower than the fracture pressure at the last casing shoe and suggests that the well was intact and did not suffer an underground blowout this is further supported by evidence and observation made during drilling such as circulation was done on an open bop and subsequent relief wells sonan and temperature log runs this study offers a different alternative to earlier hypothesis that events at the banjarpanji well were the trigger for the lusi mud volcano more work is needed by the scientific community to study the sequence of events in order to explain and clarify the real trigger of lusi