palaeoclimate change recorded in upper cretaceous albian cenomanian kazhdumi formation borehole spectral gamma ray logs south pars gas field persian gulf abstract th u and th k data from spectral gamma ray logs obtained from outcrop successions have been used as a rapid and inexpensive proxy for determining possible episodes of humid arid palaeoclimate change such outcrop based measurements have never been tested using spectral gamma ray data obtained from wireline logs in subsurface boreholes th k and th u ratios have traditionally been used to decipher sequence stratigraphic patterns at outcrop and in borehole the possible influence of palaeoclimate on such ratio changes has yet to be proven especially from borehole data in this work we compare borehole derived th k and to a lesser extent th u to palaeoenvironmental changes inferred from palynology and deduce that both sea level and changing hinterland weathering regimes caused discrete fluctuations observed in the spectral gamma ray logs this is the first time such subsurface information has been used in this way interpretation of wireline logs in terms of palaeoclimate as well as sea level may now be considered and the use of such logs in palaeoclimate reconstruction is strengthened

total co2 output from vulcano island aeolian islands italy 1 total co2 output from fumaroles soil gas bubbling gas discharges and water dissolved gases discharged from the island was estimated for vulcano island italy the co2 emission from fumaroles from the la fossa summit crater was estimated from the so2 crater output while co2 discharged through diffuse soil emission was quantified on the basis of 730 measurements of co2 fluxes from the soil of the island performed by using the accumulation chamber method the results indicate an overall output of 500 t day 1 of co2 from the island the main contribution to the total co2 output comes from the summit area of the la fossa cone 453 t day 1 with 362 t day 1 from crater fumaroles and 91 t day 1 from crater soil degassing the release of co2 from peripheral areas is 20 t day 1 by soil degassing palizzi and istmo areas mainly an amount comparable to both the contribution of water dissolved co2 6 t day 1 as well as to seawater bubbling co2 4 t day 1 measured in the istmo area presented data september 2007 refer to a period of moderate solphataric activity when the fumaroles temperature were 450 c and gas water molar ratio of fumaroles was up to 0 16 the calculated total co2emission allows the estimation of the mass release and related thermal energy from the volcanic hydrothermal system

regional stratigraphy of the zagros fold thrust belt of iran and its proforeland evolution the latest neoproterozoic through phanerozoic stratigraphy of the zagros fold thrust belt of iran has been revised in the light of recent investigations the revised stratigraphy consists of four groups of rocks each composed of a number of unconformity bounded megasequences representing various tectonosedimentary settings in the lowest group ranging in age from latest precambrian to devonian the uppermost neoproterozoic to middle cambrian rocks constitute a megasequence of evaporites siliciclastic deposits and interlayered carbonates which were deposited in pull apart basins that developed by the najd strike slip fault system this megasequence is overlain by a second one middle to late cambrian in age which consists of shallow marine siliciclastic and carbonate rocks representing deposition in an epicontinental platform the overlying shales siltstones and partly volcanogenic sandstones of ordovician silurian and devonian age are local remnants of stratigraphic units that were extensively eroded during development of several major unconformities the second group consists of two megasequences one permian and the other triassic composed of widespread transgressive basal siliciclastic rocks and overlying evaporitic carbonates of an equatorial epi pangean very shallow platformal sea the third group is composed of four megasequences formed of shallow and deep water carbonates with some siliciclastic and evaporite deposits which accumulated on a neo tethyan continental shelf during earliest jurassic through late turonian time the fourth group comprises siliciclastic and carbonate deposits of a largely underfilled nw to se trending forward and backward migrating late cretaceous to recent proforeland basin which has evolved as an integral part of the zagros orogen this last group consists of three megasequences ix x and xi with distinctive lateral and vertical facies variations which reflect specific tectonic events megasequence ix comprises uppermost turonian to middle maastrichtian prograding and retrograding siliciclastic and carbonate deposits whose accumulations reflect emplacement obduction of ophiolite slivers and subsequent collisional events in the zagros orogen megasequence x consists of uppermost maastrichtian to upper eocene siliciclastic and carbonate rocks which deposited first progradationally in front of the zagros orogenic wedge with reduced contractional tectonic activity and then retrogradationally due to intensified thrust stacking in the interior parts of the orogen megasequence xi consists of oligocene and lower miocene carbonate strata deposited retrogradationally shortly after a period of intensified late eocene thrust faulting in the deformational wedge and an overlying succession of upward coarsening northeasterly derived siliciclastic deposits of lower miocene to recent age which are composed of erosional byproducts of the southwest vergent zagros thrust sheets

earthquake triggering along the xianshuihe fault zone of western sichuan china western sichuan is among the most seismically active regions in southwestern china and is characterized by frequent strong m 6 5 earthquakes mainly along the xianshuihe fault zone historical and instrumental seismicity show a temporal pattern of active periods separated by inactive ones while in space a remarkable epicenter migration has been observed during the last active period starting in 1893 the sinistral strike slip xianshuihe fault of 350 km total length was entirely broken with the epicenters of successive strong earthquakes migrating along its strike this pattern is investigated by resolving changes of coulomb failure function cff since 1893 and hence the evolution of the stress field in the area during the last 110 years coulomb stress changes were calculated assuming that earthquakes can be modeled as static dislocations in an elastic halfspace and taking into account both the coseismic slip in strong m 6 5 earthquakes and the slow tectonic stress buildup associated with major fault segments the stress change calculations were performed for faults of strike dip and rake appropriate to the strong events we evaluate whether these stress changes brought a given strong earthquake closer to or sent it farther from failure it was found that all strong earthquakes and moreover the majority of smaller events for which reliable fault plane solutions are available have occurred on stress enhanced fault segments providing a convincing case in which coulomb stress modeling gives insight into the temporal and spatial manifestation of seismic activity we extend the stress calculations to the year 2025 and provide an assessment for future seismic hazard by identifying the fault segments that are possible sites of future strong earthquakes

evidence for a new shallow magma intrusion at la soufriere of guadeloupe lesser antilles insights from long term geochemical monitoring of halogen rich hydrothermal fluids more than three decades of geochemical monitoring of hot springs and fumaroles of la soufriere of guadeloupe allows the construction of a working model of the shallow hydrothermal system this system is delimited by the nested caldera structures inherited from the repeated flank collapse events and the present dome built during the last magmatic eruption 1530 ad and which has been highly fractured by the subsequent phreatic or phreatomagmatic eruptions because it is confined into the low volume highly compartmented and partially sealed upper edifice structure the hydrothermal system is highly reactive to perturbations in the volcanic activity input of deep magmatic fluids the edifice structure sealing and fracturing and meteorology wet tropical regime the current unrest which began with a mild reactivation of fumarolic activity in 1990 increased markedly in 1992 with seismic swarms and an increase of degassing from the summit of the dome in 1997 seismic activity increased further and was accompanied by a sudden high flux hcl rich gas from summit fumaroles we focus on the interpretation of the time series of the chemistry and temperature of fumarolic gases and hot springs as well as the relative behaviours of halogens f cl br and i this extensive geochemical time series shows that the deep magmatic fluids have undergone large changes in composition due to condensation and chemical interaction with shallow groundwater scrubbing it is possible to trace back these processes and the potential contribution of a deep magmatic source using a limited set of geochemical time series t co2 and total s content in fumaroles t and cl in hot springs and the relative fractionations between f cl br and i in both fluids coupling 35 years of geochemical data with meteorological rainfall data and models of ion transport in the hydrothermal aquifers has allowed us to identify a series of magmatic gas pulses into the hydrothermal system since the 1976 1977 crisis the contrasting behaviours of s and cl bearing species in fumarolic gas and in thermal springs suggests that the current activity is the result of a new magma intrusion which was progressively emplaced at shallow depth since 1992 although it might still be evolving the characteristics of this new intrusion indicate that it hasalready reached a magnitude similar to the intrusion that was emplaced during the 1976 1977 eruptive crisis the assessment of potential hazards associated with evolution of the current unrest must consider the implications of recurrent intrusion and further pressurization of the hydrothermal system on the likelihood of renewed phreatic explosive activity moreover the role of hydrothermal pressurization on the basal friction along low strength layers within the upper part of the edifice must be evaluated with regards to partial flank collapse at this stage enhanced monitoring research and data analysis is required to quantify the uncertainties related to future scenarios of renewed eruptive activity and magmatic evolution

origin of the fumarolic fluids of vulcano island italy and implications for volcanic surveillance variations in d and 18o values with h2o contents and outlet temperatures indicate that the fumaroles of la fossa crater have discharged mixtures of magmatic water and marine hydrothermal water since 1979 the contribution of meteoric water was low in the period 1979 1982 and very low afterwards the 18o values of the marine hydrothermal component of 5 to 7 2 are due to isotopic exchange with the 18o rich silicates of the rocks under high temperature and low permeability conditions the 18o value of the magmatic end member is generally 3 5 to 4 3 although values as high as 5 5 to 6 5 were reached in the summer of 1988 when magma degassing appears to have extended into the core of the magma body the d values of the end member were close to 20 typical of andesitic waters both the isotopic values and chemical data strongly support a dry model consisting of a central magmatic gas column and a surrounding hydrothermal envelope in which marine hydrothermal brines move along limited fracture zones to undergo total evaporation on approaching the conduits of magmatic fluids the vents at the eastern and western boundaries of the fumarolic field are fed by fluids whose pressure is governed by the coexistence of vapor liquid and halite giving rise to a high risk of phreato magmatic explosions should magma penetrate into these wet environments most la fossa eruptions were triggered by an initial hydrothermal blast and continued with a series of phreatomagmatic explosions the fluids discharged by the forgia vecchia fumaroles are mixed with meteoric water which is largely evaporated although subordinate loss of condensed steam may be responsible for scrubbing most of the acidic gas species the temperatures and pressures and the risk of a sudden pressure increase are low a boiling hydrothermal aquifer at 230 c is present underneath the baia di levante beach this area has a minor risk of hydrothermal explosions

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

interseismic slip rate of the northwestern xianshuihe fault from insar data 1 the xianshuihe fault is a highly active strike slip fault system near the eastern margin of the tibetan plateau we use a multi interferogram method to construct a map of line of sight deformation rate due to interseismic strain accumulation on the northwestern xianshuihe fault from a decade of sar data acquired by the ers 1 2 and envisat satellites the rate map shows a clear deformation gradient associated with the fault but slightly offset to the northeast from the surface trace joint inversion of insar rate map and gps data using monte carlo method we estimate a slip rate of 9 12 mm yr with a locking depth of 3 6 km at the 90 confidence level the slip rate agrees with the holocene fault slip rate and the historical earthquakes our results also suggest no significant across fault extension in the future insar data from both ascending and descending orbits may further constrain the 3 d fault slip rate on this fault

source rock distribution and maturation in the zagros orogenic belt provenance of the asmari and bangestan reservoir oil accumulations abstract the zagros orogenic belt of iran is one of the most prolific petroliferous areas accounting for approx 12 of proven global reserves correlation techniques reveal that a majority of the oils variously reservoired in asmari oligo miocene and bangestan group upper cretaceous anticlinal structures share a common provenance oils of the n e khuzestan fields are an exception showing a conspicuously different origin candidate source potential for the crucial central zagros embayment and contiguous areas was assessed on field survey and from well materials collected during the decade from 1968 onwards although varying locally in vertical and lateral distribution attractive sources occur throughout the section included were silurian shales the sargelu middle jurassic garau gadvan lower cretaceous kazhdumi albian gurpi upper cretaceous and pabdeh paleogene fms maturation of these source units was essentially controlled by the foredeep subsidence related to the zagros orogeny being a neogene event hydrocarbon generation and migration are very recent and essentially synorogenic consolidation of this information with the real distribution of candidate sources application of carbon isotope based source oil assignments and biomarker results successfully differentiated the provenance of the generic oil groupings over much of khuzestan the kazhdumi was recognised as the major contributor elsewhere the pabdeh fm yields isotopically distinctive oils in n e khuzestan evaluation of this basin allowed identification of prolific source rocks in low energy euxinic argillaceous lime mudstones similarly it provided an early application of pyrolysis techniques carbon isotopic correlations and subsidence history maturation migration modelling approaches now routinely employed in basin evaluation

geochemical evidence of the renewal of volcanic activity inferred from co2 soil and so2 plume fluxes the 2007 stromboli eruption italy on 27 february 2007 a new eruption occurred on stromboli which lasted until 2 april it was characterized by effusive activity on the sciara del fuoco and by a paroxysmal event 15 march this crisis represented an opportunity for us to refine the model that had been developed previously 2002 2003 eruption and to improve our understanding of the relationship between the magmatic dynamics of the volcano and the geochemical variations in the fluids in particular the evaluation of the dynamic equilibrium between the volatiles co2 and so2 released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of criticality of the volcanic activity one of the major accomplishments of this study is a 4 year database of summit soil co2 flux on the basis of which we define the thresholds low medium high for this parameter that are empirically based on the natural volcanological evolution of stromboli the so2 fluxes of the degassing plume and the co2 fluxes emitted from the soil at pizzo sopra la fossa are also presented it is noteworthy that geochemical signals of volcanic unrest have been clearly identified before during and after the effusive activity these signals were found almost simultaneously in the degassing plume so2 flux and in soil degassing co2 flux at the summit although the two degassing processes are shown to be clearly different the interpretation of the results will be useful for future volcanic surveillance at stromboli

source processes of large earthquakes along the xianshuihe fault in southwestern china the xianshuihe fault is one of the most active faults in southwestern china recently three large earthquakes occurred along it in 1967 m s 6 1 1973 m s 7 5 and 1981 m s 6 8 the 1981 event occurred near the central portion of the fault zone modeling of the body and surface waves indicates pure left lateral strike slip motion on a vertical fault striking n40 w consistent with the surface trend of the xianshuihe fault two major ruptures are suggested for this source with a total moment of 1 3 10 26 dyne cm the 1973 event occurred about 65 km northwest of the 1981 event and ruptured about 90 km bilaterally along the fault the body wave synthetics indicate three main ruptures during faulting within 43 sec with a total moment of 1 8 10 27 dyne cm the mechanisms are similar to the 1981 event and the average slip is determined to be 3 8 m the largest aftershock m s 5 9 occurred 1 day after the main event with a normal fault mechanism striking almost perpendicular to the surface breakage the 1967 event occurred at the northwestern end of the fault zone with a strike of n65 e it had a nearly normalfault mechanism with a seismic moment of 4 5 10 25 dyne cm the largest aftershock m s 5 1 occurred 7 hr later with a similar focal mechanism the primary faulting along the xianshuihe fault is left lateral strike slip but the normal faulting with strike direction about perpendicular to the xianshuihe fault trace is common especially in the northwestern segment the faulting pattern in this region is consistent with the regional stress field caused by the india tibet collision the normal event which is not on the major fault seems to have more frequent foreshocks and aftershocks than those on the main fault

response of the san andreas fault to the 1983 coalinga nunez earthquakes an application of interaction based probabilities for parkfield 1 the parkfield cholame section of the san andreas fault site of an unfulfilled earthquake forecast in 1985 is the best monitored section of the world s most closely watched fault in 1983 the m 6 5 coalinga and m 6 0 nunez events struck 25 km northeast of parkfield seismicity rates climbed for 18 months along the creeping section of the san andreas north of parkfield and dropped for 6 years along the locked section to the south right lateral creep also slowed or reversed from parkfield south here we calculate that the coalinga sequence increased the shear and coulomb stress on the creeping section causing the rate of small shocks to rise until the added stress was shed by additional slip however the 1983 events decreased the shear and coulomb stress on the parkfield segment causing surface creep and seismicity rates to drop we use these observations to cast the likelihood of a parkfield earthquake into an interaction based probability which includes both the renewal of stress following the 1966 parkfield earthquake and the stress transfer from the 1983 coalinga events we calculate that the 1983 shocks dropped the 10 year probability of a m 6 parkfield earthquake by 22 from 54 22 to 42 23 and that the probability did not recover until about 1991 when seismicity and creep resumed our analysis may thus explain why the parkfield earthquake did not strike in the 1980s but not why it was absent in the 1990s we calculate a 58 17 probability of a m 6 parkfield earthquake during 2001 2011 index terms 7223 seismology seismic hazard assessment and prediction 7230 seismology seismicity and seismotectonics 7260 seismology theory and modeling keywords coalinga earthquake parkfield stress change earthquake probability seismicity rate

influence of rainfalls on heat and steam fluxes of fumarolic zones six months records along the ty fault soufriere of guadeloupe lesser antilles fumarolic zones are permeable areas where both steam and heat are expelled to the atmosphere surface fluxes and flows which are representative of the intensity of the hydrothermal circulation in depth can be monitored by thermometers thermal infrared cameras spectrometers or condensers however the superficial activity of fumarolic zones can be modified by the meteorological conditions in particular the rainfalls which might result in erroneous estimations from this perspective we developed a set of physical equations to quantify the effects of rainfalls on the thermal behavior of fumarolic zones results were faced to continuous measurements achieved at the ty fault fumarolic zone la soufriere volcano guadeloupe lesser antilles during six months in 2010 using six vertical series of thermometers measuring the heat transfer in the ground and one condenser measuring the rising steam flux results demonstrate that in the absence of rainfalls heat and steam flux reach an equilibrium that is representa tive of the geothermal flux in depth conversely after the rainfalls the cooling of the ground provokes a deepening of the condensation level the related soil temperature drop can be estimated by computing the heat required to warm the infiltrated water up to boiling temperature while the recovery rate is directly linked to the geothermal flux our observations allow defining in which conditions flux are at steady state but also to build a first order numer ical model allowing estimating both the physical parameters of the ground thermal conductivity precipitation efficiency coefficient and surface flux constant and the long term thermal behavior of the hydrothermal system in particular our results predict that the hydrothermal activity must vanish on the zones where the geothermal flux drops under a certain threshold 60 w m 2 at la soufriere the existence of this limit may have strong implications for the precipitation rate of minerals and the possible reactivation of the fumarolic zones during volcanic crises

seismic and acoustic recordings of an unusually large rockfall at mount st helens washington 1 on 29 may 2006 a large rockfall off the mount st helens lava dome produced an atmospheric plume that was reported by airplane pilots to have risen to 6 000 m above sea level and interpreted to be a result of an explosive event however subsequent field reconnaissance found no evidence of a ballistic field indicating that there was no explosive component the rockfall produced complex seismic and infrasonic signals with the latter recorded at sites 0 6 and 13 4 km from the source an unusual very long period 50 s infrasonic signal was recorded a signal we model as the result of air displacement two high frequency infrasonic signals are inferred to result from the initial contact of a rock slab with the ground and from interaction of displaced air with a depression at the base of the active lava dome

palynofacies and geochemical analysis of the triassic yanchang formation ordos basin implications for hydrocarbon generation potential and the paleoenvironment of continental source rocks abstract the petroliferous basins that have formed in china since the mesozoic are characterized by non marine organic matter input a characteristic that is significantly different from that of marine organic sources the triassic yanchang formation in the ordos basin is a suite of typical intra continental lacustrine sediments that comprise the most important source rocks for the triassic oil reservoirs the yanchang formation is divided into ten subsections from top to bottom chan 1 to chan 10 three borehole successions in the southern ordos basin located in the huachi zhidan and yichuan areas cross the chan 4 5 to chan 10 subsections and have been studied using the palynofacies method combined with organic geochemistry data palynofacies analysis indicates that the sediments are rich in amorphous organic matter aom and phytoclasts the aom content in all of the samples positively correlated with the hydrogen index hi in contrast the transparent ligno cellulosic fragments tlf opaque particles op content are negatively correlated with the hi values additionally the gelified particles gp content has no linear correlation with the geochemistry data based on the quantitative composition of the particulate organic matter three palynofacies types are identified reflecting depositional settings in a distal dysoxic anoxic deep basin a shelf to basin transition zone and a proximal suboxic shelf the palynofacies total organic carbon toc and rock eval data together indicate that type i and ii kerogen are abundant in the d48 and w22 wells in the zhidan and yichuan areas respectively these kerogen types are uncommon in the l94 well in the huachi area which suggests low hydrocarbon generation potential in detail the chan 7 and chan 9 subsections of the three wells contain abundant type i and ii kerogen indicating that these layers are likely the two primary source rocks in the southern ordos basin

toggling of seismicity by the 1997 kagoshima earthquake couplet a demonstration of time dependent stress transfer 1 two m 6 well recorded strike slip earthquakes struck just 4 km and 48 days apart in kagoshima prefecture japan in 1997 providing an opportunity to study earthquake interaction aftershocks are abundant where the coulomb stress is calculated to have been increased by the first event and they abruptly stop where the stress is dropped by the second event this ability of the main shocks to toggle seismicity on and off argues that static stress changes play a major role in exciting aftershocks whereas the dynamic coulomb stresses which should only promote seismicity appear to play a secondary role if true the net stress changes from a sequence of earthquakes might be expected to govern the subsequent seismicity distribution however adding the stress changes from the two kagoshima events does not fully capture the ensuing seismicity such as its rate change temporal decay or migration away from the ends of the ruptures we therefore implement a stress transfer model that incorporates rate state friction in which seismicity is treated as a sequence of independent nucleation events that are dependent on the fault slip slip rate and elapsed time since the last event the model reproduces the temporal response of seismicity to successive stress changes including toggling decay and aftershock migration nevertheless the match of observed to predicted seismicity is quite imperfect due perhaps to inadequate knowledge of several model parameters however to demonstrate the potential of this approach we build a probabilistic forecast of larger earthquakes on the expected rate of small aftershocks taking advantage of the large statistical sample the small shocks afford not surprisingly such probabilities are highly time and location dependent during the first decade after the main shocks the seismicity rate and the chance of successive large shocks are about an order of magnitude higher than the background rate and are concentrated exclusively in the stress triggering zones

real time simultaneous detection of volcanic hg and so2 at la fossa crater vulcano aeolian islands sicily 1 measuring hg so2 ratios in volcanic emissions is essential for better apportioning the volcanic contribution to the global hg atmospheric cycle here we report the first real time simultaneous measurement of hg and so2 in a volcanic plume based on lumex and multigas techniques respectively we demonstrate that the use of these novel techniques allows the measurements of hg so2 ratios with a far better time resolution than possible with more conventional methods the hg so2 ratio in the plume of f0 fumarole on la fossa crater vulcano island spanned an order of magnitude over a 30 minute monitoring period but was on average in qualitative agreement with the hg so2 ratio directly measured in the fumarole mean plume and fumarole ratios being 1 09 10 6 and 2 9 10 6 respectively the factor 2 difference between plume and fumarole compositions provides evidence for fast hg chemical processing the plume

the origin of oil in the cretaceous succession from the south pars oil layer of the persian gulf the origin of the oil in barremian hauterivian and albian age source rock samples from two oil wells spo 2 and spo 3 in the south pars oil field has been investigated by analyzing the quantity of total organic carbon toc and thermal maturity of organic matter om the source rocks were found in the interval 1 000 1 044 m for the kazhdumi formation albian and 1 157 1 230 m for the gadvan formation barremian hauterivian elemental analysis was carried out on 36 samples from the source rock candidates gadvan and kazhdumi formations of the cretaceous succession of the south pars oil layer spol this analysis indicated that the om of the barremian hauterivian and albian samples in the spol was composed of kerogen types ii and ii iii respectively the average toc of analyzed samples is less than 1 wt suggesting that the cretaceous source rocks are poor hydrocarbon hc producers thermal maturity and ro values revealed that more than 90 of oil samples are immature the source of the analyzed samples taken from gadvan and kazhdumi formations most likely contained a content high in mixed plant and marine algal om deposited under oxic to suboxic bottom water conditions the pristane nc17 versus phytane nc18 diagram showed type ii iii kerogen of mixture environments for source rock samples from the spol burial history modeling indicates that at the end of the cretaceous time pre permian sediments remained immature in the qatar arch therefore lateral migration of hc from the nearby cretaceous source rock kitchens toward the north and south of the qatar arch is the most probable origin for the significant oils in the spol

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

earthquakes quaternary faults and seismic hazard in california data describing the locations slip rates and lengths of quaternary faults are the primary basis in this work for constructing maps that characterize seismic hazard in california the expected seismic moment m0e and the strength of ground shaking resulting from the entire rupture of each mapped fault or fault segment are estimated using empirical relations between seismic moment m0 rupture length source to site distance and strong ground motions assuming a fault model whereby the repeat time t of earthquakes on each fault equals m0e m0g where the moment rate m0g is proportional to fault slip rate it is observed that the moment frequency distribution of earthquakes predicted from the geologic data agrees well with the distribution determined from a 150 year historical record the agreement is consistent with the argument that the geologic record of quaternary fault offsets contains information sufficient to predict the average spatial and size distribution of earthquakes through time in california the estimates of t for each fault are the foundation for constructing maps that depict the average return period of 0 1g peak horizontal ground accelerations and the horizontal components of peak acceleration peak velocity and the pseudovelocity response at 1 period and 5 damping expected to occur at the level of 0 1 probability during a 50 year period of time a map is also formulated to show the probability that 0 1g horizontal ground accelerations will occur during the next 50 years the maps serve to illustrate the potential value of quaternary fault studies for assessing seismic hazard interpretation of available slip rates indicates that the largest and most frequent occurrence of potentially destructive strong ground motions are associated principally with the san andreas san jacinto calaveras hayward and ventura basin fault zones other regions of similarly high hazard may yet remain unrecognized this inadequacy results primarily from an incomplete data set numerous faults for example are mapped along the coastal region of northern california and within the modoc plateau but relatively few studies relating to fault slip rate are reported a similar problem exists for other stretches of coastal california where marine reflection studies provide evidence of active faulting offshore yet yield little or no information of fault slip rate geological and geophysical field studies can work to remove these deficiencies a concerted effort to locate and define rates of activity on all faults in california is the most promising means to further quantify present levels of seismic hazard in california

tectonic controls on residual oil saturation below the present day fluid contact level in reservoirs of the persian gulf abstract the presence of residual oil below the present day free water level fwl and oil water contact owc is common in many oil fields in the middle east particularly those in the persian gulf this residual oil is seen in both clastic and carbonate reservoirs prior to the start of production the characterisation and modelling of these fields is difficult in practice also these residual oils below the fwl and owc could become classified as reserves if ways to produce them could be found however the first step is to better understand their origin therefore the goal of this study was to investigate the role of geological events on the presence of the residual oil zone roz below the fwl and owc it has been suggested that the presence of residual oil below the present day fwl and owc is related to the geotectonic history of the region from the middle miocene reverse faulting and overfolding propagated over the zagros leading to the amplification of folds and the migration of the zagros orogeny towards its foreland basin persian gulf in response to this additional massive loading on the continental margin the forebulge amplitude was increased its location migrated towards the uplifted zagros mountains and consequently the persian gulf became narrower this exerted a north to north east downward tilting of the entire basin including all the structures and reservoirs previously filled by hydrocarbons this basin tilting changed the equilibrium of the structures and their fluid contents and resulted in the hydrocarbons and water attempting to find a new equilibrium under these conditions the early migrated and accumulated oil was flushed out by water imbibition and a roz was left below the present day fwl and owcs the angle of regional basin tilt has been calculated to be 0 836 based on seismic sections

ground deformation induced by geothermal processes a model for la fossa crater vulcano island italy 1 since the last eruption in 1888 1890 volcanic activity at vulcano island aeolian archipelago italy has been limited to fumarolic degassing concentrated near the active cone of la fossa crater in the northern sector of the island during the period 1990 1996 edm and leveling data indicate a deflation and contraction focused on the la fossa cone we jointly inverted these data sets using for volume change both a spherical mogi 1958 source and an ellipsoid as defined by davis 1986 the best fitting source for the 1990 1996 deflation is a shallow subvertical prolate ellipsoid positioned roughly under the crater our model is consistent with increased activity in a shallow hydrothermal system supported by observations of water evaporation testified by the increase of steam emission and temperature at crater fumaroles the fluid loss from a shallow geothermal reservoir is the most likely cause of the subsidence recorded at la fossa cone during the same period this clear linkage between the deformation signals and hydrothermal activity has important implications in the hazard assessment and monitoring of the vulcano activity

a silent mw 4 7 slip event of october 2006 on the superstition hills fault southern california 1 during october 2006 the 20 km long superstition hills fault shf in the salton trough southern california slipped aseismically producing a maximum offset of 27 mm as recorded by a creepmeter we investigate this creep event as well as the spatial and temporal variations in slip history since 1992 using ers 1 2 and envisat satellite data during a 15 year period steady creep is punctuated by at least three events the first two events were dynamically triggered by the 1992 landers and 1999 hector mine earthquakes in contrast there is no obvious triggering mechanism for the october 2006 event field measurements of fault offset after the 1999 and 2006 events are in good agreement with the interferometric synthetic aperture radar data indicating that creep occurred along the 20 km long fault above 4 km depth with most of the slip occurring at the surface the moment released during this event is equivalent to a mw 4 7 earthquake this event produced no detectable aftershocks and was not recorded by the continuous gps stations that were 9 km away modeling of the long term creep from 1992 to 2007 creep using stacked ers 1 2 interferograms also shows a maximum creep depth of 2 4 km with slip tapering with depth considering that the sediment thickness varies between 3 km and 5 km along the shf our results are consistent with previous studies suggesting that shallow creep is controlled by sediment depth perhaps due to high pore pressures in the unconsolidated sediments

comprehensive source rock evaluation of the kazhdumi formation in the iranian zagros foldbelt and adjacent offshore abstract the kazhdumi formation is regarded as one of the most prolific hydrocarbon sources in the zagros foldbelt and adjacent offshore rock eval pyrolysis data were collected from 2300 rock samples of the kazhdumi formation in 64 wells core and cutting including 37 oil and gas fields and five outcrops 200 vitrinite reflectance measurements were carried out to calibrate and map thermal maturity over the study area palynofacies analyses and thermal history modeling were applied on the wells located in the study area based on the total organic carbon toc map the kazhdumi formation toc values range from 0 to 11 in the central part of dezful embayment its average value is about 5 while average toc value of the kazhdumi formation is lower than 0 5 in qatar gawbandi paleo high hydrogen index hi values represented types ii and iii kerogen for central part of the dezful embayment and qatar gawbandi paleo high respectively t max ranges from 370 to 455 c in the study area the maximum and minimum values for this parameter are recorded in the central dezful embayment and central persian gulf anticlines respectively vitrinite reflectance vr r map also confirms the concluded results of t max data reconstructed burial history and thermal modeling of three wells are also in full agreement with the results of other maturity evidence t max and vr r palynofacies analyses revealed that this formation in the central persian gulf south pars field clearly represents the dominance of terrigenous elements which were resulted from a close proximity to a fluvio deltaic source however towards the northwest amorphous organic matter aom dominates in central dezful embayment indicating a distal dysoxic anoxic environmental condition

depositional settings and palynofacies assemblages of the upper triassic fluviodeltaic mungaroo formation northern carnarvon basin western australia

rupture complexity of the 1970 tonghai and 1973 luhuo earthquakes china from p wave inversion and relationship to surface faulting the source processes of the 4 january 1970 tonghai earthquake m s 7 5 and the 6 february 1973 luhuo earthquake m s 7 5 in southwestern china were investigated using an inversion technique on the very complex body waves the two earthquakes were associated with 48 and 90 km of surficial strike slip rupture respectively and the distribution of displacement with distance along the fault was well documented by field studies of both events the source process for both earthquakes comprised three to four subevents with different moments and rupture durations these calculated parameters agree well with the field observations and aftershock distributions particularly in the total rupture length and in the amount and asymmetry of fault displacements relative to the locations of the main epicenters

heat flux based strategies for the thermal monitoring of sub fumarolic areas examples from vulcano and la soufriere de guadeloupe although it is relatively easy to set up the monitoring of soil temperature in sub fumarolic areas is quite rarely used to monitor the evolution of hydrothermal systems indeed measurements are highly sensitive to environmental conditions in particular daily and seasonal variations of atmospheric temperatures and rainfalls which can be only partially filtered by the established statistical analysis in this paper we develop two innovative processing methods both based on the computation of the heat flux in the soil the upward heat flux method uhf designed for dry environments consists in computing both the conductive and convective components of the heat flux between two thermocouples placed vertically in the cases of wet environments the excess of total heat method eth allows the integration of rain gauges data in order to correct the heat balance from the superficial cooling effect of the precipitations the performances of both processing techniques are faced to established methods temperature gradient and coefficient of determination on soil temperature time series from two test volcanoes at la fossa di vulcano italy the uhf method undoubtedly detects three thermal crises between 2009 and 2012 enabling to quantify not only the intensity but also the precise timing of the heat flux increase with respect to corresponding geochemical and seismic crises at la soufriere de guadeloupe french lesser antilles despite large rainfalls dramatically influencing the thermal behavior of the soil a constant geothermal heat flux is retrieved by the eth method confirming the absence of fumarolic crisis during the observation period february august 2010 being quantitative robust and usable in almost any context of sub fumarolic zones our two heat flux based methods increase the potential of soil temperature for the monitoring but also the general interpretation of fumarolic crises together with geochemical and seismological observations a spreadsheet allowing direct computation of uhf and eth is provided as supplemental material

organic geochemistry and petrography of kazhdumi albian cenomanian and pabdeh paleogene potential source rocks in southern part of the dezful embayment iran there are several source rock units in the zagros basin but the cretaceous kazhdumi and paleogene pabdeh formations probably have produced the majority of the commercial hydrocarbons in this area among the hydrocarbon provinces of iran the dezful embayment which is located southwest of zagros mountains is one of the most prolific regions in the middle east numerous studies have been made in the northern part of the dezful embayment but relatively few have been done in its southern part the present study focuses on organic matter characterization of two potential source rocks kazhdumi and pabdeh formations in southern part of the dezful embayment cuttings samples 114 were collected from 10 wells and evaluated using rock eval pyrolysis and organic petrography in order to characterize the content and type of organic matter and thermal maturity the results showed that the average total organic carbon toc content of kazhdumi and pabdeh formations are 2 48 and 1 62 wt respectively the highest toc contents for both formations are found in the northern compartment and decreased gradually toward the south pyrolysis data reveal that organic matter has a fair to very good hydrocarbon generation potential and are classified as type ii iii and type iii rock eval t max and vitrinite reflectance show that the majority of samples are in the early mature to mature stage of the oil generation window c 2012 elsevier ltd all rights reserved

neogene sediments and modern depositional environments of the zagros foreland basin system a sedimentological investigation of the neogene deposits of the zagros foreland basin in sw iran reveals a continuous and largely gradational passage from supratidal and sabkha sediments at the base represented by the gachsaran formation to carbonates and marine marls mishan formation with basal guri carbonate member followed by coastal plain and meandering river deposits agha jari formation and finally to braided river gravel sheets bakhtyari formation this vertical succession is interpreted to represent the southward migration of foreland basin depozones from distal foredeep and foredeep to distal wedge top and proximal wedge top respectively as the zagros fold thrust belt migrated progressively southward towards the arabian foreland this vertical succession bears a striking similarity to modern depositional environments and sedimentary deposits observed in the zagros region today where one passes from mainly braided rivers in the zagros mountains to meandering rivers close to the coast to shallow marine clastic sediments along the northern part of the persian gulf and finally to carbonate ramp and sabkha deposits along the southeastern coast of the persian gulf this link between the neogene succession and the modern day depositional environments strongly suggests that the major neogene formations of the zagros foreland basin are strongly diachronous as shown recently by others and have active modern day equivalents

forecasting the evolution of seismicity in southern california animations built on earthquake stress transfer 1 we develop a forecast model to reproduce the distribution of main shocks aftershocks and surrounding seismicity observed during 1986 2003 in a 300 310 km area centered on the 1992 m 7 3 landers earthquake to parse the catalog into frames with equal numbers of aftershocks we animate seismicity in log time increments that lengthen after each main shock this reveals aftershock zone migration expansion and densification we implement a rate state algorithm that incorporates the static stress transferred by each m 6 shock and then evolves coulomb stress changes amplify the background seismicity so small stress changes produce large changes in seismicity rate in areas of high background seismicity similarly seismicity rate declines in the stress shadows are evident only in areas with previously high seismicity rates thus a key constituent of the model is the background seismicity rate which we smooth from 1981 to 1986 seismicity the mean correlation coefficient between observed and predicted m 1 4 shocks the minimum magnitude of completeness is 0 52 for 1986 2003 and 0 63 for 1992 2003 a control standard aftershock model yields 0 54 and 0 52 for the same periods four m 6 0 shocks struck during the test period three are located at sites where the expected seismicity rate falls above the 92 percentile and one is located above the 75 percentile the model thus reproduces much but certainly not all of the observed spatial and temporal seismicity from which we infer that the decaying effect of stress transferred by successive main shocks influences seismicity for decades finally we offer a m 5 earthquake forecast for 2005 2015 assigning probabilities to 324 10 10 km cells

palynology and petroleum potential of the kazhdumi formation cretaceous albian cenomanian in the south pars field northern persian gulf abstract the kazhdumi formation of the bangestan group is a well known source rock that has produced abundant oil in most petroleum fields in the zagros basin which stretches from northwest to southwest iran over hundreds of kilometres the formation reaches a thickness of 230 m at the type section in northwest zagros but thins out to 40 50 m in wells studied from the south pars giant petroleum field where it comprises mainly grey shales with occasional intercalations of marls and sandstones south pars best known as the iranian part of the world s largest non associated gas field contains small quantities of oil above and below the kazhdumi formation palynology has been used to assess the age and palaeoenvironment of the kazhdumi formation and to evaluate its petroleum potential a total of 68 ditch cutting samples recovered from five wells of which four are oil prone have been analyzed an age between late albian and cenomanian is established for the formation based on dinoflagellate cyst biostratigraphy and four palynofacies types have been recognized using the relative proportions of terrestrial elements marine palynomorphs and amorphous organic matter aom the ratio of terrestrial to marine elements is high in most samples indicating a nearshore sedimentary environment twenty two samples from the four oil prone wells were also selected for geochemical analysis using rock eval pyrolysis results show that the kazhdumi formation at south pars in contrast to the zagros basin is gas prone predominantly type iii kerogen thermally immature and poor in terms of hydrocarbon generation it could not have produced the oil in those oil prone wells studied

re estimate of major earthquake activity in surrounding areas after the m s 6 6 jinghe earthquake in xinjiang 2017 according to theory earthquakes may produce disturbances in surrounding areas and affect the major earthquake occurrence rate of surrounding faults the ms 6 6 jinghe earthquake on 9th august 2017 occurred in the tienshan seismic belt where there is much tectonic activity and many strong earthquakes occur the impact of this earthquake on major earthquake activity of surrounding areas is worth studying this paper attempts to combine two models the brownian passage time bpt model which describes the quasi periodic recurrence of major earthquakes and the coulomb failure stress model which describes rock failure on faults the amount of change in the rate of major earthquake occurrence caused by a nearby earthquake was calculated and changes in major earthquake activity in the surrounding areas after the jinghe earthquake were re estimated there are few differences in major earthquake occurrence rate change by stress disturbances calculated with the bpt model or the coulomb failure stress model calculation results are consistent with actual earthquake cases the 2017 jinghe earthquake increased major earthquake activity on the boluokenu fault and yili basin north fault and the expected major earthquake recurrence times of the two faults were advanced by 11 years and 59 years respectively conclusions of this paper provide a reference for time dependent seismic hazard assessments in related areas

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

palynological palynofacies paleoenvironmental and organic geochemical studies on the upper cretaceous succession of the gptsw 7 well north western desert egypt abstract the present study of the abu roash and bahariya formations in well gptsw 7 refines our understanding of the subsurface cretaceous of the north western desert of egypt our investigations are based on the palynological analyses of 71 cuttings samples of which 24 have also been analyzed for geochemistry in addition to 3 sidewall cores analyzed for vitrinite reflectance r o four palynological zones and three subzones in addition to a poorly fossiliferous interval ranging in age from coniacian santonian to early cenomanian are proposed these include a poorly fossiliferous interval coniacian santonian dinogymnium vozzhennikovae interval zone late to middle turonian ephedripites ambiguus ephedripites multicostatus foveotricolpites giganteus foveotricolpites gigantoreticultus assemblage zone early turonian classopollis brasiliensis interval zone late to middle cenomanian and afropollis jardinus interval zone early cenomanian the succeeding subzones are afropollis kahramanensis interval subzone elaterosporites klaszii interval subzone and cretacaeiporites densimurus interval subzone all of early cenomanian age total organic carbon toc and rock eval pyrolysis and palynofacies analyses indicate that the bahariya formation and the abu roash g member are primarily of kerogen iii type and hence gas prone suggesting a strong influence of hydrogen enriched organic matter the abu roash a c e members may also be gas prone type iii kerogen and appear to contain highly oxidized terrestrial organic matter in contrast the abu roash f member has very high toc and hi values and contains a very high proportion of amorphous organic matter aom indicating a highly oil prone facies while this finding is not unexpected for anoxic black shale it contrasts with earlier studies that suggest a gas prone nature r o measurements show that the bahariya formation represents an immature early genesis dry gas phase this is also true for all investigated samples from the abu roash and bahariya formations based on their low thermal alteration index tai quantitative and qualitative analyses of both the palynoflora and palynofacies show that the abu roash a and c members b is missing both of coniacian santonian age represent oxic proximal and distal shelf environment the abu roash d and e members dated as turonian represent oxic proximal shelf whereas the cenomanian abu roash f member was deposited in a distal suboxic anoxic basin the cenomanian abu roash g member and the bahariya formation were deposited in a shallow marine and shallow marine to fluvio deltaic setting respectively the senonian palmae province is recognized in the palynoflora by the presence of proteacidites auriculiidites reticulatus ariadnaesporites gabonisporis vigourouxii on the other hand the albian cenomanian elaterates province is characterized by the presence of steevesipollenites gnetaceaepollenites elaterocolpites elaterosporites elateroplicites senegalosporites sofrepites afropollis and cretacaeiporites

the cretaceous source rocks in the zagros foothills of iran an example of a large size intracratonic basin the zagros orogenic belt of iran is one of the world most prolific petroleum producing area however most of the oil production is originated from a relatively small area the 60 000 km sup 2 wide dezful embayment which contains approximately 12 of the proven oil global reserves the distribution of the oil and gas fields results from the area extent of six identified source rock layers their thermal history and reservoir cap rock and trap availability in this paper the emphasis is three of the layers of cretaceous sources rocks the garau facies was deposited during the neocomian to albian interval over lurestan northeast khuzestan and extends over the extreme northeast part of fars the kazhdumi source rock which deposited over the dezful embayment and eventually the senonian gurpi formation which has marginal source rock characteristics in limited areas of khuzestan and northern fars the deposition environment of these source rock layers corresponds to semipermanent depressions included in an overall shallow water intracratonic basin communicating with the south tethys ocean these depressions became anoxic when climatic oceanographical and geological conditions were adequate i e humid climate high stand water influxes of fine grained clastics and the existence of sills separating the depressionmore from the open sea distribution maps of these source rock layers resulting from extensive field work and well control are also given the maturation history of source rocks is reconstructed from a set of isopachs it was found that the main contributor to the oil reserves is the kazhdumi source rock which is associated with excellent calcareous reservoirs less

a new scenario for the last magmatic eruption of la soufriere of guadeloupe lesser antilles in 1530 a d evidence from stratigraphy radiocarbon dating and magmatic evolution of erupted products la soufriere of guadeloupe is a dangerous volcano characterized over the last decade by moderate seismic and fumarolic unrest in the last 15 000 years it has experienced phreatic and magmatic eruptions and unusually numerous flank collapse events sometimes associated with a magmatic eruption we propose a new age of 1530 a d and a new eruptive scenario for the last magmatic eruption on the basis of a novel statistical analysis of radiocarbon age dates and new field and geochemical data this eruption is the only magmatic eruption likely to have occurred in guadeloupe during the last 1400 years the eruption mainly involved an andesitic magma which in the first phase of the eruption partially mixed with a slightly more differentiated magma stored in a small and shallow magma chamber ascent of magma to the surface generated a partial collapse of the hydrothermally altered edifice that increased the magma discharge and led to a sub plinian phase with scoria fallout and column collapse pyroclastic flows followed by near vent pyroclastic scoria fountains the eruption ended with growth of a lava dome our revised interpretation of the last magmatic eruption of la soufriere constitutes the most likely key to a future magmatic eruption scenario for this volcano which displays strong evidence of unrest since 1992

a constitutive law for rate of earthquake production and its application to earthquake clustering seismicity is modeled as a sequence of earthquake nucleation events in which the distribution of initial conditions over the population of nucleation sources and stress ing history control the timing of earthquakes the model is implemented using solutions for nucleation of unstable fault slip on faults with experimentally derived rate and state dependent fault properties this yields a general state variable constitutive formulation for rate of earthquake production resulting from an applied stressing history to illustrate and test the model some characteristics of seismicity following a stress step have been explored it is proposed that various features of earthquake clustering arise from sensi tivity of nucleation times to the stress changes induced by prior earthquakes the model gives the characteristic omori aftershock decay law and interprets aftershock parameters in terms of stress change and stressing rate earthquake data appear to support a model prediction that aftershock duration defined as the time for rates to return to the back ground seismicity rate is proportional to mainshock recurrence time observed spatial and temporal clustering of earthquake pairs arises as a consequence of the spatial depen dence of stress changes of the first event of the pair and stress sensitive time dependent nucleation applications of the constitutive formulation are not restricted to the simple stress step models investigated here it may be applied to stressing histories of arbitrary complexity the apparent success at modeling clustering phenomena suggests the possibil ity of using the formulation to estimate short to intermediate term earthquake probabil ities following occurrence of other earthquakes and for inversion of temporal variations of earthquake rates for changes in driving stress

long term tir imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment a case study in the campi flegrei southern italy the tir monitoring system was partially funded by the 2000 2006 national operating programme and by the italian civil protection department in the framework of the 2004 2006 agreement with the istituto nazionale di geofisica e vulcanologia

stress transferred by the 1995 mw 6 9 kobe japan shock effect on aftershocks and future earthquake probabilities the kobe earthquake struck at the edge of the densely populated osaka kyoto corridor in southwest japan we investigate how the earthquake transferred stress to nearby faults altering their proximity to failure and thus changing earthquake probabilities we find that relative to the pre kobe seismicity kobe aftershocks were concentrated in regions of calculated coulomb stress increase and less common in regions of stress decrease we quantify this relationship by forming the spatial correlation between the seismicity rate change and the coulomb stress change the correlation is significant for stress changes greater than 0 2 1 0 bars 0 02 0 1 mpa and the nonlinear dependence of seismicity rate change on stress change is compatible with a state and rate dependent formulation for earthquake occurrence we extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of kobe and calculating the change in probability caused by these stress changes transient effects of the stress changes are incorporated by the state dependent constitutive relation which amplifies the permanent stress changes during the aftershock period earthquake probability framed in this manner is highly time dependent much more so than is assumed in current practice because the probabilities depend on several poorly known parameters of the major faults we estimate uncertainties of the probabilities by monte carlo simulation this enables us to include uncertainties on the elapsed time since the last earthquake the repeat time and its variability and the period of aftershock decay we estimate that a calculated 3 bar 0 3 mpa stress increase on the eastern section of the arima takatsuki tectonic line attl near kyoto causes fivefold increase in the 30 year probability of a subsequent large earthquake near kyoto a 2 bar 0 2 mpa stress decrease on the western section of the attl results in a reduction in probability by a factor of 140 to 2000 the probability of a mw 6 9 earthquake within 50 km of osaka during 1997 2007 is estimated to have risen from 5 6 before the kobe earthquake to 7 11 afterward during 1997 2027 it is estimated to have risen from 14 16 before kobe to 16 22

how a mud dominated ramp changed to a carbonate clastic oil reservoir sea level fluctuations in cretaceous of the central persian gulf abstract mud dominated facies distribution of barremian turonian succession in the northeastern arabian plate in the central persian gulf represents a shallow ramp platform on the basis of petrographical studies core analysis data and gamma ray logs this succession has been studied for facies analysis defining depositional environment sequence stratigraphy and reservoir properties a total of 6 microfacies and 3 petrofacies types are recognized in this succession lagoonal environment was dominated during the deposition of dariyan kazhdumi and sarvak formations the lagoon rapidly changed to a sand shoal by falling sea level and increasing energy level of the depositional environment sequence stratigraphy of barremian turonian succession shows that mud dominated facies have been deposited in tsts and grain dominated facies in hsts of the sequences although grain dominated facies like packstone to grainstone and algal floatstone were spread during the hsts of sequences the changes in the texture and size of the grains had a negligible effect on reservoir quality during this period barremian turonian two major sea level falls caused considerable environmental changes such as platform emergence incised valley fills and clastic sediments influx into the carbonate platform meteoric diagenesis during the falling sea level had a major effect on the reservoir properties of the reservoirs under the sequence boundaries grains matrix and micrite dissolution and subsequent selective blocky and equant calcite cementation strongly modified the primary reservoir properties local dolomitization also enhance the porosity and permeability of the samples while large pores have been filled by cements microporosities remained unfilled until the late stages of diagenesis and burial

three years of so2 flux measurements of mt etna using an automated uv scanner array comparison with conventional traverses and uncertainties in flux retrieval 1 sviluppo di sistemi di monitoraggio dipartimento di protezione civile della regione sicilia 2 ingv istituto nazionale di geofisica e vulcanologia sezione di catania italy 3 novac network for observation of volcanic and atmospheric change eu funded sixth framework programme project 18354 4 uk nerc national centre for earth observation via the dynamic earth and geo hazards

an integrated perspective of the continuum between earthquakes and slow slip phenomena slow slip a mechanism by which faults can relieve stress was thought to be distinct from earthquakes however a global review of slow slip phenomena suggests that instead there is a continuum between the two types of event