continuous h2o co2 222rn and temperature measurements on merapi volcano indonesia abstract a set of analytical instruments consisting of a gas chromatograph for water and carbon dioxide an alpha scintillation counter to measure radon and a temperature sensor was especially designed and constructed to monitor volcanic gases and was successfully operated over weeks in the high temperature fumaroles at the summit of merapi volcano indonesia the analytical unit runs automatically and is remote controlled through a radio link over a period of several weeks concentrations of h 2 o and co 2 were measured every 35 min and rn activity was monitored at about 90 min intervals the fumarole temperatures were continuously recorded every minute from july 2000 to the end of january 2001 the composition and temperature of the gas emitted at merapi volcano show significant variations due to a regular stronger degassing of the magma concentrations of co 2 increase periodically while h 2 o concentrations decrease on the other hand rn activity rises with increasing atmospheric pressure and higher water concentrations after intensive rainfall infiltration of cold meteoric water into the volcanic edifice possibly causes an increase in the concentration of water vapour and a decrease in the temperature of the gases in the fumarole several seismic events recorded at merapi correlate with gas temperature

continuous monitoring of fumarole temperatures at mount etna italy abstract in this paper we present the first data of temperature continuously recorded in two fumarole fields designated vor and hor located in the summit area of mount etna volcano italy the time series embraces two distinct periods 1 october 2007 to november 2009 during which an effusive eruption occurred from may 2008 to july 2009 and 2 november 2011 to june 2012 characterized by the occurrence of strong paroxysms fire fountains and lava flow the analysis of the temperature signal in both the time and frequency domains and its comparison with meteorological observations allowed us to separate the exogenous influences from the effects of variations in the activity state of the volcano the acquired data were weakly affected by seasonal cycles of the air temperature and strongly affected by the rainfall optimization of site conditions i e sensor depth and soil permeability markedly reduced meteorological disturbances the distance from the main degassing and or eruptive fractures was crucial to maximizing the probability of the technical survival of the monitoring apparatus which was seriously affected by the emission of acidic gases tephra fallout and lava flows apart from the exogenous influences the most appreciable variation was observed at vor where a huge increase in fumarole temperature was detected immediately after the onset of the 2008 2009 eruption such an anomalous increase was attributed to the rapid ascent of magma feeding the eruptive fracture another abrupt increase in temperature was recorded at hor in march and april 2012 during this period the frequency of paroxysm occurrence increased markedly and this led us to hypothesize that the thermal anomaly was due to the intrusion of a new batch of magma in the conduits of the southeast crater medium to long term monitoring weeks to months of fumarole temperatures revealed variations that were attributed to pressurization depressurization phases of the shallow volcanic system which varied between the various monitored sectors of the volcano our observations suggest that continuous monitoring of fumarole temperature can give useful information about the activity of mount etna moreover due to the complexity of its shallow plumbing system we conclude that the monitoring systems should be extended to cover the entire fumarole network of the summit area

self potential signals preceding variations of fumarole activity at merapi volcano central java abstract this paper analyzes simultaneous self potential and gas temperature variations recorded at merapi volcano in spring 2011 the dry season shortly after the volcanic crisis 2001 temporal variations of fumarole gas temperature show characteristic quasi periodic signals at scales 1 8 h and amplitudes up to ten degrees we propose a simple graphical technique combining a wavelet scalogram and a cross correlation analysis to demonstrate that the variations of gas temperature are systematically preceded by self potential variations at the same scales the influence of meteorological variations on these correlated signals can be ruled out rather we suggest them to be related to the magma degassing in the upper conduits of the volcano we discuss a semi qualitative model to explain this correlation and the observed phase shift of about two hours

a new method for sampling and analyzing volcanic sublimates application to merapi volcano java abstract a new method for the sampling of sublimates from high temperature volcanic gases has been used at merapi volcano java in 1978 the sublimates were collected on the inner walls of silica tubes introduced into fumarolic vents volcanic gases were allowed to move freely through the tubes and as they cooled a fraction of the volatile components condensed on the inner walls of the tubes along the temperature gradient the sublimates were then analyzed by a combination of light microscopy scanning electron microscopy electron microprobe and x ray diffraction six successive zones of different compositions and mineralogical associations have been identified along the covered range of temperatures 900 to around 400 c from the high to the low temperatures these zones are composed of 1 cristobalite magnetite hercynite 2 molybdenite 3 acmite 4 halite sylvite 5 sphalerite pyrite and 6 galena equilibrium calculations show that these crystalline phases are stable for ps 2 pc 1 and po 2 values typical of magma buffered gases that have not been contaminated by atmospheric oxygen the deposits observed in the tubes may be useful in aiding the understanding of the mechanisms acting during the cooling of the gaseous phase on its way to the surface and before its emission into the atmosphere

evaluation of sulfur dioxide emissions from explosive volcanism the 1982 1983 eruptions of galunggung java indonesia abstract galunggung volcano java awoke from a 63 year quiescence in april 1982 and erupted sporadically through january 1983 during its most violent period from april to october the cikasasah volcano observatory reported 32 large and 56 moderate to small eruptions from april 5 through september 19 the total ozone mapping spectrometer toms carried on nasa s nimbus 7 satellite detected and measured 24 different sulfur dioxide clouds an estimated 1730 kilotons kt of so2 were outgassed by these explosive eruptions the trajectories and rapid dispersion rates of the so2 clouds were consistent with injection altitudes below the tropopause an additional 300 kt of so2 were estimated to have come from 64 smaller explosive eruptions based on the detection limit of the toms instrument for the first time an extended period of volcanic activity was monitored by remote sensing techniques which enabled observations of both the entire so2 clouds produced by large explosive eruptions using toms and the relatively lower levels of so2 emissions during non explosive outgassing using the correlation spectrometer or cospec based on cospec measurements from august 1982 to january 1983 and on the relationship between explosive and non explosive degassing approximately 400 kt of so2 were emitted during non explosive activity the total sulfur dioxide outgassed from galunggung volcano from april 1982 to january 1983 is calculated to be 2500 kt 30 from both explosive and non explosive activity while galunggung added large quantities of sulfur dioxide to the atmosphere its sporadic emissions occurred in relatively small events distributed over several months and reached relatively low altitudes and are unlikely to have significantly affected aerosol loading of the stratosphere in 1982 by volcanic activity

field gas chromatograph analyses of gases from a glowing dome at merapi volcano java indonesia 1977 1978 1979 abstract a new field gas chromatograph fgc and conventional evacuated bottle eb techniques have been used to study high temperature 600 c volcanic gases from merapi volcano indonesia during 1977 1978 and 1979 the fgc design allows analysis of h2o co2 so2 h2s h2 cos ch4 co n2 ar and o2 in a manner that prevents loss of sulfur and water by condensation inhibits corrosion from reactions of gases with lead in tubes and minimizes atmospheric contamination the fgc analyses are highly superior to the eb data especially with respect to prevention of sulfur loss from reaction of so2 and h2s in addition to providing much improved h2s data the fgc system minimizes oxidation of h2 and co from contaminating atmospheric o2 because of the elimination of a lengthy time interval between collection and analysis thermodynamic calculations indicated small errors for h2 and ch4 in the 1978 analyses provided by the proto type fgc device a later model fgc provided excellent analyses that were shown by thermodynamic calculations to be nearly equilibrium mixtures requiring only minor corrections the merapi gases are h2o rich 88 95 containing small amounts of co2 3 5 to 7 5 so2 0 3 to 1 2 and h2s 0 3 to 1 2 they resemble excess volatiles rubey 1955 except for too high a sulfur content thermodynamic calculations based on the analyses indicate that the gases were once at temperatures of at least 915 c with o2 fugacities near quartz magnetite fayalite and that they have not been significantly diluted by disequilibrium admixture of meteoric water below these temperatures this conclusion takes on special importance because stable isotope studies allard 1980 1982 of merapi gases have shown that the water is meteoric and that much of the carbon and sulfur could be from sedimentary sources the merapi gases therefore may be magmatic even though they are not juvenile but recycled crustal volatiles

evidence for zn isotopic fractionation at merapi volcano abstract fumarolic gases rocks and condensate samples from merapi volcano indonesia have been analyzed by multiple collector inductively coupled plasma mass spectrometry mc icp ms for their zn isotopic compositions the variation observed expressed as 66 zn 66 zn 66 zn 64 zn sample 66 zn 64 zn jmc 3 049l 1 10 3 ranges from 0 05 to 1 68 the overall reproducibility was found to be better than 0 10 2sd the 66 zn of andesitic rock samples are homogeneous with a mean value of 0 24 which is comparable to previously reported basalt data 66 zn in the woro fumerolic field are ranging from 0 05 to 0 85 and 1 48 to 1 68 in fumarolic gases and condensates respectively upon cooling from 590 to 297 c gaseous zn concentrations decrease and become increasingly enriched in the lighter zn isotopes while the condensates become increasingly enriched in the heavier isotopes gas and condensate isotopic compositions can be explained with a rayleigh condensation model with temperature dependent isotope fractionation factor solid vapor over the 574 c to 297 c range of observations 1000 ln solid vapour c 1 c 2 t c 3 t 2 with c 1 0 c 2 0 88 10 3 c 3 1 00 10 6 and t in degrees kelvin which corresponds to solid vapor of 1 00033 to 1 00153 respectively at the indicated temperatures

oxygen fugacity of gases and rocks from momotombo volcano nicaragua application to volcanological monitoring the oxygen fugacity fo2 and the fo2 versus t c relationship of high temperature 600 860 c gas emissions from momotombo volcano nicaragua was determined from both field electrochemical measurements electrolytic cell assembly and thermodynamic computations on gas samples collected between 1978 and 1985 it was then compared with the intrinsic fo2 of fresh and altered lavas from the last eruption 1905 as measured between 500 and 1100 c in laboratory the electrochemical results show that the oxygen fugacity of momotombo fumaroles at equivalent temperature is much higher than that of the fresh 1905 lava fmq buffer and closer to that of their altered wall rocks fmq buffer the equilibrium o2 fugacities calculated from the chemistry of gas samples confirm this pattern however they suggest that the gas mixtures preserve the variable memory of a higher thermal equilibrium achieved at depth under temperature and fo2 conditions of up to 1050 c and 10 9 0 atm respectively which correspond to the cross over between the fo2 t gas and lava trends these data thus support the idea that momotombo volcanic gases released in a period of increasing activity escape from a shallow magma body before suffering a variable oxidation during their ascent through both unbuffered cooling and reactions with environmental fluids and rocks this late oxidation is weaker at central fumaroles than at peripherical ones while between 1978 and 1985 the temperature of the hottest fumarole increased from 750 to 865 900 c the equilibrium fo2 of the gas decreased by nearly one order of magnitude at comparable equilibrium temperature such an evolution presumably reflects an increasing connection between the surface exhalations and the magma degassing at depth along with time this work underlines the possibility of monitoring the processes of magma ascent and gas magma separation within a volcano before an eruption by continuously recording the changes of both oxygen fugacity and temperature in hot fumaroles

volcanic activity influenced by tectonic earthquakes static and dynamic stress triggering at mt merapi 1 mt merapi is one of the most dangerous volcanoes in indonesia located within the tectonically active region of south central java this study investigates how mt merapi affected and was affected by nearby tectonic earthquakes in 2001 a mw6 3 earthquake occurred in conjunction with an increase in fumarole temperature at mt merapi in 2006 another mw6 3 earthquake took place concomitant with an increase of magma extrusion and pyroclastic flows here we develop theoretical models to study the amount of stress transfer between the earthquakes and the volcano showing that dynamic rather than static stress changes are likely responsible for the temporal and spatial proximity of these events our examination of the 2001 and 2006 events implies that volcanic activity at mt merapi is influenced by stress changes related to remote tectonic earthquakes a finding that is important for volcano hazard assessment in this densely inhabited area

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

soil gas geochemistry in relation to eruptive fissures on timanfaya volcano lanzarote island canary islands spain abstract we report herein the first results of an extensive soil gas survey performed on timanfaya volcano on may 2011 soil gas composition at timanfaya volcano indicates a main atmospheric source slightly enriched in co2 and he soil co2 concentration showed a very slight deep contribution of the timanfaya volcanic system with no clear relation to the main eruptive fissures of the studied area the existence of soil helium enrichments in timanfaya indicates a shallow degassing of crustal helium and other possible deeper sources probably form cooling magma bodies at depth the main soil helium enrichments were observed in good agreement with the main eruptive fissures of the 1730 36 eruption with the highest values located at those areas with a higher density of recent eruptive centers indicating an important structural control for the leakage of helium at timanfaya volcano atmospheric air slightly polluted by deep seated helium emissions co2 degassed from a cooling magma body and biogenic co2 might be the most plausible explanation for the existence of soil gas helium is a deep seated gas exhibiting important emission rates along the main eruptive fissure of the 1730 36 eruption of timanfaya volcano

radon surveys and real time monitoring at stromboli volcano influence of soil temperature atmospheric pressure and tidal forces on 222rn degassing abstract we used a network of stations to perform systematic radon surveys at stromboli volcano the time series of periodic measurements show that monthly average 222rn emissions reflect changes in volcanic activity and exhibit increasing trends prior and during the last major eruptive cycles maps of radon emissions indicate that diffuse degassing is operative at stromboli volcano concentrated degassing essentially occurs in the summit area and within a sector proximal to the two major ne trending faults these sites were chosen for deploying the two real time stations that are currently operating at stromboli in these devices the 222rn electronic dosimeters are connected to a radiomodem for wireless data transfer to a receiving station at the volcano observatory radon activity soil temperature and atmospheric pressure data are sampled and instantaneously transferred via web so that they can be checked remotely collected time series reveal an overall inverse correlation between radon emissions and seasonal temperature variations radon emissions in sectors of diffuse degassing are modulated by tidal forces as well radon activities recorded at the summit station located along the fracture zone where the gas flux is concentrated are positively correlated with changes in atmospheric pressure and confirm the occurrence of the atmospheric stack effect we finally emphasize that real time radon monitoring is an innovative technique that may be systematically applied in volcano surveillance

absolute gravity change associated with magma mass movement in the conduit of asama volcano central japan revealed by physical modeling of hydrological gravity disturbances the gravity signal originating from magma mass movement in a volcanic conduit is retrieved from the hydrologically disturbed absolute gravity data obtained at asama volcano central japan in 2004 using a three dimensional hydrological model we improve the hydrological model of the previous study using realistic soil parameters and boundary conditions to better estimate the spatiotemporal land water distributions and the consequent hydrological gravity disturbances the newly estimated gravity disturbances agree with the absolute gravity values observed by fg5 gravimeters in 2004 2009 within about 2 6 gal by additionally accounting for the excess discharge of groundwater mass associated with a sloping impermeable surface below the discharge area after the gravity disturbance of 20 gal amplitude is subtracted from the absolute gravity data observed during the 2004 eruptive event the gravity residual of 5 gal amplitude shows a significant decrease in synchronization with eruptions because the ascending magma mass in the conduit affects the upward attraction force to the gravimeters installed on the flank of asama volcano the magma head altitude to which the residual gravity is converted assuming a homogeneous linear density in the conduit shows a comprehensive agreement of the time variation in the magma head with those in other volcanic observations such as gas emission rate and earthquake frequency by correcting the hydrological gravity disturbances using this hydrological model and simultaneously obtained meteorological data in real time spatiotemporal variations in the magma mass can be instantaneously monitored at asama volcano even before eruptions during future volcanic events

electrochemical sensing of volcanic gases we report here the development and application of a compact geochemical nose incorporating electrochemical sensors for gas measurements in volcanic plumes a novel element of the instrument design is the arrangement of the sensors in a parallel array that enables near simultaneous exposure and fast response data analysis methods were developed that utilise the multi sensor output currents to extract gas mixing ratio abundances and eliminate cross sensitivities use of filter methods is demonstrated to remove baseline drift or instrument noise we introduce a new approach for analysis of measurements from sensors that have a slower response time e g hcl and apply this model to estimate hcl so2 ratios we deployed the sensor system at aso volcano japan detecting emissions from its fumarole field hot crater lake and a mixed plume we measured so2 h2s co and hcl ranging in abundance from 102 104 ppbv neither no2 nor cl2 were detected for the fumarolic gases molar ratios were measured as follows h2s so2 is 0 15 h2 so2 0 25 co so2 0 02 hcl so2 0 1 the crater lake plume s h2s so2 is 0 03 the compositions are discussed in terms of degassing equilibria and plume chemistry our instrument design represents a cost effective low power and highly portable system that can be readily adapted for operational surveillance of volcanic gases

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

gps observations of fault afterslip and upper crustal deformation following the northridge earthquake global positioning system gps observations indicate that significant aseismic deformation occurred in the year following the january 17 1994 northridge earthquake the postseismic observations show the same sense of motion as the coseismic compared with the coseismic displacements the far field postseismic motions 1 2 fault dimensions away are proportionally larger than those seen in the near field the postseismic data are best modeled with two faults one on the rupture plane and one located in the shallow crust the upper crustal fault may represent an actual fault or may be indicative of viscous relaxation occurring in the upper crust the inferred afterslip and or relaxation moment is approximately 2 9 1018 n m or 22 of the mainshock moment release we expect that the moment release due to the afterslip and relaxation effectively reduce the earthquake hazard locally it is not clear from this study how the postseismic deformation loads the surrounding faults or alters the state of stress on those faults

postseismic rebound in fault step overs caused by pore fluid flow near field strain induced by large crustal earthquakes results in changes in pore fluid pressure that dissipate with time and produce surface deformation synthetic aperture radar sar interferometry revealed several centimeters of postseismic uplift in pull apart structures and subsidence in a compressive jog along the landers california 1992 earthquake surface rupture with a relaxation time of 270 45 days such a postseismic rebound may be explained by the transition of the poisson s ratio of the deformed volumes of rock from undrained to drained conditions as pore fluid flow allows pore pressure to return to hydrostatic equilibrium

real time fluid analysis during drilling of the wenchuan earthquake fault scientific drilling project and its responding features abstract the wenchuan earthquake fault scientific drilling project was established shortly after the wenchuan earthquake several on site laboratories were built to perform the real time fluid analysis during drilling simultaneously the concentrations of argon methane hydrogen carbon dioxide helium nitrogen oxygen and radon in drilling mud gas were determined during the entirely process of drilling the setup for real time fluid analysis was stability for long time the mud gas such as methane and radon yielded low concentrations above the principal slip zone psz whereas yielded high concentrations under the psz the real time fluid data might provide the real time information for identifying and validating of the psz in the deep fault zone the gas concentration showed abnormal fluctuation during the ms 4 0 earthquake on april 27 2010 the abnormality occurred one hour before the earthquake and ended half an hour after the earthquake the real time fluid analysis during drilling might have captured the signal of the ms 4 0 earthquake at a quarter past six on april 27 one strong and nearest aftershock

volatilization transport and sublimation of metallic and non metallic elements in high temperature gases at merapi volcano indonesia abstract condensates silica tube sublimates and incrustations were sampled from 500 800 c fumaroles and lava samples were collected at merapi volcano indonesia in jan feb 1984 with respect to the magma merapi gases are enriched by factors greater than 105 in se re bi and cd 104 105 in au br in pb and w 103 104 in mo cl cs s sn and ag 102 103 in as zn f and rb and 1 102 in cu k na sb ni ga v fe mn and li the fumaroles are transporting more than 106 grams day g d of s cl and f 104 106 g d of al br zn fe k and mg 103 104 g d of pb as mo mn v w and sr and less than 103 g d of ni cu cr ga sb bi cd li co and u with decreasing temperature 800 500 c there were five sublimate zones found in silica tubes 1 cristobalite and magnetite first deposition of si fe and al 2 k ca sulfate acmite halite sylvite and pyrite maximum deposition of cl na k si s fe mo br al rb cs mn w p ca re ag au and co 3 aphthitalite k na sulfate sphalerite galena and cs k sulfate maximum deposition of zn bi cd se and in higher deposition of pb and sn 4 pb k chloride and na k fe sulfate maximum deposition of pb sn and cu and 5 zn cu and k pb sulfates maximum deposition of pb sn ti as and sb the incrustations surrounding the fumaroles are also chemically zoned bi cd pb w mo zn cu k na v fe and mn are concentrated most in or very close to the vent as expected with cooling atmospheric contamination and dispersion the highly volatile elements br cl as and sb are transported primarily away from high temperature vents ba si p al ca and cr are derived from wall rock reactions incomplete degassing of shallow magma at 915 c is the origin of most of the elements in the merapi volcanic gas although it is partly contaminated by particles or wall rock reactions the metals are transported predominantly as chloride species as the gas cools in the fumarolic environment it becomes saturated with sublimate phases that fractionate from the gas in the order of their equilibrium saturation temperatures devolatilization of a cooling batholith could transport enough acids and metals to a hydrothermal system to play a significant role in forming an ore deposit however sublimation from a high temperature high velocity carrier gas is not efficient enough to form a large ore deposit re se cd and bi could be used as supporting evidence for magmatic fluid transport in an ore deposit

rapid response of a hydrologic system to volcanic activity masaya volcano nicaragua hydrologic systems change in response to volcanic activity and in turn may be sensitive indicators of volcanic activity here we investigate the coupled nature of magmatic and hydrologic systems using continuous multichannel time series of soil temperature collected on the flanks of masaya volcano nicaragua one of the most active volcanoes in central america the soil temperatures were measured in a low temperature fumarole field located 3 5 km down the flanks of the volcano analysis of these time series reveals that they respond extremely rapidly on a time scale of minutes to changes in volcanic activity also manifested at the summit vent these rapid temperature changes are caused by increased flow of water vapor through flank fumaroles during volcanism the soil temperature response 5 c is repetitive and complex with as many as 13 pulses during a single volcanic episode analysis of the frequency spectrum of these temperature time series shows that these anomalies are characterized by broad frequency content during volcanic activity they are thus easily distinguished from seasonal trends diurnal variations or individual rainfall events which triggered rapid transient increases in temperature during 5 of events we suggest that the mechanism responsible for the distinctive temperature signals is rapid change in pore pressure in response to magmatism a response that can be enhanced by meteoric water infiltration monitoring of distal fumaroles can therefore provide insight into coupled volcanic hydrologic meteorologic systems and has potential as an inexpensive monitoring tool

sinian microfossils from south west china the microfossil assemblages described here are preserved in cherts from the yunnan province south west china they are the first chert facies microfossils to be discovered in the wangjiawan and meishucun stratigraphical sequences which are regarded by the international cambrian precambrian boundary working group1 as possible candidates for the stratotype section of the cambrian precambrian boundary

high resolution radon monitoring and hydrodynamics at mount vesuvius a yearlong high resolution radon survey has been carried on at mount vesuvius starting in may 1998 radon activities were acquired by exposing charcoal canisters and track etch detectors sampling stations were deployed along two major summit faults and around the caldera bottom volcanically related earthquakes with md 2 5 may be discriminated from regional seismic events since their cumulative radon anomalies are recorded from stations located along all the above structural features on the contrary radon anomalies correlated to regional earthquakes with md 4 are essentially recorded by the sampling sites located along the two summit faults whose roots extend deeper into the tertiary basement rocks that underlay the volcano radon migration to the surface is ruled by convection within a porous medium of relatively low porosity 10 5 suggesting that fluid motion is strongly localised along fractures it is suggested that fluid pressure build up followed by fluid release and migration during incipient fracturing of the porous medium precede the onset of volcanically induced earthquakes

structure and evolution of lithospheric slab beneath the sunda arc indonesia tomographic imaging reveals seismic anomalies beneath the sunda island arc indonesia that suggest that the lithospheric slab penetrates to a depth of at least 1500 kilometers the sunda slab forms the eastern end of a deep anomaly associated with the past subduction of the plate underlying the mesozoic tethys ocean in accord with previous studies the lithospheric slab was imaged as a continuous feature from the surface to the lower mantle below java with a local deflection where the slab continues into the lower mantle the deep slab seems to be detached from the upper mantle slab beneath sumatra this complex slab structure is related to the tertiary evolution of southeastern asia and the indian ocean region

field measurements of volcanic gases vulcano island italy kilauea hawaii u s a merapi java indonesia a field gas chromatograph built in 1978 was used in the field to directly analyse volcanic gases before water vapor condensation tested in vulcano italy kilauea hawaii and merapi indonesia this field measurement technique provides the actual composition of the volcanic gas mixture the technique avoids the depletion of sulfur gases and the dissolution of the acid gases in the condensed water during the cooling thus the mixture of h2s and so2 in fumarolic and high temperature gases up to 819 c in equilibrium at the emission temperature was examined

plate motion and crustal deformation estimated with geodetic data from the global positioning system we use geodetic data taken over four years with the global positioning system gps to estimate 1 motion between six major plates and 2 motion relative to these plates of ten sites in plate boundary zones the degree of consistency between geodetic velocities and rigid plates requires the one dimensional standard errors in horizontal velocities to be 2 mm yr each of the 15 angular velocities describing motion between plate pairs that we estimate with gps differs insignificantly from the corresponding angular velocity in global plate motion model nuvel 1a which averages motion over the past 3 m y the motion of the pacific plate relative to both the eurasian and north american plates is observed to be faster than predicted by nuvel 1a supporting the inference from very long baseline interferometry vlbi that motion of the pacific plate has sped up over the past few m y the eurasia north america pole of rotation is estimated to be north of nuvel 1a consistent with the independent hypothesis that the pole has recently migrated northward across northeast asia to near the lena river delta victoria which lies above the main thrust at the cascadia subduction zone moves relative to the interior of the overriding plate at 30 of the velocity of the subducting plate reinforcing the conclusion that the thrust there is locked beneath the continental shelf and slope

organic walled microfossils from the chert phosphorite member tal formation precambrian cambrian boundary india the chert member also designated chert phosphorite member of the tal formation in the lesser himalaya contains well preserved organic walled microfossil assemblage the assemblage includes small 25 m acanthomorphic acritarchs sphaeromorphic acritarchs cyanobacterial filaments sponge spicules and thallophytic remains identified as micrhystridium lanceolatum m dissimilare m tornatum m lanatum cf lophosphaeridium sp paracymatiosphaera irregularis cymatiosphaera sp estiastra minima leiosphaeridia sp siphonophycus robustum thalloidal fragments and hexactinellid sponge spicules the present assemblage rich in small acanthomorphs appears to be best developed in upper nemakit daldynian beds based on acritarch biostratigraphy the present work suggests a nemakit daldynian to early tommotian age for the chert member which is in agreement with the formerly proposed age based mainly on small shelly fossils the assemblage is correlatable to the precambrian cambrian boundary microbiotic assemblage from china central asia and east european platform the assemblage shows low diversity of species the characteristic of inshore biota

atmospheric limitations to repeat track radar interferometry in its recent radar imaging mission the shuttle imaging radar satellite sir c devoted three days to repeat track interferometry we have analyzed the data from a test site in the mojave desert of california although good topography 10 m on 21 m postings was obtained most of the error was caused by turbulent water vapor in the lower atmosphere spatial structure of 6 km and all smaller sizes was observed the rms one way time delay was found to be 0 24 cm essentially identical results were obtained at two wavelengths 24 and 5 7 cm

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

geodetic measurement of deformation in the ventura basin region southern california we have measured the deformation in the ventura basin region southern california with global positioning system gps measurements carried out over 4 6 years between 1987 and 1992 the deformation within our network is spatically variable on scales of tens of kilometers with strain rates reaching 0 6 1 micro rad yr in the east central basin blocklike rotations are observed south and northwest of the basin where the maximum shear strain rates are an order of magnitude lower 0 06 1 micro rad yr to the south we also observed clockwise rotations of 1 deg 7 deg m y shear strain rates determined by comparing angle changes from historical triangulation spanning several decades and gps measurements give consistent though less precise results the geodetic rates of shortening across the basin and western transverse ranges are lower than those estimated from geological observations but the patterns of deformation from the two methods agree qualitatively

chemical variations in fumarolic gases at vulcano island southern italy seasonal and volcanic effects abstract because of increasing in fumarolic activity at vulcano since september 1987 regular sampling and analysis is conducted on the well known f5 crater fumarole t 330 5 c significant chemical variations have been recorded over the period 1987 1989 variations of water vapour in the fumarolic fluid follow seasonal pattern and can be related to both external seasonal and internal volcanic influences suggesting a control by a shallow water aquifer significant variations of h 2 o and of some species in the anhydrous gas phase h 2 so 2 hcl hf n 2 he probably result from chemical or dynamic changes in the feeding system at depth several mechanism are considered for explaining the chemical trends results in relationship to the recent increase in activity a growing input of deep magmatic fluids is not supported by the low co content and the apparent constancy of the 3 he 4 he ratio apparent equilibrium temperatures close to the fumarolic outlet temperature 350 400 c were calculated suggesting isothermal expansion of the gas from a shallow equilibration zone comparison with the fumaroles at sea level porto di levante suggests that these latter may be fed a different hydrothermal systems variable interaction between both systems may account for some of the chemical variations observed at f5 fumarole

thermal and gas dynamic investigations at lastarria volcano northern chile the influence of precipitation and atmospheric pressure on the fumarole temperature and the gas velocity abstract fumaroles are hydrothermal manifestations commonly associated with active volcanoes the dynamics of fumaroles are affected by interactions with internal and external factors however hazardous access and corrosive gases have so far limited successful case studies in this study we report and discuss the results of continuous thermal monitoring carried out on three high temperature 250 c fumaroles at the lastarria volcano chile together with simultaneously measured meteorological parameters from december 2013 to march 2016 in addition the dynamic pressure and the co2 concentration were recorded in a fourth vent the investigated sites are located in the largest and most dominant fumarole field which developed in a fracture system on the north west flank of the volcanic edifice we detect external factors controlling the fumarole temperature and the dynamic gas pressure for a better understanding of changes in these parameters and consequently to improve the evaluation of volcanic and hydrothermal activity selected fumaroles showed a continuous decrease in temperature or remained unbiased from this trend showing that the influence of external effects on outlet temperature is strongly site dependent but generally significant decreases in all vent temperatures can be observed in response to intensive precipitation diurnal variations occur only in the coolest fourth fumarole where gas temperature gas pressure and co2 concentration are inversely correlated with atmospheric pressure small barometric pressure reductions account for an increase in mass flow subsequently resulting in a higher temperature and co2 concentration the temperatures and thermodynamic properties of the fumarolic gas and infiltrated precipitation water were used to calculate the amount of discharging gas from the investigated field with about 67 106 m3 per day which is equivalent to 3545 tons

structure and co2 budget of merapi volcano during inter eruptive periods soil temperature and gas co2 concentration and flux have been investigated at merapi volcano indonesia during two inter eruptive periods 2002 and 2007 precise imaging of the summit crater and the spatial pattern of diffuse degassing along a gas traverse on the southern slope are interpreted in terms of summit structure and major caldera organization the summit area is characterized by decreasing co2 concentrations with distance from the 1932 crater rim down to atmospheric levels at the base of the terminal cone similar patterns are measured on any transect down the slopes of the cone the spatial distribution of soil gas anomalies suggests that soil degassing is controlled by structures identified as concentric historical caldera rims 1932 1872 and 1768 which have undergone severe hydrothermal self sealing processes that dramatically lower the permeability and porosity of soils temperature and co2 flux measurements in soils near the dome display heterogeneous distributions which are consistent with a fracture network identified by previous geophysical studies these data support the idea that the summit is made of isolated and mobile blocks whose boundaries are either sealed by depositional processes or used as pathways for significant soil degassing within this context self sealing both prevents long distance soil degassing and controls heat and volatile transfers near the dome a rough estimate of the co2 output through soils near the dome is 200 230 t day 1 i e 50 of the estimated total gas output from the volcano summit during these quiescent periods on merapi s southern slope a 2 500 m long co2 traverse shows low amplitude anomalies that fit well with a recently observed electromagnetic anomaly consistent with a faulted structure related to an ancient avalanche caldera rim sub surface soil permeability is the key parameter that controls the transfer of heat and volatiles within the volcano allowing its major tectonic architecture to be revealed by soil gas and soil temperature surveys

installation of a doppler radar monitoring system at merapi volcano indonesia merapi volcano indonesia is one of the most active dome building volcanoes worldwide instabilities at the growing dome cause rockfalls and hot block and ash flows which can reach run out distances of several kilometers therefore merapi has been monitored extensively for many years however direct visual observation of the dome is often impossible due to cloud coverage of the summit in october 2001 a first prototype doppler radar system was installed to overcome this shortcoming the system is able to penetrate clouds and observe material movements at the dome giving valuable information about dynamic processes in the dome area the system also allows detection of rainfall in several distance intervals for precise positioning of the beam the system was equipped with an electromechanical mounting in 2003 a charge coupled device ccd camera attached to the radar mirror documents the radar beam position and provides visual observation of the dome recorded data camera images and status information are telemetered to the merapi volcano observatory where they can be processed and interpreted status information is also sent via short message service via a global system for mobile communications gsm modem by processing the doppler radar data we are able to discriminate between three different types of instability events sliding dome material dome material gravitationally breaking off the dome and explosive outbursts of dome material due to expansion of volcanic gas in order to independently verify our observations we compared rockfall events detected by the radar system to seismic recordings and found a good correlation

combined gps and insar models of postseismic deformation from the northridge earthquake models of combined global positioning system gps and interferometric synthetic aperture radar insar data collected in the region of the northridge earthquake indicate that significant afterslip on the main fault occurred following the earthquake additional shallow deformation occurred to the west of the main rupture plane both data sets are consistent with logarithmic time dependent behavior following the earthquake indicative of afterslip rather than postseismic relaxation aftershocks account for only about 10 of the postseismic motion the two data sets are complimentary in determining the postseismic processes fault afterslip and shallow deformation dominate the deformation field in the two years following the earthquake lower crustal deformation may play an important role later in the earthquake cycle

poroelastic rebound along the landers 1992 earthquake surface rupture maps of surface displacement following the 1992 landers california earthquake generated by interferometric processing of ers 1 synthetic aperture radar sar images reveal effects of various postseismic deformation processes along the 1992 surface rupture the large scale pattern of the postseismic displacement field includes large lobes mostly visible on the west side of the fault comparable in shape with the lobes observed in the coseismic displacement field this pattern and the steep displacement gradient observed near the emerson camp rock fault cannot be simply explained by afterslip on deep sections of the 1992 rupture models show that horizontal slip occurring on a buried dislocation in a poisson s material produces a characteristic quadripole pattern in the surface displacement field with several centimeters of vertical motion at distances of 10 20 km from the fault yet this pattern is not observed in the postseismic interferograms as previously proposed to explain local strain in the fault step overs peltzer et al 1996b we argue that poroelastic rebound caused by pore fluid flow may also occur over greater distances from the fault compensating the vertical ground shift produced by fault afterslip such a rebound is explained by the gradual change of the crustal rocks poisson s ratio value from undrained coseismic to drained postseismic conditions as pore pressure gradients produced by the earthquake dissipate using the poisson s ratio values of 0 27 and 0 31 for the drained and undrained crustal rocks respectively elastic dislocation models show that the combined contributions of afterslip on deep sections of the fault and poroelastic rebound can account for the range change observed in the sar data and the horizontal displacement measured at global positioning system gps sites along a 60 km long transect across the emerson fault savage and svarc 1997 using a detailed surface slip distribution on the homestead valley kickapoo and johnson valley faults we modeled the poroelastic rebound in the homestead valley pull apart a poisson s ratio value of 0 35 for the undrained gouge rocks in the fault zone is required to account for the observed surface uplift in the 3 5 years following the earthquake this large value implies a seismic velocity ratio vp vs of 2 1 consistent with the observed low vs values of fault zone guided waves at shallow depth li et al 1997 the sar data also reveal postseismic creep along shallow patches of the eureka peak and burnt mountain faults with a characteristic decay time of 0 8 years coseismic dilatant hardening locking process followed by post seismic pore pressure controlled fault creep provide a plausible mechanism to account for the decay time of the observed slip rate along this section of the fault

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

kinematics of postseismic relaxation from aftershock focal mechanisms of the 1994 northridge california earthquake geodetic observations of surface deformation associated with the 1994 northridge southern california earthquake generally are reproduced by simple models of a large scale elastic dislocation on a blind or buried thrust fault the smaller scale aftershocks of the northridge earthquake are distributed throughout much of the volume of crust that appears to have deformed elastically during the mainshock these aftershocks averaged over volumes that are large relative to their rupture radii reflect a distributed permanent deformation that is accommodated by local brittle fracture we use a micropolar continuum model to invert the aftershocks in such volumes for the average incremental strain and we compare that deformation both with the elastic strain from the dislocation model of the mainshock and with geodetically measured strain aftershock deformation that occurred at depths below about 6 km and which is associated with the primary rupture zone is consistent with slow continuation of the southwest side up reverse slip on the blind northridge thrust fault in contrast aftershock deformation from the upper 5 7 km of the hanging wall block directly above the thrust fault can be characterized by horizontal ne sw shortening and horizontal nw se i e fault parallel extension this pattern of deformation is similar to that associated with the mainshock as observed geodetically and as calculated from the elastic dislocation model we interpret that the aftershock activity in the hanging wall represents the quasi ductile accommodation by brittle deformation mechanisms of a permanent strain distributed through the hanging wall block the aftershocks along the mainshock rupture zone are interpreted as resulting from either 1 the time dependent release along a weakened fault zone of part of the remaining accumulated elastic strain in the upper crust or 2 the continued slip in the weakened fault zone driven by the deformation of a ductile elastic lower crustal layer that relaxes under the stress transferred by the coseismic loss of cohesion in the upper crust in either case the aftershock activity suggests that the crust undergoes quasi ductile flow as a brittle elastic material and is not a strictly elastic material

in situ observation of dome instabilities at merapi volcano indonesia a new tool for volcanic hazard mitigation understanding the mechanism and repetition frequency of dome instability events at high risk dome building volcanoes located near densely populated areas is one crucial piece of information when dealing with volcanic hazard mitigation although some visual in situ observations of such processes have been made at unzen volcano and on montserrat continuous monitoring of dome activity has been severely hampered by weather conditions such as cloud coverage using a newly designed microwave doppler system we are able to continuously monitor in situ processes at active dome systems with our instrument we can determine the velocity of material breaking off an active dome as well as the approximate amount of material passing through the radar beam allowing us to continuously identify different types of dome instabilities a data set collected during a highly active period at the end of oct early nov 2001 at merapi volcano indicates two different instability types a purely gravitational instabilities and b gravitational instabilities that are followed immediately by an explosion such information continuously collected allows tight constrains on the activity status of dome building volcanoes and is an important information for hazard mitigation the number of instabilities detected by the radar during the observational period is larger than the number of rockfall events detected by the seismic network operated at merapi during that time

a hybrid model for the summit region of merapi volcano java indonesia derived from gravity changes and deformation measured between 2000 and 2002 three dimensional displacements and gravity changes were measured at 20 points between 2000 and 2002 at merapi volcano java indonesia former models focused on the modeling of a single magmatic source located in the summit region of the volcano such models do not fit to our measurements between 2000 and 2002 a new hybrid model approach is developed consisting of an elastic gravitational source described by a mass and energy term as well as a combined dip slip strike slip fault zone in the summit region both nonlinear optimization problems given by the common inversion of three dimensional displacements and gravity changes are solved by applying a genetic algorithm the hybrid model fits the measurements accurately tested by fisher test statistics furthermore our model for merapi volcano confirms previous structural models for this region so that the new model is statistically proven as well as physically reliable

marine sedimentation of nano quartz forming flint in north sea danian chalk abstract a new theory for formation of flint in the north sea danian ekofisk formation chalk has been formulated according to which the flint formed by sedimentation of nano size quartz particles these quartz particles have crystallized in the sea from silicon supplied from dissolution of radiolarians in the present work this model has been tested by sedimentological and mineralogical investigation of sedimentary features in chalk containing silica methods applied are x ray diffraction xrd atomic force microscopy afm scanning electron microscopy sem and thermal analysis dta ega in the ekofisk formation silica was present in flint in quartz beds and as quartz particles dispersed in the chalk the quartz in the flint in the quartz intervals and the quartz particles in the chalk are one and the same kind of quartz it is composed of 0 1 0 3 m spheres of quartz having perfect three dimensional order but with slightly larger cell dimensions compared to standard quartz the quartz in the flint in the quartz horizons and dispersed in the chalk must accordingly have formed by one and the same mechanism which is crystallization in the water phase prior to sedimentation it is proposed that the difference in proportion of calcite in the flint and the quartz horizons on one side and the chalk with quartz particles on the other is due to different degrees of dissolution of the pelagic skeletal debris of coccolithophorids in the seawater during sedimentation this variation is attributed to differences in concentration of co2 in the seawater and the high amounts of co2 dissolving the calcite during sedimentation of the pure quartz are proposed to come from volcanic activity this implies that the quartz rich horizons consisting of dispersed quartz quartz horizons or flint are regional features and may as such be present as regional sheets in the pelagic danian ekofisk chalk reservoir

influence of anelastic surface layers on postseismic thrust fault deformation we present the results of a systematic modeling study of postseismic deformation following blind thrust earthquakes the results include qualitative and quantitative predictions of the surface movement caused by relaxation in viscoelastic near surface layers finite element forward models are used in conjunction with elastic dislocation inversions to characterize the post seismic deformation a viscoelastic surface layer overlying a blind thrust fault in an elastic basement shows characteristic signatures of postseismic surface movement simple equivalent elastic dislocations located in the hanging wall wedge are found to provide an effective proxy for near surface postseismic relaxation in two dimensional numerical simulations a model survey of a range of fault dip angles and layer geometries shows the time evolution and geometry of the proxy fault to be simply related to fault dip and sediment thickness the results are of significance in the interpretation of postseismic global positioning system gps strain data from the 1994 northridge california earthquake and other similar events in regions characterized by poorly consolidated or otherwise anelastic layers overlying the brittle seismogenic zone

middle upper proterozoic and lowest phanerozoic microfossil assemblages from sw china and contiguous areas abstract this paper deals briefly with microfossil assemblages from middle upper proterozoic and lowest phanerozoic c 1800 600 ma rocks of sw china and contiguous areas the five acritarch assemblages and one chert facies algal microbial fossil assemblage include several new forms that are here described for the first time the microfossils show some evolutionary trends in upward succession they show an increased size range and the taxa become more varied and more complex in texture and form data concerning these microfossils contribute to the solution of the following problems 1 stratigraphic succession and correlation of the kunyang group and contemporaneous strata in sw china 2 the sinian microfossil assemblage as the lowest part of the phanerozoic and 3 the utility of proterozoic and lowest phanerozoic microfossils in biostratigraphic subdivision and correlation the conclusions reached here are consistent with field observations by many geologists with isotopic data and with studies of stromatolites to be published elsewhere the microfossils described are radiophycus yangjiapingensis n g and sp paracymatiosphaera regularis n g and sp p irregularis n g and sp p annularis n g and sp p hunnanensis n g and sp protosolenopora distincta n g and sp micrhystridium ampliatum n sp

shortening and thickening of metropolitan los angeles measured and inferred by using geodesy geodetic observations using the global positioning system gps and other techniques record a high rate of north south shortening in an east southeast trending 5 40 km wide belt in northern metropolitan los angeles california downtown los angeles is observed to be converging upon the southern san gabriel mountains at 6 mm yr aside from the elastic strain that will be released during earthquakes rupturing the san andreas and san jacinto faults east west lengthening across northern metropolitan los angeles is minor 2 5 mm yr therefore north south shortening is accommodated mainly by vertical crustal thickening

lowermost cambrian acritarchs from the yanjiahe formation south china implication for defining the base of the cambrian in the yangtze platform the asteridium heliosphaeridium comasphaeridium ahc acritarch assemblage is composed of common organic walled microfossils in the basal cambrian chert phosphorite units in south china indicating that the ahc assemblage can be a useful biostratigraphic tool for the ediacaran cambrian boundary successions in the yangtze platform to test the validity of the ahc acritarch assemblage as a biostratigraphic tool the stratigraphic range of the ahc acritarch assemblage was confirmed and its spatial and temporal relationships to other bio and chemostratigraphic tools were analysed in the yanjiahe formation yangtze gorges area south china the result shows that the ahc assemblage temporally correlates to the anabarites trisulcatus protohertzina anabarica assemblage zone and spatially correlates to the large negative carbon isotope anomaly of the lowermost cambrian bace in the yanjiahe formation this implies that the radiation of phytoplankton occurred slightly before the radiation of the small shelly fossils and the ahc acritarch assemblage can be another important chronological reference to the lowermost cambrian successions in south china and potentially to global correlations

tracking precursors and degassing by radon monitoring during major eruptions at stromboli volcano aeolian islands italy 1 we monitored radon anomalies before during and after the recent paroxysmal eruptions of stromboli major eruptive events are preceded by relative minima in radon emissions at stations located at the base of the cone whereas three of the summit stations reached peak values 20 000 bq m3 or higher 12 to 14 days before major eruptions and are nearly coeval with earth tides radon emissions at or above such high threshold values are proposed to result from the dynamic response of the fracture network due to degassing processes associated with magma ascent relative minima recorded at the base of the cone are related to fractures self sealing within the hydrothermal system eventually coupled with the atmospheric stack effect the coexistence of the above anomalies is interpreted as the first precursory signals to major eruptive events

continuous monitoring of high temperature fumaroles on an active lava dome volcan colima mexico evidence of mass flow variation in response to atmospheric forcing rapid multichannel monitoring of fumaroles on volcan colima mexico provides new insight into the time scales and magnitudes of fumarole temperature variation temperatures in five fumaroles all located along a single fracture cutting the summit lava dome of the volcano were monitored at 20 min intervals between may 1991 and may 1992 measurements were made using a programmable data logger deployed near the fumarole field and data were radiotelemetered to a nearby volcano observatory at regular intervals mean fumarole temperatures varied between 350 c and 550 c statistical analysis of these time series shows that significant diurnal variation occurs in each fumarole magnitudes of these daily fluctuations are generally between 25 c and 50 c although larger amplitude variations occur especially in cooler fumaroles simultaneous monitoring of atmospheric pressure at the fumaroles indicates that these variations in temperature are inversely correlated with barometric pressure these observations indicate that fumarole temperatures respond to atmospheric forcing a numerical model developed to explore the dependence of fumarole temperature on mass flow demonstrates that many aspects of observed temperature variation are accounted for by mass flow variation resulting from small changes in barometric pressure the relationship between mass flow and fumarole temperature is nonlinear the response of fumarole temperatures to a given change in mass flow is greatest in fumaroles with low mass flow and cool temperatures the nature of this dependence is little affected by fumarole geometry for the cases considered continuous measurement of fumarole temperatures may be an effective means of monitoring local mass flow on volcanoes at volcan colima average temperatures changed by less than 100 c during the 1 year sampling period during and immediately following effusive activity changes in degassing were abrupt and inconsistent along the length of the fracture following this period temperatures decreased gradually and there was a higher degree of correlation between fumaroles the method described here represents a substantial improvement over traditional fumarole monitoring techniques because subtle variation can be quickly identified using standard statistical techniques and the method provides regular information about thermal activity on a volcano minimizing the hazards normally associated with the collection of these data on a regular basis

correlation of seismic activity and fumarole temperature at the mt merapi volcano indonesia in 2000 abstract in this paper we present densely sampled fumarole temperature data recorded continuously at a high temperature fumarole of mt merapi volcano indonesia these temperature time series are correlated with continuous records of rainfall and seismic waveform data collected at the indonesian german multi parameter monitoring network the correlation analysis of fumarole temperature and precipitation data shows a clear influence of tropical rain events on fumarole temperature in addition there is some evidence that rainfall may influence seismicity rates indicating interaction of meteoric water with the volcanic system knowledge about such interactions is important as lava dome instabilities caused by heavy precipitation events may result in pyroclastic flows apart from the strong external influences on fumarole temperature and seismicity rate which may conceal smaller signals caused by volcanic degassing processes the analysis of fumarole temperature and seismic data indicates a statistically significant correlation between a certain type of seismic activity and an increase in fumarole temperature this certain type of seismic activity consists of a seismic cluster of several high frequency transients and an ultra long period signal

the effects of environmental parameters on diffuse degassing at stromboli volcano insights from joint monitoring of soil co2 flux and radon activity abstract soil co 2 flux and 222 rn activity measurements may positively contribute to the geochemical monitoring of active volcanoes the influence of several environmental parameters on the gas signals has been substantially demonstrated therefore the implementation of tools capable of removing or minimising the contribution of the atmospheric effects from the acquired time series is a challenge in volcano surveillance here we present 4 years long continuous monitoring from april 2007 to september 2011 of radon activity and soil co 2 flux collected on the ne flank of stromboli volcano both gases record higher emissions during fall winter up to 2700 bq m 3 for radon and 750 g m 2 day 1 for co 2 than during spring summer seasons short time variations on 222 rn activity are modulated by changes in soil humidity rainfall and changes in soil co 2 flux that may be ascribed to variations in wind speed and direction the spectral analyses reveal diurnal and semi diurnal cycles on both gases outlining that atmospheric variations are capable to modify the gas release rate from the soil the long term soil co 2 flux shows a slow decreasing trend not visible in 222 rn activity suggesting a possible difference in the source depth of the of the gases co 2 being deeper and likely related to degassing at depth of the magma batch involved in the february april 2007 effusive eruption to minimise the effect of the environmental parameters on the 222 rn concentrations and soil co 2 fluxes two different statistical treatments were applied the multiple linear regression mlr and the principal component regression pcr these approaches allow to quantify the weight of each environmental factor on the two gas species and show a strong influence of some parameters on the gas transfer processes through soils the residual values of radon and co 2 flux i e the values obtained after correction for the environmental influence were then compared with the eruptive episodes that occurred at stromboli during the analysed time span 2007 2011 but no clear correlations emerge between soil gas release and volcanic activity this is probably due to i the distal location of the monitoring stations with respect to the active craters and to ii the fact that during the investigated period no major eruptive phenomena paroxysmal explosion flank eruption occurred comparison of mlr and pcr methods in time series analysis indicates that mlr can be more easily applied to real time data processing in monitoring of open conduit active volcanoes like stromboli where the transition to an eruptive phase may occur in relatively short times

radon mapping automatic measurements and extremely high 222rn emissions during the 2002 2007 eruptive scenarios at stromboli volcano abstract we report additional radon data collected at stromboli during 2002 2007 the whole data set of periodic measurements has been systematically analyzed to retrieve the values of background threshold and anomaly for all the stations of the network maps of radon concentrations in space and time correlate with changes in volcanic activity higher radon emissions are essentially concentrated at summit stations and may also affect some stations located onto the summit eastern sector of the cone along the n60 e fracture zone as well as two stations placed at the ne edge of sciara del fuoco most of these stations are well above their threshold values during effusive eruptions namely 2002 2003 and 2007 due to the progressive structural adjustment of the volcano edifice coupled with the opening and resetting of the fracture network a two year long timeseries of automatic 222 rn measurements 2005 2007 was analyzed together with local environmental parameters and selected geophysical data on seismic tremor and infrasonic puffing the data show good correlation between radon and the latter parameters particularly during periods of high strombolian activity march april 2006 and before the onset of the february 27 2007 lava effusion with radon emissions being well above 20 000 bq m 3 extremely high radon emissions up to 1 7 10 6 bq m 3 were recorded along the fractures of the sw crater during the first two months of the 2002 2003 effusive eruption very high radon emissions up to 470 000 bq m 3 for 222 rn and 780 000 bq m 3 for 220 rn respectively were also detected by the automatic measurements at the summit station during june 20 early july 2007 i e just prior to the resuming of the strombolian activity at summit craters these data give us the opportunity to estimate the relative depths of the summit fractures during fracturing being constrained between 200 and 310 m this is in good agreement with the hypocentral depths of the so called hybrid events and the source of the very long period seismic signals vlp localized at a depth of about 500 m a s l below the upper central part of the sciara del fuoco

self potential and ground temperature at merapi volcano prior to its crisis in the rainy season of 2000 2001 abstract rainwater infiltration into the active lava dome of merapi volcano central java has often been suggested as a triggering mechanism for partial dome collapse and subsequent eruptive behavior however the phenomenon has not been systematically investigated we use a multi parametric approach to study the interaction of the hydrologic and magmatic system near the lava dome prior to its crisis in early 2001 we describe the hardware concept for a continuous monitoring system for self potentials u sp and ground temperature t installed in august 2000 at the solfatara woro only 150 m from the active lava dome relating the data from this station to measurements of rainfall air pressure solfatara temperature and seismicity several effects can be distinguished a a long term correlation is observed between electrode temperature difference and sp with estimated coupling coefficients of 2 1 0 5 mv c b after individual rainfall events u t signatures show a typical pattern of positive charge accumulation at the hot electrodes near the fumarolic vents c an exceptional anti correlation between u and t is observed in january 2001 during a period of rapid dome growth prior to the collapse and eruptive crisis d wavelet analysis of sp reveals the sporadic occurrence of periodic fluctuations with a clear 12 h s2 component because of their amplitude of up to 100 mv km and their periodicity s2 but not 24 h or lunar 12 h 25 min these fluctuations are unlikely to be caused by natural magnetic field variation or by earth tides instead they do seem correlated but not in phase with atmospheric pressure changes we discuss effects a d in the framework of source mechanisms related to water lava interactions

reconciling rapid strain accumulation with deep seismogenic fault planes in the ventura basin california global positioning system measurements across the east central ventura basin transverse ranges southern california before the nearby 1994 northridge earthquake show high strain rates interpreting this rapid strain accumulation using the usual model of deep slip on a dislocation in a uniform elastic half space requires slip to extend to within 5 km of the surface such shallow slip is difficult to reconcile with the substantial coseismic displacement at depths from 7 to 19 km during the northridge earthquake here we model the displacement and velocity fields throughout the earthquake cycle using a two dimensional finite element model with a viscoelastic rheology displacements are driven by far field and basal velocity boundary conditions and by imposed periodic earthquakes on the thrust faults bounding the basin the thrust faults rupture through an elastic upper crust to a depth of 15 km after a transient stage during which stresses and strains build up to quasi equilibrium values the behavior of the model becomes periodic the sum of the coseismic displacement divided by the repeat interval plus the average interseismic velocity is equal to the geologic velocity the temporal variation in surface velocity depends mainly on the elsasser relaxation time proportional to the product of the maxwell time of the lower crust and the ratio of the thicknesses of the entire crust and viscoelastic lower crust we are able to match the observed high strain rate only if we include the observed variations in elastic modulus associated with the deep basin sediments the model reconciles geologic geodetic and seismological observations of deformation there are trade offs among the far field convergence rate the elsasser time the earthquake repeat time and the time into the earthquake cycle acceptable convergence rates range from 8 mm yr for a relaxation time of the lower crust of 300 years to 12 mm yr for a 30 year relaxation time

crustal deformation across and beyond the los angeles basin from geodetic measurements we combine 6 years of global positioning system gps data with 20 years of trilateration data and a century of triangulation taped distance and astronomic azimuth measurements to derive 66 interseismic station velocities in the greater los angeles region we interpolate the velocities to construct a regional strain rate map beyond the los angeles basin our results generally agree with the model proposed by the working group on california earthquake probabilities in 1995 important regional findings of this study are as follows 1 there is a significant n s convergence and e w extension about 0 22 and 0 17 0 05 strain yr respectively for the two components along the southern frontal fault system of the san gabriel mountains 2 the crustal deformation around the big bend of the san andreas fault saf cannot be explained solely by wrench style motion across the saf remaining motion could be part of a nw se extension which is the response to nfsw compression in the central transverse ranges region alternatively it could be caused by left lateral faulting on an oblique blind thrust beneath the san gabriel mountains 3 low strain rates axe found along the elsinore fault and newport inglewood 4 north south compression decreases from the raymond hill fault westward to the santa monica fault there is little east west extension along this fault system

the rise and decline of the ediacaran biota palaeobiological and stable isotopic evidence from the nw and ne lesser himalaya india