the application of geochemical methods in earthquake prediction in china several geochemical anomalies were observed before the haichen longling tangshan and songpan earthquakes and their strong aftershocks they included changes in groundwater radon levels chemical composition of the groundwater concentration of ca mg cl so4 and hco3 ions conductivity and dissolved gases such as h2 co2 etc in addition anomalous changes in water color and quality were observed before these large earthquakes before some events gases escaped from the surface and there were reports of ground odors being smelled by local residents the large amount of radon data can be grouped into long term and short term anomalies the long term anomalies have a radon emission build up time of from a few months to more than a year the short term anomalies have durations from a few hours or less to a few months

radon earthquake precursor studies in iceland discrete samples of geothermal water have been collected from a network of nine stations for analysis of radon 222 rn content the sampling network consisted of wells that range in wellhead temperature from 48 c to 100 c and the depths range from 38 m to 1338 m the sampling frequency at most stations was about once per week and twice per week at the station fludir the wells are either artesian or pumped more or less continuously the network covered two regions of transform faulting in iceland with seven stations in the southern iceland seismic zone sisz and two stations in northern iceland in the tjornes fracture zone tfz during 1978 and 1979 several anomalous changes in radon content were observed to precede some of the local earthquakes criteria based on tectonic regimes a magnitude distance relationship and time clustering were applied to select a set of 23 earthquakes that could be expected to be preceded by a radon anomaly the magnitude of these earthquakes ranged between 1 0 and 4 3 each of the 23 earthquakes was within the distance range of one or more stations such that altogether 57 potential observations of possible anomalies were available the method of analysis applied to the radon and earthquake data consisted of identifying radon anomalies in retrospect and resulted in nine precursory anomalies 48 cases of failure to observe an anomaly and seven false alarms the probability of observing radon anomalies before earthquakes with magnitudes between 2 0 and 4 3 the largest event observed was found to be approximately 65 based on a weekly sampling rate in the sisz five out of eight earthquakes m 2 were preceded by an anomaly in two cases anomalies were observed at two different stations prior to the same earthquake the anomalies appeared to occur farther away for larger earthquake magnitude an aquiclude that divides the sisz did not seem to affect the occurrence of radon anomalies but the amplitude of anomalies on the east side were larger than the ones on the west side the duration times of the anomalies ranged from 17 to 37 days the large number of failures to observe an anomaly indicated that the occurrence of an anomaly was more strongly dependent on local conditions and earthquake parameters than distance between epicenter and radon station some stations also appeared to be less sensitive than others and three stations never showed an anomaly during periods of bursts in local seismicity some stations reflected distinctively larger background fluctuations which hampered the correlation of the seismicity with the radon data most of the false alarms were related to disturbances caused by changes in well operation in the sisz the high rate of failure to observe an anomaly and the occurrence of false alarms was partly compensated for by operating a dense network of sampling stations wells that are utilized at moderate flow rates are less likely to show false alarms than wells utilized at high flow rates wells situated close to rock formations rich in radioactive minerals may be more likely to show anomalies than others

fault location by radon and mercury detection at an active volcano in nicaragua the masaya caldera complex nicaragua with the active crater santiago fig 1 is the site of present day basaltic volcanism1 2 some of the faults that bound the caldera and lie within it can be located geologically others are postulated a possible older caldera rim lies to the south of the present margin to investigate whether one can identify faults in this environment of active volcanism concentrations of radon and mercury in the regolith were determined at 232 selected points in and adjacent to the caldera higher concentrations of hg0 or rn or both occurred over 75 of the known structures studied some hitherto suspected structures were confirmed while others were not lack of a chemical signature may be ascribed to the absence of a structure inappropriate sampling sites post fault lava cover or other sealing of the structure we show here how the use of rn and hg0 determinations has helped in structural analysis at this active volcano

radon variation in groundwaters in the campi flegrei caldera southern italy during and after the 1982 1984 bradyseismic crisis groundwater rn concentration has been monitored at several sites in the campi flegrei caldera since the time of the last episode of bradyseismic activity the results concerning the period 1983 88 indicate that the rn concentration is spatially variable due to the different chemico physical characteristics of the waters or structural features rn concentration is generally influenced by the long term changes of meteorological factors rainfalls appear to affect the rn content of the most superficial aquifers several short term spike like rn anomalies have been detected both during and after the period of the bradyseismic crisis they do not show correlation with temporal changes of the ph and or temperature of waters a systematic correlation between rn anomalies and episodic strong rainfall events is also absent furthermore a clear relationship between rn spikes and both uplift velocity changes and seismic activity has not been found the overall evidence makes it very difficult to understand the temporal changes of groundwater rn concentration that have occurred during and after the 1982 84 bradyseismic crisis nevertheless a clear causal relationship between rn concentration and the dynamics of the bradyseism is observed in some monitored sites its appearance may have been favoured by the low rn concentration in the groundwaters during periods of quiescent activity

apoyo caldera nicaragua a major quaternary silicic eruptive center apoyo caldera near granada nicaragua was formed by two phases of collapse following explosive eruptions of dacite pumice about 23 000 yr b p the caldera sits atop an older volcanic center consisting of lava flows domes and ignimbrite ash flow tuff the earliest lavas erupted were compositionally homogeneous basalt flows which were later intruded by small andesite and dacite flows along a well defined set of n s trending regional faults collapse of the roof of the magma chamber occurred along near vertical ring faults during two widely separated eruptions field evidence suggests that the climactic eruption sequence opened with a powerful plinian blast followed by eruption column collapse which generated a complex sequence of pyroclastic surge and ignimbrite deposits and initiated caldera collapse a period of quiescence was marked by the eruption of scoria bearing tuff from the nearby masaya caldera and the development of a soil horizon violent plinian eruptions then resumed from a vent located within the caldera a second phase of caldera collapse followed accompanied by the effusion of late stage andesitic lavas indicating the presence of an underlying zoned magma chamber detailed isopach and isopleth maps of the plinian deposits indicate moderate to great column heights and muzzle velocities compared to other eruptions of similar volume mapping of the apoyo airfall and ignimbrite deposits gives a volume of 17 2 km3 within the 1 mm isopach crystal concentration studies show that the true erupted volume was 30 5 km3 10 7 km3 dense rock equivalent approximately the volume necessary to fill the caldera a vent area located in the northeast quadrant of the present caldera lake is deduced for all the silicic pyroclastic eruptions this vent area is controlled by n s trending precaldera faults related to left lateral motion along the adjacent volcanic segment break fractional crystallization of calc alkaline basaltic magma was the primary differentiation process which led to the intermediate to silicic products erupted at apoyo prior to caldera collapse highly atypical tholeiitic magmas resembling low k high ca oceanic ridge basalts were erupted along tension faults peripheral to the magma chamber the injection of tholeiitic magmas may have contributed to the paroxysmal caldera forming eruptions

measurements of indoor radon concentration on the south eastern flank of mount etna volcano southern italy a study of indoor radon concentration has been carried out using a ionization chamber and charcoal canisters in an area located on the south eastern flank of mt etna volcano comparing the results obtained from these two types of detectors used at the same time we found that the measured values of radon concentration converge under particular meteorological conditions a large number of tests using charcoal canisters have been performed on inhabited areas only measurements with humidity values lower than 80 were taken into account the results show that higher values of radon concentration were obtained in constructions built near or on geological structures as faults and fractures in fact these tectonic disturbances in the earth s crust are preferential pathways for the radon migration and could enhance the indoor accumulation the charcoal canisters in volcanic areas and under particular meteorological conditions can be used as a cheap and fast radon detection method in order to individuate radon prone areas subsequently long period indoor measurements using other methodology should be carried out with the aim to evaluate radon and its components and levels of exposure for public health

catastrophic collapse at stratovolcanoes induced by gradual volcano spreading unlike ordinary mountains which are formed by slow uplift and erosion volcanoes are constructed rapidly as a consequence many are liable to massive flank failures leading to debris avalanches for example at mount st helens in 1980 such failures occur worldwide about once every 25 years ref 1 and even small ones can present a major hazard in particular if far reaching tsunamis are generated as at mayu yama in 1792 ref 2 previous work has tended to emphasize differences in eruption style associated with flank failure2 but here we focus on the fundamental structural causes of failure most volcanic failures are generated by magmatic intrusion and flank spreading3 we present evidence however that mombacho volcano in nicaragua experienced a previously unrecognized type of failure triggered by sub volcanic basement spreading notably collapses related to basement spreading do not require that the volcano be magma tically active and thus flank failure may pose a significant risk even at inactive volcanoes which are rarely monitored

radiocarbon ages for the timing of debris avalanches at mombacho volcano nicaragua radiocarbon dated lake sediments provide minimum limiting ages for two major debris avalanches originating from mombacho volcano in nicaragua a basal age from lake el gancho indicates that the northeast debris avalanche las isletas occurred sometime before 140 to 345 a d basal ages from lakes blanca and verde indicate that the southern el crater debris avalanche occurred sometime before 270 to 650 a d both events therefore occurred in the space of a few centuries yet there is strong evidence that the mechanisms varied for destabilization of each flank possibly the influence of a developing hydrothermal system lead first to deeper structural failure in the substrata to produce the las isletas sector collapse progressing to higher level destabilization within the edifice and the el crater collapse

impulsive radon emanation on a creeping segment of the san andreas fault california radon emanation was continuously monitored for several months at two locations along a creeping segment of the san andreas fault in central california the recorded emanations showed several impulsive increases that lasted as much as five hours with amplitudes considerably larger than meteorologically induced diurnal variations some of the radon increases were accompanied or followed by earthquakes or fault creep events they were possibly the result of some sudden outbursts of relatively radon rich ground gas sometimes triggered by crustal deformation or vibration

study of soil gas radon variations in the tectonically active dharamshala and chamba regions himachal pradesh india soil gas radon measurements were made in chamba and dharamshala regions of himachal pradesh india to study the correlation if any between the soil gas radon radium activity concentration of soil and the geology active tectonics of the study region soil gas radon surveys were conducted around the local fault zones to check their tectonic activities using the soil gas technique soil gas radon activity concentration at thirty five different locations in dharamshala region has been found to be varying from 13 2 1 5 to 110 8 5 0 kbq m 3 with a geometrical mean of 35 9 kbq m 3 and geometrical standard deviation of 1 8 radon activity concentration observed in the thirty seven soil gas samples collected from the chamba region of himachal pradesh varies from 5 2 1 0 to 35 6 2 5 kbq m 3 with geometrical mean of 15 8 kbq m 3 and geometrical standard deviation of 1 6 average radium activity concentrations in thirty four soil samples collected from different geological formations of dharamshala region and chamba region are found to be 40 4 17 and 38 6 1 7 bq kg 1 respectively it has been observed that soil gas radon activity concentration has a wide range of variation in both dharamshala and chamba regions while radium activity concentrations in soil samples are more or less same in both the regions moreover soil gas radon activity concentration has a better positive correlation with the radium activity concentration in soil samples collected from chamba region as compared to dharamshala region

radon variations at arrowhead and murrieta springs continuous and discrete measurements two continuous radon monitors crms have been deployed at arrowhead hot springs along the san andreas fault near san bernardino and at murrieta hot springs along the elsinore fault the recorded hourly and daily radon variations during 1983 are within 5 of the mean values the radon levels increased however by about 10 20 above their normal baseline levels in midyear several small magnitude earthquakes m 3 0 3 5 occurred within 20 km of the arrowhead site near the end of the period of the radon increase

monitoring of hydrogen along the san andreas and calaveras faults in central california in 1980 1984 hydrogen h2 has been monitored continuously at 1 5 m depth at nine sites along the san andreas and calaveras faults in central california since december 1980 site characteristic small noninstrumental diurnal variations were recorded during quiescent periods at most sites abrupt h2 changes were observed concurrently at two sites on the calaveras fault some of these were correlated with oscillatory fault slips large 1000 4000 ppm h2 increases were recorded at some sites on the san andreas fault between july 1982 and november 1983 which may be correlated with eleven m 5 earthquakes that occurred near coalinga during this period we attribute both the h2 increases and the triggering of the earthquakes to a large scale compressive stress field within the ductile mafic crust near the plate boundary the stress perhaps caused bulging of the base of the brittle upper crust and thus caused dilation of the san andreas fault zone allowing the escape of pent up h2 generated by hydration reaction of the mafic crust at the same time mobile serpentinites may have squeezed into the seismogenic fault beneath the coalinga area triggering the earthquakes

radon signals related to seismic activity in ecuador march 1987 a radon concentration measurement survey was carried out in ecuador using the ssntd technique the data analysis shows a definite radon anomaly prior to march 6 1987 m 6 9 earthquake anomalies found before october 18 and october 28th mild earthquakes in 1986 could be correlated with these events other anomalies that we cannot correlate with any geophysical event were also found

sedimentary and tectonic evolution of the eastern hyblean plateau southeastern sicily during late cretaceous to quaternary time abstract two palaeogeographic domains have been distinguished in the cretaceous quaternary sequences which crop out in the hyblean region of southeastern sicily in the northeast shallow water algal bryozoan calcarenites of oligocene miocene age overlie either cretaceous rudist limestones or volcanics further to the northeast the stratigraphic gap increases as the miocene limestone thins and in the a g i p well catania 10 plio pleistocene sediments and volcanics directly overlie upper jurassic rocks in the southwestern part of the hyblean plateau pelagic sediments occupy the cretaceous miocene interval they were deposited in a shallow basin dipping gently towards the southwest the transition between the two zones is marked by much evidence of synsedimentary tectonic activity such as widespread slumping and the development of megabreccias composed of cretaceous and eocene blocks the palaeogeographic picture is one of carbonate reefs and volcanic seamounts developing in the upper cretaceous they formed platforms fault bounded to the west and southwest from which were derived the detrital sediments found in the basin and occasional spectacular gravity slides in present day terms the structural high probably corresponds to the northeastern margin of the hyblean plateau and in part to the siracusa syracuse malta escarpment the pattern is little changed in the upper miocene with volcanoclastics of phreatomagmatic origin intercalated with coral bioherms overlying algal bryozoan calcarenites upper tortonian lower messinian limestones with a restricted fauna indicate a shallow water environment which grades up into continental conditions in the eastern hyblean plateau the tertiary sequence is capped by pliocene submarine to subaerial mafic lava flows lower pleistocene sediments consist of biocalcarenites and clays which fill deep graben delimited by plio pleistocene faults the inshore continuation of the malta syracuse escarpment system of faults from a tectonic standpoint the hyblean region a gently deformed segment of the african continental margin acted as a foreland during tertiary times a cretaceous eocene tectonic phase was responsible for the palaeogeographic pattern which existed during most of the cenozoic the present pattern is the result of three main tectonic phases following the regional upper miocene uplift of early middle pliocene plio pleistocene and middle pleistocene recent age which influenced the tectonic evolution of the present ionian coast and the malta syracuse escarpment

anomalous hydrogen emissions from the san andreas fault observed at the cienega winery central california we began continuous monitoring of h2 concentration in soil along the san andreas and calaveras faults in central california in december 1980 using small h2 o2 fuel cell sensors ten monitoring stations deployed to date have shown that anomalous h2 emissions take place occasionally in addition to diurnal changes among the ten sites the cienega winery site has produced data that are characterized by very small diurnal changes a stable baseline and remarkably distinct spike like h2 anomalies since its installation in july 1982 a major peak appeared on 1 10 november 1982 and another on 3 april 1983 and a medium peak on 1 november 1983 the occurrences of these peaks coincided with periods of very low seismicity within a radius of 50 km from the site in order to methodically assess how these peaks are related to earthquakes three h2 degassing models were examined a plausible correlational pattern was obtained by using a model that 1 adopts a hemicircular spreading pattern of h2 along an incipient fracture plane from the hypocenter of an earthquake 2 relies on the feo h2o reaction for h2 generation and 3 relates the accumulated amount of h2 to the mass of serpentinization of underlying ophiolitic rocks the mass was tentatively assumed to be proportional to the seismic energy of the earthquake

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

late pleistocene vertebrate bearing deposits at san teodoro cave north eastern sicily preliminary data on faunal diversification and chronology abstract this paper deals with the chronology and the possible correlations among levels of different excavated areas in the pleistocene vertebrate bearing deposits at the large san teodoro cave north eastern sicily two trenches have been excavated along the eastern side of the cave located at a distance from the entrance respectively of 8 m trench and 28 m trench and at different depths lithological features biometrical data from small mammals and ecological data from molluscs point to similar environmental conditions for the trench deposits and those located along the eastern wall of the cave in the eastern part of the trench the same evidence and the taphonomic features of large mammals points to different environmental conditions and perhaps to different ages for the deposits located in the western part of the trench the survival of elephants in sicily up to 32 000 years ago is a new significant result of the 230 th 234 u dating carried out from a concretionary stratum from the trench and represents the youngest elephant survival in the western mediterranean islands

first combined flux chamber survey of mercury and co2 emissions from soil diffuse degassing at solfatara of pozzuoli crater campi flegrei italy mapping and quantification of gas release abstract there have been limited studies to date targeting gaseous elemental mercury gem flux from soil emission in enriched volcanic substrates and its relation with co 2 release and tectonic structures in order to evaluate and understand the processes of soil air exchanges involved at solfatara of pozzuoli volcano the most active zone of campi flegrei caldera italy an intensive field measurement survey has been achieved in september 2013 by using high time resolution techniques soil air exchange fluxes of gem and co 2 have been measured simultaneously at 116 points widely distributed within the crater quantification of gas flux has been assessed by using field accumulation chamber method in conjunction with a lumex ra 915 portable mercury vapor analyzer and a licor for co 2 determination respectively the spatial distribution of gem and co 2 emissions correlated quite closely with the hydrothermal and geological features of the studied area the highest gem fluxes from 4 04 to 5 9 10 5 g m 2 d 1 were encountered close to the southern part of the crater interested by an intense fumarolic activity and along the se sw tectonic fracture 1 26 10 6 6 91 10 5 g gem m 2 d 1 conversely the lowest values have been detected all along the western rim of the crater characterized by a weak gas flux and a lush vegetation on a very sealed clay soil which likely inhibited mercury emission range 1 5 10 7 7 18 10 6 g gem m 2 d 1 results indicate that the gem exchange between soil and air inside the solfatara crater is about 2 3 orders of magnitude stronger than that in the background areas 10 8 10 7 g m 2 d 1 co 2 soil diffuse degassing exhibited an analogous spatial pattern to the gem fluxes with emission rates ranging from about 15 to 20 000 g co 2 m 2 d 1 from the outermost western zones to the south eastern sector of the crater the observed significant correlation between gem and co 2 suggested that in volcanic system gem volatilizes from substrate in a similar manner to the release of co 2 the quantitative estimation of the total amount of co 2 and gem released from the solfatara crater gave values of about 304 13 and 3 7 0 2 10 6 t d 1 respectively finally based on our dataset and previous work we propose that an average gem co 2 molar ratio of 2 10 8 n 9 is best representative of hydrothermal degassing taking into account the uncertainty in global hydrothermal co 2 emissions from sub aerial environments 10 12 mol yr 1 we infer a global volcanic gem flux from hydrothermal environments of about 8 5 t yr 1 although this value has to be considered as a lower limit for the global emission of gem from these sources we suggest that on a local scale hydrothermal activity can be regarded as a significant source of gem than previously recognized to the atmospheric pool

palaeoenvironmental paleontologic and stratigraphic significance of vertebrate remains in pleistocene limnic and alluvial deposits from southeastern sicily abstract in southeastern sicily on the hyblean plateau limnic deposits overlie early pleistocene marine sediments and are covered by early middle pleistocene marine sands in the limnic deposits fossil remains of large mammals have been collected and these represent the oldest found in a well established pleistocene stratigraphic succession in sicily the faunal association includes elephas falconeri busk the smallest sicilian elephant an elephant less reduced in size than e falconeri a canid vulpes sp rodents leithia melitensis adams chiroptera insectivora fishes birds amphibians bufo sp discoglossus sp and reptiles lacerta sp testudo sp emys orbicularis linnaeus alluvial fan deposits overlying the limnic deposits contain elephas mnaidriensis adams hippopotamus pentlandi meyer cervus siciliae pohlig and bovidae these new findings provide the stratigraphic evidence to definitively discredit previous chronological schemes for the pleistocene dwarf elephants which assumed a progressive decrease of the size with time a hypothesis recently questioned by isoleucine epimerization age determination which however were object of discussion these findings also represent a new step toward a better knowledge of the taphonomic conditions of the pleistocene mammal bearing deposits in mediterranean islands traditionally linked to karstic environment distribution of mammal faunas in the hyblean plateau proves fundamental in recognizing and dating pleistocene mammal faunas in sicily the new findings fully confirm the assumption that sicily experienced two elephant immigrations in pleistocene times

a case of correlation between rn anomalies and seismic activity on a volcano vulcano island southern tyrrhenian sea a factor of 10 increase in the rn concentration in a shallow aquifer forefunning a shallow seismic swarm was observed at the island of vulcano aeolian island arc the peak of rn anomaly preceded by about one month the seismic swarm which had a cumulative magnitude of 2 1 the time lag between the two phenomena is much longer than expected given the small energy released by the swarm the observed phenomena may not have a direct cause effect relationship but they both can be a consequence of volcanic phenomena

variations of radon content in groundwaters and possible correlation with seismic activities in northern taiwan radon 222rn concentration in geothermal waters and co2 rich cold springwaters collected weekly in duplicate samples from four stations in northern taiwan were measured from july 1980 to december 1983 seven spike like radon anomalies increases of 2 to 3 times the standard deviation above the mean were observed at three stations following every anomaly except one an earthquake ofml above 4 6 occurred within 4 to 51 days at an epicentral distance 14 to 45 km and at a focal depth of less than 10 km the distribution of the earthquakes preceded by radon anomalies is skewed in certain directions from the radon stations the radon stations seem to be insensitive to earthquakes occurring in the other directions at the fourth station near a volcanic area much gas mainly co2 is discharged from the well together with hot water a very high concentration of radon was detected in the discharged gas therefore trapping of gas in the water can result in anomalously high radon contents according to limited measurements the radon concentration in water appears to be undersaturated with respect to that in gas this suggests that hot water is very susceptible to radon loss and monitoring of radon in gas is more desirable

geothermal prospecting by ground radon measurements abstract radon 222 was measured using kodak lr 115 film in the soils of 2500 locations near the ngawha hot springs region new zealand which is being exploited for geothermal power the object was to determine its usefulness for predicting good drill sites unlike other surveys which have shown large areas with consistent high radon values anomalies here were scattered and corresponded mainly with fault lineaments the results suggested a major previously unnoticed fault the sampling distance was 50 m there was a strong seasonal effect on ground radon levels with summer levels about ten times higher than winter levels swamps usually had measured radon levels of near zero because of the slow diffusion of radon in stagnant water and even thermal areas mainly in the swamps usually had low measured values however where a fault crossed swamp it was sometimes detected and with high signal noise ratio so swamps should be surveyed arguments from the radon levels found on different geologies show that at ngawha radon has a maximum half value diffusion thickness of 7 m for lacustrine sediment and 25 m for basalt unless a permeable area is present e g a fault there was a weak correlation of radon levels with the temperatures found on drilling deep bores comparisons with the roac system and alphacard system for measuring radon showed no statistical inter correlations but some qualitative correspondence of radon contours the main strength of the method in regions with impermeable soils such as at ngawha seems to be in detecting or confirming the presence of faults and possibly through them indicating geological structure as deep as 300 m

correlation of groundwater radon anomalies with earthquakes in the greater palmdale bulge area recent measurements in the central transverse ranges of southern california suggest possible correlations of changes in groundwater radon content with occurences of nearby earthquakes since measurements began in 1974 three radon anomalies have been accompanied by subsequent nearby seismic events two of these anomalies were associated with moderate sized earthquakes and one with a swarm within a 60 day window prior to the seismicity groundwater radon increased in each case at sites close to the earthquake epicenters before the big bear earthquake of june 30 1979 m 4 8 radon anomalies were found at three nearby monitoring sites groundwater radon content at one site near the january 1 1979 malibu earthquake m 5 0 showed negative as well as positive anomalies both prior to and following the earthquake a radon anomaly occurred at a nearby spring prior to the fall 1976 palmdale swarm the observed pattern is similar to pre earthquake anomalies reported from russia china and japan

recent results of hydrogeochemical studies for earthquake prediction in the ussr the paper reviews the chief results of the hydrogeochemical and hydrogeodynamic investigations conducted for earthquake prediction in all seismic regions of the ussr

masaya the mouth of hell nicaragua volcanological interpretation of the myths legends and anecdotes article i nfo nicaragua s conquest started only 30years after christopher columbus arrived to america in 1492 at that moment the masaya and momotombo volcanoes were erupting simultaneously the former was the first permanent lava lake observed by europeans and this produced a strong impression and interest in it for more thanacenturytherewasgreatcontroversyoverthenatureofthisphenomenon somepeoplebelievedthatitwas

emplacement mechanisms of contrasting debris avalanches at volcan mombacho nicaragua provided by structural and facies analysis we study the lithology structure and emplacement of two debris avalanche deposits dads with contrasting origins and materials from the quaternary holocene mombacho volcano nicaragua a clear comparison is possible because both dads were emplaced onto similar nearly flat 3 slope topography with no apparent barrier to transport this lack of confinement allows us to study in nature the perfect case scenario of a freely spreading avalanche in addition there is good evidence that no substratum was incorporated in the events during flow so facies changes are related only to internal dynamics mombacho shows evidence of at least three large flank collapses producing the two well preserved debris avalanches of this study one on its northern flank las isletas directed northeast and the other on its southern flank el crater directed south other south eastern features indicate that the debris avalanche corresponding to the third collapse la danta occurred before las isletas and el crater events the materials involved in each event were similar except in their alteration state and in the amount of substrata initially included in the collapse while el crater avalanche shows no signs of substratum involvement and has characteristics of a hydrothermal weakening related collapse the las isletas avalanche involves significant substratum and was generated by gravity spreading related failure the latter avalanche may have interacted with lake nicaragua during transport in which case its run out could have been modified through a detailed morphological and structural description of the mombacho avalanches we provide two contrasting examples of non eruptive volcanic flank collapse we show that remarkably even with two distinct collapse mechanisms the debris avalanches developed the same gross stratigraphy of a coarse layer above a fine layer this fine layer provided a low friction basal slide layer whereas dad layering and the run outs are roughly similar the distribution of structures is different and related to lithology las isletas has clear proximal faults replaced distally by inter hummock depressions where basal unit zones are exhumed whereas el crater has faults throughout but the basal layer is hidden in the distal zone hummocky forms depend on material type with steep hummocks being formed of coherent lava units and low hummocks by matrix rich units in both avalanches extensional structures predominate the upper layers exclusively underwent longitudinal and lateral extension this is consistent with evidence of only small amounts of block to block interactions during bulk horizontal spreading the base of the moving mass accommodated transport by large amounts of simple shear we suggest that contractional structures and inter block collisions seen in many other avalanches are artifacts related to topographic confinement

soil222rn pulse during the initial phase of the june august 1995 eruption of cerro negro nicaragua the june august 1995 eruption of cerro negro a small volume basaltic cinder cone in nicaragua provided a unique opportunity to quantify 222rn degassing from soils in response to explosive volcanic activity 222rn was monitored at 29 stations using electrostatically charged teflon 222rn detectors distributed north and southeast of the volcano a pulse of elevated 222rn degassing occurred early in the eruption along a 1 km long zone extending at least 750 m beyond the base of the cinder cone observation of this 222rn pulse shows that large changes in soil 222rn concentration can occur simultaneously at widely separated stations in response to even comparatively small volume intrusions and volcanic eruptions frequent 222rn sampling at multiple stations provides a sense of the magnitude time scales and area affected by convective gas transport during volcanic eruptions

helium systematics of cold seep fluids at monterey bay california usa temporal variations and mantle contributions 1 we report helium isotope ratios 3he 4he as well as helium and neon abundance results for submarine cold seep fluids from extrovert cliff in monterey bay california samples were collected in copper tubing attached to submarine flux meters operating in continuous pumping mode following instrumentation recovery the tubing was sectioned to produce for the first time a high resolution time series of dissolved he and ne variations over a time span of several days noble gas concentrations are variable and appear affected by interaction with a hydrocarbon phase within the aquifer however it is still possible to resolve the he signal into components associated with air equilibration excess air entrainment and terrigenic fluxes both crustal and mantle derived the mantle he contribution reaches 25 30 in some samples up to 2 3 ra where ra air 3he 4he our quasi continuous he ne record shows remarkable fluctuations over time scales of only a few hours and reflects the combined effects of gas stripping by hydrocarbons and an episodic input of mantle derived fluids

sector collapse forming at casita volcano nicaragua catastrophic sector collapse occurs when a volcano becomes structurally unable to support its own load one process particularly capable of weakening the edifice is hydrothermal activity it can produce high pore pressures and alter strong rock to clays alteration can extend progressively over long periods 100 yr allowing deformation to develop slowly before collapse an important finding is that structures produced by such deformation are recognizable and could permit collapse prediction we present the case of casita nicaragua where hydrothermal activity has been weakening the edifice core causing flank spreading altering original constructional shape and steepening flank slopes one side is slumping outward producing a crescentic scar with a basal bulge we identify this feature as the site of a potential sector collapse with conditions ripe for failure

radon and hydrologic anomalies on the rough creek fault possible precursors to the m5 1 eastern kentucky earthquake 1980 soil radon emanation increased sharply on the rough creek fault near the illinois kentucky border in april 1980 3 1 2 months before a m5 1 earthquake in eastern kentucky july 27 1980 the spikelike anomaly was similar to a radon anomaly in the new madrid seismic zone in 1979 that preceded by 2 months a m3 9 tremor at the site of that anomaly weekly radon monitoring was initiated on the rough creek fault after abrupt cessation of spring flow on the fault occurred at a site that had experienced similar flow cessation 1 month prior to a m5 3 earthquake in southeastern illinois in 1968 although the recent kentucky epicenter was 380 km east of the site of the detected radon anomaly factors relating to regional structures recent seismicity additional radon data and the stress regime suggest that the hydrologic and radon anomalies may have been precursors to an eastward progression of strain that culminated in the eastern kentucky tremor

long term fault creep observations in central california the u s geological survey usgs has been monitoring aseismic fault slip in central california for more than 10 years as part of an earthquake prediction experiment since 1968 the usgs creep network has grown from one creep meter at the cienega winery south of hollister to a 44 station network that stretches from hayward east of san francisco bay to palmdale in southern california in general the long term slip pattern is most variable on sections of the faults where several magnitude 4 and larger earthquakes occurred during the recording period e g calaveras fault near hollister and san andreas fault between san juan bautista and bear valley these fault sections are the most difficult to characterize with a single long term slip rate in contrast sections of the faults that are seismically relatively quiet e g san andreas fault between bear valley and parkfield produce the steadiest creep records and are easiest to fit with a single long term slip rate appendix is available with entire article on microfiche order from the american geophysical union 2000 florida avenue n w washington d c 20009 document j82 004 1 00 payment must accompany order

gas geochemistry and seismotectonics a review abstract publications on soil and spring gases have been examined regarding their relationships with both tectonic and seismic activities the main sources behaviours and uses of species detected in soils and springs are displayed and their mode of sampling and analysing briefly described the main patterns of degassing in soils are described and we outline the wide range of geochemical signatures as the result of both permeability and mineralogical contrasts because thermomineral waters have been in contact with great volumes of crustal rocks at various depths spring gases might be more representative of the local environment than soil gases moreover gas signature comparisons show that spring gases are much more enriched with deep gases and slightly contaminated by atmospheric gases therefore they can be considered as better samples for identifying precursors of earthquakes environmental perturbations are examined and it is shown from divergent cases that pressure temperature soil moisture or earth tides may generate very high perturbations of the degassing process such effects demonstrate that no systematic correction law can be proposed and that removing external contributions from gas concentrations must be performed case by case this demonstrates therefore the need for the simultaneous measurement of external parameters during gas monitoring a qualitative examination of about 150 claimed precursors proposed in the literature has been reviewed as noted by previous authors anomalies appear at distances sometimes much greater than typical source dimensions and occur in the field of strain higher than 10 9 most of them being in the field of strain higher than 10 8 taking into account the very high heterogeneity of such a set of data we can suggest that amplitudes of gas anomalies are independent of both magnitudes and epicentral distances of related earthquakes suggesting local conditions to control amplitudes on the contrary precursory time and duration of anomalies seem to increase both with magnitudes and epicentral distances abundant evidence demonstrates the major role of crustal fluids in the earthquake cycle many works have outlined the fact that crustal instabilities can appear as the result of low stress strain perturbations during loading it has been suggested that motion of fluids may occur at various scales from microcrack fluid transfer up to changes of hydraulic levels of water tables the study of subsequent anomalies is expected to supply a tool for earthquake prediction following previous authors we outline the need for further methodological improvements including the setting up of multiparameter station networks and the simultaneous recording of the main external parameters atmospheric pressure water and air temperature soil moisture for signal processing

radon content of groundwater as an earthquake precursor evaluation of worldwide data and physical basis the properties of a worldwide data set of 91 radon 222 rn anomalies the frequency of occurrence the precursor time interval and the distribution of peak amplitudes are correlated with earthquake data such as the respective magnitude and epicentral distance these anomalies were reported as precursors to earthquakes in the united states ussr china japan and iceland although the data set is incomplete and limited by experimental deficiencies several consistent patterns emerge radon anomalies from different tectonic regions show similar patterns the radon anomalies occur at greater epicentral distances for earthquakes of the larger magnitude anomalies preceding large earthquakes m 6 are frequently observed at a distance of 100 to 500 km these distances are larger than several times the rupture dimensions of the future earthquakes the time from the onset of an anomaly to the time of the earthquake the precursor time increases with magnitude but decreases with distance between epicenter and radon station in addition radon anomalies are observed more frequently prior to large earthquakes than prior to small ones indicating that the preparation zone increases in size as magnitude increases the peak amplitude does not scale with magnitude but forms a consistent pattern with epicentral distance in that the larger the earthquake magnitude the farther away the largest amplitudes tend to occur the preparation zone of the earthquake where the anomalies occur forms an almost continuous annulus that expands with time away from the future rupture zone the outer radius of this annulus scales with the earthquake magnitude model calculations indicate that strain fields of at most 10 6 to 10 8 strain caused the radon anomalies if these strains are divided by the appropriate precursor time minimum strain rates from 10 7 day 1 to 10 10 day 1 are obtained such small strains and strain rates suggest that in most cases neither mechanical crack growth induced by dilatancy nor mechanical coupling between pore pressure and the rock matrix caused the anomalies large changes in the orientation of the local strain field however could occur and affect the local stress intensity factor since changes in the stress intensity factor can result in stress corrosion the occurrence of radon anomalies is attributed to slow crack growth controlled by stress corrosion in a rock matrix saturated by groundwater

soil radon and elemental mercury distribution and relation to magmatic resurgence at long valley caldera the response of a large geothermal system to magmatic resurgence was analyzed by a survey of soil gas radon and elemental mercury at 600 sites in the silicic long valley caldera california the broad geochemical anomaly over the caldera has superimposed on it a small zone of pronounced radon enrichment and mercury depletion coincident with the surface projection of a postulated dike of rising magma soil gas geochemistry studies can complement traditional geophysical and geodetical methods in the evaluation of potential volcanic eruption hazards

volcan el chichon mexico pre 1982 s rich eruptive activity abstract mapping and sampling of the interior of el chichon volcano was made possible by the exposures of the 1982 explosion crater the 1 km diameter 200 m deep crater exposes rocks produced during several eruptive episodes volcanic domes talus breccias plinian airfall deposits and pyroclastic flow deposits of compositionally similar alkalic hornblende trachyandesites with phenocrysts of anhydrite all of the rocks except those leached of anhydrite have extremely high s contents el chichon consists of a volcanic dome complex airfall debris and pyroclastic outflow sheets prior to 1982 its last major activity was about 650 100 yr b p

radon emanometry in soil gases and activity in ashes from el chichon volcano radon 222em emanation measurements in soil gases are reported in connection with the 1982 eruptions of el chichon volcano 222em detection is performed with lr 115 cellulose nitrate track detectors results show a general decreasing pattern of222em concentration in soil with time after the eruptions activity measurements of radon daughters in ashes show that a large amount of222em and220em was released from magma degassing during the eruptions and that only a fraction of the degassed magma was erupted an important fluid interaction between the magma chamber and the surrounding sedimentary rock is also suggested

holocene eruptive activity of el chichon volcano chiapas mexico geologic and radiometric age data indicate that el chichon was frequently and violently active during the holocene including eruptive episodes about 600 1250 and 1700 years ago and several undated older eruptions these episodes involving explosive eruptions of sulfur rich magma and associated dome growth processes were apparently separated by intervals of approximately 350 to 650 years some of el chichon s eruptions may correlate with unusual atmospheric phenomena around a d 1300 and possibly a d 623

anomalous radon emanation at local and regional distances preceding earthquakes in the new madrid seismic zone and adjacent areas of the central mid continent of north america 1981 84 anomalous soil radon activity including several spike like surges over periods of 5 2 and 2 1 2 months and a year long declining trend preceded the most significant earthquakes of the central mid continental region of north america during 1981 and early 1984 the 5 month period of erratic weekly radon activity february june 1981 was followed by a tremor of magnitudem 4 0 40 km from the monitoring site in the new madrid seismic zone an unusual earthquake swarm in central arkansas 160 km from the new madrid seismic zone and 230 km from the monitoring site in the seismic zone began in january 1982 shortly after a year long declining trend in anomalous radon emanation earthquakes of magnitudes 4 5 4 1 and 4 0 occurred at the swarm s outset in early 1982 fitting a pattern anticipated for the new madrid seismic zone on the basis of the radon activity two periods of coincident peak radon emanation have since been observed in the arkansas and new madrid seismic regions as have synchronous seismic pulses for the two separate areas

crater lake and post eruption hydrothermal activity el chichon volcano mexico abstract explosive eruptions of volcan el chichon in chiapas mexico on march 28 and april 3 4 1982 removed 0 2 km3 of rock to form a 1 km wide 300 m deep summit crater by late april 1982 a lake had begun to form on the crater floor and by november 1982 it attained a maximum surface area of 1 4 105 m2 and a volume of 5 106 m3 accumulation of 4 5 m of rainfall between july and october 1982 largely formed the lake in january 1983 temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115 c by october 1983 the maximum temperature of fumarole emissions was 99 c in january 1983 fumarole gas emissions were greater than 99 vol h2o with traces of co2 so2 and h2s the water of the lake was a hot t 52 58 c acidic ph 0 5 dilute solution 34 046 mg l 1 dissolved solids cl s 20 5 sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits together with less than 1 of elemental sulfur the composition and temperature of the lake water is attributed to 1 solution of fumarole emissions 2 reaction of lake water with hot rocks beneath the lake level 3 sediments washed into the lake from the crater walls 4 hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement 5 evaporation and 6 precipitation

a geochemical and geophysical investigation of the hydrothermal complex of masaya volcano nicaragua abstract masaya volcano nicaragua is a persistently active volcano characterized by continuous passive degassing for more than 150 years through the open vent of santiago crater this study applies self potential soil co 2 and ground temperature measurements to highlight the existence of uprising fluids associated to diffuse degassing structures throughout the volcano the diffuse degassing areas are organized in a semi circular pattern and coincide with several visible and inferred surface volcanic structures cones fissure vents and likely consist of a network of buried faults and dykes that respectively channel uprising flow and act as barrier to gravitational groundwater flow water depths have been estimated by multi scale wavelet tomography of the self potential data using wavelets from the poisson kernel family compared to previous water flow models our water depth estimates are shallower and mimic the topography typically less than 150 m below the surface between 2006 and 2010 the depths of rising fluids along the survey profiles remained stable suggesting that hydrothermal activity is in a steady state this stable activity correlates well with the consistency of the volcanic activity expressed at the surface by the continuously passive degassing when compared to previous structural models of the caldera floor it appears that the diffuse degassing structures have an important effect on the path that shallow groundwater follows to reach the laguna de masaya in the eastern part of the caldera the hydrogeological system is therefore more complex than previously published models and our new structural model implies that the flow of shallow groundwater must bypass the intrusions to reach the laguna de masaya furthermore these diffuse degassing structures show clear evidence of activity and must be connected to a shallow magmatic or hydrothermal reservoir beneath the caldera as such the heat budget for masaya must be significantly larger than previously estimated

propagation and attenuation characteristics of the crustal phase lg thelg wave consists of the superposition ofs waves supercritically reflected and thus trapped in the crust this mode of propagation explains the strong amplitude of this phase and the large distance range in which it is observed the numerical simulation leads to successful comparison between observed seismograms in stable continental areas and synthetics computed for simple standard crustal models in regions with strong lateral variations the influence of large scale heterogeneities on thelg amplitude is not yet clearly established in terms of the geometrical characteristics of the crustal structure

lacustrine stable isotope record of precipitation changes in nicaragua during the little ice age and medieval climate anomaly discerning the infl uences of the el nino southern oscillation enso and the north atlantic oscillation nao on drought variability in the tropics during the medieval climate anomaly mca and little ice age lia will help to improve our understanding of climate system responses to internal and external forcing sediments from lago el gancho nicaragua provide an 1400 yr record of water balance precipitation and evaporation changes from a region that is sensitive to teleconnected pacifi c and atlantic ocean atmosphere dynamics oxygen isotope values of ostracod carapaces 18 o ostracod are consistently low in el gancho sediments between ca a d 950 and 1250 indicating that wetter conditions prevailed during the mca a period of la nina like mean state conditions in the tropical pacifi c and a positive mean state of the nao the 150 yr period between the mca and lia was marked by an abrupt shift to persistently drier conditions at a time of highly variable pacifi c sea surface temperatures and a transition toward a more negative nao phase in sediment from ca a d 1450 to the present 18 o ostracod values increase suggesting that drier conditions persisted through most of the lia a time of a relatively negative nao phase and el nino like mean state conditions in the tropical pacifi c the long term precipitation trends inferred from the el gancho data are not entirely consistent with modern associations between precipitation in the circum caribbean region and the nao suggesting that present day hydroclimatic shifts resulting from variability in synoptic climate patterns are dissimilar to changes resulting from teleconnected ocean atmosphere dynamics that operated during the mca and lia

ground variation of radon 222 for location of hidden structural features example of the south of france alpes maritimes we report two examples from the south of the french alps showing that radon emanation monitored by alpha sensitive film may be used to locate certain discrete structural features revealed in data collected by remote sensing from a satellite the variations observed in our data over a period of several months are in accordance with atmospheric changes and might correlate with local seismic activity when the detectors are located directly above structural fractures and the magnitude of the seismic event is greater than 2

bioindication of volcanic mercury hg deposition around mt etna sicily mt etna is a major natural source of hg to the mediterranean region total mercury concentrations hg tot in castanea sativa sweet chestnut leaves sampled 7 13 km from etna s vents during six campaigns in 2005 2011 were determined using atomic absorption spectroscopy hg tot in c sativa was greatest on etna s se flank reflecting hg deposition from the typically overhead volcanic plume hg tot also showed hg accumulation over the growing season increasing with leaf age and recent eruptive activity hg tot in c sativa was not controlled by hg tot in soils which instead was greatest on etna s nw flank and was correlated with the proportion of organic matter in the soil org an elevated hg tot org ratio in soils on etna s se flank is indicative of increased hg deposition this ratio was also found to decrease with local soil ph suggesting that hg deposited to the low ph and organic poor soils on etna s se flank may not be retained but will instead be released to groundwater or re emitted to the atmosphere these results show that the deposition of volcanic hg

transient deformation associated with explosive eruption measured at masaya volcano nicaragua using interferometric synthetic aperture radar abstract deformation caused by processes within a volcanic conduit are localised transient and therefore challenging to measure however observations of such deformation are important because they provide insight into conditions preceding explosive activity and are important for hazard assessment here we present measurements of low magnitude transient deformation covering an area of 4 km 2 at masaya volcano spanning a period of explosive eruptions 30th april 17th may 2012 radial uplift of duration 24 days and peak displacements of a few millimeters occurred in the month before the eruption but switched to subsidence 27 days before the onset of the explosive eruption on 30th of april uplift resumed during and continued for 16 days after the end of the explosive eruption period we use a finite element modelling approach to investigate a range of possible source geometries for this deformation and find that the changes in pressurisation of a conduit 450 m below the surface vent radius 160 m and length 700 m surrounded by a halo of brecciated material with a young s modulus of 15 gpa gave a good fit to the insar displacements we propose that the pre eruptive deformation sequence at masaya is likely to have been caused by the movement of magma through a constriction within the shallow conduit system although measuring displacements associated with conduit processes remains challenging new high resolution insar datasets will increasingly allow the measurement of transient and lower magnitude deformation signals improving the method s applicability for observing transitions between volcanic activity characterised by an open and a closed conduit system

surface mercury geochemistry as a guide to volcanic vent structure and zones of high heat flow in the valley of ten thousand smokes katmai national park alaska abstract a reconnaissance survey of hg was designed to model the 1912 novarupta vent structure and delineate zones of near surface high heat flow statistical analysis of 294 regolith samples collected at 127 sites from fossil active fumaroles and relatively unaltered ash flow tuff and air fall ejecta indicates two hg sample populations one associated with fumarole deposits and the other corresponding to the relatively unaltered regolith measured hg concentrations range from 12 to 6913 ppb sample threshold upper limit of background hg concentrations fumarole deposits 351 ppb unaltered regolith 110 ppb and contrast sample value threshold determinations enable differentiation between relict and actively accumulating hg contents all significant hg anomalies contrast values 1 5 occur within novarupta basin high magnitude active hg2 enrichment was found on the turtle a dome like feature northeast of the novarupta extrusive dome the hg data coupled with available geologic and geophysical evidence suggest a shallow intrusion beneath the turtle results from two novarupta basin sample traverses do not support the presence of a near surface magma feeder dike connecting the proposed intrusion beneath the turtle with the novarupta dome based on the hg data the preferred vent model is one generated by collapse of supporting walls after the major eruptive phase into a cored out explosive vent collapse of vent walls is initiated along a series of deep extending faults which subsequently serve as migration pathways for hg to the surface the overall vent morphology is funnel like with subsidence concentrated in the narrow funnel center results of this study show that hg surveys can further constrain the morphology of the 1912 vent and aid in delineating zones of near surface high heat flow in this region

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

spatial radon anomalies on active faults in california abstract radon emanation has been observed to be anomalously high along active faults in many parts of the world we tested this relationship by conducting and repeating soil air radon surveys with a portable radon meter across several faults in california the results confirm the existence of fault associated radon anomalies which show characteristic features that may be related to fault structures but vary in time due to other environmental changes such as rainfall across two creeping faults in san juan bautista and hollister the radon anomalies showed prominent double peaks straddling the fault gouge zone during dry summers but the peak to background ratios diminished after significant rain fall during winter across a locked segment of the san andreas fault near olema the anomaly has a single peak located several meters southwest of the slip zone associated with the 1906 san francisco earthquake across two fault segments that ruptured during the magnitude 7 5 landers earthquake in 1992 anomalously high radon concentration was found in the fractures three weeks after the earthquake we attribute the fault related anomalies to a slow vertical gas flow in or near the fault zones radon generated locally in subsurface soil has a concentration profile that increases three orders of magnitude from the surface to a depth of several meters thus an upward flow that brings up deeper and radon richer soil air to the detection level can cause a significantly higher concentration reading this explanation is consistent with concentrations of carbon dioxide and oxygen measured in soil air samples collected during one of the surveys

enhancement of radon signals in geophysical studies with the track technique the existence of a suspected geological fault has been confirmed using solid state nuclear track detectors ssntds by measuring radon concentration variations in the upper soil above its inferred position the results obtained prompted us to increase the natural radon signal in the soil using an additional radon source this enhancement technique has been experimentally checked with ssntd detectors

radon recording of uttarkashi earthquake spatial and temporal distribution of radon is recorded in both soil gas and groundwater using two different techniques viz track etch method and emanometry radon recording stations have been set up at one site in amritsar and four sites in the kangra valley himachal pradesh under the himalayan seismicity project the track etch method gives integrated measurement of radon over a week or a fortnight whereas emanometry is used for daily recording of radon activity in soil gas and groundwater the uttarkashi earthquake mb 6 5 ms 7 0 occurred on october 20 1991 oct 19 u t in the garhwal himalayas 30 78 n 78 77 e about 330 km from our recording stations in the kangra valley and about 450 km from amritsar respectively radon anomalies were recorded at all sites in kangra valley and amritsar about a week before the uttarkashi earthquake which clearly establishes that radon changes can be effective for forecasting some earthquakes

geological hazards of sw natib volcano site of the bataan nuclear power plant the philippines the sw sector of mount natib a potentially active volcano in the bataan volcanic arc in western luzon is the site of a mothballed nuclear power plant that members of the national legislature have proposed to activate detailed geological fieldwork was conducted to assess the capability of the volcano and to identify any volcanic hazards it might pose to the nuclear plant the nearest eruptive centre is 5 5 km away from the plant sw natib volcano is underlain by lava flows lahar deposits and at least six pyroclastic density current pdc deposits three directly underlying the nuclear reactor facility a fault trending n308e is aligned with the lubao fault a capable fault ne of the volcanic edifice radon emissions at the traces of these faults are high and comparable to those at known active faults an associated thrust fault at the nuclear site cuts through lahars up to the ground surface the results presented here can be used for general hazard preparedness of local communities and may assist the government to decide whether or not to recommission the nuclear power plant

multiproxy dietary trait reconstruction in pleistocene hippopotamidae from the mediterranean islands abstract geographically isolated insular species face energetic restrictions and commonly evolve adaptations that distinguish them from their mainland ancestors during the pleistocene several mediterranean islands were inhabited by now extinct hippopotamidae they underwent diverse changes in locomotion dentition and body size based on these differences it is supposed that they occupied different ecological niches depending on their respective faunal complexes and available resources in this paper we assess the paleoecology of dwarfed hippopotami from crete malta sicily and cyprus using a novel dental multiproxy approach we applied dental topography analysis saga gis to measure the mean slope of the dental occlusal surface mirroring dietary adaptations as well as 3d surface texture analysis 3dst to quantify the surface of occlusal wear facets which correlate with dietary abrasiveness low slope values were found in the larger more hypsodont hippopotami whilst the smaller phanourios minor displayed the highest occlusal relief with large compression basins since hippopotamus pentlandi exhibited lower mean slope values than the larger more hypsodont hippopotamus amphibius we conclude that lower occlusal reliefs reflect adaptations to lower diet quality and arid environments which are characteristic of freshwater limited island habitats the 3dst analysis revealed distinct ecological niches for the investigated insular hippos hippopotamus creutzburgi exhibited enamel surface textures analogous to those of hippopotamus amphibius a fresh grass grazer thus confirming a semiaquatic lifestyle at the upland lake at katharo crete hippopotamus pentlandi was bound to a similar niche to the extant form probably due to the mainland character of its fauna but experienced more dust intake hippopotamus melitensis had to cope with high ingestion of abrasives seemingly on account of a more generalistic diet in its resource limited and small habitat results point to either phanourios minor broadening its dietary niche in its almost competition free habitat or suggest a dietary shift following a climatic change the adopted multiproxy approach proved to be useful in identifying dental adaptations and individual foraging strategies linked to energetically restricted habitats and therefore contributes to a better understanding of basic evolutionary and ecological principles

earthquake forerunners in a selected area of northern italy recent developments in automatic geochemical monitoring abstract this article describes the monitoring of certain mud volcanoes in the northern apennines of italy this monitoring was carried out from a geochemical point of view and its aim was to verify the seismic precursory nature of the mud volcano fluids the operational strategy began by determining the regional character of the main physical and chemical precursors and a multidisciplinary approach to the historical research was used to achieve this the utility of such an approach in monitoring strategy has been confirmed a series of experiments was carried out to identify the physical model the main geochemical characteristics and the origin of the seismic precursory phenomena with particular reference to radon 222 the technological apparatus necessary for a reliable automatic continuous monitoring system of the geochemical parameters of mud volcanoes were then extensively tried out the first results of this monitoring system refer to dec 1988 jan 1989 in this period there were some seismic events which were preceded by certain phenomena we can call precursory an interpretative model has been created from all the information collected so that similar situations can be better understood from a physical and chemical point of view

fumarolic gases at mombacho volcano nicaragua presence of magmatic gas species and implications for volcanic surveillance mombacho is a deeply dissected volcano belonging to the quaternary volcanic chain of nicaragua the southern historic collapse crater el crater currently hosts a fumarolic field with a maximum temperature of 121 c chemical and isotopic data from five gas sampling field campaigns carried out in 2002 2003 and 2005 highlight the presence of high temperature gas components e g so2 hcl and hf which indicate a significant contribution of juvenile magmatic fluids to the hydrothermal system feeding the gas discharges this is strongly supported by the mantle derived helium and carbon isotopic signatures although the latter is partly masked by either a sedimentary subduction related or a shallow carbonate component the observed chemical and isotopic composition of the mombacho fluids seems to indicate that this volcanic system although it has not experienced eruptive events during the last centuries can be considered active and possibly dangerous in agreement with the geophysical data recorded in the region systematic geochemical monitoring of the fumarolic gas discharges coupled with a seismic and ground deformation network is highly recommended in order to monitor a possible new eruptive phase

high spatial resolution radon measurements reveal hidden active faults on mt etna radon emissions are frequently monitored in volcanically and tectonically active areas in order to reveal changes in soil degassing as radon acts a tracer for the more abundant co2 degassing commonly observed in such areas between july 2002 and may 2003 a series of discrete measurements of radon concentrations in soil were made with high spatial resolution similar to5 100 m in the santa venerina area on mt etna these measurements revealed well defined linear anomalies that we interpret as being caused by active faults whose higher porosity than surrounding soils allows an increased co2 flux carrying radon from beneath these faults were not visible at the surface and were therefore revealed at high spatial resolution by our radon survey our hypothesis that the positive anomalies are attributable to active faults was strengthened by the observation of concentrated damage along this geometry during the earthquakes that struck this area in late october 2003

deposition models for chronological records abstract long term sedimentary sequences provide a wealth of useful information for research into the palaeo environment especially in relation to past climate change shorter records provide similar information in many archaeological contexts however if such records are to be used to provide precise timing of events and more critically the relative timing between different records methods are needed to provide accurate and precise age depth models for these sequences given the imprecision of individual calibrated radiocarbon determinations it is necessary to use the information we have about the deposition process to refine our chronologies and also to provide interpolation between dated levels in any sequence even with layer counted chronologies the uncertainties are sometimes hard to quantify this paper outlines a range of bayesian models for deposition which have been implemented in the computer programme oxcal these models can be used to combine information from the sediments themselves with radiocarbon or other direct dating information such models have the potential to integrate information between different records and provide a coherent chronology on which to base environmental or archaeological research