long range triggered earthquakes that continue after the wave train passes 1 large earthquakes can trigger distant earthquakes in geothermal areas some triggered earthquakes happen while the surface waves pass through a site but others occur hours or even days later does this prolonged seismicity require a special mechanism to store the stress from the seismic waves that differs from ordinary aftershock mechanisms these questions have driven studies of long range triggering since the phenomenon s discovery here i attempt to answer the questions by examining the statistics of triggered sequences two separate observations are consistent with the prolonged sequences being simply local aftershocks of earthquakes triggered early in the wave train first the sequences obey omori s law over both short 1 hour and longer 5 day time intervals secondly the number of observed triggered earthquakes in the first hour after the wave train can be predicted from the number of earthquakes triggered during the wave train even the very vigorous 10 day triggering at long valley from the 1992 landers mw 7 3 earthquakes can be interpreted as the aftershocks of either a local m 4 1 earthquake or an equivalent combination of several smaller mainshocks therefore long range triggering does not need to include a mechanism to produce sustained stresses other than the process that generates aftershocks of the earthquakes that occur while the wave train is passing

the athens greece earthquake ms 5 9 of 7 september 1999 an event triggered by the izmit turkey 17 august 1999 earthquake the athens greece earthquake m w 5 9 of 7 september 1999 occurred in a region of low seismicity at a distance of ca 620 km from the epicenter of and only 21 days after the large m w 7 5 izmit marmara sea earthquake of 17 august 1999 the possibility that the izmit event triggered the athens one is examined on the basis of three independent approaches first a stochastic test was used showing that the probability for a strong shock to occur randomly in any 21 day time interval 1 in the region of athens radius 30 km and 2 in the broad region of athens radius 70 km is of the order of only 5 75 10 5 and 2 3 10 3 respectively second a model that considers an earthquake triggered by another earthquake as an instability to transient slip was used to calculate the distant shear stress increase at the athens earthquake fault as a result of the superimposed unrelaxed coseismic and relaxed stress change caused by the izmit earthquake because of a deep aseismic viscous slip the total stress accumulation within about 1 month of the izmit earthquake was found to be of the order of 4 2 10 3 bars which is rather significant in that it nearly doubles the yearly mean rate of tectonic stress accumulation in the region finally a time to failure analysis showed that the process of small 4 0 m l 2 0 earthquake generation at a distance of about one source dimension 30 km from the athens earthquake epicenter started accelerating very slowly from the beginning of 1994 however only immediately after the izmit earthquake the process culminated with short term foreshock activity the independent results shown previously favor the conclusion that the athens earthquake was likely advanced in time possibly because of the stress changes generated by the izmit large shock manuscript received 28 july 2000

new mineral occurrences and mineralization processes wuda coal fire gas vents of inner mongolia five unique mineral assemblages that include the sulfates millosevichite alunogen anhydrite tschermigite coquimbite voltaite and godovikovite as well as the halide salammoniac and an unidentified phase according to x ray diffraction and eds data were found as encrustations on quartzofeldspathic sand and sandstone adjacent to coal fire gas vents associated with underground coal fires in the wuda coalfield of inner mongolia the mineral assemblage of alunogen coquimbite voltaite and the unidentified phase collected from the same gas vent is documented for the first time coquimbite also occurs as rosettes secondarily nucleated on a cryptocrystalline mass of alunogen coquimbite voltaite and the unidentified phase during storage in a sealed container at room temperature field observations analyses of vent gases sem images and mineral compositions suggest that the sulfates millosevichite alunogen coquimbite voltaite godovikovite and the unidentified phase crystallized in response to a complex sequence of processes that include condensation hydrothermal alteration crystallization from solution fluctuating vent temperatures boiling and dehydration reactions whereas the halide salammoniac crystallized during the sublimation of coal fire gas tschermigite and anhydrite formed by the reaction of coal fire gas with quartzofeldspathic rock or by hydrothermal alteration of this rock and crystallization from an acid rich aqueous solution variations in the mineral assemblages found at five gas vents are possibly due to differences in coal bed chemistry exchange reactions involving coal fire gas and the composition of sediment rock and aqueous solutions prior to the exhalation of gas at the surface as well as the temperature and cooling rate at a vent few studies have addressed the interaction of coal fire gas with sediment rock and aqueous solutions and the subsequent mineralization processes coal fires present opportunities for discovering rare and new mineral occurrences these minerals have potentially important environmental significance and may be vectors for the transmission of toxins coal fires also provide insight for the recognition in the geologic record of preserved mineral assemblages that are diagnostic of ancient fires

greenhouse gas emissions from low temperature oxidation and spontaneous combustion at open cut coal mines in australia abstract spontaneous combustion and low temperature oxidation of waste coal in open cut coal mines represents a potentially large source of greenhouse gas emissions in this paper emission fluxes of co2 and ch4 from spoil piles and waste coal dumps measured at 11 mines in the hunter valley and bowen basin in australia are presented the data displayed considerable scatter which is consistent with the inhomogeneous nature of spoil pile material and permeability of surfaces despite the scatter emissions were able to be classified into three broad categories according to the intensity of the spontaneous combustion present in the material average emissions ranged from about 12 kg co2 e yr 1 m 2 to 8200 kg co2 e yr 1 m 2 depending on the intensity of the spontaneous combustion there was also within the scatter of the data an approximately linear trend of increasing emission flux with increasing surface temperature a key finding of the research is that the emission rates of greenhouse gases from spoil piles where there is no spontaneous combustion but only low temperature oxidation of coal and coal waste are similar to the emission rates due to biological activity from vegetated surfaces however further research is required to quantify the degree to which spoil piles that have no spontaneous combustion contribute to the anthropogenic atmospheric co2 burden

influence of soil cover on reducing the environmental impact of spontaneous coal combustion in coal waste gobs a review and new experimental data abstract the process of spontaneous combustion of coal and coal waste gobs including emitted gases condensation of inorganic and organic species in vents and leachable potential are examined in this study which encompasses a literature review and new experimental data furthermore the potential environmental benefits of cover soil reclamation for reduction of atmospheric and water leachable pollutant emissions are also considered the datong district shanxi province is one of the most important coal production areas in china the resulting large accumulations of mining waste are susceptible to spontaneous combustion three coal gangue dumps in the datong region subjected to a range of reclamation conditions were investigated to assess the influence on coal fires coal coal gangue and condensates from gaseous emissions were characterized in terms of chemical composition particle morphology mineralogy and leaching potential the condensates include tar like deposits elemental sulfur gypsum anhydrite ammonium and hg salts and a broad array of al k fe sulfates the latter may give rise to strongly acidic leachates with high metal loads which may pose a serious threat to the environment these findings led to the development of a proposed condensation sequence model for coal gangue fires the presence and distribution of organic compounds in the condensates deposited at vents were used as geothermometers in support of the proposed condensation model additionally the present study has also explored some feasible remediation measures it was found that covering these coal waste dumps with a layer of compacted soils appears to be an excellent cost effective method to reduce spontaneous combustion scavenge pollutants from gaseous emissions and minimize risks associated with the leaching of readily soluble salts condensed on the surface

potential health impacts of burning coal beds and waste banks uncontrolled release of pollutants from burning coal beds and waste banks presents potential environmental and human health hazards on a global scale the emissions of large volumes of greenhouse gases from burning coal beds may contribute to climate change that alters ecosystems and patterns of disease occurrence on regional and local scales the emissions from burning coal beds and waste banks of acidic gases particulates organic compounds and trace elements can contribute to a range of respiratory and other human health problems although there are few published reports of health problems caused by these emissions the potential for problems can be significant in india large numbers of people have been displaced from their homes because of health problems caused by emissions from burning coal beds volatile elements such as arsenic fluorine mercury and selenium are commonly enriched in coal deposits burning coal beds can volatilize these elements which then can be inhaled or adsorbed on crops and foods taken up by livestock or bioaccumulated in birds and fish some of these elements can condense on dust particles that can be inhaled or ingested in addition selenium arsenic lead tin bismuth fluorine and other elements condense where the hot gaseous emissions come in contact with ambient air forming mats of concentrated efflorescent minerals on the surface of the ground these mats can be leached by rainwater and washed into local water bodies providing other potential routes of exposure although there are little data linking burning coal beds and waste banks to known health problems a possibly analogous situation exists in rural china where mineralized coal burned in a residential environment has caused widespread and severe health problems such as fluorosis and arseniasis

propagation of slow slip leading up to the 2011 mw 9 0 tohoku oki earthquake many large earthquakes are preceded by one or more foreshocks but it is unclear how these foreshocks relate to the nucleation process of the mainshock on the basis of an earthquake catalog created using a waveform correlation technique we identified two distinct sequences of foreshocks migrating at rates of 2 to 10 kilometers per day along the trench axis toward the epicenter of the 2011 moment magnitude mw 9 0 tohoku oki earthquake in japan the time history of quasi static slip along the plate interface based on small repeating earthquakes that were part of the migrating seismicity suggests that two sequences involved slow slip transients propagating toward the initial rupture point the second sequence which involved large slip rates may have caused substantial stress loading prompting the unstable dynamic rupture of the mainshock

nanominerals and ultrafine particles from coal fires from santa catarina south brazil abstract coal mining in santa catarina south brazil impacted the environment by means of a large number of coal waste piles emplaced over the old mine sites and the adjacent areas of the criciuma urussanga and sideropolis poor disposal of coal cleaning rejects represents significant environmental concerns due to their potential influence on soils and river sediments as well as on the surface and groundwater in the surroundings of these zones in this research advanced analytical techniques were performed to provide an improved understanding of the complex processes related with sulfide rich coal waste oxidation spontaneous combustion sequences of mineral formation and the transport mechanisms of hazardous elements by neoformed soluble nanominerals and ultrafine particles the results showed the presence of massive amorphous si al fe ti zr oxy hydroxides and fe hydr oxides with goethite and hematite with various degrees of crystallinity containing hazardous elements such as cr hf hg mo ni se pb th u zr and others several of the neoformed nanominerals found in the burned coal rejects are the same as those commonly associated with coal mine drainage in which oxidation of sulfides plays an important role to environment and human health this is the first brazilian coal spontaneous combustion research

gaseous emissions and sublimates from the truman shepherd coal fire floyd county kentucky a re investigation following attempted mitigation of the fire abstract the truman shepherd coal mine fire floyd and knott counties kentucky has been the subject of several field investigations over the last four years during july and november 2011 and january 2012 field investigations we measured gas emissions collected minerals and characterized the nature of the fire new vents opened over the course of the study and have continued to open since january 2012 coincident with the eastward advance of the fire this is the first study of kentucky coal fires where the original vents were able to be studied in addition to new vents on each subsequent trip neoformed minerals associated with the vents are primarily ammonium sulfates and ammonium chlorides with minor zeolites btex emissions especially benzene vary considerably ranging from relatively low to comparable to those from very large fires such as the ankney coal fire in wyoming vent emission data collected displays a general trend of decreasing carbon dioxide and carbon monoxide emissions from july through january the projected annual greenhouse gas and mercury emissions from the fire are 65 69 t of co 2 4 51 t of co 5 73 t of ch 4 and 1 667 kg hg the november 2011 co co 2 ratios are indicative of more complete combustion than at any other time during the study possibly indicative of decreased moisture in the system

burning of coal waste piles from douro coalfield portugal petrological geochemical and mineralogical characterization abstract in the douro coalfield anthracites were exploited for decades 1795 1994 besides many small mines douro coalfield had two principal mining areas s pedro da cova and pejao coal mining activities cause several impacts on the environment one of which is the amount of discard or waste which was disposed of all over douro coalfield resulting in one of the most significant and severe impacts on the environment over 20 waste piles exist in the old mining areas geographically dispersed and three of them are presently burning their ignition was caused by forest fires during the summer of 2005 samples from the burning and unburned zones of the waste piles were studied as were the gas from vents and the minerals resulting after combustion geochemical processes and mineralogical transformations in the burning coal waste pile were investigated microscopic analyses of the samples identified some particular aspects related with combustion oxidation of pyrite the presence of iron oxides organic particles with cracks and rims with lowered suppressed rr devolatilization vacuoles and some char structures the occurrence of vitreous glassy material as well as fe al spinels in the burning coal waste provide evidences that the combustion temperature could have reached values above 1000 c due to combustion and as expected the samples studied reported high ash yields samples taken from the burning zones reported an increase of as cr li nb ni pb rb sr and lree concentrations and a decrease in zr and hree concentrations enrichment in cs li and rb was noted when comparing with the geochemical composition of black shales and world coals composition that is related with the contribution of granitic rocks in the sediments that originated the main lithologies of the douro coalfield carbonaceous shale and lithic arenites cluster analyses r type and q type were performed to understand the trend between the unburned and burning samples and it seems that some chemical variations are responsible for this separation elemental sulphur and salammoniac ammonium salt are the coal fire gas minerals neoformed on the surface of piles near the burning zones they were identified by different techniques mainly sem edx xrd and ftir relatively high concentrations of several aromatic compounds were detected in the gas collected at the studied areas as well as aliphatic hydrocarbons the highest concentrations of aromatic hydrocarbons were measured in gas samples from s pedro da cova waste pile the exposure to hazardous compounds present in the gas is a serious risk to human health and the environment

seismicity rate immediately before and after main shock rupture from high frequency waveforms in japan 1 we analyze seismicity rate immediately before and after 82 main shocks with the magnitudes ranging from 3 to 5 using waveforms recorded by the hi net borehole array in japan by scrutinizing high frequency signals we detect 5 times as many aftershocks in the first 200 s as in the japan meteorological agency catalogue after correcting for the changing completeness level immediately after the main shock the aftershock rate shows a crossover from a slower decay with an omori s law exponent p 0 58 0 08 between 20 and 900 s after the main shock to a faster decay with p 0 92 0 04 after 900 s the foreshock seismicity rate follows an inverse omori s law with p 0 73 0 08 from several tens of days up to several hundred seconds before the main shock the seismicity rate in the 200 s immediately before the main shock appears steady with p 0 35 0 50 these observations can be explained by the epidemic type aftershock sequence etas model and the rate and state model for a heterogeneous stress field on the main shock rupture plane alternatively nonseismic stress changes near the source region such as episodic aseismic slip or pore fluid pressure fluctuations may be invoked to explain the observation of small p values immediately before and after the main shock

remotely triggered seismicity in continental china following the 2008 mw 7 9 wenchuan earthquake we perform a systematic search of remotely triggered seismicity in con tinental china following the 2008 mw 7 9 wenchuan earthquake we visually identify earthquakes as impulsive seismic energy with clear p and s arrivals on 5 hz high pass filtered three component velocity seismograms 1 hr before and after the wenchuan earthquake out of the 271 stations in the updated chinese digital seismic network csn 17 stations show statistically significant seismicity increase with statistic values larger than 2 following the wenchuan earthquake these include 11 stations in the north china block which is seismically active and is in the rupture propagation direction of the wenchuan earthquake three stations along the coastal lines in the relatively stable south china block one station near the haiyuan fault zone in north west china and two stations near the tanlu fault zone and the longgang volcano in northeast china these observations suggest that dynamic triggering in intraplate regions tends to occur near active faults that have ruptured in historic times and in the rupture propagation directions of the mainshock however it is worth noting that many sites that satisfy the criteria are not triggered suggesting that these conditions would help but are not sufficient enough to guarantee remote triggering in intraplate regions the tectonic environments near the sites with clear triggered activity range from transpressional to tranextentional and most regions are not associated with active geothermal or volcanic activity indicating that dynamic triggering could occur in a wide range of tectonic environments online material tables of station information and measured parameters and two supplementary figures showing locally triggered earthquakes

tandem afterslip on connected fault planes following the 2008 nima gaize tibet earthquake 1 on 9 january 2008 a m 6 4 normal faulting earthquake occurred in central tibet near the border of nima and gaize counties and just north of the bangong nujiang suture zone a week later a m 5 9 aftershock occurred a few kilometers to the northwest of the main shock here we consider interferometric synthetic aperture radar insar data from the japanese alos and european envisat satellites covering both the coseismic phase and 9 months of postseismic deformation the coseismic interferograms clearly show surface deformation resulting from both main shock and aftershock ruptures and data inversions using elastic dislocation models suggest that two northwest dipping faults form a synthetic system with the more steeply dipping aftershock plane meeting the main shock plane at depth postseismic interferograms show first order similarities with their coseismic counterparts indicating that afterslip occurred on both main shock and aftershock rupture surfaces during the months following the earthquakes the afterslip occurred at comparable depths to the coseismic slip but the amount of slip was about an order of magnitude smaller a slip template method is used to obtain moment release estimates at different postseismic time intervals and hence document the time dependence of the postseismic transient the exponential decay time of the afterslip is 34 days and the moment release due to the afterslip was about 10 of the coseismic moment models of viscoelastic stress relaxation in a maxwell half space place a strong lower bound on midcrust to lower crustal viscosity of 3 1017 pa s postseismic data covering a longer time span have the potential to improve this constraint

major ion bulk deposition around an active volcano mt etna italy bulk atmospheric deposition of major cations na k ca mg and anions cl f so4 were measured at 15 sites around an active volcano mount etna from 2001 to 2003 their composition indicates several natural sources among which deposition of plume derived volcanogenic gas compounds is prevalent for f cl and s plume derived acidic compounds are also responsible for the prevailing acidic composition of the samples collected on the summit of the volcano ph in the 2 45 5 57 range cation species have complex origin including deposition of plume volcanogenic ash and aerosols and soil dust wind re suspension of either volcanic or carbonate sedimentary rocks

the chemical and hydrologic structure of poa s volcano costa rica comparison of the chemical characteristics of spring and river water draining the flanks of poa s volcano costa rica indicates that acid chloride sulfate springs of the northwestern flank of the volcano are derived by leakage and mixing of acid brines formed in the summit hydrothermal system with dilute flank groundwater acid chloride sulfate waters of the rio agrio drainage basin on the northwestern flank are the only waters on poa s that are affected by leakage of acid brines from the summit hydrothermal system acid sulfate waters found on the northwestern flank are produced by the interaction of surface and shallow groundwater with dry and wet acid deposition of so2 and h2so4 aerosols respectively the acid deposition is caused by a plume of acid gases that is released by a shallow magma body located beneath the active crater of poa s no evidence for a deep reservoir of neutral ph sodium chloride brine is found at poa s the lack of discharge of sodium chloride waters at poa s is attributed to two factors 1 the presence of a relatively volatile rich magma body degassing at shallow depths 1 km into a high level summit groundwater system and 2 the hydrologic structure of the volcano in which high rates of recharge combine with rapid lateral flow of shallow groundwater to prevent deep seated sodium chloride fluids from ascending to the surface the shallow depth of the volatile rich magma results in the degassing of large quantities of so2 and hcl these gases are readily hydrolyzed and quickly mix with meteoric water to form a reservoir of acid chloride sulfate brine in the summit hydrothermal system high recharge rates and steep hydraulic gradients associated with elevated topographic features of the summit region promote lateral flow of acid brines generated in the summit hydrothermal system however the same high recharge rates and steep hydraulic gradients prevent lateral flow of deep seated fluids thereby masking the presence of any sodium chloride brines that may exist in deeper parts of the volcanic edifice structural stratigraphic and topographic features of poa s volcano are critical in restricting flow of acid brines to the northwestern flank of the volcano a permeable lava lahar sequence that outcrops in the rio agrio drainage basin forms a hydraulic conduit between the crater lake and acid chloride sulfate springs spring water residence times are estimated from tritium data and indicate that flow of acid brines from the active crater to the rio agrio source springs is relatively rapid 3 to 17 years hydraulic conductivity values of the lava lahar sequence calculated from residence time estimates range from 10 5 to 10 7 m s these values are consistent with hydraulic conductivity values determined by aquifer tests of fractured and porous lava pyroclastic sequences at the base of the northwestern flank of the volcano fluxes of dissolved rock forming elements in rio agrio indicate that approximately 4300 and 1650 m3 of rock are removed annually from the northwest flank aquifer and the active crater hydrothermal system respectively over the lifetime of the hydrothermal system 100 s to 1000 s of years significant increases in aquifer porosity and permeability should occur in marked contrast to the reduction in permeability that often accompanies hydrothermal alteration in less acidic systems average fluxes of fluoride chloride and sulfur calculated from discharge and compositional data collected in the rio agrio drainage basin over the period 1988 1990 are approximately 2 38 and 30 metric tons day these fluxes should be representative of minimum volatile release rates at poa s in the last 10 to 20 years

geologic history of natural coal bed fires powder river basin usa abstract coal bed fires ignited by natural processes have baked and fused overlying sediments to form clinker a hard red or varicolored rock through much of the northern great plains of the united states usa the gently dipping coal beds in the region burn when regional downwasting brings them above the local water table the resulting clinker forms a rim along the exposed edge of the coal bed in an ongoing process through geologic time the resistant clinker is left capping buttes and ridges after the softer unbaked strata erode away clinker outcrops cover more than 4100 km2 in the powder river basin prb which lies in wyoming wy and montana mt the clinker in place records tens of billions of tons of coal that have burned releasing gases into the atmosphere the amount of clinker that has eroded away was at least an order of magnitude greater than the clinker that remains in place fission track and uranium thorium helium ages of detrital zircon crystals in clinker and paleomagnetic ages of clinker show that coal beds have burned naturally during at least the past 4 million years ma the oldest in place clinker that has been dated collected from a high isolated clinker capped ridge has a fission track age of 2 8 0 6 ma evidence of erosion and downcutting is also preserved by clinker clasts in gravel terraces one clinker boulder in a terrace 360 m above the yellowstone river has a fission track age of 4 0 0 7 ma coal bed fires are caused by lightning wildfires spontaneous combustion or human activity on coal outcrops and in mines miners government agencies and ranchers have extinguished thousands of coal bed fires but natural ignition continues where fresh coal has access to air at any given time hundreds of fires mostly small are burning in the powder river basin the total amount of coal burned by natural fires in the last 2 ma is one to two orders of magnitude greater than the total amount of coal removed by mining in the past century however current annual rates of coal mining are three to four orders of magnitude greater than estimated prehistoric annual rates of coal consumption by natural fires

remote triggering not evident near epicenters of impending great earthquakes recently there have been numerous great m w 8 devastating earthquakes with a rate in the last seven years that is 260 of the average rate during the 111 year seismological history each great earthquake presents an opportunity to study a major fault at the very beginning and end of the inferred seismic cycle in this work we use these events as both targets and sources to probe susceptibility to dynamic triggering in the epicentral region before and after a large earthquake this study also carefully addresses the possibility that large earthquakes interact in a cascade of remotely triggered sequences that culminates in further large earthquakes we seek evidence of triggering associated with the 16 great m w 8 events that occurred between 1998 and 2011 using regional and global earthquake catalogs to measure changes in interevent time statistics statistical significance is calculated with respect to a nonstationary reference model that includes mainshock aftershock clustering we find limited evidence that a few great earthquakes triggered an increase in seismicity at the site of the next great earthquake in the sequence however this evidence is not corroborated by all statistical tests nor all earthquake catalogs systematic triggered rate changes in the years to decades before each great earthquake are less than 19 at the 95 confidence level too small to explain the observed rate increase the catalogs are insufficient for the purpose of resolving more moderate triggering expected from previous studies we calculate that an improvement in completeness magnitude from 3 7 to 3 5 could resolve the expected triggering signal in the international seismic center isc catalog taken as a whole but an improvement to m 2 0 would be needed to consistently resolve triggering on a regional basis

eruption of the nevado del ruiz volcano colombia on 13 november 1985 gas flux and fluid geochemistry the 13 november 1985 eruption of nevado del ruiz volcano in colombia released a small volume of pyroclastic material and a disproportionately large volume of volcanic gas before the eruption summit fumarole gases became less water rich and the sulfur chlorine ratio increased remote measurements of sulfur dioxide flux after the eruption indicated active degassing at levels associated with eruptive or inter eruptive stages of other volcanoes thermal water analyses revealed increases in magnesium calcium and potassium and an increase in the magnesium chlorine ratio suggesting that these elements may have been leached from new magma ash leachate data showed sulfate and chloride concentrations and ratios that would be expected for the late stages ofa major plinian eruption water from the lahar contained high concentrations of sulfate and had a sulfur chlorine ratio of 4 67 suggesting that water ejected from the crater lake and turbulent mixing of pyroclasts and glacial ice triggered the lahar microprobe analyses of pumice from this eruption and the most recent previous event showed similar mixed andesites the uniform composition of the pumices and the unusually high ratio of gas to magma suggest that although a new batch of magma triggered this eruption the pumice that erupted may actually be old large volumes of new magma and glacial ice make the volcano dangerous and should stimulate development of an integrated long term monitoring program to include tolima volcano 25 kilometers to the south

global ubiquity of dynamic earthquake triggering surface waves that were generated by 12 out of 15 earthquakes with magnitudes greater than 7 since 1990 led to a global increase in the number of small earthquakes this suggests that dynamic triggering of earthquakes is common and is independent of the tectonic environment earthquakes can be triggered by local changes in the stress field static triggering1 2 3 4 5 6 7 due to nearby earthquakes or by stresses caused by the passage of surface rayleigh and love waves from a remote large earthquake dynamic triggering8 9 10 11 12 13 14 15 16 17 18 however the mechanism frequency controlling factors and the global extent of dynamic triggering are yet to be fully understood because rayleigh waves involve compressional and dilatational particle motion volumetric changes as well as shearing whereas love waves only involve shearing triggering by either wave type implies fundamentally different physical mechanisms here we analyse broadband seismograms from over 500 globally distributed stations and use an automated approach to systematically identify small triggered earthquakes the low amplitude signals of such earthquakes would normally be masked by high amplitude surface waves our analysis reveals that out of 15 earthquakes studied of magnitude m greater than 7 0 that occurred after 1990 12 are associated with significant increases in the detection of smaller earthquakes during the passage of both the love and rayleigh waves we conclude that dynamic triggering is a ubiquitous phenomenon that is independent of the tectonic environment of the main earthquake or the triggered event

seismicity rate changes in the salton sea geothermal field and the san jacinto fault zone after the 2010 mw 7 2 el mayor cucapah earthquake

dynamic triggering of microearthquakes in three geothermal volcanic regions of california geothermal volcanic regions are most susceptible to local earthquake triggering by regional and remote earthquakes transient stresses caused by surface waves of these earthquakes can activate critically stressed faults though earthquakes can be triggered in geothermal volcanic regions it is less understood how these regions differ in their triggering responses to distant earthquakes we conduct a systematic survey of local earthquakes triggered by distant earthquakes in three geothermal volcanic regions of california long valley caldera coso geothermal field and geysers geothermal field we examine waveforms of distant earthquakes with magnitudes 5 5 occurring between 2000 and 2012 and compute statistics to confirm the significance of our findings we find that long valley coso and geysers vary in triggering frequency 2 0 3 8 and 6 8 in the 12 year period respectively and when compared to the triggering of deep tectonic tremors along the parkfield cholame section of san andreas fault 9 2 in the 12 year period stress triggering thresholds vary among the regions with long valley having the highest of 5 kpa and 1 kpa for the other regions because dynamic stresses from distant earthquakes are similar in these three regions the varying triggering behavior likely reflects faults having a tendency to be at or near failure this is compatible with geysers having a higher a value in the gutenberg richter relationship and higher geothermal productivity than the other two regions the observation of more frequent triggering of tremor than microearthquakes is consistent with recent laboratory studies on increasing triggerability with lower effective stress

a hypothesis for delayed dynamic earthquake triggering 1 it s uncertain whether more near field earthquakes are triggered by static or dynamic stress changes this ratio matters because static earthquake interactions are increasingly incorporated into probabilistic forecasts recent studies were unable to demonstrate all predictions from the static stress change hypothesis particularly seismicity rate reductions however current dynamic stress change hypotheses do not explain delayed earthquake triggering and omori s law here i show numerically that if seismic waves can alter some frictional contacts in neighboring fault zones then dynamic triggering might cause delayed triggering and an omori law response the hypothesis depends on faults following a rate state friction law and on seismic waves changing the mean critical slip distance dc at nucleation zones

mineralogy and geochemistry of a superhigh organic sulfur coal yanshan coalfield yunnan china evidence for a volcanic ash component and influence by submarine exhalation abstract the mineralogy and geochemistry of a superhigh organic sulfur shos coal of late permian age from the yanshan coalfield yunnan province southwestern china have been studied using optical microscope low temperature ashing plus x ray diffraction analysis scanning electron microscope equipped with energy dispersive x ray spectrometer a sequential chemical extraction procedure and inductively coupled plasma mass spectrometry the m9 coal from the yanshan coalfield is a shos coal that has a total sulfur content of 10 12 11 30 and an organic sulfur content of 8 77 10 30 the minerals in the coal consist mainly of high temperature quartz sanidine albite muscovite illite pyrite and trace amounts of kaolinite plagioclase akermanite rutile and dawsonite as compared with ordinary worldwide bituminous coals and anthracite and chinese coals the m9 coal is remarkably enriched in b 268 g g f 841 g g v 567 g g cr 329 g g ni 73 9 g g mo 204 g g and u 153 g g in addition elements including se 25 2 g g zr 262 g g nb 20 1 g g cd 2 07 g g and tl 2 03 g g are also enriched in the coal occurrence of high temperature quartz sanidine muscovite and illite in the m9 coal is evidence that there is a volcanic ash component in the coal that was derived from acid volcanic ashes fallen into the swamp during peat accumulation occurrence of albite and dawsonite in the coal and strong enrichment of some elements including f s v cr ni mo and u are attributed to the influence by submarine exhalation which invaded along with seawater into the anoxic peat swamp abundances of lithophile elements including rare earth elements nb y zr and tio2 indicate that the silicate minerals in the coal were derived from the northern vietnam upland to the south of the basin

distal volcanic impacts on peatlands palaeoecological evidence from alaska abstract despite the fact that volcanic ash tephra layers are found preserved in peat deposits around the world comparatively little research has investigated the impacts of distal volcanic emissions on peatlands this study investigates the impacts of several late holocene volcanic eruptions on five peatlands in southern alaska using a palaeoecological approach testate amoebae analysis peat humification analysis and a basic analysis of plant macrofossil components were applied across 11 tephra layers changes in macrofossil and testate amoebae assemblages occur across several of the tephra layers the humification results were considered unreliable because of a methodological problem a finding which may have implications for other studies using this technique redundancy analyses on testate amoebae data show statistically significant changes associated with two tephras the most likely causes of the impacts are volcanic gases acidic precipitation or tephra derived leachates the finding that some tephras are associated with impacts whereas others are not may relate to the season of the eruption or meteorological conditions at the time of ash fall these results suggest the sensitivity of peatlands and peatland microbial communities to distal volcanic products and imply that changes in key palaeoclimatic proxies may be caused by a mechanism independent of climate change implications of the results for peat based palaeoclimatic studies are discussed as are possible directions for future research

geochemistry of the late permian no 30 coal seam zhijin coalfield of southwest china influence of a siliceous low temperature hydrothermal fluid this paper describes the influence of siliceous low temperature hydrothermal fluid on the elemental concentrations and mineralogical characteristics of the late permian anthracitic ro max 3 58 coal seam no 30 from the zhijin coalfield in western guizhou province sw china coal samples were examined using instrumental neutron activation analysis inductively coupled plasma mass spectroscopy inductively coupled plasma atomic emission spectrometry x ray fluorescence powder x ray diffraction scanning electron microscopy equipped with energy dispersive x ray and isotope analysis the modes of occurrence of elements were determined using a sequential chemical extraction procedure the studies indicate that the no 30 coal seam has a very high content of veined quartz vol 9 4 whose isotope values of 30si and 18o are 0 6 and 15 4 respectively indicating that the quartz originated from siliceous low temperature hydrothermal fluid formation temperature 160 220 c rather than detrital material of terrigenous origin or magmatic hydrothermal inputs results of scanning electron microscopy equipped with energy dispersive x ray and sequential chemical extraction procedure show that the veined quartz is the dominant source of fe cu u pd pt and ir which are as high as 2 31 356 8 2 1 2 43 and 0 006 g g in this coal seam respectively the studies have also found that elements such as fe and cu are mainly in the veined quartz and they do not occur as sulfides in this coal seam in sharp contrast to many other coal seams in china the geochemical and mineralogical anomalies of the coal are attributed to the siliceous low temperature hydrothermal fluid

triggered creep as a possible mechanism for delayed dynamic triggering of tremor and earthquakes the passage of radiating seismic waves generates transient stresses in the earth s crust that can trigger slip on faults far away from the original earthquake source the triggered fault slip is detectable in the form of earthquakes 1 3 and seismic tremor 4 7 however the significance of these triggered events remains controversial 8 9 in part because they often occur with some delay long after the triggering stress has passed here we scrutinize the location and timing of tremor on the san andreas fault between 2001 and 2010 in relation to distant earthquakes we observe tremor on the san andreas fault that is initiated by passing seismic waves yet migrates along the fault at a much slower velocity than the radiating seismic waves we suggest that the migrating tremor records triggered slow slip of the san andreas fault as a propagating creep event we find that the triggered tremor and fault creep can be initiated by distant earthquakes as small as magnitude 5 4 and can persist for several days after the seismic waves have passed our observations of prolonged tremor activity provide a clear example of the delayed dynamic triggering of seismic events fault creep has been shown to trigger earthquakes 10 12 and we therefore suggest that the dynamic

regional earthquakes in northern tibetan plateau implications for lithospheric strength in tibet 1 a total of 400 regional earthquakes were located in northern tibetan plateau from data recorded by indepth iv and pku eastern kunlun arrays from may 2007 to june 2009 the distribution of these earthquakes is compatible with a continuously deforming tibetan lithosphere most earthquakes occur at a depth range of 0 15 km but no event is deeper than 30 km this observation strongly supports the existence of a hot and weak lower crust beneath the northern tibet the crustal seismogenic zone appears slightly thicker beneath the northern tibet than in the southern plateau possibly reflecting a difference in the rheological dry vs wet structure of the crust the absence of lower crustal and uppermost mantle earthquakes in northern tibet is consistent with a localized asthenospheric upwelling under the qiangtang and songpan ganze terranes finally the lack of mantle earthquakes should be fully addressed in any models of subduction in northern tibet

seismicity around parkfield correlates with static shear stress changes following the 2003 mw6 5 san simeon earthquake 1 earthquakes trigger other earthquakes but the physical mechanism of the triggering is currently debated most studies of earthquake triggering rely on earthquakes listed in catalogs which are known to be incomplete around the origin times of large earthquakes and therefore missing potentially triggered events here we apply a waveform matched filter technique to systematically detect earthquakes along the parkfield section of the san andreas fault from 46 days before to 31 days after the nearby 2003 mw6 5 san simeon earthquake after removing all possible false detections we identify 8 times more earthquakes than in the northern california seismic network catalog the newly identified events along the creeping section of the san andreas fault show a statistically significant decrease following the san simeon main shock which correlates well with the negative static stress changes i e stress shadow cast by the main shock in comparison the seismicity rate around parkfield increased moderately where the static stress changes are positive the seismicity rate changes correlate well with the static shear stress changes induced by the san simeon main shock suggesting a low friction in the seismogenic zone along the parkfield section of the san andreas fault

environmental characterization of burnt coal gangue banks at yangquan shanxi province china the environmental characteristics of coal gangue dumps in yangquan shanxi province china were investigated the amounts of coal gangue are very high in this coal region given the large coal production as a result widespread spontaneous coal gangue combustion gives rise to serious environmental problems coal gangue including bulk gangue and specific lithologies such as coal kaolinite rich material sandstone carbonate minerals and sulfide mineralizations fired coal gangue and condensate products from gas vents were fully characterized with respect to mineralogy chemistry and leaching potential the mineral paragenesis of the fired coal gangue cristobalite mullite hematite trydimite cordierite showed that the combustion temperature could reach 1200 c this was also corroborated by laboratory calcination tests during this combustion some elements such as c cl f s n as cd hg pb sn ge and se are emitted into the atmosphere however condensation processes accounted for the partial trapping of gaseous emissions of as s n hg and se thus condensate mineralizations of elemental sulfur and ammonium salts enriched in se as and other trace elements are frequent in the gas vents the leaching potential of trace elements in the fresh coal gangue was relatively low but the leaching of weathered coal gangue and the gas vents condensates could give rise to environmental problems as these materials produce acidic leachates and yield relatively high leachable levels of a number of elements

the 2005 catastrophic acid crater lake drainage lahar and acidic aerosol formation at mount chiginagak volcano alaska usa field observations and preliminary water and vegetation chemistry results 1 a mass of snow and ice 400 m wide and 105 m thick began melting in the summit crater of mount chiginagak volcano sometime between november 2004 and early may 2005 presumably owing to increased heat flux from the hydrothermal system or possibly from magma intrusion and degassing in early may 2005 an estimated 3 8 106 m3 of sulfurous clay rich debris and acidic water with an accompanying acidic aerosol component exited the crater through a tunnel at the base of a glacier that breaches the south crater rim over 27 km downstream the acidic waters of the flood inundated an important salmon spawning drainage acidifying mother goose lake from surface to depth approximately 0 5 km3 in volume at a ph of 2 9 to 3 1 killing all aquatic life and preventing the annual salmon run over 2 months later crater lake water sampled 8 km downstream of the outlet after considerable dilution from glacial meltwater was a weak sulfuric acid solution ph 3 2 so4 504 mg l cl 53 6 mg l and f 7 92 mg l the acid flood waters caused severe vegetation damage including plant death and leaf kill along the flood path the crater lake drainage was accompanied by an ambioructic flow of acidic aerosols that followed the flood path contributing to defoliation and necrotic leaf damage to vegetation in a 29 km2 area along and above affected streams in areas to heights of over 150 m above stream level moss species killed in the event contained high levels of sulfur indicating extremely elevated atmospheric sulfur content the most abundant airborne phytotoxic constituent was likely sulfuric acid aerosols that were generated during the catastrophic partial crater lake drainage event two mechanisms of acidic aerosol formation are proposed 1 generation of aerosol mist through turbulent flow of acidic water and 2 catastrophic gas exsolution this previously undocumented phenomenon of simultaneous vegetation damaging acidic aerosols accompanying drainage of an acidic crater lake has important implications for the study of hazards associated with active volcanic crater lakes

geochemical and environmental risk assessment of hazardous elements in river sediment the peninsular river damodar is the life line of eastern india facing critical pollution problems due to sewage industrial waste disposal as well as coal mining along the river valley sediment samples were collected and analyzed for various geochemical phases of hazardous elements and associated environmental risks were evaluated this paper provides chemical fractionation of nine cd mn zn ni cu pb co cr fe elements from river sediment by using tessier five step sequential extraction method the study was aimed 1 to understand dynamics and mobility of elements in different geochemical fractions 2 to evaluate bioavailability and ecological risk of these elements by rac and 3 to identify contaminated and uncontaminated sites by using cluster analysis the result of the study revealed maximum bioavailable fraction was that of cd bioavailable elements in studied sediment followed the order cd 23 76 mn 14 19 zn 13 54 ni 12 82 cu 7 12 pb 7 05 co 6 09 fe 4 98 cr 2 03 maximum of the reducible fraction was found for fe 14 38 while in organic fraction cu 11 25 was maximum residual fraction dominates in all elements with a maximum percentage of 83 85 for co risk assessment by rac reveals that the river was under medium risk due to cd mn zn and ni while at low risk for rest of the elements cluster analysis shows that three sampling sites were highly contaminated three were moderately contaminated and six were contaminated while only one site was uncontaminated

detecting low frequency earthquakes within non volcanic tremor in southern taiwan triggered by the 2005 mw8 6 nias earthquake 1 we use a matched filter technique to detect 41 low frequency earthquakes lfes within 700 s of triggered tremor signals in the southern central range in taiwan during the surface waves of the 2005 mw8 6 nias earthquake off the coast of northern sumatra the depth distributions of lfes after double difference relocations concentrate at the depth range of 12 38 km below the background seismicity and above the moho depth inferred from receiver function studies the locations of lfes are close to the downward extension of the steep dipping chaochou lishan fault with only modestly high vp vs ratios 1 75 1 85 our observation indicates that at least portions of triggered tremor consists of many lfes similar to ambient tremor observed at other major plate boundary faults

atmospheric dispersion environmental effects and potential health hazard associated with the low altitude gas plume of masaya volcano nicaragua masaya volcano 560 m a s l nicaragua re sumed its degassing activity in mid 1993 with the con tinuous emission of so 2 at rates increasing from 600 metric tons t day 1 7 0 kg s 1 in 1995 to 1800 t day 1 21 0 kg s 1 in 1999 the low altitude gas plume is typically blown westward by the prevailing wind across the masaya caldera and las sierras high lands which are at a higher elevation than the gas vent in this study the areal distribution of atmospheric so 2 concentrations was monitored within 44 km of the vent with a network of passive samplers measured so 2 air concentrations ranged from 2 to 90 ppbv in 1998 and from 2 to 230 ppbv in 1999 the data suggest that the volcanic emissions influenced air quality across a 1 250 km2 area downwind local topography exerts a strong control on plume dispersal and hilltops are particularly prone to fumigation and thus to high ambient so 2 lev els in a zone 22 km2 in size located within 15 km of the source the response of vegetation to sustained exposure to high atmospheric dose of volcanic so 2 and hf result ed in a strong reduction in the number of plant communi ties a transition zone of somewhat indefinite boundary surrounds the devastated zones and exhibits vegetation damage in the form of leaf injury in addition to the envi ronmental impacts of the volcanic emissions both short and long term public health hazards may exist in areas most exposed to the plume the harmful effects of the volcanic emissions on cultivated vegetation could be di minished by using windbreaks made of gas tolerant trees and shrubs such as eugenia jambos brosimum utile and clusia rosea the current gas crisis at masaya volcano provides an unique opportunity for investigating the at mospheric environmental and medical impacts of volca nic gases and aerosols

the great sumatra andaman earthquake of 26 december 2004 the two largest earthquakes of the past 40 years ruptured a 1600 kilometer long portion of the fault boundary between the indo australian and southeastern eurasian plates on 26 december 2004 seismic moment magnitude mw 9 1 to 9 3 and 28 march 2005 mw 8 6 the first event generated a tsunami that caused more than 283 000 deaths fault slip of up to 15 meters occurred near banda aceh sumatra but to the north along the nicobar and andaman islands rapid slip was much smaller tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer

remotely triggered seismic activity in hakone volcano during and after the passage of surface waves from the 2011 m9 0 tohoku oki earthquake abstract immediately after the march 11 2011 m9 0 tohoku oki earthquake seismic activity increased remarkably beneath hakone volcano central japan at an epicentral distance of 450 km the heightened seismicity was initiated during the passage of the large amplitude surface waves from the main shock and continued over the subsequent 2 months we obtained hypocenters and focal mechanisms of the seismic sequence with the aim of clarifying the physical mechanism responsible for the remotely triggered seismicity we used data from a dense seismic network containing 56 online permanent and offline temporary stations in and around the hakone volcano we found that the earthquakes that occurred during the passage of the surface waves are located at the lower depth limit of ordinary seismicity in the caldera these earthquakes have larger magnitudes than both the ordinary seismicity prior to the tohoku oki earthquake and the seismicity triggered after the passage of the surface waves the focal mechanism that we determined is a strike slip fault type with the p axis in the nw se direction which is consistent with the focal mechanisms of earthquakes that occurred after the passage of the surface waves and the tectonic stress field in the region we also tried to detect missing events that occurred immediately after the passage of the surface waves by using a waveform correlation technique the detected events are distributed near the hypocenters of the earthquakes that occurred during the passage of the surface waves the origin times of the first four events after the arrival of surface waves are consistent with the phases of the decrease in normal stress generated by the surface waves the results suggest that the changes in dynamic stress due to the surface waves from the 2011 tohoku oki earthquake contributed significantly to the initiation of the sequence of triggered seismic activity assuming that normal stress changes on the faults did play an important role in the triggering of earthquakes we propose that fluid flow induced by the oscillation of permeability on the faults is the main mechanism for the initiation of post tohoku oki earthquakes beneath the hakone volcano

impacts of acid emissions from nevado del ruiz volcano colombia on selected terrestrial and aquatic ecosystems abstract emissions of acidic gases and thermal waters from nevado del ruiz volcano have recently increased in concert with the november 13 1985 eruption this study examines the downwind and downstream effects of these emissions on alpine ecosystems high on the slopes of the volcano 4100 m and on coffee plantations at lower elevations 30 km samples of bulk deposition rain soils soil solutions and streams were collected over a six month period january july 1987 to examine the impacts of this volcanogenic acidity bulk deposition falling on the higher slopes of the volcano is usually acidified however deposition reaching the distal coffee plantations seldom is acidic the sources of the acids are hydrogen chloride and sulfur dioxide in the plume of the volcano although sulfur dioxide is by far the more abundant gas hydrogen chloride is most responsible for acidification of rain falling on the slopes of the volcano with distance from the vent the chloride sulfate ratio drops exponentially the only major influence on regional precipitation chemistry in addition to the volcano appears to be land use related activities around the coffee plantations deposition on these areas is enriched by an order of magnitude in nitrate and base cations compared to all other stations throughfall chemistry in the coffee plantations shows a dramatic response to occasional acid rain events a base leaching process on coffee plant leaves is triggered by acid rain for each equivalent of hydrogen ion in rain on the leaf surface over 23 equivalents of potassium ion are leached from the leaf in spite of this dramatic response by the vegetation the plantation soils appear relatively unaffected by acidic deposition in contrast the alpine soils on the volcano exhibit low phs high sulfate and chloride concentrations in soil solutions and high extractable sulfate concentrations all of these factors indicate that these soils have undergone significant acid loading while the deposition of the region is acidified by hydrogen chloride the streams flowing off the volcano are apparently acidified by sulfuric acid in thermal waters discharging into the streams the acidity of these streams decreases downstream while the silica concentrations increase downstream the composition of stream water is most influenced by thermal water discharges as well as equilibrium dissolution of amorphous silica glass and non equilibrium leaching of unweathered ash the impacts of acid gases and thermal water released from the volcano appear to be restricted to ecosystems on the slope of the volcano the only impact of nevado del ruiz on surrounding coffee plantations appears to be potassium leaching of coffee leaves from occasional acid deposition events

mineral speciation and fate of some hazardous contaminants in coal waste pile from anthracite mining in portugal the coal anthracite a in douro coalfield nw of portugal has been exploited for many years and has been mainly used as fuel supply by a thermal power plant the mining activities inevitably impacted the environment which includes a large number of coal waste piles emplaced over the old mine sites and adjacent areas of the douro coalfield the disposal of coal mining residues represents significant environmental concerns due to their potential influence on soils and sediments as well as on the surface and groundwater of the surrounding areas in the present study the development of sequential extraction combined with various advanced analytical techniques was performed to provide an improved understanding of the complex processes related with sulfide rich coal waste oxidation sequences of mineral formation and the transport mechanisms of hazardous elements by specific neoformed soluble minerals the results showed the presence of amorphous iron oxy hydroxides and goethite with various degrees of crystallinity containing hazardous elements such as as cr hg mo se pb u and others some of the neoformed minerals found in the coal waste material are the same as those commonly associated with coal acid drainage in which oxidation of sulfides plays an important role the precipitated neoformed minerals include pickeringite blodite and a mixture of epsomite pickeringite and hexahydrite as these sulfates may dissolve after the first rain they may release above mentioned elements into surrounding water bodies

looking back at the centralia coal fire a synopsis of its present status abstract centralia is in the anthracite region of eastern pennsylvania the town is part of the western middle field a large synclinorium in columbia and schuylkill counties residents of centralia set fire to a garbage dump in 1962 and in the process ignited the buck mountain coal bed fractured and moderately dipping strata at the site permitted air to circulate into the subsurface thereby promoting combustion and making it difficult to extinguish the centralia fire as the fire advanced during the 1960s 1970s and early 1980s it did so along four fronts however the fire appears to be advancing on only two fronts today the pennsylvania department of environmental protection is currently monitoring the fire fire associated with the first or cemetery front is advancing approximately 20 m year although attempts were made to fight the fire they were unsuccessful for logistical and monetary reasons most residents of centralia relocated with the assistance of funds approved by the u s congress and disbursed by the state of pennsylvania the inexperience of community leaders in working with state bureaucracy contributed to the difficulties of fighting the fire

continuous deformation of the tibetan plateau from global positioning system data global positioning system velocities from 553 control points within the tibetan plateau and on its margins show that the present day tectonics in the plateau is best described as deformation of a continuous medium at least when averaged over distances of 100 km deformation occurs throughout the plateau interior by ese wnw extension and slightly slower nne ssw shortening relative to eurasia material within the plateau interior moves roughly eastward with speeds that increase toward the east and then flows southward around the eastern end of the himalaya crustal thickening on the northeast ern and eastern margins of the plateau occurs over a zone 400 km wide and cannot be the result of elastic strain on a single major thrust fault shortening there accommodates much of india s penetration into eurasia a description in terms of movements of rigid blocks with elastic strain associated with slip on faults between them cannot match the velocity field

geochemistry of the acid kawah putih lake patuha volcano west java indonesia abstract kawah putih is a summit crater of patuha volcano west java indonesia which contains a shallow 300 m wide lake with strongly mineralized acid sulfate chloride water the lake water has a temperature of 26 34 c ph s tot 2500 4600 ppm and cl 5300 12 600 ppm and floating sulfur globules with sulfide inclusions are common sulfur oxyanion concentrations are unusually high with s 4 o 6 2 s 5 o 6 2 s 6 o 6 2 2400 4200 ppm subaerial fumaroles thermodynamic modeling of the lake fluids indicates that the lake water is saturated with silica phases barite pyrite and various pb sb cu as bi bearing sulfides when sulfur saturation is assumed precipitating phases predicted by the model calculations are consistent with the bulk chemistry of the sulfur rich bottom sediments and their identified mineral phases much of the lake water chemistry can be explained by congruent rock dissolution in combination with preferential enrichments from entering fumarolic gases or brines and element removal by precipitating mineral phases as indicated by a comparison of the fluids volcanic rocks and lake bed sediment flank springs on the mountain at different elevations vary in composition and are consistent with local rock dissolution as a dominant factor and ph dependent element mobility discharges of warm sulfate and chloride rich water at the highest elevation and a near neutral spring at lower level may contain a small contribution of crater lake water the acid fluid induced processes at patuha have led to the accumulation of elements that are commonly associated with volcano hosted epithermal ore deposits the dispersal of heavy metals and other potentially toxic elements from the volcano via the local drainage system is a matter of serious environmental concern

remote triggering of non volcanic tremor around taiwan summary we perform a systematic survey of triggered deep non volcanic tremor beneath the central range cr in taiwan for 45 teleseismic earthquakes from 1998 to 2009 with mw 7 5 and epicentral distance 1000 km to the broad band station tpub triggered tremors are visually identified as bursts of high frequency 2 8 hz non impulsive and long duration seismic energy that are coherent among many seismic stations and modulated by the teleseismic surface waves out of the 45 earthquakes we identified nine teleseismic events associated with nine tremor sources in the southern and five in the northern cr most of the tremor sources are located within the depth range of 15 25 km in the lower crust above the moho we find that the amplitudes of the surface waves play an important role in determining the triggering potential and the apparent triggering threshold is 0 1 cm s 1 or 7 8 kpa however such threshold is partially controlled by the background noise level which could prevent weaker tremor triggered by surface waves with smaller amplitudes from being identified the amplitudes of the triggered tremor show a positive correlation with the amplitudes of the triggering surface waves consistent with the predictions by the clock advance model in addition to amplitudes other factors such as frequency contents and incidence angles also affect the triggering potential we find that intermediate period 30 10 s surface waves could trigger modulate tremors suggesting that long period 30 s surface waves are not always required in long range triggering tremors appear to be triggered by both love and rayleigh waves when the incidence angles are parallel to the strike of the cr all six events triggered tremor primarily during the rayleigh waves for strike normal incidence only the 2001 mw7 8 kunlun earthquake showed predominant love wave triggering this observation can be qualitatively explained by a simple coulomb failure for a left lateral shear on the low angle detachment fault beneath the southern cr

decay and expansion of the early aftershock activity following the 2011 mw9 0 tohoku earthquake the 2011 m w9 0 tohoku earthquake was followed by an abundant amount of seismicity providing a unique opportunity to analyze the triggering mechanism of great earthquakes although the tohoku earthquake occurred close to a dense seismic network many aftershocks that occurred in the first few hours after the mainshock are not recorded in the earthquake catalogs here we use a template waveform approach to recover as many as possible missing events in the first 12 hours following the tohoku mainshock our analysis is able to detect about 1 4 times more events than those listed in the high sensitivity seismograph hi net earthquake catalog combining our new dataset with earthquakes that occurred at latter times we are able to observe a continuous decay of the aftershock rate and along strike expansion of aftershock area we relate the latter observation to the occurrence of post seismic slip over the deep interface

static stress interactions in extensional earthquake sequences an example from the south lunggar rift tibet 1 an extensional earthquake sequence occurred in 2004 8 across a graben in the south lunggar rift on the tibetan plateau we use insar data to determine the location fault geometry and slip distribution of these earthquakes and to test whether the sequence is compatible with static stress triggering the mw 6 2 and 6 3 earthquakes in 2004 and 2005 both ruptured west dipping faults on the east side of a graben in 2008 a mw 6 7 earthquake ruptured a pair of east dipping fault segments on the other side of the graben offset from the earlier ruptures we compute first order dislocation models of stress change and demonstrate that the order and spatial configuration of this sequence of events is compatible with triggering by static stress transfer a continuation of the sequence would be most likely to occur on the northern extension of the 2008 rupture although variable slip rate along the rift may mean that the sequence has run its course the insar data for the 2008 earthquake also reveal slip on a fault that cuts the graben at a highly oblique angle we suggest that this is a release fault accommodating differential throw in the hanging wall and associate the deformation with a mw 6 0 aftershock activity on such a release fault has not been directly imaged before the zhongba sequence is one of several examples of recent clustered normal fault earthquakes on the plateau and may be an example of phase locking of similar faults

remote triggering of tremor along the san andreas fault in central california received 30 august 2008 accepted 16 april 2009 published 18 july 2009 1 we perform a systematic survey of triggered tremor along the san andreas fault in central california for the 31 teleseismic earthquakes with mw 7 5 since 2001 we identify 10 teleseismic events associated with clear triggered tremor about 52 of the tremor is concentrated south of parkfield near cholame where ambient tremor has been identified previously and the rest is widely distributed in the creeping section of the san andreas fault north of parkfield tremor is generally initiated and is in phase with the love wave particle velocity however the pattern becomes complicated with the arrival of the rayleigh waves and sometimes tremor continues after the passage of the surface waves we identify two cases in which tremor is triggered during the teleseismic pkp phase these results suggest that while shear stress from the passage of the love waves plays the most important role in triggering tremor in central california other factors such as dilatational stresses from the rayleigh and p waves also contribute we also examine the ambient tremor occurrence rate before and after the teleseismic events and find a transient increase of stacked tremor rate during the passage of the teleseismic surface waves this observation implies that the occurrence time of tremor is temporally advanced by the dynamic stresses of the teleseismic waves the amplitude of the teleseismic waves correlates with the occurrence of triggered tremor and the inferred tremor triggering threshold is 2 3 kpa the relatively low triggering threshold indicates that the effective stress at the tremor source region is very low most likely due to near lithostatic fluid pressure

dynamic triggering of shallow earthquakes near beijing china summary we perform a comprehensive analysis of dynamic triggering around the babaoshan and huangzhuang gaoliying faults near beijing china the triggered earthquakes are identified as impulsive seismic arrivals with clear p and s waves in 5 hz high pass filtered three component velocity seismograms during the passage of large amplitude body and surface waves of large teleseismic earthquakes we find that this region was repeatedly triggered by four earthquakes in east asia including the 2001 mw 7 8 kunlun 2003 mw 8 3 tokachi oki 2004 mw 9 2 sumatra and 2008 mw 7 9 wenchuan earthquakes in most instances the microearthquakes coincide with the first few cycles of the love waves and more are triggered during the large amplitude rayleigh waves such an instantaneous triggering by both the love and rayleigh waves is similar to recent observations of remotely triggered non volcanic tremor along major plate boundary faults and can be explained by a simple coulomb failure criterion we are able to locate five of the earthquakes triggered by the kunlun and tokachi oki earthquakes these events occurred at shallow depth 5 km above the background seismicity near the boundary between nw striking babaoshan and huangzhuang gaoliying faults and the fangshan pluton we suggest that these triggered earthquakes occur near the transition between the velocity strengthening and weakening zones in the top few kilometres of the crust and are likely driven by relatively large dynamic stresses on the order of few tens of kpa

simulating the impacts of distal volcanic products upon peatlands in northern britain an experimental study on the moss of achnacree scotland the potential impact of prehistoric volcanism on distal areas has been the subject of some discussion in both ecology and archaeology an experimental approach is used here to examine the potential effects of distant volcanism on a peatland environment simulations of different tephra and acidity loading designed to approximately replicate the prehistoric hekla 4 ashfall were monitored over 2 years impacts on the peatland ecosystem were assessed by qualitative observations of plant health and abundance semi quantitative observations of flowering measurements of peat ph humification and testate amoebae community composition plots with higher acid loading showed immediate and lasting impacts on plants although other treated plots were less affected changes in testate amoebae and peat humification were inconsistent both within and between plots the experiment demonstrates the potentially severe effects of high acid loading on peatland plants although some responses remain unclear

complex nonvolcanic tremor near parkfield california triggered by the great 2004 sumatra earthquake 1 in several instances the passing surface waves from large earthquakes have ignited nonvolcanic tremor nvt on major faults still the mechanism of tremor and its reaction to the dynamic stressing from various body and surface waves is poorly understood we examine tremor near parkfield california beneath the san andreas fault triggered by the mw 9 2 2004 sumatra earthquake the prolonged shaking produces the richest and the most varied observations of dynamically triggered tremor to date the tremor appears in at least three distinct locations and shows activity pulsing with encouraging stress as has been observed in other cases the greatest amount of triggering and tremor modulation accompanies the long period love waves rayleigh waves on the other hand appear to be less effective in exciting tremor sources also at times the tremor stops before the surface waves are complete at other times it continues quivering after the waves have passed while tremor is found to be sensitive to small stress changes there are times when stresses of comparable magnitudes do not trigger noticeable tremor some tremors in this nvt sequence appear to be associated with the passage of p waves which is unusual and surprising given the small stresses they impart

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

mineralogy and geochemistry of a late permian coal in the dafang coalfield guizhou china influence from siliceous and iron rich calcic hydrothermal fluids abstract this paper describes the influence of siliceous and iron rich calcic low temperature hydrothermal fluids lthf on the mineralogy and geochemistry of the late permian no 11 coal anthracitic r r 2 85 in the dafang coalfield in northwestern guizhou province china the no 11 coal has high contents of vein ankerite 10 2 vol and vein quartz 11 4 vol with formation temperatures of 85 and 180 c respectively indicating that vein ankerite and vein quartz were derived from low temperature calcic and siliceous hydrothermal fluids in two epigenetic episodes the vein quartz appears to have formed earlier than vein ankerite did and at least three distinct stages of ankerite formation with different ca sr and fe mn ratios were observed the two types of mineral veins are sources of different suites of major and trace metals scanning electron microscope and sequential extraction studies show that in addition to fe mg and ca vein ankerite is the dominant source of mn cu ni pb and zn in the coal and the contents of these five elements are as high as 0 09 and 74 0 33 6 185 and 289 g g respectively in contrast vein quartz is the main carrier mineral for platinum group elements pges pd pt and ir in the coal and the contents of pd pt and ir are 1 57 0 15 and 0 007 g g respectively sequential extraction showed a high pge content in the silicate fraction up to 10 4 g g pd 1 23 g g pt and 0 05 g g ir respectively it is concluded that the formation of ankerite and quartz and the anomalous enrichment of trace elements in the no 11 coal in the dafang coalfield guizhou result from the influx of calcic and siliceous low temperature hydrothermal fluids

increasing background seismicity and dynamic triggering behaviors with nearby mining activities around fangshan pluton in beijing china dynamic triggering in western fangshan pluton beijing china has been repeatedly identified but previous studies are limited by sparse seismic station coverage here we systematically analyze continuous waveforms recorded by both permanent stations and a temporary seismic network 40 days before and after the 11 march 2011 mw 9 1 tohoku oki and the 14 april 2012 mw 8 6 indian ocean earthquakes we first build a template database using a short term average to long term average method next we apply the matched filter technique that cross correlates the template waveforms with continuous data to detect additional seismic events overall we detect 1956 and 950 seismic events around the tohoku oki and indian ocean main shocks respectively most detected events are shallow 5 km and clustered at beiling syncline in western fangshan pluton which is adjacent to a running coalmine seven and 10 events are detected during the large amplitude surface waves of the two main shocks respectively but no similar burst is detected following their major foreshock and aftershocks multiple statistical tests indicate that the short term bursts after the two main shocks are dynamically triggered we suggest that mining related activities may perturb the subsurface stress conditions and hence make the region more susceptible for dynamic triggering than other places

model test on rainfall induced loess mudstone interfacial landslides in qingshuihe china loess mudstone interfacial landslide is one of the most prominent landslide hazards that occurred in soil rock contacting zones in the world a semi similar material physical model test was conducted to investigate the startup conditions and sliding mechanism of rainfall induced loess mudstone interfacial landslides based on the landslides which occurred in qingshuihe county inner mongolia autonomous region china when rainwater infiltrates downward along loess strata and gradually gathers near the interface the soil strata near the interface are softened causing frictional constraint reduction the mudstone strata serve as an aquifuge between underlying mudstone and overlying loess strata due to different permeability coefficients as rainfall continues the softened zone is expanded and gradually developed into fluidization ultimately leading to interfacial landslide this instability process is studied and reproduced experimentally through a self designed physical model test in this paper the model test results indicate that startup conditions of interfacial landslides are related to rainfall intensity and duration as well as thickness of overlying loess strata this study also indicates that the more the impact is from the rock at the back of the slope the more likely an interfacial landslide is to occur but this is not a decisive factor to induce the interfacial landslide the gradient of slope is also a potential factor to induce interfacial landslide when the gradient exceeds 24 the cutting layer landslide is likely to occur because impact of gravity is greater than that of interface friction resistance this study exploring startup conditions and the sliding mechanism of rainfall induced loess mudstone interfacial landslides provides a scientific guidance for the prevention monitoring early warning and control for geologic landslide hazards

underplating in the himalaya tibet collision zone revealed by the hi climb experiment we studied the formation of the himalayan mountain range and the tibetan plateau by investigating their lithospheric structure using an 800 kilometer long densely spaced seismic array we have constructed an image of the crust and upper mantle beneath the himalayas and the southern tibetan plateau the image reveals in a continuous fashion the main himalayan thrust fault as it extends from a shallow depth under nepal to the mid crust under southern tibet indian crust can be traced to 31 n the crust mantle interface beneath tibet is anisotropic indicating shearing during its formation the dipping mantle fabric suggests that the indian mantle is subducting in a diffuse fashion along several evolving subparallel structures

dynamic stresses coulomb failure and remote triggering corrected abstract dynamic stresses associated with crustal surface waves with 15 30 s periods and peak amplitudes

mineralogy and leaching characteristics of beneficiated coal products from santa catarina brazil abstract petrographic mineralogical and geochemical studies have been carried out on beneficiated coal products from mines and preparation plants in the santa catarina basin southern brazil to investigate the range of characteristics exhibited by the materials and the potential impact of their stockpiling and storage on the environment the coals contain varying proportions of vitrinite and inertinite macerals and have vitrinite reflectance values ranging from 0 44 to 1 38 with the exception of one material blended with peat from an external source they have relatively high percentages of ash 30 58 and mineral matter 36 66 the mineral matter consists mainly of clay minerals kaolinite illite and illite smectite together with 15 25 quartz up to 10 feldspar up to 5 calcite and or dolomite and up to 5 pyrite and around 1 anatase and or rutile bassanite is also present in low temperature ash derived from the coals mainly derived from interaction of ca and s associated with the organic matter jarosite is formed by pyrite oxidation in coals that have been exposed in stockpiles for extended periods most of the trace elements in most of the coals have higher concentrations than average values for world coals generally probably due to the relatively high mineral matter content a lower ash product representing a blend of coal and peat has similar to lower concentrations of most elements but higher concentrations of b ba be cd ge and mn which may be associated with the peat component interaction of relatively fresh coals with water in laboratory tests produces leachates with near neutral to mildly acid ph values but leaching of oxidized jarosite bearing coal produces a strongly acid leachate with higher concentrations of cd co cu ni and zn leachates derived from coals in which the pyrite has been oxidized during storage would thus be expected to have a more adverse environmental impact than leachates derived from coals in which such oxidation has not had an opportunity to develop

multiple slow slip events during a foreshock sequence of the 2014 iquique chile mw 8 1 earthquake to obtain a precise record of the foreshock sequence before the 2014 iquique chile mw 8 1 earthquake we applied a matched filter technique to continuous seismograms recorded near the source region we newly detected about 10 times the number of seismic events listed in the routinely constructed earthquake catalog and identified multiple sequences of earthquake migrations at speeds of 2 10 km d both along strike and downdip on the fault plane updip of the main shock area in addition we found out repeating earthquakes from the newly detected events likely indicating aseismic slip along the plate boundary fault during the foreshock sequence these observations suggest the occurrence of multiple slow slip events updip of the main shock area the final slow slip event migrated toward the main shock nucleation point we interpret that several parts of the plate boundary fault perhaps experienced slow slip causing stress loading on the prospective largest slip patch of the main shock rupture

evidence suggesting fluid flow beneath japan due to periodic seismic triggering from the 2004 sumatra andaman earthquake 1 we show that very large surface waves from the 2004 sumatra andaman earthquake m9 2 triggered deep low frequency dlf seismic tremors beneath japan over a 500 km wide region the triggered seismicity was periodically excited synchronized with the amplitudes and phases of the oscillatory surface waves incident on the region periodic excitation implies that the specific phase of the surface waves plays an important role for the triggering estimation of stress changes in the source regions showed that the volumetric dilatation larger than 10 8 was the predominant factor for triggering thereby strongly supporting the hypothesis that dlf events are caused by processes related to fluid flow

seismicity rate changes along the central california coast due to stress changes from the 2003 m 6 5 san simeon and 2004 m 6 0 parkfield earthquakes abstract we investigated the relationship between seismicity rate changes and modeled coulomb static stress changes from the 2003 m 6 5 san simeon and the 2004 m 6 0 parkfield earthquakes in central california coulomb stress modeling indicates that the san simeon mainshock loaded parts of the rinconada hosgri and san andreas strike slip faults along with the reverse faults of the southern los osos domain all of these loaded faults except for the san andreas experienced a seismicity rate increase at the time of the san simeon mainshock the parkfield earthquake occurred 9 months later on the loaded portion of the san andreas fault the parkfield earthquake unloaded the hosgri fault and the reverse faults of the southern los osos domain which both experienced seismicity rate decreases at the time of the parkfield event although the decreases may be related to the decay of san simeon triggered seismicity coulomb stress unloading from the parkfield earthquake appears to have altered the aftershock decay rate of the southern cluster of san simeon aftershocks which is deficient compared to the expected number of aftershocks from the omori decay parameters based on the pre parkfield aftershocks dynamic stress changes cannot explain the deficiency of aftershocks providing evidence that static stress changes affect earthquake occurrence however a burst of seismicity following the parkfield earthquake at ragged point where the static stress was decreased provides evidence for dynamic stress triggering it therefore appears that both coulomb static stress changes and dynamic stress changes affect the seismicity rate

formation of carbon nano balls and carbon nano tubes from northeast indian tertiary coal value added products from low grade coal abstract the paper reports the presence of carbon nano balls and nano tubes in the clean coal product during our experiments on desulfurization and deashing of northeast indian high sulfur tertiary coal by molten caustic leaching mcl method the scanning electron microscopy sem high resolution transmission electron microscopy hr tem x ray diffraction xrd raman and fourier transform infrared ft ir spectroscopy analyses revealed the formation of varied sizes of carbon nanomaterials in the clean coal product mcl product the nano balls are in the range of 5 10 nm with nominal areas in the range of 40 100 nm2 160 220 nm2 and 550 650 nm2 the diameters of the carbon nano tubes cnts formed are in the range of 18 24 nm the diameters of the branch carbon nano tubes bcnts are in the range of 35 92 nm it is further observed that the alkaline treatment followed by acid treatment favored the formation of the carbon nano balls carbon nano tubes cnts and branch carbon nanotubes bcnts in the coal product the low grade coals could also be used for the preparation of nano carbon based high value added products

eruption of the nevado del ruiz volcano colombia on 13 november 1985 tephra fall and lahars a small plinian eruption of the nevado del ruiz volcano in colombia ejected 3 5 x 1010 kilograms of mixed dacite and andesite tephra on 13 november 1985 with a maximum column height of 31 kilometers above sea level small pyroclastic flows and surges generated during the initial stage of the eruption caused surface melting of approximately 10 of the volcano9s ice cap leading to meltwater floods the erosive floods incorporated soils and loose sediments from the volcano9s flanks and developed into lahars which claimed at least 25 000 lives

migration of early aftershocks following the 2004 parkfield earthquake a significant number of the early aftershocks following large shallow earthquakes are missing in existing earthquake catalogues an analysis of the waveforms of 3 647 relocated earthquakes along the parkfield section of the san andreas fault reveals 11 times more aftershocks within three days of the 2004 parkfield earthquake than listed in a standard catalogue large shallow earthquakes are immediately followed by numerous aftershocks a significant portion of these events is missing in existing earthquake catalogues mainly because seismicity after the mainshock can be masked by overlapping arrivals of waves from the mainshock and aftershocks1 2 3 4 however recovery of the missing early aftershocks is important for understanding the physical mechanisms of earthquake triggering2 3 4 and for tracking postseismic deformation around the rupture zone associated with the mainshock5 6 7 here we use the waveforms of 3 647 relocated earthquakes8 along the parkfield section of the san andreas fault as templates9 10 to detect missing aftershocks within three days of the 2004 magnitude 6 0 parkfield earthquake we identify 11 times more aftershocks than listed in the standard catalogue of the northern california seismic network we find that the newly detected aftershocks migrate in both along strike and down dip directions with logarithmic time since the mainshock consistent with numerical simulations of the expansion of aftershocks caused by propagating afterslip11 12 the cumulative number of early aftershocks increases linearly with postseismic deformation in the first two days supporting the view that aftershocks are driven primarily by afterslip13 14

cretaceous tertiary shortening basin development and volcanism in central tibet the geologic map pattern of the qiangtang terrane in central tibet defines a 600 km long and up to 270 km wide east plunging structural culmination it is characterized by early mesozoic blueschist bearing melange and upper paleozoic strata in the core and mainly triassic jurassic strata along the limbs in the western qiangtang terrane 84 e the culmination is unconformably overlain by weakly deformed mid cretaceous volcanic flows and tuffs along the bangong suture to the south 32 n 84 e mid cretaceous nonmarine red beds and volcanic rocks lie unconformably on jurassic suture zone rocks these relationships demonstrate that west central tibet was above sea level during the mid cretaceous and experienced significant denudation prior to mid cretaceous time growth of the qiangtang culmination is inferred to have initiated during southward emplacement of a thrust sheet of early mesozoic melange and upper paleozoic strata during the early cretaceous lhasa qiangtang collision the north south width of the inferred thrust sheet provides a minimum slip estimate of 150 km at 84 e decreasing eastward to 70 km at 87 e paleogene deformation in the qiangtang terrane is characterized by widely distributed mainly north dipping thrust faults that cut eocene oligocene red beds and volcanic rocks in their footwall along the bangong suture the north dipping shiquanhe gaize amdo thrust system cuts 64 and 43 m y old volcanic tuffs in its footwall and accommodated 40 km of post mid cretaceous shortening the tertiary south dipping gaize siling co backthrust bounds the southern margin of the bangong suture and marks the northernmost limit of mid cretaceous marine strata in central tibet cretaceous deformation and denudation in central tibet is attributed to northward underthrusting of the lhasa terrane beneath the qiangtang terrane along the bangong suture this model implies that 1 cretaceous strata along the bangong suture and in the northern lhasa terrane were deposited in a flexural foreland basin system and derived at least in part from the qiangtang terrane and 2 the central tibetan crust was thickened substantially prior to the indo asian collision although its magnitude is poorly known tertiary shortening in the qiangtang terrane is more prevalent than in the lhasa terrane this difference may be attributed to the presence of underthrust melange in the deeper central tibetan crust which would have made it weaker than the lhasa terrane during the indo asian collision

seismicity in the western great basin apparently triggered by the landers california earthquake 28 june 1992 within 24 hr after the landers earthquake there were three magnitude 3 4 events in western nevada and an unexpected widespread increase in the rate of small events based on combined catalogs for northern nevada southern nevada and southern california and a model that assumes statistical independence of events in these regions the probability of this happening in a 24 hr period by random chance is less than 10 12 per day therefore there is high statistical confidence that the increased seismicity was triggered by the landers event based on the statistical model we develop a list of 227 earthquakes in the first 83 days following the landers earthquake each of which has no more than 10 probability of occurring by random chance the suspect events are broadly distributed in regions that correlate with historical activity in the great basin the events are not uniquely associated with known volcanic activity or with zones that were previously active with microearthquakes or aftershock sequences the magnitudes of the largest triggered events appear to decrease with distance with time the number of suspect events decreases at a rate comparable to the rate of decrease of aftershocks of the landers and big bear earthquakes three of the most significant triggered events that that occurred were as follows mina 500 km from landers m 4 36 min after landers smith valley 590 km from landers m 3 4 56 min after landers and little skull mountain 280 km from landers m 5 6 22 3 hr after landers the evidence for triggering is particularly strong in the case of the little skull mountain event where an increased rate of microseismicity was evident as soon as small events could be identified in the coda of the landers earthquake we evaluate the seismic history for the past 3 yr to understand what was unique about the landers earthquake this includes identifying the previous earthquakes most likely to have caused the strongest shaking in various frequency bands based on a simple screening model the strains from the landers earthquake were uniquely large at low frequencies but at high frequencies they were exceeded frequently by small more local events thus we hypothesize that the cause of triggering is low frequency dynamic strains at periods of about 10 sec or greater and that there is a regional threshold that must be exceeded since previous events with calculated strains that were almost as strong were not causes of widespread triggering this mechanism for triggering satisfies the criterion of being a relatively rare phenomenon since it is likely to occur only when a large long period wave is radiated into an area where strain has been building slowly toward the point where faults are unstable

trace element emissions from spontaneous combustion of gob piles in coal mines shanxi china the emissions of potentially hazardous trace elements from spontaneous combustion of gob piles from coal mining in shanxi province china have been studied more than ninety samples of solid waste from gob piles in shanxi were collected and the contents of twenty potentially hazardous trace elements be f v cr mn co ni cu zn as se mo cd sn sb hg tl pb th and u in these samples were determined trace element contents in solid waste samples showed wide ranges as compared with the upper continental crust the solid waste samples are significantly enriched in se 20x and tl 12x and are moderately enriched in f as mo sn sb hg th and u 2 5x the solid waste samples are depleted in v cr mn co ni cu and zn the solid waste samples are enriched in f v mn cr co ni cu zn sb th and u as compared with the shanxi coals most trace elements are higher in the clinker than in the unburnt solid waste except f sn and hg trace element abundances are related to the ash content and composition of the samples the content of f is negatively correlated with the ash content while pb is positively correlated with the ash the concentrations of as mn zn and cd are highly positively correlated with fe2o3 in the solid waste the as content increases with increasing sulfur content in the solid waste the trace element emissions are calculated for mass balance the emission factors of trace elements during the spontaneous combustion of the gobs are determined and the trace element concentrations in the flue gas from the spontaneous combustion of solid waste are calculated more than a half of f se hg and pb are released to the atmosphere during spontaneous combustion some trace element concentrations in flue gas are higher than the national emission standards thus gob piles from coal mining pose a serious environmental problem

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

remotely triggered earthquakes in south central tibet following the 2004 mw 9 1 sumatra and 2005 mw 8 6 nias earthquakes