on the ulf magnetic ratio increase before the 2008 iwate miyagi nairiku earthquake by hirano and hattori 2011 abstract hirano and hattori 2011 hereafter cited as h h report the observation of anomalous increases in the ulf geomagnetic field spectral density ratio which the authors claim to be possible precursors of the 2008 iwate miyagi nairiku earthquake here the results of h h are reviewed taking into account the global geomagnetic activity level by means of k p index this paper cast serious doubts on the seismogenic origin of the magnetic signatures documented by h h showing that the anomalous signals are normal ulf magnetic variations induced by solar terrestrial interaction in summary h h s claims that magnetic field disturbances about a month before the mw 6 9 iwate miyagi nairiku earthquake on june 13 2008 are precursors to the earthquake are unlikely to be correct

carbon mineralization and lignin content of eroded sediments from a grazed watershed of south africa abstract despite the increasing interest in the role of soil erosion on the global carbon cycle few studies were carried out to evaluate the fate of eroded organic carbon oc at the landscape level although eroded c may constitute an atmospheric c source upon mineralization or a c sink if entrapped it is largely unknown how landscape position and molecular composition influence the fate of terrestrial c mobilized during erosion induced storm events the objective of this study was to assess the impact of soil water erosion on potential carbon mineralization and to interpret these results using additional information on organic matter composition in both soils and sediments the study was conducted in a 23 ha grassland catchment of the south african drakensberg foothill showing numerous features of land degradation the elemental and stable isotope composition and the lignin component of soils from different landscape positions were compared to those of sediments eroded from 1 1 m microplots in addition and to assess changes in oc availability during soil erosion co 2 emissions from soil and eroded sediments were measured continuously under laboratory conditions over a 20 day period the lignin component of the samples was characterized by cuo oxidation our results showed that eroded sediments were enriched in organic carbon by factor 1 8 and in lignin by factor 3 7 lignin characterization indicated that it was less decomposed in eroded sediments than in the original soils but did not control carbon mineralization a negative trend was observed between the c n ratio of eroded sediments and soil and co 2 production suggesting that microbial biomass could be n limited carbon mineralization in eroded sediments greatly exceeded that of soils and was described by a single pool first order model whereas mineralization of soil c followed a sigmoidal pattern we conclude that organic matter present in eroded sediments consists of relatively undecomposed plant material and is mineralized to a greater extent than soil organic matter regardless of landscape position

are there new findings in the search for ulf magnetic precursors to earthquakes moore 1964 in a letter published in nature reported disturbances in geomagnetic field data prior to the 27 march 1964 alaska earthquake after the publication of this report many papers have shown magnetic changes preceding earthquakes however a causal relationship between preearthquake magnetic changes and impending earthquakes has never been demonstrated as a consequence after 50 years magnetic disturbances in the geomagnetic field are still candidate precursory phenomena some researchers consider the investigation of ultra low frequency ulf 0 001 10 hz magnetic data the correct approach for identifying precursory signatures of earthquakes other researchers instead have recently reviewed many published ulf magnetic changes that preceded earthquakes and have shown that these are not actual precursors the recent studies by currie and waters 2014 and han et al 2014 aim to provide relevant new findings in the search for ulf magnetic precursory signals however in order to contribute to science alleged precursors must be shown to be valid and reproducible by objective testing here we will briefly discuss the state of the art in the search for ulf magnetic precursors paying special attention to the recent findings of currie and waters 2014 and han et al 2014 we do not see in these two reports significant evidence that may support the observation of precursory signatures of earthquakes in ulf magnetic records

on claimed ulf seismogenic fractal signatures in the geomagnetic field 1 during the last ten years fractal analysis of ultra low frequency ulf geomagnetic field components has been proposed as one of the most promising tools to highlight magnetic precursory signals possibly generated by the preparation processes of earthquakes several papers claim seismogenic changes in the fractal features of the geomagnetic field some months before earthquakes occur the target of the present paper is to put forth a qualitative investigation on the fractal characteristics of ulf magnetic signatures that previous authors have claimed to be related without doubt to strong earthquakes this analysis takes into account both the temporal evolution of the geomagnetic field fractal parameters reported in previous researches and the temporal evolution of global geomagnetic activity running averages of the geomagnetic indices kp and ap are plotted into the original figures from the previous publications this simple analysis shows that the fractal features of the ulf geomagnetic field are closely related to the geomagnetic activity both before and after the earthquake occurs the correlation between the geomagnetic field fractal parameters and geomagnetic activity is clearly shown over both long and short time scales in light of this the present paper shows that fractal behaviors of previously claimed seismogenic ulf magnetic signatures depend mainly on geomagnetic activity due to solar terrestrial interaction therefore previously reported association with the preparation process of the earthquake is dubious

detection of ultra low frequency emissions connected with the spitak earthquake and its aftershock activity based on geomagnetic pulsations data at dusheti and vardzia observatories abstract ulf electromagnetic emissions from the spitak armenia earthquake site have been detected observations were carried out at the dusheti and vardzia georgia observatories at distances 120 200 km from the epicentre in a frequency range 0 005 1 hz it is shown that the emission appears several hours before the main shock and some of the powerful aftershocks and is not connected with geomagnetic pulsations of magnetospheric sources

direction finding of precursory radio emissions associated with earthquakes a proposal abstract the direction finding of precursory radio emissions associated with earthquakes is proposed based on the simultaneous measurement of the waveforms of multiple electric and magnetic field components at elf 1 525 khz 5 hz and ulf 0 10 hz at a few stations this measurement enables us to determine the wave mode of the observed signal for example its direction of arrival by measuring such parameters as the wave impedance wave polarization and wave coherence from these observations we hope to be able to obtain the first convincing evidence on the precursory emissions of earthquakes

on the reported magnetic precursor of the 1993 guam earthquake 1 using 1 second magnetometer data recorded 67 km from the epicenter of the 1993 mw 7 7 guam earthquake hayakawa et al 1996 and miyahara et al 1999 identify anomalous precursory changes in ultra low frequency magnetic polarization the ratio of vertical to horizontal field components in a check of their results we compare their data gam with 1 second data from the kakioka observatory kak in japan and the global magnetic activity index kp we also examine log books kept by usgs staff working on the guam magnetic observatory we find 1 analysis problems with both hayakawa et al and miyahara et al 2 significant correlation between the gam kak and kp data and 3 an absence of identifiable localized anomalous signals occurring prior to the earthquake the changes we do find in polarization are part of normal global magnetic activity they are unrelated to the earthquake

pre seismic electromagnetic phenomena in the framework of percolation and fractal theories abstract understanding the electromagnetic response to geodynamic processes occurring in the earth s upper crust in particular pre seismic and seismic processes is a challenging task in modern geophysics there is increasing evidence that seismo electromagnetic sem phenomena are difficult to describe quantitatively by linear models using averaged parameters of the medium such as electrical and hydraulic conductivities because the upper crust is highly inhomogeneous at all scales porous and can be fully or partially water saturated the most natural way to describe its parameters is via fractal theoretic and percolation theoretic models recent studies indicate that the electrokinetic effect is the most likely driving mechanism for the various types of sem signals here we considered the hydraulic electric and electrokinetic conductances of a porous water saturated medium as a function of porosity and moisture content utilizing a percolation fractal approach we show that the electric conductivity and electrokinetic current in such a medium are both proportional to c 2 and c 2 where c and c are the critical values of porosity and moisture content respectively this behavior admits the possibility of a relatively large change in the respective electric and electrokinetic parameters due to a small change in the mechanical strain field this is significant because it may account for the appearance of some types of sem signals at large distances from the earthquake origin which is the main deficiency of most models indeed the anticipated strain changes related to pre earthquake processes is usually very small except near the focal area the expected averaged electromagnetic response also would be very small unless a local underground water system exists not necessarily near the focal area but which is close to critical point s we discuss the conditions under which electrotelluric and geomagnetic variations can accompany mechanical disturbances in the earth s crust

investigating non uniform scaling behavior in ultra low frequency ulf earthquake related geomagnetic signals abstract the scaling properties of the time dynamics of 2000 2001 ulf geomagnetic data in the frequency range between 1 mhz and 10 hz observed at izu peninsula in japan were investigated on the basis of detrended fluctuation analysis dfa which is a powerful method to detect scaling in non stationary time series deviations from uniform power law scaling were identified and quantified our results suggest that a significant non uniform scaling behavior in ulf geomagnetic data could be related to the occurrence of intense seismic clusters these first results could be useful in the framework of short term earthquake prediction

fractal analysis of ulf geomagnetic data associated with the guam earthquake on august 8 1993 this paper presents a fractal analysis of the ulf electromagnetic data obtained at guam observatory during a strong ms 8 0 earthquake occurred on august 8 1993 near the guam island we have already reported the presence of seismogenic ulf emissions for this quake hayakawa et al grl 1996 the chosen period covered four months before and two months after the earthquake it was found that the spectrum of emissions at noon exhibited a power law behavior f which is typical for self organized critical dynamics the slope of the spectrum in the noon sector fluctuates in a range from 2 5 to 0 7 with a tendency to gradually decrease during the process of the earthquake preparation we consider this to be a candidate for a precursory signature the similar effect was found for the night sector we suggest that the focal zone was at the critical stage of self organized criticality process before the quake related to active microfracturing processes followed by the generation of ulf emissions as we detected

natural time analysis on the ultra low frequency magnetic field variations prior to the 2016 kumamoto japan earthquakes abstract on 15 april 2016 a very strong and shallow earthquake eq m w 7 0 depth 10 km occurred in southwest japan under the city of kumamoto while two very strong foreshocks m w 6 2 and m w 6 0 preceded by about one day the kumamoto eqs being very catastrophic have already attracted much attention among the scientific community in a quest for understanding the generation mechanism as well as for reporting any preseismic anomalies in various observables and assessing the effectivity of the current early warning systems in the present article we report precursory behavior of the ground based observed ultra low frequency ulf magnetic field variations before the kumamoto eqs by analyzing specific ulf magnetic field characteristics in terms of the recently introduced natural time nt analysis method we identified that ulf magnetic field variations presented critical features from 2 weeks up to 1 month before the kumamoto eqs specifically the ulf magnetic field characteristics f h f z d h and d e p were analyzed the first two represent variations of the horizontal and vertical components of the geomagnetic field the third and fourth characteristics correspond to the depression decrease and a relative depression of the horizontal magnetic field variations respectively the latter depends on the degree of ionospheric disturbance all of them were found to reach criticality before the kumamoto eqs however in different time periods for each characteristic

carbon enhanced electrical conductivity during fracture of rocks changes in electrical resistance during rock fracture in the presence of a carbonaceous atmosphere have been investigated using nugget sandstone and westerly granite the experiments were performed in an internally heated gas pressure vessel with a load train that produced strain rates between 10 6 and 10 5 s 1 samples were deformed at temperatures of 354 to 502 c and pressures of 100 to 170 mpa in atmospheres of ar or mixtures of 95 co2 with 5 co or 5 ch4 compositions that are well within the field of graphite stability at the run conditions in experiments using nugget sandstone resistance reached a minimum value when the maximum temperature was achieved and good electrode contact was made the resistance then increased as the experiment continued probably due to dry out of the sample a change in the oxidation state of the fe oxide associated with the cement or destruction of current bearing pathways at approximately 200 mpa end load the rock sample failed plots of load and resistance versus time show several interesting features in one experiment for example as the end load reached about 175 mpa resistance stopped increasing and remained fairly constant for a period of approximately 0 5 hour during loading the end load displayed small decreases that were simultaneous with small decreases in resistance when the end load and the displacement indicated rock failure resistance decreased dramatically from 150 m to 100 m in a single experiment the westerly granite also showed a decrease in resistance during dilatancy the nature and distribution of carbon in the run products were studied by electron microprobe and time of flight secondary ion mass spectroscopy top sims carbon observed by mapping with the former is clearly observed on micro cracks that based on the microtexture are interpreted to have formed during the deformation the tof sims data confirm the electron probe observations that carbon is present on fracture surfaces these observations and experimental results lead to the hypothesis that as microfractures open in the time leading up to failure along a fracture carbon is deposited as a continuous film on the new reactive mineral surfaces and this produces a decrease in resistance subsequent changes in resistance occur as connectivity of the initial fracture network is altered by continued deformation such a process may explain some electromagnetic effects associated with earthquakes

catchment scale carbon redistribution and delivery by water erosion in an intensively cultivated area large uncertainties still exist on both the rates of soil organic carbon soc mobilization by soil erosion as well as the fate of the eroded c using a range of techniques we characterized soil c redistribution by water erosion in two small agricultural catchments in the belgian loess belt results from rainfall simulations showed that c enrichment in eroded sediments was much higher than clay enrichment average enrichment ratios of 2 47 and 1 36 on average respectively selectivity was also observed in depositional processes sediments deposited within the catchments were depleted in c and finer fractions as compared to the source soil selectivity was much more pronounced in winter than in summer which is related to the degree of aggregation of the transported deposited sediment the combined selectivity of erosion and depositional processes resulted in a significant c enrichment of the sediment exported from the catchments with the c enrichment ratio cer between 1 2 and 3 0 overall catchment scale c enrichment was higher than clay enrichment enrichment ratios varied both with season and event intensity the uncertainties on catchment wide erosion and deposition rates precluded the closure of the sediment c budgets however using a simple model we were able to show that both the magnitude and variation of observed catchment scale cer was as expected from our understanding of c mobilization and deposition within the catchment this suggests that most of the mobilized c was not mineralized during the erosion events but either re deposited within the catchment or exported with the runoff this was confirmed by the comparison of the elemental and isotopic signatures between exported sediments and source soil in order to assess the role of erosion in the c cycle understanding how c is mobilized and re deposited selectively by erosion appears therefore as important as improving our understanding of the impact of erosion on c mineralization

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

statistical analysis of ulf seismomagnetic phenomena at kakioka japan during 2001 2010 to clarify and verify the ultralow frequency ulf seismomagnetic phenomena we have performed statistical studies on the geomagnetic data observed at the kakioka kak station japan during 2001 2010 we investigated the energy of ulf geomagnetic signals of the frequency around 0 01 hz using wavelet transform analysis to minimize the influences of artificial noises and global geomagnetic perturbations we used only the geomagnetic data observed at nighttime lt 2 30 a m to 4 00 a m and utilized observations from a remote station kanoya as a reference statistical results of superposed epoch analysis have indicated that ulf magnetic anomalies are more likely to appear before sizable earthquake events es 108 rather than after them especially 6 15 days before the events further statistical investigations show clearly that the ulf geomagnetic anomalies at kak station are more sensitive to larger and closer events finally we have evaluated the precursory information of ulf geomagnetic signals for local sizable earthquakes using molchan s error diagram the probability gain is around 1 6 against a poisson model the above results have indicated that the ulf seismomagnetic phenomena at kak clearly contain precursory information and have a possibility of improving the forecasting of large earthquakes

potential relationships between seismo deformation and seismo conductivity anomalies abstract this study examines the relationships between seismo deformation and seismo conductivity anomalies during two m6 earthquakes that occurred on march 27th and june 2nd 2013 in taiwan the hilbert huang transform is applied on surface displacement data to remove the effects of noise semi annual and annual cycles and the long term plate movements the residual displacements have similar orientations when earthquake related stress accumulates in the crust once the accumulated stress approaches the threshold for fault rupture the orientations of the residual displacements generally become random except in a small region near the epicenter interestingly high conductivity anomalies which can be detected from the 3 component magnetic data via the magnetic transfer function exist in places very close to this small region near the epicenter spatial and temporal correlations between the high conductivity anomalies and the small region of seismo deformation anomalies suggest that electric charges may migrate and become trapped in the region during seismogenic processes due to differential stress accumulation these electric charges form a high conductivity material that affects the parkinson vector of the geomagnetic field

potential earthquake precursory pattern from space the 2015 nepal event as seen by magnetic swarm satellites abstract a large earthquake of 7 8 magnitude occurred on 25 april 2015 06 26 utc with the epicenter in nepal here taking advantage of measurements provided by the swarm magnetic satellites we investigate the possibility to detect some series of pre earthquake magnetic anomalous signals likely due to a lithosphere atmosphere ionosphere coupling that can be a potential earthquake precursory pattern different techniques have been applied to swarm data available during two months around earthquake occurrence from the detected magnetic anomalies series during night and magnetically quiet times or with an automatic detection algorithm we show that the cumulative number of anomalies follows the same typical power law behavior of a critical system approaching its critical time and hence recovers as the typical recovery phase after a large event the similarity of this behavior with the one obtained from seismic data analysis and the application of the analyses also to another period without significant seismicity do support a lithospheric linked origin of the observed magnetic anomalies we suggest that they might be connected to the preparation phase of the nepal earthquake

anomalous behaviors of geomagnetic diurnal variations prior to the 2011 off the pacific coast of tohoku earthquake mw9 0 there have been many reports on ultra low frequency ulf electromagnetic phenomena associated with earthquakes in a very wide frequency range in this study unusual behaviors of geomagnetic diurnal variations prior to the 2011 off the pacific coast of tohoku earthquake mw9 0 have been reported ratios of diurnal variation range between the target station esashi esa which is about 135 km from the epicenter and the remote reference station kakioka kak about 302 km distant to the epicenter have been computed the results of 10 day running mean of the ratios showed a clear anomaly exceeding the statistical threshold in the vertical component about 2 months before the mega event this anomaly is unique over a 3 year background and the further stochastic test indicates that this anomaly is unlikely a random anomaly which is highly suggestive of correlation with the mega event the original records of geomagnetic fields of the esa station also exhibit continuous anomalous behaviors for about 10 days in the vertical component approximate 2 months prior to the mw9 0 earthquake

retrospective investigation of geomagnetic field time series during the 2009 l aquila seismic sequence abstract this paper reports the analyses of ulf ultra low frequency geomagnetic field observations coming from the geomagnetic observatory of l aquila during the period 2008 2009 this period includes the l aquila 2009 seismic sequence where the main shock of 6 april heavily damaged the medieval centre of the town and its surrounding area causing 308 deaths more than 1000 injuries and about 60 000 displaced people recently several publications have documented the observation of precursory signals which occurred before the 6 april earthquake e g eftaxias et al 2009 2010 while others do not find any pre earthquake anomaly e g villante et al 2010 di lorenzo et al 2011 in light of this the goal of this study is to carry out further retrospective investigations ulf magnetic field data are investigated by means of conventional analyses of magnetic polarization ratio improved magnetic polarization ratio and fractal analysis in addition total geomagnetic field data coming from the ingv central italy tectonomagnetic network have also been investigated using the simple inter station differentiation method within the limits of these methods no magnetic anomalous signal which may be reasonably characterized as a precursor of the l aquila earthquakes has been found

on the reported magnetic precursor of the 1989 loma prieta earthquake among the most frequently cited reports in the science of earthquake prediction is that by fraser smith et al 1990 and bernardi et al 1991 they found anomalous enhancement of magnetic field noise levels prior to the 18 october 1989 loma prieta earthquake in the ultra low frequency range 0 0110 10 001 hz from a ground based sensor at corralitos ca just 7 km from the earthquake epicenter in this analysis we re examine all of the available corralitos data 21 months from january 1989 to october 1990 and the logbook kept during this extended operational period we also examine 1 0 hz 1 s data collected from japan 0 0167 hz 1 min data collected from the fresno ca magnetic observatory and the global kp magnetic activity index the japanese data are of particular importance since their acquisition rate is sufficient to allow direct comparison with the lower frequency bands of the corralitos data we identify numerous problems in the corralitos data evident from both straightforward examination of the corralitos data on their own and by comparison with the japanese and fresno data sets the most notable problems are changes in the baseline noise levels occurring during both the reported precursory period and at other times long before and after the earthquake we conclude that the reported anomalous magnetic noise identified by fraser smith et al and bernardi et al is not related to the loma prieta earthquake but is an artifact of sensor system malfunction 2008 elsevier b v all rights reserved

water erosion impact on soil and carbon redistributions within uplands of mekong river 1 this study quantified the soil and carbon fluxes caused by water erosion within the sloping uplands of the mekong river basin a river system carrying one of the greatest worldwide amounts of sediment to the ocean losses of sediment and soil organic carbon soc including black carbon bc were evaluated within an agricultural catchment of 62 ha with steep slopes on a tributary of the mekong river at nested scales of micro plot 1 m2 micro catchment 0 6 ha and catchment 62 ha in an attempt to explain the processes involved in water erosion in 2002 carbon erosion occurred during 35 rainfall events amounting to 1023 mm of an annual total of 1651 mm water erosion removed annually 14 1 t ha 1 of sediment and 0 69 t ha 1 of soc from the study site this is equivalent to 7 75 and 0 51 pg yr 1 respectively for the uplands of the mekong basin as a whole when compared to the bulk soil the eroded soil material was enriched in soc and bc by factors of 2 3 and 1 4 respectively the annual yields of soil material from the micro catchment were 3 times lower for sediment and 6 times lower for soc than those from the micro plots from the micro plots to the catchment the yields decreased by a factor of 25 for sediment and 59 for soc although a considerable amount of soil material is detached from its original site by water erosion most of this material is redistributed within the landscapes being deposited in places acting as sinks such as hillslopes and valley bottoms where bc is preferentially deposited the loads from the catchment of 0 56 t ha 1 yr 1 for sediment and 0 016 t ha 1 yr 1 for soc were considerable corresponding to 0 31 pg of sediment and 0 01 pg of soc for the mekong basin uplands as a whole these results on the selective water erosion of soil material soc and bc on sloping lands of southeast asia allow the source and sink functions of the sloping lands of tropical landscapes to be better understood

results of ultra low frequency magnetic field measurements during the guam earthquake of 8 august 1993 we report the results of measurements of ultra low frequency magnetic noise during a large earthquake ms 7 1 at guam of 8 august 1993 depth 60 km the ulf observing system is located in the guam island about 65 km from the epicenter several distinct features of this analysis are summarized 1 we have proposed rather sophisticated statistical analyses monthly mean standard deviation in order to estimate the wave intensity and polarization i e ratio z h 2 a comparison between the ulf wave activity and kp is useful in distinguishing between the space geomagnetic pulsations and non space emissions 3 then the use of the ratio z h is found to be of essential importance in discrimating the emissions presumably of seismic origin from space plasma waves 4 the statistical analysis of the temporal evolution of this ratio has yielded that it shows a broad maximum only about one month before the earthquake and this suggests that the emissions during this period are very likely to be magnetic precursors 5 the temporal variation of z component is similar to that for the loma prieta earthquake such that it shows a broad maximum ten days two weeks before the earthquake and another increase a few days before the earthquake 6 the emissions presumably associated with the earthquake are of noise like nature and their main frequency is 0 02 0 05 hz with maximum intensity 0 1 nt

subionospheric vlf signal perturbations possibly related to earthquakes a likely vlf subionospheric signal effect related to seismic activity was first reported by hayakawa et al 1996a b in association with the great kobe earthquake we have analyzed similar data during periods around 10 other great earthquakes magnitude m 6 in order to understand the main features of such an effect the following characteristics emerged from our analysis the effect appears as a transient oscillation with a 5 to 10 day period which is initiated a few days before a large earthquake and decays over a few days to weeks after it it is mainly related to crustal earthquakes it appears when resonant atmospheric oscillations with periods in a range of 5 11 days exist before the earthquake the seismic influence on the vlf signal is probably explained by the generation of long period gravity waves during the earthquake process and their intensification at heights of 70 90 km

low frequency magnetic field measurements near the epicenter of the ms 7 1 loma prieta earthquake the authors report the results of measurements of low frequency magnetic noise by two independent monitoring systems prior to the occurrence of the m sub s 7 1 loma prieta earthquake of 17 october 1989 their measurements cover 25 narrow frequency bands in the more than six decade frequency range 0 01 hz 32 khz with a time resolution varying from a half hour in the ulf range 0 01 10 hz to one second in the elf vlf range 10 hz 32 khz the ulf system is located near corralitos about 7 km from the epicenter the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf data has revealed no precursor activity that they can identify at this time however the ulf data have some distinctive and anomalous features first a narrow band signal appeared in the range 0 05 0 2 hz around september 12 and persisted until the appearance of the second anomalous feature which consisted of a substantial increase in the noise background starting on 5 october and covering almost the entire frequency range of the ulf system third there was an anomalousmore dip in the noise background in the range 0 2 5 hz starting one day ahead of the earthquake finally and perhaps most compelling there was an increase to an exceptionally high level of activity in the range 0 01 0 5 hz starting approximately three hours before the earthquake there do not appear to have been any magnetic field fluctuations originating in the upper atmosphere that can account for this increase further while the systems are sensitive to motion seismic measurements indicate that there were no significant shocks preceding the quake thus the various anomalous features in the data and in particular the large amplitude increase in activity starting three hours before the quake may have been magnetic precursors less

ulf geomagnetic changes possibly associated with the 2008 iwate miyagi nairiku earthquake abstract there are many reports on earthquake related electromagnetic phenomena anomalous ulf geomagnetic field changes associated with earthquake is one of the most convincing and promising phenomena due to deeper skin depth since ulf signals associated with large earthquakes are weak effective signal discrimination methods should be required several methods for the signal discrimination have been developed so far which are spectrum density ratio analysis geomagnetic transfer function analysis fractal analysis principal component analysis direction finding analysis and so on in this study we investigate ulf geomagnetic changes possibly associated with the 2008 iwate miyagi nairiku earthquake based on spectral density ratio analysis geomagnetic data observed at esashi where the epicentral distance is about 47 km and kakioka the distance is about 317 km and as a reference station have been analyzed wavelet transform have been performed for the spectral density analysis instead of the conventional fft method before the earthquake the variation of spectral density ratio s z s x and s z s y at the nearest station of esashi exhibits an apparent increase from the trend on the contrary there are no corresponding significant changes at a remote station of kakioka after investigating the singularity of the increase using normalized spectrum density ratio the enhancement is the most significant in intensity and duration for the all analyzed period the level of peak is beyond the 3 and its duration is 3 days the lead time is about 3 4 weeks before the earthquake at the periods from 3 to 105 s similar anomalous changes occurred these facts suggest the anomalous change is a possible candidate of earthquake related ulf magnetic change

results of ulf magnetic field measurements near the epicenters of the spitak ms 6 9 and loma prieta ms 7 1 earthquakes comparative analysis the characteristics of the ulf magnetic field emissions measured at two magnetic observatories in the republic of georgia prior to and after the ms 6 9 earthquake that occurred near spitak armenia on december 7 1988 are compared with the apparently similar emissions associated with the ms 7 1 earthquake that occurred near loma prieta california on october 17 1989 the main features of the spitak measurements according to observations made at the dusheti station 128 km to the spitak epicenter as compared with the loma prieta measurements which were made at corralitos california 7 km to the loma prieta epicenter are the following 1 the intensity of ulf background activity started growing 3 to 5 days before the spitak earthquake whereas the corresponding increase in activity began 12 days before the loma prieta earthquake 2 a substantial ulf emission burst was recorded at dusheti starting 4 hours prior to the main shock a similar large burst of ulf activity commenced 3 hours before the loma prieta event and continued until the occurrence of the main shock 3 ulf activity remained high for about two weeks after the spitak earthquake and for several months after the loma prieta earthquake 4 ulf noise bursts were observed 1 to 6 hours before powerful aftershocks at spitak during the period of enhanced activity but there was no conclusive link between the ulf noise at corralitos and the after shocks a major difference in the ulf activity preceding the two earthquakes is a difference in amplitude 0 2 nt at spitak and 5 nt at loma prieta but this is easily explained as being caused by the different distances of the observation stations from the epicenters

short term earthquake prediction current status of seismo electromagnetics abstract loss of human lives as a result of earthquakes is caused overwhelmingly by the collapse of buildings within less than a few minutes of main shocks the most urgent countermeasure consists of two key elements one is strengthening of weak structures and the other is short term earthquake prediction short term prediction needs precursors although some promising precursors are reported the prevailing views in japan and elsewhere are overly pessimistic the pessimism largely roots in the fact that short term precursors are generally non seismic and tools developed for seismology are not designed to detect them nonetheless nationally funded large scale earthquake prediction programs always emphasize the need to reinforce seismometer networks they do not take into account the views of those in the science community who point to the importance of non seismic precursors while there are well founded causes to be skeptical the situation needs to be improved one reason for skepticism is that the observations of precursors have not yet been perfect enough and another is that some important fundamental aspects of non seismic precursors are still unresolved we review some of these problems

generation of ulf electromagnetic emissions by microfracturing microfracturing electrification is discussed as a possible explanation of ulf electromagnetic emissions observed before and after earthquakes using a space time simple model of microfracture progression it is possible to compare theoretical results and observed results with special reference to the intensity spectrum and temporal development of ulf magnetic field variations

ultra low frequency electromagnetic measurements associated with the 1998 mw 5 1 san juan bautista california earthquake and implications for mechanisms of electromagnetic earthquake precursors abstract ultra low frequency ulf 0 01 10 hz magnetic field anomalies prior to m 6 0 earthquakes have been reported in various regions of the world here we test whether smaller magnitude earthquakes have associated ulf anomalies by using continuous measurements made 9 km above and 2 km ne of the epicenter of the m w 5 1 8 12 98 san juan bautista ca earthquake half hour spectral averages of the magnetic field data in nine different ulf frequency bands show no long term days to weeks magnetic field anomaly prior to the earthquake in addition magnetic and electric field polarization shows no anomalous behavior clearly associated with seismic activity an 0 02 nt increase in activity for 2 h prior to the earthquake is close to the background noise levels precluding identification of a precursor we present scaling calculations to show if precursory ulf anomalies are related to the size of the earthquake the observed 0 02 nt increase is the approximately expected magnetic anomaly prior to the san juan bautista sbj earthquake based on the anomaly observed prior to the 1989 loma prieta lp earthquake our reexamination of previously proposed dilatant conductive and piezomagnetic mechanisms for ulf precursors shows that these effects are consistent with the observations prior to the sjb earthquake based on the observations i e lack of a strong precursor in contrast previously proposed electrokinetic and magnetohydrodynamic mhd mechanisms do not appear to be appropriate for this particular earthquake this analysis further supports the hypothesis that precursory ulf signals are related to the size of the earthquake

properties of the guin ungrouped iron meteorite the origin of guin and of group iie irons abstract guin is an ungrouped iron meteorite containing 45 g g ga and 186 g g ge it is a coarse octahedrite with an unusually high ni content 92 5 mg g its metal composition is generally similar to irons in groups iab and iiicd but its closest relative is the cruz del aire ungrouped iron guin contains 6 3 vol silicate inclusions that are petrologically and compositionally similar to those in iie irons the largest inclusion 2 4 cm consists primarily of a shock melted plagioclase rich matrix surrounding large 1 15 mm partly melted augite grains the oxygen isotopic composition of the inclusion 18 o 5 29 17 o 3 87 is near the ll chondrite field the guin inclusion is similar in bulk composition to selected melt pocket glasses in ordinary chondrites produced in situ by preferential melting of plagioclase by shock compression we suggest that the guin assemblage formed by impact melting on a chondritic parent body silicate inclusions in iie irons share many petrologic and compositional but not oxygen isotopic characteristics with the guin inclusions suggesting that iie irons also formed by impact melting of chondritic materials individual iie irons were probably derived from separate cratering events

seismomagnetic effect generated by the october 1989 ml 7 1 loma prieta california earthquake a differentially connected array of proton magnetometers operated within the epicentral region of the october 18 1989 ml 7 1 loma prieta earthquake for 12 years from 1974 to 1986 the closest magnetometer station was located 7 3 km from the epicenter of the earthquake and within 3 km of the site where anomalous ulf magnetic noise measurements were observed following the earthquake the magnetometers were reinstalled with sensors replaced in the original undisturbed sensor holders comparison of pre 1986 total intensity magnetic field data with data obtained during the months following the earthquake indicate local offsets of about 1 nt may have been generated at stations nearest the epicenter tests on other continuous differenced data from 1983 to present indicate that offsets determined could be biased by as much as 0 7 nt the offsets can be approximately fit with a simple seismomagnetic model of the earthquake for which 1 9 m of right lateral and 1 3 m of dip slip southwest side up occurred on a fault patch between 6 km and 18 km deep and 45 km long the total rock magnetization is assumed to be 1 5 a m since the offset has persisted following the earthquake an alternate explanation in terms of electokinetic effects is unlikely even though transient ground water flow occurred following the earthquake comparison of pre 1986 and similar post seismic total magnetic field noise does not indicate any change caused by aliasing of ulf 0 01 hz 10 hz magnetic noise in the vicinity of the loma prieta earthquake

analysis of ultralow frequency electromagnetic field measurements associated with the 1999 m 7 1 hector mine california earthquake sequence we installed two electromagnetic em monitoring systems in the im mediate aftermath of the 16 october 1999 hector mine earthquake to search for possible continuing ultralow frequency ulf em activity due to the mainshock as well as for any precursory or coseismic em signals that might be associated with large aftershocks we installed the first portable monitoring system 2 5 days after the m 7 1 hector mine earthquake at a location 16 km southeast of the epicenter and 2 km east of the surface rupture a second system was installed on 29 october 1999 10 km northwest of the epicenter and within 100 m of the surface rupture our continuous measurements of multiple component magnetic field electric field and ground motion span the low frequencies appropriate for recording possible em sig nals generated at seismogenic depths and were carried out during 3 months following the mainshock continuous magnetic field measurements at observatory em stations operating in california are used as remote reference sites to remove global atmo spheric signals which helps isolate local terrestrial sources of interest our analysis of preseismic ulf em variations the coseismic response the 2 month long magnetic field power spectra and electric field polarization shows no anomalous behavior clearly associated with seismic activity

ulf electromagnetic precursors for an earthquake at biak indonesia on february 17 1996 ulf electromagnetic emissions associated with a large earthquake occurred at biak island indonesia at 5h 59m ut on february 17 1996 magnitude mw 8 2 and depth 20 km from usgs catalog have been investigated on the basis of ulf magnetic observations at two stations biak and darwin in australia about 1 200 km apart though a simple analysis of magnetic field intensity horizontal and vertical magnetic field components at both stations was found to be closely correlated with geomagnetic kp activity a detailed analysis of the difference of h and z components at the two stations the polarization analysis z h and fractal analysis frequency spectrum slope at these two stations has yielded that the ulf emissions in the frequency range from 5 mhz to 30 mhz about 1 5 1 0 months before the quake are likely to be a precursory signature of the quake with its intensity on the order of 0 2 0 3 nt

effects of water erosion on the redistribution of soil organic carbon in the hilly red soil region of southern china abstract water erosion processes can significantly affect the delivery and distribution patterns of soil organic carbon soc within the landscape while many studies focus on the erosion processes and runoff transport of soc little attention has been paid to the on site redistribution and vertical transport of soc this study characterizes soc erosion dynamics including infiltration associated movement and discusses the effects of rainfall intensity and slope position on soc transport within the hilly red soil region of southern china the results show that soc loss was likely due to sediment transport rather than runoff the eroded soc was not significantly enriched which may be due to the soil properties and the type of rainfall event the initial soc concentration affected the enrichment ratio of eroded soc in the sediment on site horizontal redistribution occurred regardless of rainfall intensity whereas the soc transport trends varied with rainfall intensity and slope positions this demonstrates that soil preservation could reduce soc loss and thus influence the global carbon cycle

error propagation in electromagnetic transfer functions what role for the magnetotelluric method in detecting earthquake precursors summary whether electromagnetic precursors exist is a contentious issue that should be considered in the context of the focal depth and epicentral distance at which earthquakes nucleate and with due regard to externally driven changes in the electromagnetic fields recorded at the earth s surface if high frequency electromagnetic signals are generated by earthquakes then these signals may not be detectable because of attenuation occurring between the focal depth of the earthquake and the earth s surface this is particularly true in seismotectonic regions e g subduction zones where saline fluids including seawater raised heat flow and partial melts often lead to enhanced conductivities a technique for examining temporal variations in magnetotelluric mt spectra is presented which i considers both non inductive and inductive parts of the mt transfer function ii allows electromagnetic skin depths and adjustment distances to be calculated iii takes account of error propagation in the transfer functions and and iv acknowledges possible nonearthquake sources of observed variations in transfer functions and their errors data processing tends to eliminate non stationary electromagnetic disturbances of the source field hence the method is more suited to detecting hypothesized changes in subsurface conductivity than short lived electromagnetic bursts the technique is applied to mt data from seismotectonic regions in new zealand mt ruapehu the andes western cordillera and the mediterranean montecristo island and to a culturally quiet control site situated on a stable craton in central australia we demonstrate that the mt method can resolve apparent conductivity changes of the order of a few percent over 48 hr time intervals and give thresholds for other interval lengths comparison of the results obtained from seismotectonic regions with those from central australia and consideration of external source field effects highlight how temporal variations of electromagnetic fields might be speciously interpreted as earthquake precursors

a statistical study on elf whistlers emissions and m 5 0 earthquakes in taiwan 1 in this paper we conduct statistical approaches to study the potential relation between elf whistlers emissions below 100 hz and 20 m 5 0 earthquakes occurred in taiwan in the period from 26 august 2003 to 13 july 2004 occurrence ratios of the elf whistler and elf emission of the entire study period are computed as the reference backgrounds our study shows that the elf whistlers and elf emissions during the earthquake period appear less and more frequently than their associated backgrounds respectively for the elf emission the larger earthquakes generally yield the higher occurrence ratios the statistical analyses confirm that the occurrence ratios of the elf emission significantly enhance 5 7 days before the earthquakes and are proportional to the earthquake magnitude but inversely to the distance from the observatory to the epicenter

seismomagnetic effects from the long awaited 28 september 2004 m 6 0 parkfield earthquake precise measurements of local magnetic fields have been obtained with a differentially connected array of seven synchronized proton magnetometers located along 60 km of the locked to creeping transition region of the san andreas fault at parkfield california since 1976 the m 6 0 parkfield earthquake on 28 september 2004 occurred within this array and generated coseismic magnetic field changes of between 0 2 and 0 5 nt at five sites in the network no preseismic magnetic field changes exceeding background noise levels are apparent in the magnetic data during the month week and days before the earthquake or expected in light of the absence of measurable precursive deformation seismicity or pore pressure changes obser vations of electric and magnetic fields from 0 01 to 20 hz are also made at one site near the end of the earthquake rupture and corrected for common mode signals from the ionosphere magnetosphere using a second site some 115 km to the northwest along the fault these magnetic data show no indications of unusual noise before the earthquake in the ulf band 0 01 20 hz as suggested may have preceded the 1989 ml 7 1 loma prieta earthquake nor do we see electric field changes similar to those suggested to occur before earthquakes of this magnitude from data in greece uni form and variable slip piezomagnetic models of the earthquake derived from strain displacement and seismic data generate magnetic field perturbations that are con sistent with those observed by the magnetometer array a higher rate of longer term magnetic field change consistent with increased loading in the region is apparent since 1993 this accompanied an increased rate of secular shear strain observed on a two color edm network and a small network of borehole tensor strainmeters and increased seismicity dominated by three m 4 5 5 earthquakes roughly a year apart in 1992 1993 and 1994 models incorporating all of these data indicate increased slip at depth in the region and this may have played a role in the final occurrence of the 28 september 2004 m 6 0 parkfield earthquake the absence of electric and magnetic field precursors for this and other earthquakes with m 5 7 3 elsewhere in the san andreas fault system indicates useful prediction of damaging earthquakes seems unlikely using these electromagnetic data

investigation of ionospheric electron content variations before earthquakes in southern california 2003 2004 1 it has been proposed that earthquakes are preceded by electromagnetic signals detectable from ground and space based measurements ionospheric anomalies such as variations in the electron density a few days before earthquakes are one of the precursory signals proposed since global positioning system gps data can be used to measure the ionospheric total electron content tec the technique has received attention as a potential tool to detect ionospheric perturbations related to earthquakes here we analyze 2 years 2003 2004 of data from the southern california integrated gps network scign a dense network of 265 continuous gps stations centered on the los angeles basin for possible precursors this time period encompasses the december 2003 m6 6 san simeon and september 2004 m6 0 parkfield earthquakes we produce tec time series at all scign sites and apply three different statistical tests to detect anomalous tec signals preceding earthquakes we find anomalous tec signals but no statistically significant correlation in time or in space between these tec anomalies and the occurrence of earthquakes in southern california for the 2003 2004 period this result does not disprove the possibility of precursory phenomena but show the signal to noise ratio of a hypothetical tec precursor signature is too low to be detected by the analysis techniques employed here precursors may still be revealed for future large earthquakes in well instrumented areas such as california and japan if the tests can be developed into techniques that can better separate external influences from the actual tec signal

ultra low frequency magnetic field measurements in southern california during the northridge earthquake of 17 january 1994 measurements of ultra low frequency ulf magnetic field fluctuations by two independent monitoring systems in southern california were in progress during january 1994 when the moderately large m6 7 northridge earthquake occurred on 17 january our two measuring systems are located at table mountain on the other side of the san gabriel mountains and at a distance of 81 km from the epicenter and at pinon flat south of palm springs and at a distance of 206 km from the epicenter both systems operated well throughout the month and without interruption due to the earthquake as a result of the occurrence of a moderate magnetic storm on 11 january which was followed by a period of enhanced ulf magnetic activity that persisted until after the time of the earthquake the sensitivity of our measurements throughout california was reduced for roughly a week before the earthquake took place nevertheless no large signals that could be associated with the earthquake were evident at any time except for the usual co seismic shaking response of the detectors subsequent removal of the upper atmosphere signals from the table mountain measurements using the measurements from the more distant pinon flat location as reference essentially left no significant residual thus assuming that ulf magnetic fields were produced by the earthquake their amplitudes were too small to produce obvious increases in the ulf background noise at 81 km from the epicenter which is in agreement with our earlier estimate of a range of about 100 km for the ulf magnetic field fluctuations observed prior to the m7 1 loma prieta earthquake these results imply that a network of conventional magnetic field detectors spaced less than 100 km apart would be required to detect ulf magnetic field fluctuations prior to earthquakes with magnitudes greater than 7 under the same conditions superconducting magnetic field gradiometers could offer greater sensitivity and range