mid crustal deformation in a continental margin orogen structural evolution and timing of the famatinian orogeny nw argentina new structural data from a mid crustal segment in the eastern sierras pampeanas coupled with geochronological methods and p t estimates reveal polyphase contractional deformation and metamorphism during the famatinian orogeny over a long period of time peaks of metamorphic monazite and zircon ages are recorded at c 500 ma between 484 and 465 ma and at c 440 ma between 484 and 465 ma the region attained high temperature ht low pressure lp conditions that resulted in widespread partial melting peak at c 470 ma a contractional phase occurred during this event as suggested by syn anatectic structures as well as folding at subsolidus conditions renewed contraction under subsolidus conditions is evidenced by reverse ductile shearing and folding at c 440 ma thrusting along the la chilca shear zone caused metamorphic inversion the consistent orientation of folds in the quebrada del molle metamorphic complex el portezuelo metamorphic igneous complex and the la chilca shear zone as well as wsw directed thrusting at the later shear zone indicate uniform wsw ene directed shortening this late deformation records the ocloyic tectonic phase and brought the famatinian orogeny to an end in the late ordovician to early silurian supplementary material analytical methods methods and description of the calculated p t pseudosection diagrams bulk compositions and electron microprobe u pb and 40ar 39ar data are available at https doi org 10 6084 m9 figshare c 4697189

seismomagnetic observation during the 8 july 1986 magnitude 5 9 north palm springs earthquake a differentially connected array of 24 proton magnetometers has operated along the san andreas fault since 1976 seismomagnetic offsets of 1 2 and 0 3 nanotesla were observed at epicentral distances of 3 and 9 kilometers respectively after the 8 july 1986 magnitude 5 9 north palm springs earthquake these seismomagnetic observation are the first obtained of this elusive but long anticipated effect the data are consistent with a seismomagnetic model of the earthquake for which right lateral rupture of 20 centimeters is assumed on a 16 kilometer segment of the banning fault between the depths of 3 and 10 kilometers in a region with average magnetization of 1 ampere per meter alternative explanations in terms of electrokinetic effects and earthquake generated electrostatic charge redistribution seem unlikely because the changes are permanent and complete within a 20 minute period

periodicity of the earth electric precursor before strong earthquakes abstract data on the anomalous behaviour of the earth electrical potential before strong earthquakes are compared the data are taken from two different locations in the balkan seismic region the existence of an approximately 24 h anomalous impulse variation of the potential with a maximum amplitude just before an approaching earthquake is pointed out the variation starts to occur a few days before the main shock and coincides with the maximum of the last impulse

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

experimental measurement of electromagnetic emissions possibly related to earthquakes in japan recent observations in the ussr appear to suggest that wide band electromagnetic radiation occurs just prior to earthquakes to apply this phenomenon to earthquake prediction measurements have been carried out at the sugadaira space radiowave observatory in japan under the ussr japan cooperation program in 1980 the recorded noise level at 81 khz is comparatively quiet throughout the day and night however about one half hour before the main shock of a magnitude 7 earthquake at 0733 ut on march 31 1980 the instrument recorded an anomalous amplitude increase to 15 db higher than the normal level vlf data recorded synoptically at sugadaira suggest that unusual impulsive radiation at frequencies below 1 5 khz also occurred shortly before the earthquake similar 81 khz emissions were observed prior to magnitude 5 and 6 earthquakes on september 25 1980 and january 28 1981

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

ulf geomagnetic anomalies of possible seismogenic origin observed at teoloyucan station mexico in 1999 2001 intermediate and short time analysis abstract the analysis of ulf geomagnetic field measured at teoloyucan station central mexico 11 35 735 w 19 44 45 100 n 2280 m height is presented in an intermediate 15 days and short time scale the day of the eq occurrence in relation to 7 major earthquakes occurred in mexico in 1999 2001 local changes in the fractal dynamics of the magnetic field are found to be important a pronounced fall of the fractal index is frequently observed prior to the main shock the study of the ulf resonant structure recently discovered in the frequencies fr1 10 2 11 1 mhz and fr2 13 6 14 5 mhz reveals changes in their character probably related to the processes of the earthquakes preparation the success of the observation of the mentioned anomalies specially the fractal index decrease strongly depends on how close is the station from the epicenter and what is the magnitude of the earthquake

field strength variations of lf radio waves prior to earthquakes in central italy abstract the electric field strength of the lf radio broadcasting rmc principality of monaco which operates at 216 khz has been recorded since january 1991 by two receivers in central italy during the monitoring period we observed two evident attenuations of the field strength in one receiver with durations of 6 10 days the geomagnetic and ionospheric observations carried out in the same time interval do not seem able to explain the attenuation of the radio signal an analysis of the seismic activity occurring in the area between transmitter and receiver has revealed that some days after the attenuations the energy released by earthquakes reaches a maximum the observed attenuation might therefore be precursors of earthquakes we also checked meteorological conditions and found that advections of warm air occurred during both the two anomalous periods it seems possible that these conditions can help the action of preseismic effects in generating irregularities in the vertical gradient of the tropospheric radio refractivity able to produce defocusing of lf radiobroadcast propagation

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

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

anomalous variations of the geomagnetic field in east fergana magnetic precursor of the alay earthquake with m 7 0 1978 november 2 summary a secular variation anomaly has been discovered at the north east part of the fergana vdey by repeated measurements every year or less the change of total field f at the magnetic epicentre was 9 nt in 1977 and 16 nt in 1978 relative to the level of 1973 in 1977 an anomalous region was recognized where according to the data from 25 observation points f increased in the northern part up to 5 2 nt and decreased by 4 7ntin the southern part according to a further 22 points permanent observations were begun at the epicentre in 1978 october we normally observed variations of f differences with magnitude 2 3 nt which were not correlated with worldwide magnetic activity anomalous variations appeared on october 26 and rose to a maximum value of 23 nt on october 30 the decrease of this anomalous field began on october 31 this made it possible to predict a potential earthquake the alay earthquake with m 7 0 occurred on november 2 six hours after the prediction was issued f then returned to the initial level thus using the geomagnetic field variations in the fergana region geophysicists were able to predict the moment of a strong earthquake

electro magnetic earthquake bursts and critical rupture of peroxy bond networks in rocks abstract we propose a mechanism for the low frequency electromagnetic emissions and other electromagnetic and electric phenomena which have been associated with earthquakes the mechanism combines the critical earthquake concept and the concept of crust acting as a charging electric battery under increasing stress the electric charges are released by activation of dormant charge carriers in the oxygen anion sublattice called peroxy bonds or positive hole pairs php where a php represents an o 3 x oo yo 3 with x y si 4 al 3 i e o in a matrix of o 2 of silicates we propose that php are activated by plastic deformations during the slow cooperative build up of stress and the increasingly correlated damage culminating in a large critical earthquake recent laboratory experiments indeed show that stressed rocks form electric batteries which can release their charge when a conducting path closes the equivalent electric circuit we conjecture that the intermittent and erratic occurrences of em signals are a consequence of the progressive build up of the battery charges in the earth crust and of their release when crack networks percolate through the stressed rock volumes providing a conductive pathway for the battery currents to discharge em signals are thus expected close to the rupture either slightly before or after that is when percolation is most favored the proposed mechanism should be relevant for the broader understanding of fractoemissions

some statistical results on very low frequency radiowave emissions in the upper ionosphere over earthquake zones abstract an anomalous increase in the intensity of low frequency 0 1 16 khz radiowave emissions was detected using intercosmos 19 data when the satellite was nearly over the epicentre of an earthquake zone ample statistical data are the basis for a determination of the probable spatial temporal dimensions of the region of the upper ionosphere in justify which elf vlf emissions were detected the reliability of the detected phenomenon is 0 8 0 9 the ionospheric regions with the low frequency emissions observed by intercosmos 19 have been found to be formations noise belts extended along 60 of geographic longitude and 2 of geographic latitude the spectral characteristics of elf vlf emissions near seismic areas are specified the earthquake depth and location under a continent or under an ocean has an effect on the results of the satellite observations of earthquakes possible mechanisms of the phenomenon are discussed

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

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

seismo induced effects in the near earth space combined ground and space investigations as a contribution to earthquake prediction abstract the paper aims at giving a few methodological suggestions in deterministic earthquake prediction studies based on combined ground based and space observations of earthquake precursors up to now what is lacking is the demonstration of a causal relationship with explained physical processes and looking for a correlation between data gathered simultaneously and continuously by space observations and ground based measurements coordinated space and ground based observations imply available test sites on the earth surface to correlate ground data collected by appropriate networks of instruments with space ones detected on board of leo satellites at this purpose a new result reported in the paper is an original and specific space mission project esperia and two instruments of its payload the esperia space project has been performed for the italian space agency and three esperia instruments arina and lazio particle detectors and egle search coil magnetometer have been built and tested in space the egle experiment started last april 15 2005 on board the iss within the eneide mission the launch of arina occurred on june 15 2006 on board the resurs dk 1 russian leo satellite as an introduction and justification to these experiments the paper clarifies some basic concepts and critical methodological aspects concerning deterministic and statistic approaches and their use in earthquake prediction we also take the liberty of giving the scientific community a few critical hints based on our personal experience in the field and propose a joint study devoted to earthquake prediction and warning

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

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

coccolithophore export production species composition and coccolith caco3 fluxes in the ne atlantic and abstract coccolithophores were examined in two sediment traps deployed for one year april 1989 to april 1990 at approximately 1 km water depth in the subtropical ne atlantic at 34 n 21 w station nabe 34 and in the temperate ne atlantic 48 n 21 w station nabe 48 as part of the jgofs north atlantic bloom experiment nabe at both stations maximum coccolith and coccosphere fluxes were recorded during local spring bloom periods the average coccolith and coccosphere fluxes at nabe 34 were 1 12 10 9 m 2 d 1 and 4 90 10 6 m 2 d 1 respectively at this station coccoliths from 51 taxa were identified a marked seasonal change was noticed in relative abundances of emiliania huxleyi and deep photic zone species e huxleyi dominated during spring while in late autumn the coccolith assemblage was dominated by florisphaera profunda and the coccosphere assemblage by g flabellatus and algirosphaera spp emiliania huxleyi was the most abundant species in the overall coccolith and coccosphere assemblages with 69 and 64 respectively at nabe 48 the average daily fluxes were significantly lower with 3 88 10 8 coccoliths m 2 d 1 and 8 45 10 5 coccospheres m 2 d 1 and only 36 taxa were recorded in the trap samples emiliania huxleyi was the dominant species in the coccolith assemblage throughout the year with 72 and showed maximum fluxes during spring 1990 coccolithus pelagicus exhibited a distinct seasonal pattern with maximum fluxes in early june 1989 probably related to the development of a mesoscale cyclonic eddy in the vicinity of the trap site holococcolithophore fluxes were highest during maximum sea surface temperatures in summer the coccosphere assemblage was dominated by gephyrocapsa spp syracosphaera spp and e huxleyi estimated caco3 fluxes of coccoliths coccospheres and calcareous dinophytes were compared with the caco3 content in the fine m fraction the annual mass estimated caco3 flux of coccoliths and coccospheres was 5 1 g m 2 yr at nabe 34 and 2 7 g m 2 yr at nabe 48 and that of calcareous dinophytes 0 9 and 0 1 g m 2 yr respectively these summed mass estimated values contributed on average only 55 at nabe 34 and 60 at nabe 48 to the fine fraction caco3

physical properties of the variations of the electric field of the earth preceding earthquakes i abstract in an earlier paper we described the physical properties of the preseismic transient variations in the electrotelluric field the present letter clarifies a few points that were not properly emphasized in our previous publications furthermore recent results like that of the destructive kalamata earthquake on september 13 1986 indicate that the duration of a preseismic electric signal may reach considerably high values lasting up to several hours

vlf emissions associated with earthquakes and observed in the ionosphere and the magnetosphere abstract several electromagnetic phenomena recorded at the time of earthquakes were recorded independently by the geostationary satellite geos 2 above africa longitude 37 e and the polar orbiting satellite aureol 3 apogee 2012 km perigee 408 km inclination 82 5 period 109 5 min the observations were made with magnetic and electric antennae in the frequency range 10 hz 15 khz characteristics of the emissions and differences between low and high altitude observations are presented some geos 2 very low frequency data can be correlated with ionospheric measurements made on ground at the djibouti station latitude 11 n longitude 42 e where increases of the critical frequency f 0 e s of the sporadic e s layer are observed when earthquakes occur nearby time differences between disturbance at ionospheric level and at the height of geos 2 seem to indicate that earthquakes cause two distinct types of electromagnetic disturbance an electromagnetic wave in the ionosphere and a density increase of the e s layer

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