insar analysis of the 2008 reno mogul earthquake swarm evidence for westward migration of walker lane style dextral faulting and post seismic slip over an area of more than 150 km 2 this earthquake is one of the smallest magnitude events modeled with insar to date in the seismically active western basin and range and it provides new insights into regional neotectonic relations inverse modeling of the insar data suggests that the earthquake swarm was generated by 25 75 cm of dextral displacement on a n44wstriking fault with a 3 km rupture length and a rupture depth of 2 km the insar detected strike slip ground deformation is unique for the reno basin which is in the purely extensional domain of the sierra nevada basin and range transition zone an area dominated by north striking normal faults the insar modeling of the 2008 earthquake swarmsupports the concept of westward migration of walker lane transcurrent faulting and overprinting of extensional basin and range structures in this case the westward migration of dextral shear associated with the northern walker lane into the extension dominated reno basin citation bell j w f amelung and c d henry 2012 insar analysis of the 2008 reno mogul earthquake swarm evidence for westward migration of walker lane style dextral faulting geophys res lett 39 l18306 doi 10 1029 2012gl052795

large scale velocity field and strain tensor in iran inferred from gps measurements new insight for the present day deformation pattern within ne iran a network of 26 gps sites was implemented in iran and northern oman to measure displacements in this part of the arabia eurasia collision zone we present the gps velocity field obtained from three surveys performed in 1999 september 2001 october and 2005 september and the deduced strain tensor this study refines previous studies inferred from only the two first surveys improvements are significant in ne iran the present day shortening rate across the mountain belts of ne iran is estimated to 5 1 mm yr 1 at about n11 2 1 mm yr 1 of ns shortening across the eastern kopet dag and 3 1 mm yr 1 of ns shortening across binalud and kuh e sorkh our gps measurements emphasize the varying character of the kopet dag deformation between its southeastern part with prevailing thrusting at low rates and its northwestern part with dominant strike slip activity at increasing rates the principal axes of the horizontal strain tensor appears very homogeneous from the zagros to the alborz and the kopet dag n20 and in eastern iran makran and lut block n30 only nw iran suffers a variable strain pattern which seems to wrap the caspian basin the strain tensor map underlines the existence of large homogeneous tectonic provinces in terms of style and amplitude of the deformation

strain partitioning in the northern walker lane western nevada and northeastern california abstract paleomagnetic studies constrain both the kinematics and the timing of neogene intracontinental strain in the walker lane of northwestern nevada northeastern california the northwest trending walker lane is a zone of complex faulting and dextral offset along the boundary between the sierra nevada and the basin and range here an extensive tertiary volcanic section provides a paleomagnetic test for vertical axis rotation the 25 1 ma nine hill tuff covered the two structural domains of northern walker lane and parts of the adjacent provinces in the northernmost domain the pyramid lake domain the nine hill tuff is unrotated or rotated slightly counter clockwise in contrast nine hill tuff is rotated 35 44 clockwise in the northeastern part of the adjacent carson domain usable exposures of the tuff are lacking elsewhere in the carson domain but 9 13 ma basalts record 37 51 clockwise vertical axis rotation these basalts were sampled at three sites encompassing the n s length of the carson domain younger basalts from the carson domain show smaller clockwise rotations the paleomagnetic studies show that the deformation in the northern walker lane is partitioned into domains dominated by translation rotation and extension dextral slip along the walker lane is accommodated primarily by northwestward translation in the pyramid lake domain and by clockwise vertical axis rotation in the carson domain some neogene extension is also accommodated in the walker lane but most of it is occurring to the west of the walker lane along the edge of the sierra nevada comparison of paleomagnetic results from rocks of different ages constrains the timing of the present deformation regime in the walker lane the similar rotations recorded in 25 ma and 9 13 ma rocks indicates that virtually all of the rotation in the carson domain occurred after the eruption of the 9 13 ma basalts smaller rotations recorded in younger rocks constrain rotation rate

the southern caspian a compressional depression floored by a trapped modified oceanic crust the south caspian intracontinental depression floored by oceanic basement is a relatively stable block with minor deformation surrounded by active fold thrust belts of arcuate form talesh alborz and kopeh dagh mountains which have undergone intense late cainozoic crustal shortening the basin is interpreted as a neogene quaternary compressional depression bounded by multi role mountain bordering reverse faults and apparently floored by a late paleozoic triassic or late mesozoic early tertiary modified oceanic crust trapped along an old geosuture it may be a relic of an old paleozoic triassic ocean or else a marginal sea developed behind a mesozoic paleogene ocean and analysis of geological and geophysical data enables a scheme to be suggested the general arcuate shape of the alborz and the talesh bordering mountain belts follows the pattern of the supposed rigid and thickened ocean crust of south caspian depression a tectono sedimentary study of the south caspian region coupled w

tracking earthquake archaeological evidence in late minoan iiib 1300 1200 b c crete greece a proof of concept late minoan lm iiib 1300 1200 b c represents a crucial period in the history of bronze age crete heralding the transition to the iron age through a wave of site destruction and abandonment according to the traditional view earthquakes may have played a significant role in these events a new archaeoseismological approach is proposed to test this hypothesis and to attribute destruction and abandonment to earthquakes potential earthquake archaeological effects peaes are defined and documented at lm iiib sites synchronisms of peaes between sites are based on ceramic evidence the reliability of the peaes is furthermore assessed using empirical ground motion relationships defined for three types of earthquake mechanisms that can be considered to occur in the seismotectonic context of crete 1 normal faulting earthquakes located within the overriding aegean lithosphere 2 earthquakes located on the subduction interface or on splay faults merging with the interface at depth 3 earthquakes within the subducting african lithosphere in the case of lm iiib1 early malia and sissi northeastern crete this proof of concept is successfully applied and supports the hypothesis that seismic shaking is likely to be responsible for the peaes observed a 12 october 1856 a d type earthquake located within the subducting african plate is suggested as the most likely earthquake mechanism in other lm iiib archaeological contexts no convincing evidence for earthquake effects could be identified the hypothesis of a seismic storm causing the demise of minoan crete is not supported by our analysis of archaeological evidence

seismicity triggered by fluid injection induced aseismic slip anthropogenic fluid injections are known to induce earthquakes the mechanisms involved are poorly understood and our ability to assess the seismic hazard associated with geothermal energy or unconventional hydrocarbon production remains limited we directly measure fault slip and seismicity induced by fluid injection into a natural fault we observe highly dilatant and slow 4 micrometers per second m s aseismic slip associated with a 20 fold increase of permeability which transitions to faster slip 10 m s associated with reduced dilatancy and micro earthquakes most aseismic slip occurs within the fluid pressurized zone and obeys a rate strengthening friction law 0 67 0 045ln v v with v 0 1 m s fluid injection primarily triggers aseismic slip in this experiment with micro earthquakes being an indirect effect mediated by aseismic creep

moment tensor solutions of the 1994 to 1996 double spring flat nevada earthquake sequence and implications for local tectonic models abstract the 12 september 1994 m w 5 8 double spring flat nevada earthquake initiated at the intersection of a northeast and northwest striking set of conjugate faults within an overlapping zone between the genoa and antelope valley fault zones of the eastern sierra nevadan range frontal fault system the mainshock ruptured on the northeast striking fault plane eight days after the mainshock the aftershock activity migrated from the mainshock fault plane to the northwest striking conjugate fault over the next 2 years aftershocks migrated southward onto another set of conjugate faults and then onto the antelope valley fault zone the focal mechanisms of 17 m 4 aftershocks were estimated from a time domain moment tensor inversion using regional broadband data the t axis minimum stress direction is oriented east west n80 e to n100 e for the m 4 events as is commonly observed along the eastern sierra nevadan range front in northwestern nevada from these results we make some general points that can be considered in seismic hazard assessment the maximum magnitude in overlapping normal fault zone is limited to the size of the overlapping zone this makes small to moderate size m m 7 earthquakes the seismicity within this overlapping zone may indicate interseismic strain accumulation from east west extension mainly through strike slip deformation the apparent scarcity of modern normal faulting earthquakes along the sierran range front faults suggests a characteristic model while a gutenberg and richter model for the recurrence behavior of earthquakes applies to the overlap zones between the normal faults the pattern of seismicity and principle stress directions from the aftershock fault plane solutions suggest a tectonic model of changing fault geometry for the overlapping zone between the genoa and antelope valley fault zones two plausible long term tectonic outcomes may develop with this model a normal fault growth model where the overlapping segments of the genoa and antelope valley faults eventually become hard linked form a throughgoing fault or a normal fault growth model where the overlapping segment of the genoa fault system grows southward while the antelope valley fault is isolated in the formation of new basins and ranges

the 2012 brawley swarm triggered by injection induced aseismic slip it has long been known that fluid injection or withdrawal can induce earthquakes but the underlying mechanisms remain elusive for example the 2012 brawley swarm which produced two strike slip shocks with magnitudes larger than 5 3 and surface ruptures in the close vicinity of a geothermal field started with earthquakes about 5 km deeper than the injection depth 1 5 km this makes the causality between the injection and seismicity unclear here we jointly analyze broadband and strong motion waveforms uavsar leveling measurements and field observations to reveal the detailed seismic and aseismic faulting behaviors associated with the 2012 brawley swarm in particular path calibration established from smaller events in the swarm allows waveform inversion to be conducted up to 3 hz to resolve finite rupture process of the mw 4 7 normal event our results show that the 2012 earthquake sequence was preceded by aseismic slip on a shallow normal fault beneath the geothermal field aseismic slip initiated in 2010 when injection rate rapidly increased and triggered the following earthquakes subsequently including unusually shallow and relatively high frequency seismic excitations on the normal fault in this example seismicity is induced indirectly by fluid injection a result of mediation by aseismic creep rather than directly by a pore pressure increase at the location of the earthquakes

kinematics of the 2015 san ramon california earthquake swarm implications for fault zone structure and driving mechanisms abstract earthquake swarms represent a sudden increase in seismicity that may indicate a heterogeneous fault zone the involvement of crustal fluids and or slow fault slip swarms sometimes precede major earthquake ruptures an earthquake swarm occurred in october 2015 near san ramon california in an extensional right step over region between the northern calaveras fault and the concord mt diablo fault zone which has hosted ten major swarms since 1970 the 2015 san ramon swarm is examined here from 11 october through 18 november using template matching analysis the relocated seismicity catalog contains 4000 events with magnitudes between 0 2 m d 3 6 the swarm illuminated three sub parallel southwest striking and northwest dipping fault segments of km scale dimension and thickness of up to 200 m the segments contain coexisting populations of different focal mechanisms suggesting a complex fault zone structure with several sets of en echelon fault orientations the migration of events along the three planar structures indicates a complex fluid and faulting interaction processes we searched for correlations between seismic activity and tidal stresses and found some suggestive features but nothing that we can be confident is statistically significant

the 1992 little skull mountain earthquake sequence southern nevada test site the ml 5 6 5 8 little skull mountain nevada 29 june 1992 earth quake occurred in the southwest portion of nevada test site nts approximately 20 km from yucca mountain a potential site for a high level radioactive waste repository the earthquake involved predominantly down to the southeast dip slip motion with a small left slip component on a steeply dipping 70 northeast striking fault the mainshock nucleated near the base of the aftershock zone and ruptured up and to the northeast and the mainshock rupture and the majority of the aftershock sequence were confined to depths between 6 and 12 km all three ml 4 largest ml 4 5 aftershocks occurred off the mainshock fault plane on secondary structures within the aftershock zone the nearest strong motion instrument located 11 km southwest of the epicenter recorded a peak acceleration of 0 206g the earthquake occurred adjacent to the rock valley fault zone within an area of prior concentrated background seismicity and near the intersection of several northeast striking faults in the southern nts that have experienced quaternary motion

spatiotemporal variation of stress drop during the 2008 mogul nevada earthquake swarm we estimate stress drops for 148 shallow 6 km earthquakes in the complex 2008 mogul nevada swarm using empirical green s function derived spectral ratios near source temporary broadband seismometers deployed before the mw4 9 main shock provide high quality records of many foreshocks and aftershocks and an ideal opportunity to investigate uncertainties in corner frequency measurement as well as stress drop variation related to space time depth mechanism and magnitude we explore uncertainties related to source model measurement approach cross correlation limit and frequency bandwidth p s wave results range from 0 2 0 15 0 3 0 15 to 36 20 58 7 mpa a variation greater than the error range of each individual estimate although this variation is not explained simply by any one parameter spatiotemporal variation along the main shock fault plane is distinct coherent clusters of high and low earthquakes are seen and high foreshocks correlate with an area of reduced aftershock productivity these observations are best explained by a difference in rheology along the fault plane average s of 3 9 1 1 4 0 1 1 mpa using p s are similar to those found for earthquakes in a variety of settings implying that these shallow potentially fluid driven earthquakes do not have systematically lower than average tectonic earthquakes 4 mpa and therefore have similar or higher due to proximity to the surface expected ground motions compared to typical earthquakes the unprecedented detail achieved for these shallow small magnitude earthquakes confirms that when measured precisely is a valuable observation of physically meaningful fault zone properties and earthquake behavior

late cretaceous and early miocene andean type plutonic activity in northern makran and central iran two calc alkaline plutonic complexes bazman and natanz intruded through the south eastern active and south western ancient continental margins of central iran have been dated by the rb sr whole rock isochron method at 74 2 and 24 4 5 ma respectively detailed trace element studies together with low 87 sr 86 sr initial ratios 87 sr 86 sr ratios and the gabbros at least were intruded some 10 ma earlier

hierarchical interlocked orthogonal faulting in the 2019 ridgecrest earthquake sequence a nearly 20 year hiatus in major seismic activity in southern california ended on 4 july 2019 with a sequence of intersecting earthquakes near the city of ridgecrest california this sequence included a foreshock with a moment magnitude mw of 6 4 followed by a mw 7 1 mainshock nearly 34 hours later geodetic seismic and seismicity data provided an integrative view of this sequence which ruptured an unmapped multiscale network of interlaced orthogonal faults this complex fault geometry persists over the entire seismogenic depth range the rupture of the mainshock terminated only a few kilometers from the major regional garlock fault triggering shallow creep and a substantial earthquake swarm the repeated occurrence of multifault ruptures as revealed by modern instrumentation and analysis techniques poses a formidable challenge in quantifying regional seismic hazards

earthquake damage orientation to infer seismic parameters in archaeological sites and historical earthquakes abstract studies to provide information concerning seismic parameters and seismic sources of historical and archaeological seismic events are used to better evaluate the seismic hazard of a region this is of especial interest when no surface rupture is recorded or the seismogenic fault cannot be identified the orientation pattern of the earthquake damage ed e g fallen columns dropped key stones that affected architectonic elements of cities after earthquakes has been traditionally used in historical and archaeoseismological studies to infer seismic parameters however in the literature depending on the authors the parameters that can be obtained are contradictory it has been proposed the epicenter location the orientation of the p waves the orientation of the compressional strain and the fault kinematics and authors even question these relations with the earthquake damage the earthquakes of lorca in 2011 christchurch in 2011 and emilia romagna in 2012 present an opportunity to measure systematically a large number and wide variety of earthquake damage in historical buildings the same structures that are used in historical and archaeological studies the damage pattern orientation has been compared with modern instrumental data which is not possible in historical and archaeoseismological studies from measurements and quantification of the orientation patterns in the studied earthquakes it is observed that there is a systematic pattern of the earthquake damage orientation edo in the proximity of the seismic source fault trace

clustering and periodic recurrence of microearthquakes on the san andreas fault at parkfield california the san andreas fault at parkfield california apparently late in an interval between repeating magnitude 6 earthquakes is yielding to tectonic loading partly by seismic slip concentrated in a relatively sparse distribution of small clusters 20 meter radius of microearthquakes within these clusters which account for 63 of the earthquakes in a 1987 92 study interval virtually identical small earthquakes occurred with a regularity that can be described by the statistical model used previously in forecasting large characteristic earthquakes sympathetic occurrence of microearthquakes in nearby clusters was observed within a range of about 200 meters at communication speeds of 10 to 100 centimeters per second the rate of earthquake occurrence particularly at depth increased significantly during the study period but the fraction of earthquakes that were cluster members decreased

fault orientations in extensional and conjugate strike slip environments and their implications seismically active conjugate strike slip faults in california and japan typically have mutually orthogonal right and left lateral fault planes normal fault dips at earthquake nucleation depths are concentrated between 40 and 50 the observed orientations and their strong clustering are surprising because conventional faulting theory suggests fault initiation with conjugate 60 and 120 intersecting planes and 60 normal fault dip or fault reactivation with a broad range of permitted orientations the observations place new constraints on the mechanics of fault initiation rotation and evolutionary development we speculate that the data could be explained by fault rotation into the observed orientations and deactivation for greater rotation or by formation of localized shear zones beneath the brittle ductile transition in earth9s crust initiation as weak frictional faults seems unlikely

the grip deuterium excess record abstract ice cores from greenland and antarctica are ideal archives for retrieving long time series of deuterium excess d d 8 18 o a parameter influenced by conditions prevailing in the oceanic regions which provide moisture for polar snow the central greenland grip deuterium excess record has recently been interpreted in terms of oceanic source temperatures both for the holocene and for the last glacial period this approach being less straightforward for the latter period because of changes in the precipitation seasonality between glacial and interglacial periods this article examines why a conventional or sea surface temperature interpretation of the grip excess record seems inconsistent with inferred site and source temperature changes in addition the grip excess record is extended back into the penultimate glacial period and we assess its geographic significance through a comparison with existing dye 3 and north grip data we examine why low d 18o slopes observed during glacial times are associated with low deuterium excess values similarities between the greenland grip and antarctic vostok excess records are discussed in terms of potential links with insolation and insolation gradient changes finally the isotope records in specific do events are examined in light of intruiging differences between the isotope ratios d or 18o and the excess records that may result from a feedback mechanism linked with freshwater oceanic input

earthquakes and archaeology abstract this article examines the use of archaeological evidence for the assessment of historical earthquakes in the eastern mediterranean region and middle east long before the advent of modern seismology we ask the questions when and where have large earthquakes happened in the past how can this evidence contribute to our scientific understanding of earthquake activity is it possible on literary and archaeological grounds to distinguish between earthquake damage and damage from other causes it is found that archaeological evidence for an earthquake is not always clear or unambiguous and that there is a need for collaboration between archaeologists historians geologists engineering seismologists and workers in other disciplines to evaluate the traces of earthquakes in excavations both for understanding their effects at the site and for the information they can provide about the nature of the earthquake implicated

repeating earthquake finite source models strong asperities revealed on the san andreas fault 1 we investigate the rupture process of a sequence of repeating mw 2 1 earthquakes on the san andreas fault in parkfield spanning the occurrence of the september 28 2004 mainshock by inverting seismic moment rate functions obtained from empirical green s function deconvolution the results show that these events have extremely concentrated slip patches with radii on the order of 10 20 m with peak slip between 8 4 and 11 4 cm the rupture speed and rise time are consistent with values of larger earthquakes the spatial distribution of stress drop for the events shows low average values 2 5 5 6 mpa and very large peak values of 66 7 93 9 mpa the results show that strong asperities can exist at small scales on an otherwise weak fault and helps reconcile differences between traditional spectra based and tectonic loading methods for determining the stress drop of small repeating earthquakes

holocene itcz and indian monsoon dynamics recorded in stalagmites from oman and yemen socotra abstract high resolution oxygen isotope 18o profiles of holocene stalagmites from four caves in northern and southern oman and yemen socotra provide detailed information on fluctuations in precipitation along a latitudinal transect from 12 n to 23 n 18o values reflect the amount of precipitation which is primarily controlled by the mean latitudinal position of the itcz and dynamics of the indian summer monsoon ism during the early holocene rapidly decreasing 18o values indicate a rapid northward displacement in the mean latitudinal position of the summer itcz and the associated ism rainfall belt with decadal to centennial scale changes in monsoon precipitation correlating well with high latitude temperature variations recorded in greenland ice cores during the middle to late holocene the summer itcz continuously migrated southward and monsoon precipitation decreased gradually in response to decreasing solar insolation a trend which is also recorded in other monsoon records from the indian and east asian monsoon domains importantly there is no evidence for an abrupt middle holocene weakening in monsoon precipitation although abrupt monsoon events are apparent in all monsoon records they are short lived and clearly superimposed on the long term trend of decreasing monsoon precipitation for the late holocene there is an anti correlation between ism precipitation in oman and inter monsoon spring autumn precipitation on socotra revealing a possible long term change in the duration of the summer monsoon season since at least 4 5 ka bp together with the progressive shortening of the ism season gradual southward retreat of the mean summer itcz and weakening of the ism the total amount of precipitation decreased in those areas located at the northern fringe of the indian and asian monsoon domains but increased in areas closer to the equator

scaling of small repeating earthquakes explained by interaction of seismic and aseismic slip in a rate and state fault model because of short recurrence times and known locations small repeating earthquakes present a rare predictable opportunity for detailed field observations they are used to study fault creeping velocities earthquake nucleation stress drops and other aspects of tectonophysics earthquake mechanics and seismology an intriguing observation about repeating earthquakes is their scaling of recurrence time with seismic moment which is significantly different from the scaling based on a simple conceptual model of circular ruptures with stress drop independent of seismic moment and no aseismic slip here we show that a model of repeating earthquakes based on laboratory derived rate and state friction laws reproduces the observed scaling in the model a small fault patch governed by steady state velocity weakening friction is surrounded by a much larger velocity strengthening region long term slip behavior of the fault is simulated using a methodology that fully accounts for both aseismic slip and inertial effects of occasional seismic events the model results in repeating earthquakes with typical stress drops and sizes comparable with observations for a fixed set of friction parameters the observed scaling is reproduced by varying the size of the velocity weakening patch in simulations a significant part of slip on the velocity weakening patches is accumulated aseismically even though the patches also produce seismic events the proposed model supplies a laboratory based framework for interpreting the wealth of observations about repeating earthquakes provides indirect evidence that rate and state friction acts on natural faults and has important implications for possible scenarios of slip partition into seismic and aseismic parts

seismological studies at parkfield vi moment release rates and estimates of source parameters for small repeating earthquakes abstract waveform data from a borehole network of broadband seismographic stations have been used to study microearthquakes along the parkfield segment of the san andreas fault saf analysis of almost 10 years of such data demonstrates that much of the seismicity in this region consists of repeating sequences quasiperiodic sequences of earthquakes that are essentially identical in terms of waveform size and location scalar seismic moments have been estimated for 53 of these repeating sequences and combined with equivalent estimates from 8 similar but larger event sequences from the stone canyon section of the fault and the main parkfield sequence these estimates show that seismic moment is being released as a function of time in a very regular manner measurements of the moment release rate combined with an assumed tectonic loading rate lead to estimates of the seismic parameters source area slip and recurrence interval such parameters exhibit a systematic dependence upon source size over a range of 10 10 in seismic moment that can be described by three simple scaling relationships several implications of these scaling relationships are explored including the repeat time of earthquakes average stress drop strength of the fault and heat generated by earthquakes what emerges from this analysis of moment release rates is a quantitative description of an earthquake process that is controlled by small strong asperities that occupy less than 1 of the fault area this means that the fault is highly heterogeneous with respect to stress strength and heat generation such heterogeneity helps to explain many of the apparent contradictions that are encountered in the study of earthquakes such as why faults appear weak why significant heat flow is not observed how significant high frequencies can be generated by large earthquakes and how various geologic features such as pseudotachylytes might form

holocene climate and cultural evolution in late prehistoric early historic west asia abstract the precipitation climatology and the underlying climate mechanisms of the eastern mediterranean west asia and the indian subcontinent are reviewed with emphasis on upper and middle tropospheric flow in the subtropics and its steering of precipitation holocene climate change of the region is summarized from proxy records the indian monsoon weakened during the holocene over its northernmost region the ganges and indus catchments and the western arabian sea southern regions the indian peninsula do not show a reduction but an increase of summer monsoon rain across the holocene the long term trend towards drier conditions in the eastern mediterranean can be linked to a regionally complex monsoon evolution abrupt climate change events such as the widespread droughts around 8200 5200 and 4200 cal yr bp are suggested to be the result of altered subtropical upper level flow over the eastern mediterranean and asia the abrupt climate change events of the holocene radically altered precipitation fundamental for cereal agriculture across the expanse of late prehistoric early historic cultures known from the archaeological record in these regions social adaptations to reduced agro production in both dry farming and irrigation agriculture regions are visible in the archaeological record during each abrupt climate change event in west asia chronological refinement in both the paleoclimate and archaeological records and transfer functions for both precipitation and agro production are needed to understand precisely the evident causal linkages

the experimental calibration of the iron isotope fractionation factor between pyrrhotite and peralkaline rhyolitic melt abstract a first experimental study was conducted to determine the equilibrium iron isotope fractionation between pyrrhotite and silicate melt at magmatic conditions experiments were performed in an internally heated gas pressure vessel at 500 mpa and temperatures between 840 and 1000 c for 120 168 h three different types of experiments were conducted and after phase separation the iron isotope composition of the run products was measured by mc icp ms i kinetic experiments using 57 fe enriched glass and natural pyrrhotite revealed that a close approach to equilibrium is attained already after 48 h ii isotope exchange experiments using mixtures of hydrous peralkaline rhyolitic glass powder 4 wt h 2 o and natural pyrrhotites fe 1 x s as starting materials and iii crystallisation experiments in which pyrrhotite was formed by reaction between elemental sulphur and rhyolitic melt consistently showed that pyrrhotite preferentially incorporates light iron no temperature dependence of the fractionation factor was found between 840 and 1000 c within experimental and analytical precision an average fractionation factor of 56 fe 54 fe pyrrhotite melt 0 35 0 04 2se n 13 was determined for this temperature range predictions of fe isotope fractionation between fes and ferric iron dominated silicate minerals are consistent with our experimental results indicating that the marked contrast in both ligand and redox state of iron control the isotope fractionation between pyrrhotite and silicate melt consequently the fractionation factor determined in this study is representative for the specific fe 2 fe ratio of our peralkaline rhyolitic melt of 0 38 0 02 at higher fe 2 fe ratios a smaller fractionation factor is expected further investigation on fe isotope fractionation between other mineral phases and silicate melts is needed but the presented experimental results already suggest that even at high temperatures resolvable variations in the fe isotope composition can be generated by equilibrium isotope fractionation in natural magmatic systems

contribution of archaeological data to studies of earthquake history in the iranian plateau we use archaeological evidence to identify ancient earthquakes in the vicinity of large 20th century events in the iranian plateau two large earthquakes on the zagros main recent fault were preceded by historical earthquakes in ad 1008 and ad 1107 and by earthquakes in the intervals ad 224 459 and 1650 1600 bc giving return times of 1800 2100 500 800 and 850 950 years the ad 1962 ms 7 2 bo in zahra earthquake on the ipak fault in north central iran was preceded by an earthquake in 2000 1500 bc recorded at the sagzabad mound a return time of 3500 4000 years if there are no missing events the ad 1990 ms 7 3 rudbar tarom earthquake in the western alborz mountains was preceded by an earthquake in 1000 800 bc recorded at the marlik mound a return time of 2800 3000 years the ad 1948 ms 7 2 kopeh dagh earthquake that destroyed ashkabad capital of turkmenistan was preceded by an earthquake in 10 bc ad 10 recorded at mithradatkert nesa mound and by an earthquake in 2000 bc recorded at ak tapeh mound assuming no missing earthquakes this region has an earthquake return time of about 2000 years in khorasan province which was struck by a sequence of large earthquakes from ad 1936 to 1997 a mosque at qa en was destroyed in the mid 11th century ad probably the historical earthquake of ad1066 in the absence of palaeoseismic investigations archaeology offers the promise of recording earthquakes through more than one seismic cycle in different regions of iran q 2001 elsevier science ltd all rights reserved

centennial scale climate cooling with a sudden cold event around 8 200 years ago the extent of climate variability during the current interglacial period the holocene is still debated temperature records derived from central greenland ice cores show one significant temperature anomaly between 8 200 and 8 100 years ago which is often attributed to a meltwater outflow into the north atlantic ocean and a slowdown of north atlantic deep water formation this anomaly provides an opportunity to study such processes with relevance to present day freshening of the north atlantic anomalies in climate proxy records from locations around the globe are often correlated with this sharp event in greenland but the anomalies in many of these records span 400 to 600 years start from about 8 600 years ago and form part of a repeating pattern within the holocene more sudden climate changes around 8 200 years ago appear superimposed on this longer term cooling the compounded nature of the signals implies that far field climate anomalies around 8 200 years ago cannot be used in a straightforward manner to assess the impact of a slowdown of north atlantic deep water formation and the geographical extent of the rapid cooling event 8 200 years ago remains to be determined

timing of atmospheric precipitation in the zagros mountains inferred from a multi proxy record from lake mirabad iran abstract a sediment core 7 2 m long from lake mirabad iran was examined for loss on ignition mineralogy oxygen isotopic composition of authigenic calcite and trace element composition of ostracodes to complement earlier pollen and ostracode assemblage studies pollen ostracode inferred lake level and high sr ca ratios indicate that the early holocene 10000 to 6500 cal yr bp was drier than the late holocene low 18 o values during this interval are interpreted as resulting from winter dominated precipitation characteristic of a mediterranean climate increasing 18 o values after 6500 cal yr bp signal a gradual increase in spring rains which are present today a severe 600 yr drought occurred at ca 5500 cal yr bp shortly after the transition from pistachio almond to oak forest during the late holocene two milder droughts occurred at about 1500 and 500 cal yr bp within the resolution of the record no drought is evident during the collapse of the akkadian empire 4200 3900 cal yr bp rather a decrease in 18 o values to early holocene levels may indicate the return to a mediterranean precipitation regime

aftershocks driven by afterslip and fluid pressure sweeping through a fault fracture mesh a variety of physical mechanisms are thought to be responsible for the triggering and spatiotemporal evolution of aftershocks here we analyze a vigorous aftershock sequence and postseismic geodetic strain that occurred in the yuha desert following the 2010 m w 7 2 el mayor cucapah earthquake about 155 000 detected aftershocks occurred in a network of orthogonal faults and exhibit features of two distinct mechanisms for aftershock triggering the earliest aftershocks were likely driven by afterslip that spread away from the main shock with the logarithm of time a later pulse of aftershocks swept again across the yuha desert with square root time dependence and swarm like behavior together with local geological evidence for hydrothermalism these features suggest that the events were driven by fluid diffusion the observations illustrate how multiple driving mechanisms and the underlying fault structure jointly control the evolution of an aftershock sequence

present day crustal deformation and plate kinematics in the middle east constrained by gps measurements in iran and northern oman summary a network of 27 gps sites was implemented in iran and northern oman to measure displacements in this part of the alpine himalayan mountain belt we present and interpret the results of two surveys performed in 1999 september and 2001 october gps sites in oman show northward motion of the arabian plate relative to eurasia slower than the nuvel 1a estimates e g 22 2m m yr 1 at n8 5 e instead of 30 5 mm yr 1 at n6 e at bahrain longitude we define a gps arabia eurasia euler vector of 27 9 0 5 n 19 5 1 4 e 0 41 0 1 myr 1 the arabia eurasia convergence is accommodated differently in eastern and western iran east of 58 e most of the shortening is accommodated by the makran subduction zone 19 5 2m m yr 1 and less by the kopet dag 6 5 2m m yr 1 west of 58 e the deformation is distributed in separate fold and thrust belts at the longitude of tehran the zagros and the alborz mountain ranges accommodate 6 5 2m m yr 1 and 8 2m m yr 1 respectively the right lateral displacement along the main recent fault in the northern zagros is about 3 2m m yr 1 smaller than what was generally expected by contrast large rightlateral displacement takes place in northwestern iran up to 8 mm yr 1 the central iranian block is characterized by coherent plate motion internal deformation 2m m yr 1 sites east of 61 e show very low displacements relative to eurasia the kinematic contrast between eastern and western iran is accommodated by strike slip motions along the lut block to the south the transition zone between zagros and makran is under transpression with right lateral displacements of 11 2m m yr 1

archeoseismicity and environmental crises at the sialk mounds central iranian plateau since the early neolithic during the long lasting cultural sequences of the shurand sialk archeological mounds 6200e550bc theinhabitantsencounterednumerousdiversifiedcrisesalonganarrowfertilepassageway at the edge of the central iranian plateau great desert some of the threats may be attributed to earth quakes drastic climatic changes and man made environmental deterioration which possibly led to the settlement withdrawing at different stages toward a more suitable location our study identified the occurrence of a large magnitude earthquake around 3800 bc along the k fault which is well documented by various lines of circumstantial evidence including i numerous contemporaneous

fault slip rates at depth from recurrence intervals of repeating microearthquakes unique attributes in sequences of recurring similar microearthquakes at parkfield california provide a means for inferring slip rate at depth throughout the active fault surface from the time intervals between sequence events application of the method using an 11 year microseismicity record revealed systematic spatial and temporal changes in the slip rate that were synchronous with earthquake activity and other independent measures of fault zone slip if this phenomenon is found to be generally common behavior in active faults it forms the basis for a method to monitor the changing strain field throughout a seismogenic fault zone

active faulting in the walker lane 1 deformation across the san andreas and walker lane fault systems accounts for most relative pacific north american transform plate motion the walker lane is composed of discontinuous sets of right slip faults that are located to the east and strike approximately parallel to the san andreas fault system mapping of active faults in the central walker lane shows that right lateral shear is locally accommodated by rotation of crustal blocks bounded by steep dipping east striking left slip faults the left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area including rattlesnake and garfield flats teels columbus and rhodes salt marshes and queen valley the benton springs and petrified springs faults are the major northwest striking structures currently accommodating transform motion in the central walker lane right lateral offsets of late pleistocene surfaces along the two faults point to slip rates of at least 1 mm yr the northern limit of northwest trending strike slip faults in the central walker lane is abrupt and reflects transfer of strike slip to dip slip deformation in the western basin and range and transformation of right slip into rotation of crustal blocks to the north the transfer of strike slip in the central walker lane to dip slip in the western basin and range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long lived feature of the deformation field the complexity of faulting and apparent rotation of crustal blocks within the walker lane is consistent with the concept of a partially detached and elastic brittle crust that is being transported on a continuously deforming layer below the regional pattern of faulting within the walker lane is more complex than observed along the san andreas fault system to the west the difference is attributed to the relatively less cumulative slip that has occurred across the walker lane and that oblique components of displacement are of opposite sense along the walker lane extension and san andreas contraction respectively despite the gross differences in fault pattern the walker lane and san andreas also share similarities in deformation style including clockwise rotations of crustal blocks leading to development of structural basins and the partitioning of oblique components of slip onto subparallel strike slip and dip slip faults

recognition of earthquake related damage in archaeological sites examples from the dead sea fault zone abstract archaeological structures that exhibit seismogenic damage expand our knowledge of temporal and spatial distribution of earthquakes afford independent examination of historical accounts provide information on local earthquake intensities and enable the delineation of macroseismic zones they also illustrate what might happen in future earthquakes in order to recover this information we should be able to distinguish earthquake damage from anthropogenic damage and from other natural processes of wear and tear the present paper reviews several types of damage that can be attributed with high certainty to earthquakes and discusses associated caveats in the rare cases where faults intersect with archaeological sites offset structures enable precise determination of sense and size of slip and constrain its time among the characteristic off fault damage types i consider horizontal shifting of large building blocks downward sliding of one or several blocks from masonry arches collapse of heavy stably built walls chipping of corners of building blocks and aligned falling of walls and columns other damage features are less conclusive and require additional evidence e g fractures that cut across several structures leaning walls and columns warps and bulges in walls circumstantial evidence for catastrophic earthquake related destruction includes contemporaneous damage in many sites in the same area absence of weapons or other anthropogenic damage stratigraphic data on collapse of walls and ceilings onto floors and other living horizons and burial of valuable artifacts as well as associated geological palaeoseismic phenomena such as liquefaction land and rock slides and fault ruptures additional support may be found in reliable historical accounts special care must be taken in order to avoid circular reasoning by maintaining the independence of data acquisition methods

imbricated aseismic slip and fluid diffusion drive a seismic swarm in the corinth gulf greece the primary processes driving seismic swarms are still under debate here we study the temporal evolution of a seismic swarm that occurred over a 10 day period in october 2015 in the extensional rift of the corinth gulf greece using high resolution earthquakes relocations the seismicity radially migrates on a normal fault at a fluid diffusion velocity 125 m day however this migration occurs intermittently with periods of fast expansion 2 to 10 km day during short seismic bursts alternating with quiescent periods moreover the growing phases of the swarm illuminates a high number of repeaters the swarm migration is likely the results of a combination of multiple driving processes fluid up flow in the fault may induce aseismic slip episodes separated by phases of fluid pressure build up the stress perturbation due to aseismic slip may activate small asperities that produce bursts of seismicity during the most intense phase of the swarm

holocene forcing of the indian monsoon recorded in a stalagmite from southern oman a high resolution oxygen isotope record from a thorium uranium dated stalagmite from southern oman reflects variations in the amount of monsoon precipitation for the periods from 10 3 to 2 7 and 1 4 to 0 4 thousand years before the present ky b p between 10 3 and 8 ky b p decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in greenland ice cores indicating that early holocene monsoon intensity is largely controlled by glacial boundary conditions after approximately 8 ky b p monsoon precipitation decreases gradually in response to changing northern hemisphere summer solar insolation with decadal to multidecadal variations in monsoon precipitation being linked to solar activity

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

inferring the coseismic and postseismic stress changes caused by the 2004 mw 6 parkfield earthquake from variations of recurrence times of microearthquakes 1 kinematic models of coseismic stress inverted from ground motion data do not usually find good correlation between the location of aftershocks and high stress patches in particular numerous earthquakes are recorded in areas of the fault where the stress decreases however most of coseismic slip distributions have limited spatial resolution typically not better than 1 km here we investigate the stress changes produced by the 2004 mw 6 parkfield earthquake on and near its rupture zone at the scale of magnitude 2 earthquake asperities approximately tens of meters after relocating earthquakes in this zone between 1984 and 2007 we form repeating highly similar earthquake sequences and study how the quasiperiodicity of occurrence at each sequence observed during the 20 years preceding the 2004 main shock is perturbed by this event we apply a simple model of the seismic cycle to infer the coseismic and postseismic stresses experienced by the repeatedly failing asperities despite being spatially sparse these stress distributions have resolutions only limited by the typical scale of an asperity we propose that the high spatial variability of the seismicity patterns following the mw 6 earthquake results from an heterogeneous coseismic stress field the emergence of the omori utsu law observed at large scale greater than kilometers at parkfield is simply the outcome of averaging such quasi deterministic patterns over many sequences the fact that the coseismic stress can significantly change over distances of the order of 100 m adds credence to the hypothesis that earthquake rupture is intrinsically very heterogeneous

centennial to millennial scale variability of the indian monsoon during the early holocene from a sediment pollen and isotope record from the desert of yemen lacustrine deposits of al hawa 15 52 n 46 53 e 710 m above sea level document the climatic and environmental history of the inland desert of yemen during the early to mid holocene a freshwater lake expanded in one of the most arid areas of the world in response to increased indian monsoon fluxes from 12 000 to 7500 cal b p three dry intervals punctuated the lacustrine phase recording episodes of weaker summer monsoon activity over arabia dry intervals were coeval with cold periods recorded in the north atlantic confirming the links between the indian monsoon and the north atlantic systems during the holocene we demonstrate that the regional vegetation remained of semi arid character throughout the lacustrine period

microphenocrystic pyrrhotite from dacite rocks of satsuma iwojima southwest kyushu japan and the solubility of sulfur in dacite magma microphenocrystic pyrrhotites were observed in the glassy groundmass of two dacite rocks from satsuma iwojima southwest kyushu japan it suggests that the dacite magma was saturated with respect to pyrrhotite at the time of eruption and thus the sulfur contents in the groundmass can be taken as the solubility of sulfur in the dacite magma the solubility of sulfur in the dacite rocks thus calculated is 65 to 72 ppm sulfur at the estimated conditions of t 900 50 c f text o text 2 10 12 pm 1 and f text s text 2 10 0 6 pm 0 6 atm

complex spatiotemporal evolution of the 2008 mw 4 9 mogul earthquake swarm reno nevada interplay of fluid and faulting after approximately two months of swarm like earthquakes in the mogul neighborhood of west reno nv seismicity rates and event magnitudes increased over several days culminating in an mw 4 9 dextral strike slip earthquake on 26 april 2008 although very shallow the mw 4 9 mainshock had a different sense of slip than locally mapped dip slip surface faults we relocate 7 549 earthquakes calculate 1 082 focal mechanisms and statistically cluster the relocated earthquake catalog to understand the character and interaction of active structures throughout the mogul nv earthquake sequence rapid temporary instrument deployment provides high resolution coverage of microseismicity enabling a detailed analysis of swarm behavior and faulting geometry relocations reveal an internally clustered sequence in which foreshocks evolved on multiple structures surrounding the eventual mainshock rupture the relocated seismicity defines a fault fracture mesh and detailed fault structure from approximately 2 6 km depth on the previously unknown mogul fault that may be an evolving incipient strike slip fault zone the seismicity volume expands before the mainshock consistent with pore pressure diffusion and the aftershock volume is much larger than is typical for an mw 4 9 earthquake we group events into clusters using space time magnitude nearest neighbor distances between events and develop a cluster criterion through randomization of the relocated catalog identified clusters are largely mainshock aftershock sequences without evidence for migration occurring within the diffuse background seismicity the migration rate of the largest foreshock cluster and simultaneous background events is consistent with it having triggered or having been triggered by an aseismic slip event