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

active deformation within the zagros mountains deduced from gps measurements we present and interpret the results of global positioning system gps measurements at 35 stations in and beside the zagros mountain belt sw iran for three campaigns ending march 1998 december 1999 and june 2001 preliminary motion estimates show clearly the change in character along the strike of the belt stations to the se move at 13 22 3 mm a 1 towards n 7 5 e with respect to eurasia most of the shortening indicated by the gps velocities seems to occur in the se zagros along two major seismic zones and along the zagros front to the nw stations move oblique to the trend of the belt towards n 12 8 w at 14 19 3 mm a 1 most of the shortening in the nw zagros seems to occur along the mountain front fault with its major earthquakes as well as along the zagros front the change in direction and magnitude of the velocity vectors across the north south trending kazerun and karebas faults involves extension of up to 4 mm a 1 along the strike of the zagros belt

infrasonic forerunners exceptionally fast acoustic phases 1 a vapor cloud explosion occurred at an oil depot near buncefield in the uk in 2005 three infrasound arrays in the netherlands detected various stratospheric phases some of these phases appeared with celerities i e horizontal propagation velocity in the conventional range of 0 28 to 0 31 km s exceptionally fast arrivals infrasonic forerunners were identified with celerities of 0 31 to 0 36 km s these phases could be explained by head wave like propagation in a high velocity acoustic channel between 40 and 50 km height where stratospheric zonal winds reached values of 120 m s the manifestation of infrasonic forerunners is validated by modeling with raytracing through actual atmospheric models and determining the celerity apparent velocity and back azimuth one phase occurred with a celerity of 0 25 km s hence we propose a new celerity range for fast stratospheric phases of 0 31 to 0 36 km s and to lower the limit of the conventional range to 0 25 km s

three dimensional deformation along the rupture trace of the september 21st 1999 taiwan earthquake a case study in the kuangfu school abstract in central taiwan the destructive chichi earthquake m w 7 6 of september 21st 1999 produced a nearly 100 km long rupture trace following the chelungpu fault this paper shows how the geometry of the fault slip can locally be determined in three dimensions based on analyses of earthquake fault in the kuangfu stadium the fault at this site is reverse and left lateral the three dimensional geometrical analysis done with a variety of data through independent determination modes all applied to the deformation of the surface layer of the stadium tracks allows complete verification of the results not only do these analyses constrain the fault behaviour in terms of trend dip angle obliquity and amount of slip but also they reveal variations in both the horizontal and the vertical fault geometry the comparison with relative displacements recorded at larger distances from the fault reveals that slip partitioning occurs with nearly dip slip thrusting along the rupture trace and distributed left lateral shear in a deformed zone of the hanging wall adjacent to the main fault

calibration of the late pliocene early pleistocene transition in the continental beds of the guadix baza basin southeastern spain in this paper a survey of the correlation between magnetic polarity and the mammalian succession in the plio pleistocene sequence of the guadix baza basin is presented in this basin a complete continental sequence from the early pliocene to the middle pleistocene is present allowing the correlation of mammalian biozones with the geomagnetic polarity scale two sections of the baza sector of the basin have been analyzed in order to calibrate the pliocene pleistocene transition the galera middle pliocene to early pleistocene and the orce late pliocene to early pleistocene it is concluded that the boundary between the mn 15 late ruscinian and the mn 16 early villanyian is placed between the 2an 3n chron and the 2an in subchron the late villanyian mn 17 extends up to the upper part of chron 2r 1r the entry of the pleistocene marker allophaiomys pliocaenicus can be placed within subchron 2n olduvai

magnetostratigraphic characterization of a thick lower pleistocene lacustrine sequence from the baza basin betic chain southern spain abstract the magnetic polarity stratigraphy from a lacustrine sequence of the baza basin betic chain southern spain has been interpreted as having a lower pleistocene age fifty nine paleomagnetic sites have been obtained and a set of 179 specimens has been demagnetized with both thermal and alternating field procedures several magnetic parameters that depend on the lithology have been obtained the characteristic remanent magnetization polarity has been unambiguously recovered over the whole sequence the materials studied span chron 1r 2 located in the upper matuyama epoch this allows the placement of the faunas studied ranging from the late villanyian to the late biharian in the magnetic polarity time scale mpts this work also proves that magnetostratigraphy can be established in lacustrine sediments even with extremely low magnetic intensities

infrasound radiated by the gerdec and chelopechene explosions propagation along unexpected paths summary infrasound propagation paths through the atmosphere are controlled by the temporally and spatially varying sound speed and wind speed amplitudes because of the complexity of atmospheric acoustic propagation it is often difficult to reconcile observed infrasonic arrivals with the sound speed profiles predicted by meteorological specifications this paper provides analyses of unexpected arrivals recorded in europe and north africa from two series of accidental munitions dump explosions recorded at ranges greater than 1000 km two explosions at gerdec albania on 2008 march 15 and four explosions at chelopechene bulgaria on 2008 july 3 the recorded signal characteristics include multiple pulsed arrivals celerities between 0 24 and 0 34 km s 1 and some signal frequency content above 1 hz often such characteristics are associated with waves that have propagated within a ground to stratosphere waveguide although the observed celerities extend both above and below the conventional range for stratospheric arrivals however state of the art meteorological specifications indicate that either weak or no ground to stratosphere waveguides are present along the source to receiver paths by incorporating realistic gravity wave induced horizontal velocity fluctuations into time domain parabolic equation models the pulsed nature of the signals is simulated and arrival times are predicted to within 30 s of the observed values 1 per cent of the source to receiver transit time modelling amplitudes is highly dependent upon estimates of the unknown acoustic source strength or equivalent chemical explosive yield current empirical explosive yield relationships derived from infrasonic amplitude measurements from point source chemical explosions suggest that the equivalent chemical yield of the largest gerdec explosion was of the order of 1 kt and the largest chelopechene explosion was of the order of 100 t when incorporating these assumed yields the parabolic equation simulations predict peak signal amplitudes to within an order of magnitude of the observed values as gravity wave velocity perturbations can significantly influence both infrasonic arrival times and signal amplitudes they need to be accounted for in source location and yield estimation routines both of which are important for explosion monitoring especially in the context of the comprehensive nuclear test ban treaty

extrusion tectonics and subduction in the eastern south caspian region since 10 ma reply we examine active deformation of the region surrounding the eastern south caspian sea using a combination of seismic geological geodetic and geomorphological data global positioning system gps velocities indicate a westward component of motion of the south caspian basin relative to eurasia and central iran we identify major zones of shear the ashkabad and shahrud fault zones that accommodate this westward extrusion on either side of the south caspian block estimates of total strike slip motion could at present day slip rates derived from gps observations be achieved in 10 m y therefore the northwest extrusion of the south caspian region which is accommodated by subduction beneath the north caspian region stable eurasia along the apsheron balkan sill may also date from that time this suggests that the onset of subduction may be older than previous estimates ranging from 1 8 to 5 5 ma our results are summarized in a new kinematic model that significantly clarifies the active tectonics of this complicated region

a reappraisal of earthquake focal mechanisms and active shortening in the zagros mountains of iran summary the zagros mountains of sw iran are one of the most seismically active intra continental fold and thrust belts on earth and an important element in the active tectonics of the middle east surface faulting associated with earthquakes is extremely rare and so most information about the active faulting comes from earthquakes we use long period teleseismic p and sh body waves to determine the orientation and depth of faulting in 16 new earthquakes and then evaluate and synthesize all the available teleseismic data on earthquake source parameters in the zagros we use this information to investigate the style and distribution of active faulting in the zagros and how it contributes to the n s shortening of the arabia eurasia collision when the data are ranked in quality and carefully evaluated simple patterns are seen that are not apparent when routine catalogue data are taken at face value an important change in the fault configuration occurs along strike of the belt in the nw overall convergence is oblique to the trend of the belt and the surface anticlines and is achieved by a spatial separation partitioning of the orthogonal strike slip and shortening components on separate parallel fault systems by contrast in the se overall convergence is orthogonal to the regional strike and achieved purely by thrusting in the central zagros between these two structural regimes deformation involves parallel strike slip faults that rotate about vertical axes allowing extension along the strike of the belt the overall configuration is similar to that seen in other curved shortening belts such as the himalaya and the java sumatra trench all the zagros earthquakes we have been able to check have centroids shallower than 20 km and are confined to the upper crust many of the larger earthquakes are likely to occur in the basement beneath the sedimentary cover which is active even beneath areas of known shallow structural decollement such as the dezful embayment the dominant style of shortening is high angle reverse faulting with dips 30 though some lower angle thrusting occurs in places active thrust and reverse faulting is relatively confined to the lower topography on the sw edge of the belt today and only strike slip faulting affects the higher topography profound vertical changes in structural and stratigraphic level indicate that a similar style of deformation was once active across the width of the simple folded belt but has progressively migrated sw over the last 5 ma there is no evidence for a seismically active structural decollement such as a low angle thrust beneath the zagros nor is there any seismic evidence for active subduction either beneath the zagros or beneath central iran instead the arabian margin seems to have shortened by distributed thickening of the basement only in the syntaxis of the oman line at the se end of the zagros is there any evidence for a low angle thrust of regional extent here earthquakes continue 50 km north of the zagros thrust line the geological suture between the arabian margin and central iran reaching depths of 30 km and may represent thrusting of arabian basement beneath central iran to this extent

experimental characterization of seasonal variations in infrasonic traveltimes on the korean peninsula with implications for infrasound event location summary the dependence of infrasound propagation on the season and path environment was quantified by the analysis of more than 1000 repetitive infrasonic ground truth events at an active open pit mine over two years blast associated infrasonic signals were analysed from two infrasound arrays chnar and uldar located at similar distances of 181 and 169 km respectively from the source but in different azimuthal directions and with different path environments the chnar array is located to the nw of the source area with primarily a continental path whereas the uldar is located east of the source with a path dominated by open ocean as a result chnar observations were dominated by stratospheric phases with characteristic celerities of 260 289 m s 1 and large seasonal variations in the traveltime whereas data from uldar consisted primarily of tropospheric phases with larger celerities from 322 to 361 m s 1 and larger daily than seasonal variation in the traveltime the interpretation of these observations is verified by ray tracing using atmospheric models incorporating daily weather balloon data that characterizes the shallow atmosphere for the two years of the study finally experimental celerity models that included seasonal path effects were constructed from the long term data set these experimental celerity models were used to constrain traveltime variations in infrasonic location algorithms providing improved location estimates as illustrated with the empirical data set

macrofossil magnetobiostratigraphy for the upper santonian lower campanian interval in the western interior of north america comparisons with european stage boundaries and planktonic foraminiferal zonal boundaries magnetostratigraphic samples were collected from the milk river and pakowki formations of southeastern alberta to determine the polarity chron 34 33r boundary this boundary was located in the upper half of the deadhorse coulee member and is below the first local occurrence of the western interior ammonite baculites obtusus comparison with the laterally equivalent eagle sandstone of montana and niobrara formation of colorado indicates that the 34 33r contact is within either the baculites sp smooth or baculites sp weak flank ribs ammonite zone in the western interior of north america direct correlation of the desmoscaphites erdmanni through baculites asperifomis western interior ammonite zones with magnetobiostratigraphic sections of the upper santonian lower campanian stages in europe suggests that i the santonian campanian boundary as defined in europe is within the lower baculites obtusus zone and ii the western interior appearance of some ammonites and crinoids scaphites hippocrepis trachyscaphites spiniger marsupites uintacrinus is profoundly time transgressive relative to the appearance of these same species in europe the date of 84 ma for the santonian campanian boundary is too old and a date of around 80 ma may be more accurate the santonian campanian boundary defined by ammonites crinoids and belemnites in europe is within the lower part of chron 33r and is younger than the santonian campanian boundary as determined by planktonic foraminifera at gubbio italy

geomorphic criteria to determine direction of lateral propagation of reverse faulting and folding fault related folds develop above active faults and as these faults propagate laterally so do the folds they produce geomorphic criteria useful in evaluating rates and direction of lateral propagation of active folds in the direction of propagation are 1 decrease in drainage density and degree of dissection 2 decrease in elevation of wind gaps 3 decrease in relief of the topographic profile along the crest 4 development of characteristic drainage patterns 5 deformation of progressively younger deposits or landforms and 6 decrease in rotation and inclination of forelimb all these criteria are consistent with lateral propagation but do not prove it the presence of more than one wind or water gap formed by the same stream however is strong evidence of lateral propagation rates of lateral propagation of folding may be several times the rate of uplift and fault slip lateral propagation of anticlinal folds allows for a new explanation of how drainage may develop across active fold belts development of drainage across an active fold belt is probably a function of relatively long structurally controlled drainage diversion parallel to fold axes and development of relatively short antecedent stream reaches around the nose plunge panel of a fold water and or wind gaps form as uplift drainage diversion and stream capture associated with fold growth continue

a seismoacoustic analysis of the gas pipeline explosion near ghislenghien in belgium a high pressure gas pipeline exploded near ghislenghien in belgium on 30 july 2004 seismic energy of this event was recorded at three nearby seismometers the origin time of the explosion was determined by analyzing the rayleigh waves and found to be 06h55m27 2sec coordinated universal time utc ground truth of the explosion was invoked to assess the accuracy of the location derived from infrasound data recorded over western europe different infrasonic phases were identified by using array processing techniques and raytracing through atmospheric models the analysis showed that the derived location was situated 13 km from the true location the total area of the uncertainty ellipse or area to be searched if the source was of unknown origin was 690 km 2 after the origin time and location the yield was calculated by comparing infrasonic stratospheric amplitudes with those from a high explosives dataset and was estimated at 40 9 tons high explosives equivalent in summary this study illustrates the capability of seismic and infrasound data in forensic investigations furthermore the potential of infrasound as a monitoring or verification technique is addressed

improved gasoline powered soft sediment cutter abstract a device used for paleomagnetic sampling has been improved which allows sampling friable poorly to moderate lithified sedimentary and volcanic materials the new device attaches to a portable gasoline drill and employs two steel cutting disks with a 2 cm separation which cuts two parallel slots in the material being sampled a second set of cuts orthogonal to the first set produces a square pedestal over which a plastic sample box can be placed and oriented to extract a cubic sample this procedure permits using the same orientation parameters as for conventionally drilled cylindrical samples the method allows sampling at localities where conventional drilling fails in weak materials to test the method sedimentary sandstones of the amaga formation eocene miocene in the nw portion of the central colombian andes were sampled the anisotropy of magnetic susceptibility ams was measured on samples using the new method and compared with results from conventionally drilled cores at the same sites results show better ams within site precision for box samples compared with the drilled cores this device improves on previous battery powered samplers used for sampling by the double slot procedure also the new device can be used with the same gasoline powered motor for standard core drilling

oblique plate convergence slip vectors and forearc deformation slip vectors from thrust earthquakes at subduction zones where convergence is oblique to the trench often point between the directions of relative plate convergence and normal to the trench axis suggesting that oblique convergence is taken up by partial decoupling decoupling means that a component of arc parallel motion of the leading edge of the upper plate results in less oblique thrusting at the trench partial decoupling is modeled by partitioning of oblique convergence into slip on thrust and strike slip faults that are parallel to the trench and to each other and starting with a force equilibrium condition a relationship between the obliquity and the earthquake slip vector orientation is derived assuming that either fault slips when shear stress on it reaches a yield stress oblique slip parallel to the plate vector should occur on the thrust fault when obliquity is smaller than a critical angle for obliquity at or greater than this angle the stress on the strike slip fault is large enough to start it slipping and when both faults are active the arc parallel motion of the forearc deflects the slip vector back toward the trench normal if we assume that continued slip on either fault occurs at constant stress but the two faults can be at different stresses the slip vector will maintain a constant angle relative to the trench normal even when obliquity is larger than the critical angle this limiting angle of the slip vector called max measured relative to the trench normal is simply the arcsine of the ratio of the shear forces resisting slip on the strike slip and thrust faults a consequence is that when the obliquity exceeds max the slip vectors on the thrust fault are sensitive only to the thrust fault orientation and contain no information about the convergence direction between the plates slip vectors at the java trench southwest of sumatra show the relationship clearly with max 20 5 while slip vectors at the aleutian trench show the relationship less clearly with max 25 to 45 the greater angle at the aleutian trench suggests that the upper plate is stronger in the aleutian arc relative to the thrust fault than in the sumatran arc consistent with the sumatran arc being continental and having a well developed strike slip fault while the aleutian arc is oceanic and without a clear transcurrent fault slip vectors at the philippine trench which like sumatra has a large strike slip fault inboard of it tend to stay within 25 of the trench normal when obliquity is as large as 50 if obliquity exceeds max and continues to increase along a subduction zone the rate of motion of the forearc relative to the upper plate will vary with obliquity in which case the forearc sliver should extend or contract parallel to the arc from the geometry of modern island arcs arc parallel extension should be the more common and has been hypothesized for both sumatra and the aleutians on the basis of earthquake slip vectors and for these and other arcs from geological observations from estimates of max and the arc parallel gradients in obliquity arc parallel strain rates are estimated to be 1 to 3 10 8 yr for the sumatran forearc 2 to 6 10 8 yr for the aleutian forearc and 0 3 to 3 10 8 yr for the philippine forearc oblique convergence and subsequent arc parallel extension if accompanied by crustal thinning may provide an important yet little appreciated mechanism for bringing high grade metamorphic rocks to the surface of subduction complexes

strain partitioning along the himalayan arc and the nanga parbat antiform shortening along the himalayan arc of continental convergence is approximately in the radial direction if the underthrusting foot wall block india is not deformed the hanging wall block tibet needs to stretch along the arc as suggested by radial grabens in southern tibet in contrast the nanga parbat haramosh massif and the western himalayan syntaxis are part of a 250 km long antiform that strikes in the radial direction northeast and verges northwest the nanga parbat antiform is the structural and topographic expression of arc parallel shortening that compensates for arc parallel extension in southern tibet this shortening is predicted to be as high as 12 mm yr

the slot technique for rock magnetic sampling abstract we have developed a new technique for paleomagnetic sampling that allows one to sample extremely friable poorly to moderately lithified sedimentary and volcanic materials the method uses a portable electric drill and a dual blade masonry wheel or two sharp steel cutting blades with a 2 cm separation which cuts two parallel slots in the material being sampled a second set of cuts at right angles to the first produces a fixed cubic pedestal around which a plastic sample box can be inserted oriented and extracted the method has allowed us to take samples at localities where we were not able to sample using other methods to test the method we have sampled the bandelier tuff in northeast new mexico and have measured the anisotropy of magnetic susceptibility ams on boxes taken using the new method and on cylinders drilled at the same sites using standard techniques results show better ams within site precision for box samples taken using the new method we conclude that the method is convenient reliable and may be preferred in certain types of paleomagnetic studies

crustal strain partitioning implications for seismic hazard assessment in western california oblique strain in the lithospheric mantle and lower crust commonly partitions into nearly pure tangential and normal strain components in the upper seismogenic crust this phenomenon termed strain partitioning produces subparallel strike slip faults and dip slip faults with associated fold belts the occurrence and scale of partitioning is important for correctly identifying and characterizing potential seismic sources and thus is significant for assessing seismic hazard the scale of strain partitioning is a continuum from regional to local regional strain partitioning originates beneath or within the lower part of the seismogenic crust where large magnitude m sub s 5 5 earthquakes typically nucleate the regionally partitioned structures may be expressed by subparallel faults and folds from 5 km to hundreds of kilometers apart and should be treated as independent seismic sources in terms of characterizing earthquake magnitude recurrence slip rate and sense of slip local strain partitioning occurs primarily within the upper part of the seismogenic zone above the region where large magnitude earthquakes nucleate although these structures may be expressed by subparallel faults and folds up to 6 km apart they should be characterized collectively in order to estimate seismic source parameters of the underlying seismogenic source lack of recognition of strain partitioning can and probablymore will lead to an underassessment of slip rate and earthquake recurrence and an inaccurate assessment of sense of slip and fault geometry at seismogenic depth less

extension in nw iran driven by the motion of the south caspian basin contrasted tectonic styles occur in northern iran west of kopet dagh the south caspian basin is an aseismic and possibly rigid blockinvolved inthecollisionzonebetweeneurasiaandarabia tothenw largescalevelocityfield ofirangivenbyrecentrepeated gps surveys suggests 8 mm yr of right lateral displacement for the wnw ese faults in the tabriz region more surprisingly geodetic motion also suggests a prominent n 30 extension north to the tabriz fault where compression would be expected in order to quantify more precisely the right lateral movement of the tabriz region the extension of nw iran and the motion of the south caspian basin we deployed a dense gps network in nw iran from central iran to the turkish armenian and azerbaijan borders three repeated surveys from 2002 to 2004 assess that the tabriz fault concentrates entirely the 8 mm yr of right lateral movement observed in nw iran this rate is in good agreement with a recurrence interval time of 250 300 yr proposed from historical seismicity studies we found also two zones of extension one just north of the tabriz fault in the south of the talesh plateau and another close from the azerbaijan border north of the talesh plateau we suggest that the existence of a northward subduction of the south caspian basin could explain such an extension in the core of the arabia eurasia collision increasing evidences of quaternary extensional tectonics in the region from armenia to alborz may lead to significantly alter our understanding of the northern iran tectonics and challenge the traditional arabian indenter plate tectonics

a tool for obtaining oriented samples of weakly to moderately indurated sedimentary rocks for paleomagnetic measurements abstract the tool is designed to take 1 inch 2 5 cm diameter cores up to 2 inches 5 cm in length in sedimentary rocks of moderate induration that cannot normally be sampled by traditional methods a stainless steel core barrel with internal scriber is hammered vertically into the rock and twisted out the core barrel is attached to an extruder which also holds a plastic bottle the core is screwed out of the core barrel directly into the bottle of the same internal diameter the vial is later cut to an acceptable length for the magnetometer and sealed with a plastic cap inasmuch as the sample is never removed from the plastic bottle fractured and bentonitic rocks which cannot be sampled by means of hand blocks or by diamond drilling can be magnetically measured

magnetostratigraphic and biostratigraphic correlation of late campanian and maastrichtian marine and continental strata from the red deer valley to the cypress hills alberta canada two stratigraphic sequences red deer valley and cypress hills sections in alberta spanning the late campanian to paleocene are magnetostratigraphically and biostratigraphically characterized the red deer valley section had previously been studied but additional material has allowed the extension of the magnetozonation downwards into the bearpaw formation higher sample resolution has allowed the identification of a number of magnetosubzones in 32n 32r and 33n four reversed magnetosubzones have been identified in magnetozone 32n in addition to the one presently recognized in geomagnetic polarity time scales one normal subzone in 32r and one reversed subzone in 33n have also been recorded the 32r 33n boundary is shown to occur in the baculites cuneatus zone the campanian maastrichtian boundary is indicated to be at or near the baculites eliasi baculites baculus boundary at the top of 32n comparisons of the biostratigraphy between the two areas indicate that palynomorph ranges differ from data p

surface expression of thrust faulting in eastern iran source parameters and surface deformation of the 1978 tabas and 1968 ferdows earthquake sequences summary previously unrecognised thrust faults in eastern iran were responsible for a destructive earthquake at tabas 1978 september 16 which produced over 80 km of distributed and discontinuous surface ruptures above a series of low anticlinal hills to the west of a major range front analysis of long period body wave seismograms shows a simple rupture on a gently dipping 16 thrust with a slight right lateral component this is compatible with the locally recorded aftershock distribution body wave analysis of two later smaller events show similar source orientations several indicators of long term active folding at tabas can be recognised in the geomorphology and surface ruptures from 1978 are consistent with co seismic fold growth drainage incision also indicates uplift at depth on thrust faults dipping eastwards beneath the folds body wave seismograms for two earthquakes near ferdows 150 km east of tabas in september 1968 also show thrust faulting at depths of 10 km again the surface geomorphology indicates a region of folding above an eastward dipping thrust fault which is 10 km west of a fault bounded range front in both tabas and ferdows the active faulting appears to show quaternary migration away from the range front possibly in response to stresses produced by the elevated topography the identification of zones of active fault related folding is important for earthquake hazard assessment and also for an understanding of the local tectonics we conclude that the structures which gave rise to the 1968 and 1978 earthquakes could have been recognised beforehand from the clear signals in the geomorphology had we known what to look for at that time

infrasound monitoring of volcanoes to probe high altitude winds 1 active volcanoes in the vanuatu archipelago permanently generate infrasonic waves their monitoring over 1 year exhibits clear seasonal trends in the direction of arrival of the detected signals from summer to winter the azimuth variation reaches 15 this deviation is essentially due to the reversibility of the zonal stratospheric wind with season which strongly affects the deflection of the ray direction a three dimensional 3 d ray tracing modeling roughly explains the observed seasonal trend in the azimuth variation but underestimates its amplitude the discrepancy between the measurements and the results of simulation is explained by undervalued wind speeds in the upper atmosphere infrasonic observations are used as input of an inversion scheme for adjusting the vertical structure of the wind in the upper stratosphere and mesosphere it is shown that the mesospheric zonal winds are underestimated by at least 20 m s throughout the year with differences reaching 50 m s

western u s infrasonic catalog illuminating infrasonic hot spots with the usarray 1 in this study reverse time migration is applied to signals recorded by the 2007 08 usarray presumably due to acoustic to seismic coupling to detect and locate in two dimensional space and time 901 sources of atmospheric infrasound defining the western united states infrasonic catalog wusic the detections are visually inspected and ranked uncertainties are estimated using a bootstrap technique the method correctly locates most rocket motor detonations in utah and a bolide explosion in oregon with an average spatial accuracy of 50 km and 25 km respectively the origin time statistics for 2007 and 2008 events are nearly identical and suggest a predominant human origin the event locations illuminate repeating sources of infrasound or infrasonic hot spots in nevada utah and idaho that are spatially associated with active military areas the infrasonic arrivals comprise several branches that are observed to a range between 200 and 1500 km to the east and west of the epicenter in the winter and summer respectively the optimum group velocities are gaussian distributed and centered at 295 m s a seasonal variation in optimum group velocities exhibits good correlation with atmospheric temperature the results show that relatively dense seismic networks fill in the gaps between sparsely located infrasound arrays and provide valuable information for regional infrasonic source location and propagation studies specifically the catalogs presented here can be used to statistically validate and improve propagation models especially above the middle stratosphere where winds are not directly measured by ground based weather stations or meteorological satellites

active tectonics and strain partitioning along dextral fault system in central iran analysis of geomorphological observations and geophysical data in the kashan region abstract this paper uses high resolution images and field investigations in conjunction with seismic reflection data to constrain active structural deformation in the kashan region of central iran offset stream beds and qanats indicate right lateral strike slip motion at a rate of about 2 mm yr along the nw se trending qom zefreh fault zone which has long been recognized as one of the major faults in central iran however the pattern of drainage systems across the active growing folds including deep incision of stream beds and deflected streams indicate uplift at depth on thrust faults dipping sw beneath the anticlines therefore our studies in the kashan region indicate that deformation occurs within central iran which is often considered to behave as a non deforming block within the arabia eurasia collision zone the fact that the active qom zefreh strike slip fault runs parallel to the active folds which overlie blind thrust faults suggests that oblique motion of arabia with respect to eurasia is partitioned in this part of central iran

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

a study of infrasound propagation using dense seismic network recordings of surface explosions abstract we use dense seismic network recordings of accurately located surface explosions in northern utah to shed light on the propagation of infrasound through the stratosphere the data clearly show propagation of infrasound downwind from the source as expected the data also clearly show the penetration of infrasound into geometric shadow zones near the source and the spread of infrasound to a distance of 800 km from the source the spread of infrasound both toward and away from the source is not predicted by applying either ray theory or the full wave finite difference technique to smooth ground to space g2s models the mismatch between synthetics and data suggest a missing component in these models possibly a small scale gravity wave structure comparison of the network recordings of approximately 1500 infrasound signals with travel time predictions based on rays shows no significant average bias in the travel times on average recorded signals arrived 1 s earlier than predictions travel time residuals are normally distributed about the mean with a standard deviation of 15 s the small bias of the travel time predictions indicates that despite the fact that small scale structure is averaged out of commonly used g2s models the large scale structure of the atmosphere is accurately represented the scatter of travel time residuals is suggestive of small scale structure missing from the models that we used to make the predictions but firm conclusions would require a more in depth study

deciphering oblique shortening of central alborz in iran using geodetic data the alborz is a narrow 100 km and elevated 3000 m mountain belt which accommodates the differential motion between the sanandaj sirjan zone in central iran and the south caspian basin gps measurements of 12 geodetic sites in central alborz between 2000 and 2002 allow to constrain the motion of the belt with respect to western eurasia one site velocity on the caspian shoreline suggests that the south caspian basin moves northwest at a rate of 6 2 mm year with respect to western eurasia north south shortening across the alborz occurs at 5 2 mm year to the south deformation seems to extend beyond the piedmont area probably due to active thrusting on the pishva fault we also observe a left lateral shear of the overall belt at a rate of 4 2 mm year consistent with the geological motion observed along e w active strike slip faults inside the belt e g the mosha fault

late cretaceous to early tertiary magnetostratigraphy of a continental sequence red deer valley alberta canada the red deer valley exposes a conformable 350 m thick late campanian to early paleocene fluvial deltaic coal bearing sequence named the edmonton group systematic sampling and paleomagnetic analysis of the dominant lithologies mudstones sandstones and shales were carried out over five sections correlated by coal seams to provide some 500 sites stratigraphic levels primary detrital remanent magnetization directions after alternating field cleaning produce a polarity reversal pattern correlatable to sea floor magnetic anomalies 29 33 the campanian maastrichtian boundary based upon the first appearance of wodehouseia and the maastrichtian paleocene cretaceous tertiary boundary based upon an ir anomaly associated with dinosaur and cretaceous palynofloral extinctions correlate closely magnetostratigraphically with the marine foraminiferal section at gubbio italy radiometric dating of bentonites has indicated the ages of these boundaries to be approximately 71 and 64 ma respectively

an analysis of ground shaking and transmission loss from infrasound generated by the 2011 tohoku earthquake 1 the 2011 mw9 0 tohoku earthquake generated infrasound that was recorded by nine infrasonic arrays most arrays recorded a back azimuth variation with time due to the expanse of the source region we use ray tracing to predict group velocities and back azimuth wind corrections a japan accelerometer network recorded ground shaking in unprecedented spatial resolution we back projected infrasound from arrays is44 kamchatka and is30 tokyo to the source region and compare these results with acceleration data is44 illuminates the complex geometry of land areas that experienced shaking is30 illuminates two volcanoes and a flat area around the city of sendai where the maximum accelerations occurred the arrays and epicentral region define three source receiver profiles the observed broadband energy transmission loss tl follows an exponential decay law the best fitting model which has parameters that are interpreted to include the effects of geometric spreading scattering and the maximum ratio of the effective sound speed in the stratosphere to that at the ground accounts for stratospheric wind speed yields a 65 variance reduction relative to predictions from a traditional tl relationship this model is a simplified version of the model of le pichon et al 2012 which yields an 83 variance reduction for a single frequency implying that fine scale atmospheric structure is required to explain the tl for stratospheric upwind propagation our results show that infrasonic arrays are sensitive to ground acceleration in the source region of megathrust earthquakes the tl results may improve infrasonic amplitude scaling laws for explosive yield