the present day stress field of australia abstract the unusual present day crustal stress pattern of the australian continent has been the subject of scientific debate for over 25 years the orientation of maximum horizontal present day stress s hmax in continental australia is unlike all other major tectonic plates in that the stress pattern shows regional variability and it is not oriented sub parallel to the direction of absolute plate motion previous studies on the stress pattern of australia revealed that the complex stress pattern of the continent is controlled at a first order by the superposition of plate tectonic forces exerted at the plate boundaries however prior analysis of the contemporary australian crustal stress pattern have been unable to model or explain the stress pattern observed in most of eastern australia and has not extensively addressed the numerous smaller scale variations in stress orientation the recent development of unconventional reservoirs in australia has resulted in a greatly increased amount of new data for stress analysis in previously unstudied or poorly constrained areas in eastern australia in addition stress analysis in conventional hydrocarbon mineral and geothermal exploration in all other parts of the continent provides the opportunity to review and update the australian stress map asm this study presents the new release of the asm with a total of 2150 stress data records in australia increased from 594 data records in 2003 the 2016 asm contains 1359 data records determined from the interpretation of drilling related stress indicators 650 from earthquake focal mechanism solutions 139 from shallow engineering measurements and two from geological indicators the results reveal four distinct regional trends for the s hmax orientation in australia including a nne ssw s hmax trend in northern and northwestern australia which rotates to a prevailing e w orientation in most western and south australia the orientation of s hmax in eastern australia is primarily ene wsw and swings to nw se in southeastern australia a comparison between the new asm database and neotectonic features further confirms the role of contemporary stress in recent deformation of the australian crust the 2016 asm reveals significant discrepancies between newly observed s hmax orientations and predictions by published geomechanical numerical models for the australian continent forces generated at the boundary of indo australian plate remain the major control on the regional crustal stress pattern in continental australia however the increased data density particularly in eastern australia reveals numerous local perturbations of the stress field that were not previously clearly captured hence the key findings of the new release are that local intra plate stress sources are more significant than previously recognized particularly in eastern australian basins and cause substantial local scale rotations of the present day crustal stress pattern that have not been factored into existing australian stress models

an orientation based correction method for sfm mvs point clouds implications for field geology abstract advancements in computing capabilities over the last decade have allowed for the routine creation of structure from motion multiview stereo sfm mvs terrain models that can serve as base for high resolution geologic mapping outcrops models developed from these systems are high resolution photo realistic 3d base providing unprecedented capability for geometric analysis yet before this technology becomes a mainstay of field geology the potential errors associated with it must be well understood here we compare orientation measurements from multi point analyses on the sfm mvs point clouds to those taken in the field with the objective of resolving the geometry of complex folds within the outcrop we also analyzed two point clouds of the same exposure created from different ground based cameras to compare the ranges of error we found that the point clouds produced from ground based photos exhibited significant rigid body rotation relative to the real world despite well distributed ground control yet the models maintained a realistic scale and internal geometry to correct the error the model values were rotated and the discrepancy reassessed the two point clouds produced similar results however the sony compact digital camera based point cloud ultimately corresponded more closely to field values we suggest that the primary cause of the error in the point clouds was gps based and was enhanced by the lack of significant topographic relief in our camera positions allowing rigid body rotations along the axis of the photographic array this outcome suggests that care must be taken when gps errors are a significant fraction of the outcrop size and relatively 2d outcrops imaged by a relatively 1d image array are subject to rotation errors that are difficult to remove without high resolution ground control short of using a uav and or rtk gps we show how this can be resolved simply by collecting several known orientations in the field which can then be used to orient the model more accurately akin to ground control points this addition is a key step if this method is to be used for more thorough analysis and is a general method that could be used to orient virtual outcrops with no geographic reference

uncertainty analysis of earthquake source parameters determined from insar a simulation study 1 we assessed the accuracy of earthquake source parameters inverted from simulated interferometric synthetic aperture radar insar data using focal mechanisms of australian earthquakes 1959 to the present we simulated synthetic two pass insar observations with realistic spatial noise derived from the characteristics of actual ers 2 and envisat insar data observed over australia the precision of two pass satellite sar interferometry with ers 2 and envisat sar data in the australian region can approach 2 mm 1 and is routinely at the 4 mm level the use of spatially correlated observational weights has minimal impact on the accuracy of earthquake source parameters inverted from insar data in most cases single geometry i e ascending or descending insar observations can be used to accurately determine earthquake source parameters although typically a combined geometry reduces the source parameter uncertainties by a factor of 1 5 in general earthquakes of magnitude 4 8 are unlikely to be observable by insar although very shallow events would be detectable insar is insensitive to magnitude 6 2 earthquakes deeper than 10 km and magnitude 5 5 deeper than 6 km for earthquake magnitudes 5 8 average depth 6 5 km we could estimate the epicenter of the rupture with an average accuracy of 0 25 km depth to within 0 5 km and the fault orientation to better than 2 our findings based on simulated australian earthquakes are representative of typical intraplate earthquakes and would be valid in many other regions to date no actual earthquakes have been observed by insar in australia

estimating bedrock depth in the case of regolith sites using ambient noise analysis abstract subsurface geometry particularly the depth of bedrock is crucial in seismic hazard studies because the basin geometry has been shown to play an important role in the altering of seismic waves estimating the bedrock surface using ambient seismic noise analysis has been undertaken by many researchers with most studies focusing on sites with a strong impedance contrast between the bedrock and the overlying materials the application of this technique at regolith sites which is subjected to impedance contrasts in the low to high range is underdeveloped and requires further attention this study seeks to address this need and is focused on the city of adelaide in south australia which exhibits site amplification and is associated with various impedance contrasts analyses of ambient noise data are carried out using the generic function gf of the classic horizontal vertical spectral ratio hvsr method and the spatial autocorrelation spac technique to estimate the depth to bedrock comparison of the bedrock depth predictions from the seismic methods with boreholes drilled in close proximity to the measured sites demonstrate that the spac method provides superior estimates especially to those obtained from the other approach this work demonstrates that the microtremor spac method is an effective tool for estimating bedrock structure at regolith sites

detection and geometric characterization of rock mass discontinuities using a 3d high resolution digital outcrop model generated from rpas imagery ormea rock slope italy abstract the use of a remotely piloted aircraft system rpas and digital photogrammetry is valuable for the detection of discontinuities in areas where field mapping and terrestrial photogrammetry or laser scanner surveys cannot be employed because the slope is unsafe inaccessible or characterized by a complex geometry with areas not visible from the ground using the structure from motion method the acquired images can be used to create a 3d texturized digital outcrop model tdom and a detailed point cloud representing the rock outcrop discontinuity orientations in a complex rock outcrop in italy were mapped in the field using a geological compass and by manual and automated techniques using a tdom and point cloud generated from rpas imagery there was a good agreement between the field measurements and manual mapping in the tdom semi automated discontinuity mapping using the point cloud was performed using the dse qfacet fm and qfacet kd tree methods applied to the same 3d model significant discrepancies were found between the semi automatic and manual methods in particular the automatic methods did not adequately detect discontinuities that are perpendicular to the slope face bedding planes in the case study these differences in detection of discontinuities can adversely influence the kinematic analysis of potential rock slope failure mechanisms we use the case study to demonstrate a workflow that can accurately map discontinuities with results comparable to field measurements the combined use of tdom and rpas dramatically increases the discontinuity data because rpas can supply a good coverage of inaccessible or hidden portions of the slope and tdom is a powerful representation of the reality that can be used to map discontinuity orientations including those that are oriented perpendicular to the slope

a new methodological approach to assess the stability of discontinuous rocky cliffs using in situ surveys supported by uav based techniques and 3 d finite element model a case study abstract this paper aims to present a new methodological approach for the stability assessment of coastal cliffs constituted of discontinuous rock masses the method entails in situ specific geostructural and geomechanical surveys three dimensional uav based photogrammetric structural models laboratory geotechnical tests and two and three dimensional finite element analysis fem the application of the method to a case study is then presented and discussed it regards a 600 m long sea rocky cliff located at sant andrea melendugno south of apulia se italy and faced to the southern adriatic sea here the cliff is made up of an about 15 m thick sequence of laminate calcisiltites alternate with bioturbated calcarenites belonging to the uggiano la chiesa fm middle upper pliocene the structural discontinuities detected with photogrammetry techniques were compared and validated with those derived from conventional in situ survey methods later on the paper discusses assumptions and results of two and three dimensional finite element models developed to investigate the potential failure mechanisms of the sea cliff accounting for pre existing weak planes or discontinuities with unfavourable orientation the failure mechanisms obtained by both fem analysis agree well with those typically observed in the study area

influence of landscape coverage on measuring spatial and length properties of rock fracture networks insights from numerical simulation natural fractures are ubiquitous in the earth s crust and often deeply buried in the subsurface due to the difficulty in accessing to their three dimensional structures the study of fracture network geometry is usually achieved by sampling two dimensional 2d exposures at the earth s surface through outcrop mapping or aerial photograph techniques however the measurement results can be considerably affected by the coverage of forests and other plant species over the exposed fracture patterns we quantitatively study such effects using numerical simulation we consider the scenario of nominally isotropic natural fracture systems and represent them using 2d discrete fracture network models governed by fractal and length scaling parameters the groundcover is modelled as random patches superimposing onto the 2d fracture patterns the effects of localisation and total coverage of landscape patches are further investigated the fractal dimension and length exponent of the covered fracture networks are measured and compared with those of the original non covered patterns the results show that the measured length exponent increases with the reduced localisation and increased coverage of landscape patches which is more evident for networks dominated by very large fractures i e small underlying length exponent however the landscape coverage seems to have a minor impact on the fractal dimension measurement the research findings of this paper have important implications for field survey and statistical analysis of geological systems

reproducibility of uav based earth topography reconstructions based on structure from motion algorithms combination of uav based aerial pictures and structure from motion sfm algorithm provides an efficient low cost and rapid framework for remote sensing and monitoring of dynamic natural environments this methodology is particularly suitable for repeated topographic surveys in remote or poorly accessible areas however temporal analysis of landform topography requires high accuracy of measurements and reproducibility of the methodology as differencing of digital surface models leads to error propagation in order to assess the repeatability of the sfm technique we surveyed a study area characterized by gentle topography with an uav platform equipped with a standard reflex camera and varied the focal length of the camera and location of georeferencing targets between flights comparison of different sfm derived topography datasets shows that precision of measurements is in the order of centimetres for identical replications which highlights the excellent performance of the sfm workflow all parameters being equal the precision is one order of magnitude higher for 3d topographic reconstructions involving independent sets of ground control points which results from the fact that the accuracy of the localisation of ground control points strongly propagates into final results 2015 elsevier b v

3d digital outcrop modelling of the lower cretaceous los santos formation sandstones mesa de los santos region colombia implications for structural analysis abstract the increasing development of the geological data acquisition and processing techniques for outcrops from photographs acquired with the unmanned aerial vehicles has had a great impact on various branches of geology such as structural geology when approaching structural analysis one of the main inputs is given by the fracture orientations therefore the use of unmanned aerial vehicles is a great benefit for acquiring in a very short time a large georeferenced dataset for fractures distribution and orientation even in normally non accessible outcrops access during the fieldwork as well as the ease of data processing and visualization constitute great advantages provided by the use of unmanned aerial vehicles in structural analysis and modelling in this study data were acquired from two outcrops from the lower cretaceous los santos formation sandstones mesa de los santos region colombia el duende and la mojarra outcrops the data was processed in photogrammetry software based on the structure from motion technique with which a dense point cloud was obtained for each outcrop the dense point cloud was processed with the discontinuity set extractor software obtaining the main families of discontinuities and their associated clusters later as a validation these orientations which obtained in a digital way were contrasted with field data previously acquired in the area obtaining a good consistency between both datasets finally the data was associated with the regional structural trends evidenced in the field data generating more data to improve the structural models of the area

origin of sheet structure 1 morphology and boundary conditions abstract sheet structure or large scale exfoliation is the division of a rock mass into lenses plates or sheets approximately parallel to the earth s surface sheet fractures which separate the plates are characterized by surface markings resembling those formed during the brittle fracture of metals glass and ceramics and those on joints in rock lineations or hackle marks parallel to the direction of fracture propagation are common branching occurs during propagation so that the fractures appear as many echelon segments in profile the opposing surfaces of sheet fractures observed in quarry walls and natural exposures are typically in contact damage if any to rock adjacent to sheet fractures is generally limited to a zone less than one centimeter wide sheets tend to parallel preferred orientations of microcracks in many rock masses most sheets that are exposed today are of prehistoric origin but in some rock masses such as chelmsford granite in massachusetts new sheets continue to form sheet structure forms in environments of high differential stress dominated by large scale compression parallel to an exposed rock surface in parts of the chelmsford granite the magnitude of this compression is greater than 30 mpa in the zone of sheeting high differential stresses near the ground surface can result from several natural agents including contemporary tectonic forces vertical unloading of a rock mass that formed at depth under high triaxial compression and suppression of expansion that would otherwise result from temperature increases or chemical alteration of the rock exfoliation of boulders during forest fires and spheroidal weathering of boulders appears to occur under similar states of stress although the agents responsible for the stresses differ

nw australian intraplate seismicity and stress regime 1 the interrelations between stress orientation regional deformation and seismic activity in the context of intraplate seismicity continue to pose difficult questions stress models of the australian continent are largely based on nonseismic information our study of 26 microearthquakes in nw australia shows that they are good indicators of the seismogenic stress field by inverting focal mechanisms calculated from the events we obtained deviatoric stress tensors in full agreement with the known in situ stress field the stress tensors corroborate the elastic modeling of the continent the methods used here have widespread applicability in determining crustal stress field parameters in regions where in situ stress data are sparse or absent

lidar uav or compass clinometer accuracy coverage and the effects on structural models abstract light detection and ranging lidar and structure from motion sfm provide large amounts of digital data from which virtual outcrops can be created the accuracy of these surface reconstructions is critical for quantitative structural analysis assessment of lidar and sfm methodologies suggest that sfm results are comparable to high data density lidar on individual surfaces the effect of chosen acquisition technique on the full outcrop and the efficacy on its virtual form for quantitative structural analysis and prediction beyond single bedding surfaces however is less certain here we compare the accuracy of digital virtual outcrop analysis with traditional field data for structural measurements and along strike prediction of fold geometry from stackpole syncline in this case the sfm virtual outcrop derived from uav imagery yields better along strike predictions and a more reliable geological model in spite of lower accuracy surface reconstructions than lidar this outcome is attributed to greater coverage by uav and reliable reconstruction of a greater number of bedding planes than terrestrial lidar which suffers from the effects of occlusion irrespective of the chosen acquisition technique we find that workflows must incorporate careful survey planning data processing and quality checking of derived data if virtual outcrops are to be used for robust structural analysis and along strike prediction

a large amplitude traveling ionospheric disturbance produced by the may 18 1980 explosion of mount st helens a remarkable long lived large scale traveling ionospheric disturbance tid excited by the may 18 1980 explosion of mount st helens has been detected in total electron content monitor data oscillatory perturbations in the electron column density of the ionosphere with amplitudes about 10 of the nominal daytime content were detected at three stations whose ionospheric penetration points lie between 1610 and 1890 km from mount st helens smaller perturbations were detected at five of six additional stations between 3760 and 4950 km away the period of the tid increased linearly with great circle distance from mount st helens ranging from 37 min at the nearest station to 116 min at the most distant one the tid persisted for at least four cycles at the three close stations and three cycles at the more distant stations and was qualitatively similar to tids produced by the low altitude thermonuclear detonations of the 1960 s the disturbance front of this tid accelerated from an average velocity of 350 m s between mt st helens and the close stations to an average velocity of 550 m s to the more distant ones in analogy with the bomb excited disturbances this tid is interpreted as the ionospheric fluctuations induced by a gravity wave excited by the explosion of mount st helens propagating in the neutral atmosphere a model based on the free wave response of an isothermal atmosphere to a point disturbance provides a good fit to the data at the three closest stations but no such model can account for all of the data modeling of the long distance behavior of the mount st helens tid in terms of upper atmosphere guided gravity waves is complicated by the requirement of exciting them by a ground level explosion a comprehensive explanation would probably include the propagation of energy to ionospheric heights in free modes and the excitation thereby of guided modes there was no evidence for a strong supersonic shock wave in the ionosphere as a result the mount st helens disturbance may prove to be a cleaner test of detailed theories of the point excitation and propagation of gravity waves in a realistic atmosphere than were tids excited by thermonuclear weapons

ground based and uav based photogrammetry a multi scale high resolution mapping tool for structural geology and paleoseismology this contribution reviews the use of modern 3d photo based surface reconstruction techniques for high fidelity surveys of trenches rock exposures and hand specimens to highlight their potential for paleoseismology and structural geology we outline the general approach to data acquisition and processing using ground based photographs acquired from standard dslr cameras and illustrate the use of similar processing approaches on imagery from unmanned aerial vehicles uavs it is shown that digital map and trench data can be acquired at ultra high resolution and in much shorter time intervals than would be normally achievable through conventional grid mapping the resulting point clouds and textured models are inherently multidimensional x y z point orientation colour texture archival and easily transformed into orthorectified photomosaics or digital elevation models dems we provide some examples for the use of such techniques in structural geology and paleoseismology while pointing the interested reader to free and commercial software packages for data processing visualization and 3d interpretation photogrammetric models serve to act as an ideal electronic repository for critical outcrops and observations similar to the electronic lab book approach employed in the biosciences this paper also highlights future possibilities for rapid semi automatic to automatic interpretation of the data and advances in technology

uav based surveying in volcano tectonics an example from the iceland rift abstract in the present work we applied the use of an unmanned aerial vehicle uav a quadcopter and the aerial structure from motion digital photogrammetry image processing technique asfm to study volcano tectonics and tectonic features in an active icelandic rift data have been collected in order to evaluate the holocene deformation in the northern volcanic zone of iceland we mapped 397 structures mainly related to extension fractures and subordinately normal faults in the theistareykir fissure swarm obtaining 1098 and 21 structural data respectively this allowed to reconstruct an overall spreading direction of n108 during holocene times and to calculate a stretch of 1 013 regarding 8 10 ka old lava units deformation in the area is related to both dyke intrusions and extensional tectonics furthermore detailed geological structural field and uav surveys were also performed in two test areas in order to determine data accuracy and the associated reliability of this approach in addition to the above different flight heights were tested suggesting that photo collection with a 12 4 mpx camera at 100 m is efficient to study fracture dilation and kinematics

earthquakes in the ductile regime pseudotachylytes from a crustal scale shear zone in central australia have developed in a cyclical manner once developed an individual pseudotachylyte is deformed in a ductile manner only to be overprinted at a later stage by a new generation of pseudotachylytes such cyclic generation and deformation of pseudotachylyte has been interpreted in the past as representing conditions at the brittleductile transition a different interpretation however is presented here it is proposed that psuedotachylytes and associated ultramylonites can develop entirely within the ductile regime as ductile instabilities such instabilities are different in nature to those previously discussed at length in the geophysical literature but are identical in principle with the instabilities that develop for velocity weakening frictional behavior in spring slider systems at a given strain rate a critical temperature tc is defined at which the transient work hardening equals the product of stress relaxation due to a thermal fluctuation and the heat generated by shearing a necessary condition for ductile instability at a given strain rate is that the temperature is belowtc then the rate of change of stress with respect to strain is negative an additional requirement is that this rate of change exceeds in magnitude the effective elastic stiffness of the loading system ductile instabilities are marginally possible at geological strain rates in quartzites but are possible at mid crustal temperatures in other rock types on the basis of these observations a new interpretation is presented for the base of the seismogenic zone in crustal regions

site classification for earthquake hazard and risk assessment in australia while site response phenomena are well recognized globally the influence of regolith properties on ground motion has not previously been investigated for much of australia in an effort to characterize the regolith in terms of its ability to modify earthquake ground shaking this validation study assesses the national site classification map of australia which has been developed for application in first order earthquake hazard and risk assessment in the absence of regolith thickness and fundamental period data site classes are assigned based on a method developed in california that uses the relationship between geological material and the shear wave velocity of the upper 30 m v s 30 the classification scheme is then adjusted to suit the australian geological environment including a correction for the presence of weathered in situ regolith commonly encountered in this stable tectonic setting the results are validated using geophysical and geotechnical data from a variety of quaternary sedimentary environments in the newcastle sydney and perth urban areas and from bedrock dominated environments at a range of sites across australia the results of these analyses demonstrate the utility but also highlight the limitations of applying a depth limited shear wave velocity method in site classification for seismic hazard assessment

analysis of fluvial architecture in the blackhawk formation wasatch plateau utah u s a using large 3d photorealistic models abstract there are numerous allocyclic and autocyclic factors which influence fluvial sandbody geometry unraveling the relative importance of such factors is challenging because fluvial systems can migrate and avulse across significant distances on the floodplain so that collecting datasets that cover a large enough area with sufficient detail is difficult this problem has been addressed by acquiring an oblique helicopter mounted lidar survey over 16 km of exposed sections from cretaceous coastal plain deposits cropping out in the wasatch plateau of east central utah the exposures of the blackhawk formation occur in steep cliffs which are continuous for several tens of kilometers and have been previously inaccessible for study the recorded lidar data were used to build detailed photorealistic models virtual outcrops from which quantitative dimensional data on fluvial architectural elements mostly sandstone channel bodies were collected those channelized bodies show significant variation in width and thickness 26 of the sandbodies were identified as being multistory channel bodies with a thickness of 9 1 m 4 67 m 1 and a width of 142 6 m 180 7 m which are significantly larger than the measured single story sandbodies 5 9 m and 96 9 m respectively 50 of all sandbodies have aspect ratios smaller 13 1 and the highest values reach 78 1 the spatial constraint of the 397 fluvial sandbodies enabled the recognition of a series of vertical trends within the dataset these trends include a subtle upward increase in width and thickness of both the mean and maximum values this is coupled with a general upward decrease in the number of sandbodies and results in a broadly constant channel to overbank ratio a clear correlation between wider channels with increased distance to the shoreline could also be documented these observations can be explained by considering the entire blackhawk formation as the deposits of a large distributive fluvial system in this model the key control on channel architecture is the distance to the shoreline contrasting with previous interpretations of the blackhawk depositional system in which the rate of accommodation creation in the coastal plain was thought to be the key control on channel geometry and stacking patterns

signals recorded by demeter satellite over active volcanoes during the period 2004 august 2007 december more than 1500 volcanoes can potentially enter into eruption but only some tens of them are equipped with monitoring networks most of volcanic eruptions can be predicted by the integration of continuous real time observations data processing and analysing in the electromagnetic field em a long history of ground observations shows that electric magnetic and electromagnetic signals may precede and accompany volcanic eruptions the possibility that volcanic eruptions may also be preceded by transient electromagnetic anomalies in the ionosphere can be analysed on the basis of demeter mission this microsatellite launched by cnes in 2004 covers 14 orbits per day over seismic and volcanic regions of the earth two complementary and systematic studies are presented over the time period 2004 august 2007 december the first study shows that three types of electric and or magnetic anomalies can be observed in the time window of 30 d preceding an eruption and 15 d after on the 74 eruptions occurring on 50 volcanoes under consideration 48 anomalies are recognised along 30 eruptions 41 per cent of the eruptions were accompanied by em signals on board of the satellite 81 per cent of the anomalies are observed before the eruptions for the period 30 d 15 d and 69 per cent for the period 15 d 15 d in the second study the anomalies above three nearby volcanoes lopevi ambrym and aoba are systematically looked for all orbits between 2004 august and 2006 december anomalies are only observed during periods of larger activity on each of them taking into account that no anomaly is observed a long time before an eruption on can allocate the anomalies to each volcano although the database is still limited the study shows that volcanic activity may be preceded by em perturbations of the ionosphere

rayleigh wave signature in ionograms induced by strong earthquakes 1 after the magnitude 9 0 earthquake off the pacific coast of tohoku near the east coast of honshu japan which occurred on 11 march 2011 an unusual multiple cusp signature mcs was observed in ionograms at three ionosonde stations across japan to investigate the general characteristics of mcss we examined ionograms obtained during the period 1957 to 2011 from five ionosonde stations in japan after earthquakes with a seismic magnitude of 8 0 or greater a total of 43 such earthquakes occurred after 1957 as recorded in the database of the united states geological survey mcss were observed in 8 of 43 earthquakes allowing us to investigate the specific conditions of mcs appearance the appearance of mcss at different epicentral distances exhibits traveling characteristics at a velocity of 4 0 km s which is in the range of rayleigh waves there is a 7 min offset in delay time after the earthquake at each epicentral distance in the travel time diagram this offset is consistent with the propagation time of acoustic waves from the ground to the ionosphere launched by rayleigh waves mcss in ionograms provide a snapshot of vertical disturbances induced by a wave because the sweep time for the whole ionospheric echo traces is much shorter than the propagation time of acoustic waves the vertical scale of the disturbances is 10 30 km which corresponds to an acoustic wave period of 20 50 s at ionospheric heights

geomorphological evidence for late quaternary tectonic deformation of the cape region coastal west central australia abstract a late pleistocene marine isotope stage 5e emergent marine sequence fringes the coastline of the cape region of coastal west central australia and provides elevation and age control to characterize the locations and rates of crustal deformation there is a systematic measurable change in relative paleo sea level elevations across the cape region high precision leveling of modern and pleistocene shoreline features indicates the minimum elevation range of mis 5e shoreline features along the coast is 10 4 m this compares with the 2 5 m elevation range for observed modern shoreline analogs the lack of continuity of mis 5e shoreline elevations along 300 km of coastline demonstrates continuing tectonic deformation along coastal anticlines in the cape region topographic expression of mis 5e features indicates tectonic uplift consistent with late neogene to quaternary deformation on the cape cuvier and cape range anticlines post mis 5e tectonic uplift rates are up to 0 054 0 035 mm yr at fold axial locations estimated subsidence rates are 0 013 0 034 mm yr on fold limbs while the estimated vertical tectonic deformation is small and the rates are low the geomorphological data also demonstrate tectonic activity not stability

insights into mantle type volatiles contribution from dissolved gases in artesian waters of the great artesian basin australia abstract the geochemical features of the volatiles dissolved in artesian thermal waters discharged over three basins millungera galilee and cooper basin of the australian great artesian basin gab consistently indicate the presence of fluids from multiple gas sources located in the crust e g sediments oil reservoirs granites as well as minor but detectable contributions of mantle magma derived fluids the gases extracted from 19 water samples and analyzed for their chemical and isotopic composition exhibit amounts of co2 up to about 340 mlstp lh2o marked by a 13ctdc total dissolved carbon ranging from 16 9 to 0 18 vs pdb while ch4 concentrations vary from 4 4 10 5 to 4 9 mlstp lh2o helium contents were between 9 and 2800 times higher than equilibrium with air saturated water asw with a maximum value of 0 12 mlstp lh2o helium isotopic composition was in the 0 02 0 21 ra range ra air normalized 3he 4he ratio the three investigated basins differ from each other in terms of both chemical composition and isotopic signatures of the dissolved gases whose origin is attributed to both mantle and crustal volatiles mantle he is present in the west central and hottest part of the gab despite no evidence of recent volcanism we found that the partial pressure of helium significantly higher in crustal fluids than in mantle type volatiles enhances the crustal he signature in the dissolved gases thus masking the original mantle contribution neotectonic activity involving deep lithospheric structures and magma intrusions highlighted by recent geophysical investigations is considered to be the drivers of mantle magmatic volatiles towards the surface the results although pertaining to artesian waters from a vast area of 542 000 km2 provide new constraints on volatile injection and show that fluids geochemistry can provide additional and independent information on the geo tectonic settings of the great artesian basin and its geothermal potential

exploiting seismic signal and noise in an intracratonic environment to constrain crustal structure and source parameters of infrequent earthquakes in many regions of the world characterized by a relatively low rate of seismicity the determination of local and regional seismic source parameters is often restricted to an analysis of the first onsets of p waves or first motion analysis due to incomplete information about earth structure and the small size of the events when rare large earthquakes occur in these regions their waveforms can be used to model earth structure this however makes the nature of the earthquake source determination problem circular as source information is mapped as structure presented here is one possible remedy to this situation where through a two step approach we first constrain earth structure using data independent of the earthquake of interest in this study we focus on a region in western australia with low seismicity and minimal instrument coverage and use the capra lp temporary deployment to demonstrate that reliable structural models of the upper lithosphere can be obtained from an independent collection of teleseismic and ambient noise datasets apart from teleseismic receiver functions rfs we obtain group velocities from the cross correlation of ambient noise and phase velocities from the traditional two station method using carefully selected teleseismic earthquakes and station pairs crustal models are then developed through the joint inversion of dispersion data and rfs and structural green s functions are computed from a layered composite model in the second step of this comprehensive approach we apply full waveform inversion three component body and surface waves to the 2007 ml 5 3 shark bay western australia earthquake to estimate its source parameters seismic moment focal mechanism and depth we conclude that the full waveform inversion analysis provides constraints on the orientation of fault planes superior to a first motion interpretation

distribution of discontinuous mudstone beds within wave dominated shallow marine deposits star point sandstone and blackhawk formation eastern utah deposits of wave dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as tanks of sand however important heterogeneities that can act as barriers to fluid flow occur at the parasequence bedset and bed scales especially in viscous oil or low permeability oil fields heterogeneities at the parasequence and bedset scales have been well studied but discontinuous mudstone beds occurring within the shoreface have received little attention the book cliffs and wasatch plateau are among the best exposed and best studied deposits of wave dominated shallow marine systems in the world two parasequences within these outcrops have been studied in detail to investigate the distributions of intrashoreface shales and to propose models for the controls on their distribution a data set consisting of 30 km 18 6 mi of virtual outcrops derived from oblique helicopter mounted light detection and ranging lidar scanning with supporting stratigraphic sections makes it possible to collect a large quantity of accurate geometric data of depositional elements from inaccessible cliffs nine hundred and twenty one discontinuous mudstone beds were measured these occur as ellipses with long axes oriented normal to the paleoshoreline lengths and widths of these mudstone beds exhibit a lognormal distribution with means of 21 9 and 13 8 m 71 9 and 45 3 ft respectively within the shoreface succession the number of mudstone beds increases downward whereas size does not vary significantly with stratigraphic height an average of 100 m 328 ft cumulative length of shale exists per 100 m 328 ft of horizontal outcrop this increases threefold near both wave dominated deltas and bedset boundaries that reflect minor sea level fluctuations during progradation

high resolution lidar and photogrammetric survey of the fumanya dinosaur tracksites catalonia implications for the conservation and interpretation of geological heritage sites increasing political and social awareness of the importance of protecting the geological heritage is compelling geoscientists to consider new methods for reconciling conservation and exploration of their research sites terrestrial light detection and range lidar imaging is an accurate method of collecting 3d spatial data that has so far been under utilized in the geological sciences this aim of this paper is to assess the value of integrated lidar and photogrammetric imaging as a tool for synchronizing scientific exploration with conservation of geological heritage sites fumanya catalonia is one of the most important cretaceous tracksites in europe but the nature of exposure of the track bearing surface has hindered quantitative documentation of the ichnites using integrated light detection and range lidar imaging and photogrammetry it has been possible to construct high resolution digital outcrop models dom of the tracksites photo textured doms are a powerful visualization tool and function as fully 3d interactive databases that preserve information about the site that would otherwise be lost to erosion lidar derived doms have the potential to contribute profoundly to future geoconservation projects particularly as a tool for documenting and monitoring heritage sites and promoting education and tourism lidar scanning also provides sufficient resolution to perform robust quantitative analysis of dinosaur tracks

evaluation of a workflow to derive terrestrial light detection and ranging fracture statistics of a tight gas sandstone reservoir analog understanding natural fracture networks in the subsurface is highly challenging as direct one dimensional borehole data are unable to reflect their spatial complexity and three dimensional seismic data are limited in spatial resolution to resolve individual meter scale fractures here we present a prototype workflow for automated fracture detection along horizontal scan lines using terrestrial light detection and ranging t lidar data are derived from a kilometer scale pennsylvanian locally upper carboniferous reservoir outcrop analog in the lower saxony basin northwestern germany the workflow allows the t lidar data to be integrated into conventional reservoir modeling software for characterizing natural fracture networks with regard to orientation and spatial distribution the analysis outlines the lateral reorientation of fractures from a west southwest east northeast strike near a normal fault with approximately 600 m 1970 ft displacement toward an east west strike away from the fault fracture corridors 10 20 m 33 66 ft wide are present in unfaulted rocks with an average fracture density of 3 4 3 9 m 1 11 2 12 8 ft 1 a reservoir scale digital outcrop model was constructed as a basis for data integration the fracture detection and analysis serve as input for a stochastically modeled discrete fracture network demonstrating the transferability of the derived data into standard hydrocarbon exploration and production industry approaches the presented t lidar workflow provides a powerful tool for quantitative spatial analysis of outcrop analogs in terms of natural fracture network characterization and enriches classical outcrop investigation techniques this study may contribute to a better application of outcrop analog data to naturally fractured reservoirs in the subsurface reducing uncertainties in the characterization of this reservoir type at depth

identification of possible quaternary deformation in the northeastern mississippi embayment using quantitative geomorphic analysis of drainage basin asymmetry to investigate neotectonism in the mississippi embayment east of the new madrid seismic zone we identified geomorphic domains that show evidence of ground tilting during quaternary time transverse basin profiles were converted to two dimensional vectors that denote channel position with respect to basin divides these basin asymmetry vectors record the net direction and degree of lateral migration of trunk streams more than 2500 vectors were measured and spatially averaged within 400 km 2 bins this field of 300 mean vectors delineates several domains that show preferred directions of stream migrations possibly driven by ground tilting the timing of stream migration was interpreted using across valley distributions of quaternary alluvial terraces comparison of our mean vector field with subsurface structures suggests that some domain boundaries may be related to reactivated faults late quaternary activity is suggested for two northeast striking faults of the southeastern reelfoot rift margin we acquired two seismic profiles showing near surface faulting beneath scarps that follow the domain boundary associated with one of these northeast striking faults big creek fault zone reelfoot thrust seismicity ends on the south against this fault suggesting that the rift margin has dextral slip accommodating northeastward movement of the thrust hanging wall our vector field also suggests late quaternary movement on the reelfoot thrust and on two other northwest striking faults here termed the hatchie river fault and the wolf river fault several other weak domains may imply minor elements of neotectonism our results demonstrate that morphometric analysis of drainage basin asymmetry can be an effective reconnaissance tool within neotectonic settings

lidar based digital outcrops for sedimentological analysis workflows and techniques f rarity x m t van lanen d hodgetts r l gawthorpe p wilson i fabuel perez j redfern

morphological impacts of low magnitude seismic events on granite viewing certain landforms with new eyes abstract several landforms developed in massive brittle rocks located in cratonic settings and formerly thought to be caused by external agencies are now attributed to low magnitude seismic events or earth tremors field observations and particularly monitoring of specific sites have shown that the frequent joggling of shield areas has given rise to miniature scarps that define dislodged segments furthermore sheeting fractures previously well known as offloading joints are planes of dislocation and are initiated during low energy earthquakes a tents or pop ups were in past times widely attributed to insolation and less commonly to offloading but they too and like sheet structures and rock wedges are formed by compressive stress applied either instantly during earth tremors or gradually over decades many of these forms develop after exposure but some a tents are almost certainly initiated at the weathering front wedges also develop in the subsurface rock bursts and slabs and blocks are displaced or split during earth tremors it is not suggested that lithostatic pressure can be overlooked but applied compression as well as reduced lithostatic loading are necessary for the development of sheet fractures and the other forms cited

source parameters of seven large australian earthquakes determined by body waveform inversion summary we determine source mechanisms and centroid depths for the seven largest earthquakes in and near the australian continent in the past 20yr using teleseismic body waves six of the earthquakes were thrusts and one was strike slip all five earthquakes that occurred beneath the continent were shallower than 10 km the ranges of centroid depths are constrained to be 1 5 2 4 0 3 5 11 and 6 10km and indicate nearly pure thrust faulting the three shallowest events were associated with surface faulting while the published first motion solutions for these three events included large amounts of strike slip our thrust mechanisms are more consistent with displacements observed at the surface of the earth the range of possible centroid depths for a strike slip earthquake beneath the continental shelf off the northwest coast is 23 29 km and that for a thrust earthquake in oceanic lithosphere beneath the tasman sea is 22 26 km below sea level the pressure axis is consistently near horizontal and in the western half of the continent five earthquakes indicate that the azimuth of the maximum compressive stress is e ene azimuthal range of 66 91 on the basis of one earthquake we conclude that the p axis is oriented nnw beneath the tasman sea

numerical modeling of flexural stresses in the upper crust of ne brazil implications for stress regimes in intraplate settings abstract we model the contribution of the stresses generated by the topography and density heterogeneities in the stress field of ne brazil and the interplay between these and regional stresses our model consists of a horizontally layered elastic slab the lithosphere that floats above an inviscid fluid the asthenosphere where the surface load is generated by the topography and bathymetry and the internal loads are calculated from the bouguer anomalies the deviatoric flexural stresses are calculated in the fourier domain our results showed local flexural stresses with magnitudes comparable to those of the plate wide stresses and mainly controlled by the long wavelength bouguer anomalies scenarios for the total stress field were calculated by superposing different values for an e w oriented regional compression we predict the stress axes orientations and stress regimes for the equatorial margin and the pernambuco shear zone pesz region however we highlight the importance of spreading stresses not considered here in rotating the maximum horizontal compression shmax predictions the prediction of stress regime and stress axes orientation in pesz using low to zero regional compression suggest that a decoupling of the shallow stresses from the plate wide stresses might occur in this region another possible explanation found was that the spreading stresses might counterbalance the regional stresses we conclude that the superposition of principally flexural and plate wide stresses explains reasonably the observed stress regimes and shmax orientations in a great part of ne brazil furthermore flexural stresses are playing an important role in the reactivation of the pesz possibly controlling the stress field

sheet fractures other stress forms and some engineering implications field evidence shows that contrary to common belief sheet fractures and structures are due to compressive stress a suite of minor forms including a tents or pop ups are of similar origin this interpretation carries a range of implications for civil engineering and quarrying projects the minor forms are also indicators of seismicity

harmonic ionospheric oscillation by the 2010 eruption of the merapi volcano indonesia and the relevance of its amplitude to the mass eruption rate abstract using continuous data from ground based global satellite navigation system gnss receivers in java and sumatra indonesia we studied the response of ionospheric total ionospheric electron content tec to the 2010 nov 5 eruption of the merapi volcano in central java we then compared the results with the case of the 2014 feb 13 eruption of the kelud volcano eastern java the tec showed a quasi periodic oscillation of a frequency 4 mhz with average amplitudes of 0 9 and 1 8 relative to background values lasting for 20 and 120 min for the merapi and kelud eruptions respectively by comparing the two cases together with the 2015 april eruption of the calbuco volcano chile we found the relative tec oscillation amplitude may scale with the mass eruption rate this suggests that the product of such tec oscillation amplitude and the duration provides a new measure for the total volume of the volcanic deposits

terrestrial laser scanning in geology data acquisition processing and accuracy considerations terrestrial laser scanning or lidar is a recent innovation in spatial information data acquisition which allows geological outcrops to be digitally captured with unprecedented resolution and accuracy with point precisions and spacing of the order of a few centimetres an enhanced quantitative element can now be added to geological fieldwork and analysis opening up new lines of investigation at a variety of scales in all areas of field based geology integration with metric imagery allows 3d photorealistic models to be created for interpretation visualization and education however gaining meaningful results from lidar scans requires more than simply acquiring raw point data surveys require planning and typically a large amount of post processing time the contribution of this paper is to provide a more detailed insight into the technology data collection and utilization techniques than is currently available the paper focuses on the workflow for using lidar data from the choice of field area and survey planning to acquiring and processing data and finally extracting geologically useful data because manufacturer specifications for point precision are often optimistic when applied to real world outcrops the error sources associated with lidar data and the implications of them propagating through the processing chain are also discussed

fracture characterization and modeling from virtual outcrops advances in virtual outcrop technologies and their introduction to fracture characterization allow extraction of fracture data from very large and inaccessible areas the recent development of automated or semiautomated methods for fracture extraction aims to reduce or avoid tedious time consuming and biased manual interpretation of fractures from virtual outcrops we present a benchmarking exercise between a previously proposed automated fracture picking method manual picking and fieldwork methods comparison between the three methods highlighted their relative advantages and limitations the automated fracture picking method provided excellent results in terms of fracture orientation size spatial distribution and density fieldwork is complementary to fracture extraction from virtual outcrops and it should focus on quality control of remote sensing data poorly exposed areas small scale observations diagenesis timing of fracture development building conceptual models and linking fracture stratigraphy to rock properties we propose a best practice for the use and integration of manual and or automated fracture extraction from virtual outcrop and fieldwork data for fracture characterization and modeling from outcrop analogs we consider integration of different methods as the best way to improve the modeling exercise while reducing operational costs and risks

syndepositional fractures and architecture of the lastoni di formin carbonate platform insights from virtual outcrop models and field studies abstract the recent rapid improvement of unmanned aerial vehicles together with advances in photogrammetry and structure from motion techniques have enhanced the role of digital outcrop models in many field of geology due to the possibility to obtain quantitative information from large and inaccessible areas in this study we integrated digital outcrop modeling techniques and field survey to investigate the architecture of the middle triassic platform of lastoni di formin italian dolomites the research highlighted the presence of two superimposed carbonate bodies the lower unit cassian i is dominated by low angle clinoforms dipping north northeastward and prograding over the basinal san cassiano fm the upper unit cassian ii is characterized by a thick sequence of peritidal cycles connected northward to another generation of clinoforms the inner platform beds of the upper unit display a lateral thickening that is particularly evident near the shelf break and that has been interpreted as due to the increased subsidence and the consequent down to basin tilting of the outermost part of the platform moreover the structural analysis performed on the digital outcrop models and supported by field observations highlighted the presence of an early generation of faults and joints that indicate an early gravitational deformation of the buildup possibly caused by the platform progradation and compaction induced subsidence of the san cassiano basinal deposits these wnw ese synsedimentary structures are formed by normal faults and extensional joints that are oriented nearly perpendicular to the direction of progradation of the carbonate platform

self consistent earthquake fault scaling relations update and extension to stable continental strike slip faults using seismic moment m length l data for stable continental region scr faults augmented by data not included in previous studies this article reassesses and confirms the bilinear scaling relation for the dip slip faults of leonard 2010 furthermore using the new data i propose a separate bilinear relation for estimating magnitude from surface rupture length there are now a small number of scr strike slip earthquakes for which the fault dimensions have been estimated i use these to constrain a trilinear scaling relation for this class of fault for the four fault types interplate dip slip interplate strike slip scr intraplate dip slip and scr intraplate strike slip the scaling relations for the 10 permutations of m d l w and a are given

ionospheric disturbances observed during the period of mount pinatubo eruptions in june 1991 a series of climatic eruptions of mount pinatubo occurred in june 1991 many quasi periodic ionospheric disturbances were observed in the virtual height variations of the ionosphere at chungli in the total electron content variations at lunping kaohsiung and chihpen and in the differential doppler shift data recorded at lunping these ionospheric disturbances were characterized by quasi periodic wavelike trains lasting for several cycles with periods around 16 to 30 min wavelengths between 160 and 435 km and propagation speeds ranging from 131 to 259 m s from the direction of mount pinatubo to the observation sites the oscillation periods downward movement of distortion and inclined phase fronts all show that these ionospheric disturbances were manifested by the gravity waves that arrived from the direction of mount pinatubo by use of a simplified isothermal atmosphere model the propagation mode is interpreted as the freely propagating gravity waves 26 refs

assessment of the precision of smart phones and tablets for measurement of planar orientations a case study abstract although paper and pencil approaches to geological mapping continue digital mapping tools are being increasing implemented in field geology of particular note is the use of an electronic compass inclinometer built into tablets and smartphones for obtaining orientation data where an important question is the reliability of these digital devices relative to conventional analogue compass inclinometers this paper deals with this question through detailed tests of two android devices an honor 3c smartphone and a lenovo b8080 f tablet in order to evaluate potential electronic noise effects the devices were tested in two modes standard and airplane over 14 000 readings from the sensors were collected to evaluate the stability of the sensor s readings and showed that the magnetic sensor in the tablet was unacceptably unstable seven geological compass applications were installed on the honor 3c smartphone and tested against the analogue freiberg geological compass in a field experiment during the experiment 25 fractures varying in azimuth and dip were measured using both devices a high level of disagreement was observed with discrepancies as high as 80 with azimuthal errors dominant analysis of the time series in the data suggest the source of the problem was instability in the magnetic sensor for the smartphone despite the fact the device passed the initial stability test although only two devices were studied these data indicate care must be taken to evaluate compass accuracy on these devices

modeling the topography of shallow braided rivers using structure from motion photogrammetry abstract recent advances in computer vision and image analysis have led to the development of a novel fully automated photogrammetric method to generate dense 3d point cloud data this approach termed structure from motion or sfm requires only limited ground control and is ideally suited to imagery obtained from low cost non metric cameras acquired either at close range or using aerial platforms terrain models generated using sfm have begun to emerge recently and with a growing spectrum of software now available there is an urgent need to provide a robust quality assessment of the data products generated using standard field and computational workflows to address this demand we present a detailed error analysis of sub meter resolution terrain models of two contiguous reaches 1 6 and 1 7 km long of the braided ahuriri river new zealand generated using sfm a six stage methodology is described involving i hand held image acquisition from an aerial platform ii 3d point cloud extraction modeling using agisoft photoscan iii georeferencing on a redundant network of gps surveyed ground control points iv point cloud filtering to reduce computational demand as well as reduce vegetation noise v optical bathymetric modeling of inundated areas and vi data fusion and surface modeling to generate sub meter raster terrain models bootstrapped geo registration as well as extensive distributed gps and sonar based bathymetric check data were used to quantify the quality of the models generated after each processing step the results obtained provide the first quantified analysis of sfm applied to model the complex terrain of a braided river results indicate that geo registration errors of 0 04 m planar and 0 10 m elevation and vertical surface errors of 0 10 m in non vegetation areas can be achieved from a dataset of photographs taken at 600 m and 800 m above the ground level these encouraging results suggest that this low cost logistically simple method can deliver high quality terrain datasets competitive with those obtained with significantly more expensive laser scanning and suitable for geomorphic change detection and hydrodynamic modeling

multiphase breakdown sequence of collapse doline morphogenesis an example from quaternary aeolianites in western australia abstract the morphology of collapse dolines varies according to their maturity and effectiveness of the removal of collapsed material in addition the variable balance between various geomorphic processes due to local geologic hydrologic and climatic settings results in a diverse morphology of collapse dolines and dynamics of their morphogenesis a single generalised proposed sequence of collapse dolines morphogenesis has therefore limited value and more detailed study is needed in terrains which differ in terms of geology hydrology and or climate there is a particularly well exposed karst in stockyard gully national park in the southwestern coastal part of western australia formed in quaternary aeolianites consisting of a dense field of collapse dolines up to 100 m in diameter and on average 10 m deep extensive field work combined with available data of local rock stratigraphy and a comparison to collapse dolines worldwide revealed that the principal processes of collapse doline formation in stockyard gully national park are similar to processes responsible for collapse doline formation worldwide i e collapses above underground chambers and removal of the collapsed material however rock characteristics in the area influence their morphometry due to the mechanical weakness of aeolianite compared to well cemented limestones and a surface calcrete layer with stronger mechanical resistance than underlying aeolianite consequently we propose a new 4 stage multiphase breakdown sequence of collapse doline morphogenesis in aeolianites divided into cave dome calcrete caprock dome young collapse doline and mature collapse doline calcrete caprock dome is stabilised by the uppermost well cemented calcrete and represents a distinctive phase just before the final breakdown to form an actual collapse doline

seismic moment assessment of earthquakes in stable continental regions ii historical seismicity summary this part i study in conjunction with part 11 develops a method to determine within specified uncertainty bounds the seismic moment and thus moment magnitude of all earthquakes of stable continental regions scr for which instrumental or intensity data exist its basis is polynomial regression analysis using a database of scr earthquakes with direct seismic moment determination the independent variables include modern teleseismic magnitudes and regional magnitudes part i and isoseismal areas or number of recording stations part 11 part i11 is an application of the methodology of parts i and i1 to several major historical earthquakes all data used in the regressions are assigned individual uncertainties estimated from the literature or from experience formal confidence limits 68 per cent or 95 per cent on both the regression formulas and the predicted seismic moment values are then possible via error propagation analysis the most complete development is for the teleseismic magnitudes m and mb for both the final regression for log m is a quadratic formula that closely emulates the relationship between amplitude magnitudes and log m expected from dislocation theory and source scaling arguments regressions are also derived for the regional magnitudes mlg and m because there are many scr events mainly pre 1964 that have no teleseismic magnitudes prediction uncertainties from teleseismic magnitudes in moment magnitude units are in the ao 18 0 28 range and from regional magnitudes in the ko 23 0 38 range over a wide magnitude band finally the methodology developed here is generic even though the database is specific application to plate boundary oceanic intraplate or active continental intraplate regions should be straightforward

surveying and modeling of rock discontinuities by terrestrial laser scanning and photogrammetry semi automatic approaches for linear outcrop inspection abstract rock face diagnosis is a monitoring operation that is used to optimize rock risk treatment works in terms of ensuring that safety requirements are met at the lowest cost diagnoses require measuring the location and orientation of rock discontinuities at the surface of the rock mass these measurements are then entered into a structural model that extrapolates the data collected at the surface to the inner part of the rock mass currently most surveys are empirical and are carried out manually using a compass clinometer in addition they tend to examine only the most highly fractured area of a rock face even though safety considerations demand an exhaustive study of the whole face these deficiencies can be overcome by using dense 3d measurement techniques such as terrestrial laser scanning and optical imaging to obtain a more complete 3d model and structural statement hence we have developed a semi automatic process that allows 3d models to be combined with the results of field surveys in order to provide more precise analyses of rock faces for example by classifying rock discontinuities into subsets according to their orientation further research is being carried out in order to combine 3d data and 2d digital images as a support for structural survey trials carried out in a limestone quarry in the french alps allowed us to compare data sets obtained using manual surveying methods the well known laser scanning method and the lower cost photogrammetric survey method

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

aftershocks of the 1988 january 22 tennant creek australia intraplate earthquakes evidence for a complex thrust fault geometry summary on 1988 january 22 three earthquakes of ms 6 3 6 7 occurred in a 12 hr period near tennant creek northern territory in the proterozoic north australian craton and produced 32 km of surface rupture on two main scarps the lake surprise scarp is shaped like a boomerang with the east arm trending ese and the west arm wsw the kunayungku scarp lies 7 km to the northwest and trends ese locations of 211 aftershocks determined using data from portable seismograph arrays define a 10 km by 40 km aftershock zone elongated parallel to the trend of the surface ruptures in the western and eastern part of the fault zone aftershocks occur only south of the kunayungku and eastern lake surprise scarps respectively in the central section in contrast aftershocks lie primarily to the north of the western arm of the lake surprise scarp focal depths range from the surface to 8km in all sections the shallowest earthquakes lie closest to the scarps whereas deeper events lie further away in cross section the aftershocks lie in three distinct inclined zones which delineate fault surfaces ruptured by the main shocks aftershocks are concentrated near the edges of the inferred fault surfaces suggesting that stress was relieved in the centre of the faults by rupture during the main shocks the inferred fault plane dips are 45 to the ssw for the kunayungku fault 55 to the nnw for the western lake surprise fault and 35 to the ssw for the eastern lake surprise fault these dip directions are consistent with the sense of thrust movement inferred from surface deformation the reversal of fault dip and sense of movement between the central and end segments requires a complicated fault geometry the aftershock data would allow a second south dipping plane in the central section that does not intersect the surface this blind fault may be responsible for much of the moment release interpreted from the modelling of broad band teleseismic waveforms choy bowman 1989 rupture of the north dipping plane may have been controlled by a pre existing fault marked at the surface by a quartz ridge 5 km long and may be of secondary importance although the quartz ridge suggests previous faulting the absence of significant topographic relief together with estimates of erosion rates suggest an average repeat time in excess of 104yr preliminary interpretation of water withdrawal histories and water level data from a borefield adjacent to the eastern lake surprise scarp does not support a causal relationship between the borefield and the occurrence of the earthquakes the nearby warramunga wra seismic array provides a record of local earthquake activity from 1965 to the present the fault area was essentially aseismic until two small earthquakes in 1986 february and a series of six magnitude 4 5 earthquakes in 1987 january which were followed by more than 1000 aftershocks the frequency of occurrence of aftershocks declined very slowly in 1987 with p 0 2 in the modified omori formula whereas for the 1988 aftershock sequence p 1 the low p during 1987 may have been diagnostic of high stress in the source and water authority provided partial financial support for j r b and g g

paleoseismicity of two historically quiescent faults in australia implications for fault behavior in stable continental regions paleoseismic studies of two historically aseismic quaternary faults in australia confirm that cratonic faults in stable continental regions scr typically have a long term behavior characterized by episodes of activity separated by quiescent intervals of at least 10 000 and commonly 100 000 years or more studies of the approximately 30 km long roopena fault in south australia and the approximately 30 km long hyden fault in western australia document multiple quaternary surface faulting events that are unevenly spaced in time the episodic clustering of events on cratonic scr faults may be related to temporal fluctuations of fault zone fluid pore pressures in a volume of strained crust the long term slip rate on cratonic scr faults is extremely low so the geomorphic expression of many cratonic scr faults is subtle and scarps may be difficult to detect because they are poorly preserved both the roopena and hyden faults are in areas of limited or no significant seismicity these and other faults that we have studied indicate that many potentially hazardous scr faults cannot be recognized solely on the basis of instrumental data or historical earthquakes although cratonic scr faults may appear to be nonhazardous because they have been historically aseismic those that are favorably oriented for movement in the current stress field can and have produced unexpected damaging earthquakes paleoseismic studies of modern and prehistoric scr faulting events provide the basis for understanding of the long term behavior of these faults and ultimately contribute to better seismic hazard assessments

attenuation of ground motion spectral amplitudes in southeastern australia a dataset comprising some 1200 weak and strong motion records from 84 earthquakes is compiled to develop a regional ground motion model for southeastern australia sea events were recorded from 1993 to 2004 and range in size from moment magnitude 2 0 m 4 7 the decay of vertical component fourier spectral amplitudes is modeled by trilinear geometrical spreading the decay of low frequency spectral amplitudes can be approximated by the coefficient of r 1 3 where r is hypocentral distance within 90 km of the seismic source from approximately 90 to 160 km we observe a transition zone in which the seismic coda are affected by postcritical reflections from midcrustal and moho discontinuities in this hypocentral distance range geometrical spreading is approximately r 0 1 beyond 160 km low frequency seismic energy attenuates rapidly with source receiver distance having a geometrical spreading coefficient of r 1 6 the associated regional seismic quality factor can be expressed by the polynomial log q f 3 66 1 44 log f 0 768 log f 2 0 058 log f 3 for frequencies 0 78 f 19 9 hz fourier spectral amplitudes corrected for geometrical spreading and anelastic attenuation are regressed with m to obtain quadratic source scaling coefficients modeled vertical component displacement spectra fit the observed data well amplitude residuals are on average relatively small and do not vary with hypocentral distance predicted source spectra i e at r 1 km are consistent with eastern north american ena models at low frequencies f less than approximately 2 hz indicating that moment magnitudes calculated for sea earthquakes are consistent with moment magnitude scales used in ena over the observed magnitude range the models presented represent the first spectral ground motion prediction equations developed for the southeastern australian region this work provides a useful framework for the development of regional ground motion relations for earthquake hazard and risk assessment in sea

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

australia s large earthquakes and recent fault scarps abstract nineteen large earthquakes up to magnitude ms 6 8 have occurred within continental australia this century and at least seven recent prehistoric fault scarps have been discovered the magnitude of the earthquake causing each of these prehistoric fault scarps has been estimated from the observed fault length and maximum scarp height and none exeeds magnitude 7 0 their occurrence demonstrates that the australian plate is undergoing significant internal deformation but as yet there is no model to explain their cause nor the likely site of the next large earthquake the absence of earthquake epicentres on the current tectonic map of australia is a regrettable omission

automatic identification and characterization of discontinuities in rock masses from 3d point clouds abstract the routine application of remote surveying techniques which can quickly acquire 3d digital data with high resolution in particular digital photogrammetry light detection and ranging lidar and unmanned aerial vehicle uav for rock mass characterization has rapidly grown over the past decade in this paper a new method for automatic identification and interpretation of rock mass discontinuities clustering of discontinuity sets and characterization of discontinuity orientation persistence and spacing using 3d point clouds is presented the proposed method is based on a four stage procedure consisting of 1 normal vector calculation using the iterative reweighted plane fitting irpf method 2 discontinuity sets clustering by fast search and find of density peaks cfsfdp algorithm and fisher s k value iterative calculation to eliminate noise points 3 discontinuity segmentation using density ratio based method and discontinuity plane fitting using the random sample consensus ransac algorithm 4 persistence and spacing calculation using the theory of analytic geometry the method is applied to two case studies i e rock slopes and compared with the results from previous studies and from manual survey it is concluded that the proposed method is reliable and yields a great accuracy for automatic identification of discontinuities in rock masses

a multi tiered earthquake hazard model for australia abstract earthquakes result from tectonic processes and their distribution is strongly influenced by large scale geology and the tectonic stress field however earthquake hazard estimates particularly ground motion recurrence have traditionally been computed using source models based primarily on instrumental and historical seismicity in areas of low to moderate seismicity such as australia large earthquakes commonly occur in areas which have experienced little or no recent activity making it difficult to develop source models based solely on seismicity the seismotectonic model developed for australia that is presented here aus5 is based on geology geophysics tectonics and seismicity the model was developed using a number of tiers of information so that new information can easily be incorporated the information used includes but is not limited to tectonic provinces basins and ranges gravity magnetic topography and seismicity all on a regional scale on a local scale for a site specific earthquake hazard study active faulting can be incorporated to provide fault source zones an earthquake hazard map showing peak ground acceleration with a 10 chance of exceedance in 50 years for southeastern australia using the geologically defined seismotectonic model aus5 is presented as an indication of how the model performs

overlapping faults and their effect on fluid flow in different reservoir types a lidar based outcrop modeling and flow simulation study in this article we focus on the potential of fault overlap zones as conduits for fluid flow in a variety of reservoir types light detection and ranging lidar technology were applied to collect a three dimensional spatially constrained data set from a well exposed fault overlap zone that crops out in the devil s lane area of the canyonlands national park in utah a virtual outcrop was generated and used to extract structural and stratigraphic data that were taken into a reservoir modeling software and reconstructed the outcrop based model was flow simulated and used to test fluid flow through a real world fault overlap zone a structural framework was built based on collected outcrop data and combined with a series of nine different facies models the different facies models included an eolian model based on the outcrop and a range of synthetic fluvial and shallow marine systems results show that for certain depositional models cross fault reservoir communication may be poor despite the geometric connectivity of the relay beds this was the case for low net gross fluvial models and shoreface models conversely high net gross fluvial systems and eolian systems show good communication through the same relay zone overall the results show that in the presence of a fault overlap zone pressure communication across a relay ramp may still be poor depending on the scale of the faults and relay ramp as well as the geometry and volume of the sands

3d mechanical stratigraphy of a deformed multi layer linking sedimentary architecture and strain partitioning abstract stratigraphic influence on structural style and strain distribution in deformed sedimentary sequences is well established in models of 2d mechanical stratigraphy in this study we attempt to refine existing models of stratigraphic structure interaction by examining outcrop scale 3d variations in sedimentary architecture and the effects on subsequent deformation at monkstone point pembrokeshire sw wales digital mapping and virtual scanline data from a high resolution virtual outcrop have been combined with field observations sedimentary logs and thin section analysis results show that significant variation in strain partitioning is controlled by changes at a scale of tens of metres in sedimentary architecture within upper carboniferous fluvio deltaic deposits coupled vs uncoupled deformation of the sequence is defined by the composition and lateral continuity of mechanical units and unit interfaces where the sedimentary sequence is characterized by gradational changes in composition and grain size we find that deformation structures are best characterized by patterns of distributed strain in contrast distinct compositional changes vertically and in laterally equivalent deposits results in highly partitioned deformation and strain the mechanical stratigraphy of the study area is inherently 3d in nature due to lateral and vertical compositional variability consideration should be given to 3d variations in mechanical stratigraphy such as those outlined here when predicting subsurface deformation in multi layers

coseismic surface deformation caused by the 23 march 2012 mw 5 4 ernabella pukatja earthquake central australia implications for fault scaling relations in cratonic settings abstract on 23 march 2012 at 09 25 utc an m w 5 4 earthquake occurred in the eastern musgrave ranges of north central south australia near the community of ernabella pukatja several small communities in this remote part of central australia reported the tremor but there were no reports of injury or significant damage this was the largest earthquake recorded on mainland australia in the past 15 years and resulted in the formation of a 1 6 km long surface deformation zone that included reverse fault scarps with a maximum vertical displacement of more than 0 5 m extensive ground cracking and numerous rock falls the earthquake occurred in nonextended stable continental region scr cratonic crust more than 1900 km from the nearest plate boundary surface deformation from the ernabella earthquake provides additional constraint on relations of surface rupture length to earthquake magnitude such relations aid in interpreting australia s rich record of prehistoric seismicity and contribute to improved estimates of scr seismic hazard worldwide based upon an analysis of new and reinterpretation of existing surface rupture length data faults in nonextended stable cratonic australia appear to produce longer surface ruptures for earthquakes larger than m w 6 5 than rupture lengths estimated using existing moment to rupture length scaling relations the implication is that the estimated maximum or characteristic magnitude of paleoearthquakes in such settings may be overestimated where the estimate is based only on the length of the prehistoric fault scarp

quantifying clinothem geometry in a forced regressive river dominated delta panther tongue member utah usa this study presents a methodology for the quantitative description of small scale delta clinothems the quantitative bed data analysis is based on three dimensional virtual outcrop models generated by ground based laser scanning light detection and ranging a large number of clinothem bed measurements have been collected from the ancient forced regressive delta system of the panther tongue that crops out in utah usa in river dominated marginal marine environments clinothems separated by clinoform surfaces represent the former position of the delta front as it prograded systematic collection of data from virtual outcrop models has allowed for accurate spatially constrained measurement of individual bed thicknesses and the compilation of a detailed database on clinothems and associated clinoform geometries measurement locations were selected so that each measurement was 10 m down depositional dip from the previous one the study area covers 5 km2 within which 2376 measurements were made from 50 separate clinothems in 320 different positions within the virtual outcrop a bed taper parameter permitted the thinning of the clinothems to be described as a single number and thus allowed relative comparison between beds combined measurements were also used to calculate the average dip angle of the clinothems analysis of the vertical and lateral stacking of the clinothems has revealed a series of stratigraphic cycles which are termed bedsets stream mouth bars the surfaces that bound the bedsets are unremarkable and it is unlikely that their significance would be recognized without this style of detailed analysis a cyclic depositional pattern interpreted as related to autocyclic processes and compensational stacking of mouth bars is proposed as the origin of these packages mapped length thickness trends constrain the spread of these variables and can be used to constrain subsurface models of analogous hydrocarbon reservoirs

optimising uav topographic surveys processed with structure from motion ground control quality quantity and bundle adjustment structure from motion sfm algorithms greatly facilitate the production of detailed topographic models from photographs collected using unmanned aerial vehicles uavs however the survey quality achieved in published geomorphological studies is highly variable and sufficient processing details are never provided to understand fully the causes of variability to address this we show how survey quality and consistency can be improved through a deeper consideration of the underlying photogrammetric methods we demonstrate the sensitivity of digital elevation models dems to processing settings that have not been discussed in the geomorphological literature yet are a critical part of survey georeferencing and are responsible for balancing the contributions of tie and control points we provide a monte carlo approach to enable geomorphologists to 1 carefully consider sources of survey error and hence increase the accuracy of sfm based dems and 2 minimise the associated field effort by robust determination of suitable lower density deployments of ground control by identifying appropriate processing settings and highlighting photogrammetric issues such as over parameterisation during camera self calibration processing artefacts are reduced and the spatial variability of error minimised we demonstrate such dem improvements with a commonly used sfm based software photoscan which we augment with semi automated and automated identification of ground control points gcps in images and apply to two contrasting case studies an erosion gully survey taroudant morocco and an active landslide survey super sauze france in the gully survey refined processing settings eliminated step like artefacts of up to 50 mm in amplitude and overall dem variability with gcp selection improved from 37 to 16 mm in the much more challenging landslide case study our processing halved planimetric error to 0 1 m effectively doubling the frequency at which changes in landslide velocity could be detected in both case studies the monte carlo approach provided a robust demonstration that field effort could by substantially reduced by only deploying approximately half the number of gcps with minimal effect on the survey quality to reduce processing artefacts and promote confidence in sfm based geomorphological surveys published results should include processing details which include the image residuals for both tie points and gcps and ensure that these are considered appropriately within the workflow

radio interferometric detection of a traveling ionospheric disturbance excited by the explosion of mount st helens a large amplitude traveling ionospheric disturbance tid was detected over owens valley california on may 18 1980 by a highly sensitive very long baseline interferometry vlbi radio astronomy experiment this tid is interpreted as the response of the ionosphere to a gravity wave excited in the neutral atmosphere by the explosion of mount st helens that took place at 1532 ut on that day a model invoking the point excitation of internal gravity waves in an isothermal atmosphere which fits observations of the tid at several other stations leads to identification of the features observed in the vlbi data small amplitude higher frequency changes in the ionosphere were detected for several hours after the passage of the large amplitude mount st helens tid but it is not clear whether these were excited by the passage of the gravity wave or were background fluctuations