retrospective investigation of geophysical data possibly associated with the ms8 0 wenchuan earthquake in sichuan china abstract the ms8 0 wenchuan earthquake is one of the most catastrophic earthquakes occurred recently although the geophysical network around the epicentral region is not dense enough partially due to the inactivity of the longmenshan fault the retrospective investigation of geophysical data in and around the epicentral region would be helpful for strengthening the understanding of the seismogenic process of the wenchuan earthquake this paper summarized some preliminary results of the retrospective investigation especially focusing on the seismic and electromagnetic data possibly associated with the wenchuan earthquake and its aftershocks the spatio temporal investigation of the seismicity changes indicated that there is an intermediate term seismic quiescence around the epicenter during 2006 2007 the electromagnetic data also showed some anomalous changes including co seismic electromagnetic changes which may be related with the wenchuan earthquake and its aftershocks although further work is definitely required to enhance the reliability of the relationship between the above geophysical changes and the seismogenic process the above preliminary results would provide some useful information for the related study and stimulate further validation study on the precursors of the wenchuan earthquake

secular variations of the earth s apparent resistivity monitoring carried out by the generalized magnetovariation gmv and geomagnetic depth sounding gds methods has shown a valuable variability of yearly apparent resistivities from the yr 1911 to 2010 for the selected european geomagnetic observatories these deep soundings were carried out by the two methods mentioned above correspondingly for shorter and longer periods in the range from 8 h to a month the possible changes in the source signals through an uncorrelated part of the observed field were mainly suppressed by robust coherence based statistical data processing the detected resistivity variations have periods of more than several yr while inequality of induction arrows obtained by the gmv method may be seen already during a couple of yr the 11 yr variability of the apparent resistivity correlates with wolf numbers with some phase lags the variations with shorter periods have been found to change synchronously with the number of the earthquakes at a region including some seismically active areas in europe the peculiarities and possible origins of the phenomenon are discussed

further investigations of geomagnetic diurnal variations associated with the 2011 off the pacific coast of tohoku earthquake mw 9 0 abstract as one of the most promising candidates for short term earthquake forecasting the seismo electromagnetic phenomena have been intensively studied for several decades recently xu et al 2013 have reported unusual behaviors of geomagnetic diurnal variations in the vertical component prior to the 2011 off the pacific coast of tohoku earthquake mw 9 0 to validate this result further investigations have been applied in this study geomagnetic data of 16 years long term observation have been analyzed using the same method in xu et al 2013 ratios of diurnal variation range between the target station esashi esa which is about 130 km from the epicenter and the remote reference station kakioka kak about 300 km distant to the epicenter have been computed after removing seasonal variations revealed by wavelet transform analysis the 15 day mean values of the ratios in the vertical component shows a clear anomaly exceeding the statistical threshold about 2 months before the mega event this anomaly is unique over a 16 year long background and further discussions indicate that this anomaly is unlikely caused by strong geomagnetic storms or a statistical fluke therefore this study has provided a strong support to the previous results in xu et al 2013

misorientation analysis and the formation and orientation of subgrain and grain boundaries in contrast to the behaviour of individual grains both inter and intra granular boundaries within rocks have received much less attention however many geological processes particularly during deformation e g yielding dislocation creep recrystallisation superplasticity and various fracture mechanisms and petrophysical properties depend to some extent on the nature of boundaries present in a rock in this contribution we consider the role of intergranular and intragranular crystal boundaries a precise characterisation of such boundaries depends on defining the crystallographic and dimensional orientations of the boundary and the misorientation between the adjacent regions i e grains subgrains etc separated by the boundary although several theoretical descriptions of boundary configuration are available practical precision is lacking and approximations are necessary we describe two specific approximations for boundary formation and orientation obtained using the sem electron channelling technique the first is a geometrical interpretation of electron channelling patterns ecp in terms of the likely formation and orientation of the intervening boundary the second considers the misorientation between adjacent regions across a boundary this involves a model which assumes a simple geometrical relationship between crystal slip systems responsible for the rotation and misorientation between adjacent regions and the formation and orientation of the resulting boundary these approximations are capable of a identifying trends in the dispersion of crystallographic directions during deformation b identifying active slip systems c calculating the relative schmid factors for each crystal slip system and therefore the most likely system to be activated d modelling synthetic misorientations and predicting the crystal slip systems and boundary configurations to be expected and e comparing real data with synthetic models our analyses are illustrated via natural examples of dynamic recrystallisation in quartzite and a theoretical simulation of the behaviour of an individual quartz grain during deformation

grain boundary contact effects during faulting of quartzite an sem ebsd analysis abstract during low temperature faulting of cambrian quartzite assynt nw scotland stress concentrations develop at grain contacts either at the onset of deformation prior to the establishment of a through going fault plane or within the damage zone remote from the main displacement segment such concentrations contribute to the development of intragranular microfractures cataclastic microstructures and fault rocks this contribution considers the progressive deformation sequence that precedes microfracturing and cataclasis the complexity of this deformation is revealed by scanning electron microscope sem electron backscattered diffraction ebsd dauphine twinning is a widespread feature associated with grain contact stress concentration and forms distinctive ebsd microstructures automatic sem ebsd analysis reveals that whilst initial indentation causes dauphine twinning of many grains continued indentation results in the formation of an arcuate array of subgrains via low temperature plasticity and or microcracking which overprint the dauphine twins these observations are consistent with transmission electron microscopic analysis of quartz crystals used for microhardness indentation tests which reveal that indentation causes an intensely deformed region to develop comprising a high density of microfractures and a submicron scale blocky microstructure that accommodates any plastic deformation deformation mechanisms and associated microstructures develop sequentially with progressive indentation and may provide sites of microfracture nucleation via low temperature ductile fracture the new microstructures assist diffusive mass transfer dmt processes by the formation of a cellular or subgrain array that represents a reduction of several orders of magnitude in apparent grain size and hence in diffusion path length concomitantly associated microfracturing perturbs local thermodynamic equilibrium leading to enhanced dmt crack healing and cementation overgrowths together these processes form the aseismic creep and sealing components of fault zone development

unexpected changes in resistivity monitoring for earthquakes of the longmen shan in sichuan china with a fixed schlumberger sounding array abstract an electrical resistivity monitoring experiment using a fixed schlumberger sounding array was conducted at pixian in sichuan province china from january 1984 to june 1989 for the purposes of better understanding some geoelectrical phenomena and detecting earthquake associated changes ancillary data of well water fluctuations and rainfall changes along with seismicity pattern fault map atmospheric humidity and temperature have been collected a very peculiar resistivity behavior was observed the direction of the change in apparent resistivity for large electrode expanders was opposite to that of the resistivity change for the overburden the geoelectrical structure beneath the monitoring array could be inferred from resistivity sounding data and available geological information a method of data analysis applying singular value decomposition to the first order sensitivity matrix yields the estimated change in true resistivity for the constituent medium in the sense of generalized least squares the sensitivity analysis shows that for the pixian station the abnormal annual variations in resistivity monitoring with large electrode spacings are related to the multilayered resistivity section with conductive substratum and are caused by the resistivity changes of overlying layer because the sensitivity coefficient for the topmost layer for such a section is negative the resistivity changes of the overlying layer could be attributed mainly to seasonal rainfall changes during the experiment no significant resistivity changes are correlated with the earthquakes of ml 5 4 or less in the longmen shan and adjacent regions however a detailed interpretation of the observed phenomenon is helpful to improve our understanding of possible resistivity precursors to earthquakes

individual orientation measurements in quartz polycrystals advantages and limitations for texture and petrophysical property determinations individual orientation determination of quartz grains by electron channelling in principle gives the complete orientation however in routine analysis the noise level in electron channelling patterns ecps does not permit the determination of handedness of a quartz grain in a polycrystal in practice all quartz grains are arbitrarily indexed as right handed hence dauphine twins can be identified but not brazil twins this practice also means that only the centrosymmetric petrophysical properties can be determined from texture measurements these include most geologically relevant properties e g thermal conductivity thermal expansion and elasticity however other properties e g piezoelectricity which are not centrosymmetric cannot be calculated from such texture measurements some texture forming processes e g dislocation glide can also be considered to be centrosymmetric in quartz whereas others e g grain boundary migration may not be the method of quantitative texture analysis from individual measurements is briefly recalled as an example 382 grains from tongue quartzite are used to illustrate the advantages of texture analysis from ecps the orientation distribution function odf is calculated from ecps and x ray pole figures of the same sample the agreement is found to be good between the two methods proving that ecps can be used for quantitative analysis the methods used in local texture analysis and the definitions of the various misorientation distribution functions modfs are given data collected from a traverse of a quartzo feldspathic shear zone in lewisian gneiss torridon quartzite are used to illustrate local texture analysis examples from a region of shear strain of about one are given of core and mantle subgrains and dauphine twins dispersion trails of the crystallographic axes within a single grain show an apparent rotation about the intermediate structural axis y detailed analysis of the subgrain misorientation axes in specimen and crystallographic co ordinates show an important scatter implying that the subgrains resulted from local incompatibility strains rather than specimen scale kinematics the method of calculation of physical properties from individual orientation measurements is given for second and fourth order tensors using the texture data from tongue quartzite we have calculated thermal conductivity thermal expansion and seismic velocities all these properties are extremely anisotropic in quartz however it is emphasized that the presence of a second phase on grain boundaries e g water graphite may completely alter a physical property e g electric and render the values calculated from texture measurements inappropriate

sensitivity analysis of the schlumberger monitoring array application to changes of resistivity prior to the 1976 earthquake in tangshan china abstract prior to the 1976 tangshan earthquake of m 7 8 at nine out of fourteen geoelectric stations within 180 km of the epicenter resistivity decreases were observed during this same period drops in water levels were recorded in seventeen deep wells in the same region the sensitivity analysis shows that the resistivity decrease cannot be caused by a groundwater level decrease because all of the coefficients for the resistivity structure types a h and ha with a resistive substratum are positive some examples of a schlumberger monitoring array are used to illustrate the application of the analytical approach in order to detect resistivity changes associated with an earthquake such an approach is useful for survey planning checking or setting the search depth of a given array and facilitates the quantitative interpretation of resistivity data

analyzing the evolution of the tessina landslide using aerial photographs and digital elevation models abstract evolution of the tessina landslide near belluno italy from 1954 to the present situation has been documented using multitemporal landslide maps the maps were produced through the interpretation of sequential aerial photographs and direct field mapping of the landslide in 1998 and 1999 the interpretations were converted to large scale multitemporal topographical maps and digitized resulting in detailed geomorphological maps of the tessina landslide for the following periods 1954 1961 1969 1980 1991 1993 1998 and 1999 a quantitative volumetric analysis was also carried out using a series of digital elevation models derived from the available 1 5000 scale digital contour maps with 5 m contour interval for 1948 1964 1980 1991 and 1993 the total volume of material removed and accumulated was calculated for the entire tessina landslide for the different time steps available results indicate that the tessina landslide existed prior to its main reactivation in 1960 after which the landslide reduced in activity from 1991 however very large reactivations have taken place and the landslide continues to be active although the landslide has reached the lateral boundaries of the old pre 1960 landslide it is now expanding upslope where it may still mobilize large amounts of material

detection and volume estimation of large scale landslides based on elevation change analysis using dems extracted from high resolution satellite stereo imagery a new technique for quickly assessing extensive areas of large scale landslides that uses digital elevation models dems extracted from high resolution satellite images is presented in this paper the proposed technique observes the elevation changes by using multitemporal dems five meter resolution dems from spot 5 images are applied to two large scale landslide disasters the landslides triggered by the 2004 mid niigata prefecture earthquake magnitude 6 8 a moderate topography area in central japan and the landslides caused by the 2004 typhoon mindulle a steep topography area in central taiwan both events yielded elevation changes in excess of 10 m we assess the dems produced by the proposed method and their landslide application we find three main results 1 the elevation difference error increases with the slope angle the root mean square error was 4 5 m on slopes lower than 30deg in both areas whereas it was 5 6 m for slopes that exceeded 30deg in moderate topographies and 5 9 m in steep topographies 2 the proposed technique well delineated the large scale landslides the total rate of successful area detection was over 70 for slopes under 40 deg but under 40 for slopes that exceeded 40 deg 3 the landslide volume could be roughly estimated in units of 100times103 m3 the developed technique well supports damage assessments of large scale landslides because the location depth and volume can be quantitatively determined by remote sensing

topographic changes and their driving factors after 2008 wenchuan earthquake abstract the 2008 wenchuan earthquake caused topographic change in the stricken areas because of the occurrence of numerous coseismic landslides the emergence of new landslides and debris flows and movement of loose materials under the driving force of high rainfall could further shape the local topography currently little attention has been paid to continuously monitoring and assessing topographic changes after the major earthquake in this research we obtained an elevation dataset 2002 2010 2013 and 2015 based on digital elevation model dem data and a dem extracted from zy 3 stereo paired images with validation by field measurement we quantitatively assessed elevation changes in different years and qualitatively analyzed spatiotemporal variation of the terrain and mass movement across the study area the results show that the earthquake affected area experienced substantial elevation changes caused by seismic forces and subsequent rainfalls high rainfall after the earthquake have become the biggest driver of elevation reduction which overwhelmed elevation increase caused by the major earthquake increased post earthquake erosion intensity has caused large amounts of loose materials to accumulate in river channels and gullies and on upper middle mountain slopes which increases the risk of flooding and geo hazards in the area

significant resistivity changes in the fault zone associated with the 1999 chi chi earthquake west central taiwan abstract the purpose of this paper is to demonstrate the possible influence of an earthquake on the resistivity distribution in a fault zone we collected resistivity image profiles across a proposed fault trace prior to the 7 3 magnitude 1999 shallow earthquake in the chi chi area of taiwan significant positive resistivity anomalies were observed in the hanging wall after the earthquake however there were negligible resistivity changes in the footwall from an examination of geoelectric phenomena and surface rupture in the fault zone it is believed that geoelectric anomalies are associated with abrupt displacement along the active chelungpu fault this result indicates a potential for resistivity methods to provide a basis for the monitoring of an active fault

forecasting the magnitude of potential landslides based on insar techniques abstract a new method combining empirical modeling with time series interferometric synthetic aperture radar insar data is proposed to provide an assessment of potential landslide volume and area the method was developed to evaluate potential landslides in the heitai river terrace of the yellow river in central gansu province china the elevated terrace has a substantial loess cover and along the terrace edges many landslides have been triggered by gradually rising groundwater levels following continuous irrigation since 1968 these landslides can have significant impact on communities affecting lives and livelihoods developing effective landslide risk management requires better understanding of potential landslide magnitude fifty mapped landslides were used to construct an empirical power law relationship linking landslide area al to volume vl vl 0 333 al1 399 insar derived ground displacement ranges from 64 mm y to 24 mm y along line of sight los further interpretation of patterns based on remote sensing insar optical image and field survey enabled the identification of an additional 54 potential landslides 1 9 102 m2 al 8 1 104 m2 in turn this enabled construction of a map that shows the magnitude of potential landslide activity this research provides significant further scientific insights to inform landslide hazard and risk management in a context of ongoing landscape evolution it also provides further evidence that this methodology can be used to quantify the magnitude of potential landslides and thus contribute essential information towards landslide risk management

geoelectric precursors to strong earthquakes in china abstract the main results of searching for electrical precursors to strong earthquakes in china for the last 25 yr are presented this comprises the continuous twenty year resistivity record before and after the great tangshan earthquake of 1976 spatial and temporal variations in resistivity anomalies observed at more than 6 stations within 150 km of the tangshan earthquake epicenter the travel time curve for the front of the resistivity precursor and a method of intersection for predicting the epicenter location these results reveal a number of interesting facts 1 1 resistivity measurements with accuracies of 0 5 or better for over 20 yr show that resistivity decreases of several percent which began approximately 3 yr prior to the tangshan earthquake were larger than the background fluctuations and hence statistically significant an outstanding example of an intermediate term resistivity precursor is given 2 2 the intermediate term resistivity precursor decrease before tangshan earthquake is such a pervasive phenomenon that the mean decrease in percent can be contoured on a map of the beijing tianjin tangshan region this shows the maximum decrease centered over the epicenter 3 3 the anomalies in resistivity and self potential which began 2 0 5 months before the tangshan main shock had periods equal to that of the tidal waves m 2 and ms f respectively so that the associated anomalies can be identified as impending earthquake precursors and a modal related to stress displacement weakening is proposed

using stereo satellite imagery to account for ablation entrainment and compaction in volume calculations for rock avalanches on glaciers application to the 2016 lamplugh rock avalanche in glacier bay national park alaska

integration of dem etm geologic and magnetic data for geological investigations in the jifara plain libya we used an integrated approach to constrain the geological structure of the jifara plain in northwest libya the analysis of surface data including a digital elevation model dem landsat enhanced thematic mapper plus images and geologic maps was combined with subsurface data including well logs and magnetic data the dem data were used for the identification of geological lineaments in the study area the interpretation and analysis of the lineaments indicate that the jifara plain is controlled by three main fault systems trending northwest southeast east west and northeast southwest the three trends represent the remnants of reactivated structures that formed under the stress regimes generated during the tectonic evolution of north africa the magnetic data reveal three northwest and northeast trending sedimentary basins in the study area the depth of the basement inside the main basin ranges from 1 to 5 km the results indicate that the jifara basin is shallower than the surrounding basins the integration of the results reflects different periods of tectonic activity in the jifara plain and the adjacent jabal nafusah

remote sensing techniques for landslide studies and hazard zonation in europe abstract an inventory is presented of researches concerning the use of remote sensing for landslide studies and hazard zonation as mainly carried out in the countries belonging to the european community an overview is given of the applicability of remote sensing in the following phases of landslide studies 1 1 detection and classification of landslides special emphasis is given to the types of imagery required at different scales of analysis 2 2 monitoring the activity of existing landslides using g p s photogrammetrical techniques and radar interferometry 3 3 analysis and prediction in space and time of slope failures the different factors required in a landslide hazard study are evaluated and the optimum remote sensing imagery for obtaining each of these factors is indicated examples are given of research work carried out in these three phases from ec countries finally an evaluation is given of the aspects of uncertainty associated with the use of remote sensing data and conclusions are given as to the incorporation of remote sensing techniques within the overall framework of techniques

empirical prediction of coseismic landslide dam formation in this study we develop an empirical method to estimate the volume threshold for predicting coseismic landslide dam formation using landscape parameters obtained from digital elevation models dems we hypothesize that the potential runout and volume of landslides together with river features determine the likelihood of the formation of a landslide dam to develop this method a database was created by randomly selecting 140 damming and 200 non damming landslides from 501 landslide dams and 60 000 landslides induced by the mw 7 9 2008 wenchuan earthquake in china we used this database to parameterize empirical runout models by stepwise multivariate regression we find that factors controlling landslide runout are landslide initiation volume landslide type internal relief h and the h l ratio between h and landslide horizontal distance to river l in order to obtain a first volume threshold for a landslide to reach a river the runout regression equations were converted into inverse volume equations by taking the runout to be the distance to river a second volume threshold above which a landslide is predicted to block a river was determined by the correlation between river width and landslide volume of the known damming landslides the larger of these two thresholds was taken as the final damming threshold this method was applied to several landslide types over a fine geographic grid of assumed initiation points in a selected catchment the overall prediction accuracy was 97 4 and 86 0 for non damming and damming landslides respectively the model was further tested by predicting the damming landslides over the whole region with promising results we conclude that our method is robust and reliable for the wenchuan event in combination with pre event landslide susceptibility and frequency size assessments it can be used to predict likely damming locations of future coseismic landslides thereby helping to plan emergency response copyright 2014 john wiley sons ltd

comparison of stereo extracted dtm from different high resolution sensors spot 5 eros a ikonos ii and quickbird digital elevation models dems extracted from high resolution stereo images spot 5 eros a ikonos ii and quickbird using a three dimensional multisensor physical model developed at the canada centre for remote sensing natural resources canada were evaluated in a first step the photogrammetric bundle adjustment was setup for the stereo images with few accurate ground control points in a second step dems were generated using an area based multiscale image matching method and then compared to 0 2 m accurate light detection and ranging lidar elevation data elevation linear errors with 68 confidence level le68 of 6 5 20 6 4 and 6 7 m were achieved for spot eros ikonos and quickbird respectively the poor results for eros are mainly due to its asynchronous low orbit which generated large geometric and radiometric differences however when such differences were not large le68 of 10 m four pixels was achieved since the spot ikonos and quickbird dems were in fact digital surface models where the height of land covers was included elevation accuracy was performed only on bare surfaces soils and lakes where there was no difference between the stereo extracted elevations and the lidar data le68 of 2 2 1 5 and 1 2 m were then obtained for spot ikonos and quickbird respectively when compared to sensor resolution multidate across track spot with a smaller base to height b h ratio of 0 77 achieved three to four times better results than same date in track ikonos and quickbird with b h of around 1 0 5 pixels versus 1 5 or 2 pixels

geological and geomorphological characteristics of landslides triggered by the 2004 mid niigta prefecture earthquake in japan abstract the 2004 mid niigta prefecture earthquake mjma 6 8 triggered more than one thousand landslides in the miocene to quaternary sedimentary rocks in japan the most common landslides were shallow disrupted landslides on steep slopes which has been common in many previous disastrous earthquakes in the world the mid niigta prefecture earthquake also triggered more than one hundred deep landslides providing valuable information on the conditions for their occurrence a field investigation and the interpretation of aerial photographs taken before and after the earthquake suggest that reactivation of existing landslides and undercutting of slopes are the most important factors for deep landslides to be triggered by earthquakes in addition planar sliding surfaces seem to be essential for the generation of catastrophic landslides triggered by this earthquake planar bedding parallel sliding surfaces were formed at the boundary between the overlying permeable sandstone and underlying siltstone or along the bedding planes of alternating beds of sandstone and siltstone sliding surfaces along the slope parallel oxidation front were formed in the area of black mudstone new landslides rockslide avalanches occurred with the sliding surfaces in a several cm thick tuff interbedded in siltstone one rockslide avalanche occurred on a slope where buckling deformation preceded the earthquake gentle valley bottom sediments were mobilized in many locations probably because they were saturated and partial liquefaction had occurred due to the earthquake shaking

geoelectric signals in china and the earthquake generation process we present original apparent resistivity records for stations located in the chinese provinces of hebei and sichuan along with seismicity patterns fault maps and limited hydrologic data these records are part of a 30 year database of geoelectric signals that have been recorded in china by a nationwide network of more than 100 stations set up by the state seismological bureau of the people s republic of china the database includes the time period during which the m 7 8 1976 tangshan and m 7 2 1976 songpan earthquakes occurred resistivity data recorded in and around the epicentral region of the tangshan event show coherent changes both temporal and in areal distribution years and months before and after the earthquakes a regional change in water table occurred more than 3 years prior to the tangshan earthquake the resistivity and water table signals appear to correlate in the 2 to 3 year period prior to the earthquake rainfall records from the region around tangshan extending to the cities of beijing and tianjin do not appear to account for the resistivity changes regional seismicity and active fault patterns in north china indicate that deformation occurs mainly along the borders of large tectonic blocks the source region for the geoelectric signals appears to lie within a large shear zone at the edge of a tectonic block undergoing rotation the tangshan epicentral area is thus only part of a larger zone of deformation we suggest that dilational strain associated with the opening of fractures may lower resistivity and water table for shallow crustal depths such as those monitored by the chinese geoelectric network dilation and resistivity changes are expected to begin at stress levels well below the peak values of the seismic cycle our study suggests that in some cases the areal extent of geoelectric signals may be significantly larger than that of the eventual earthquake source dimension the chinese geoelectric database offers an opportunity to improve our understanding of possible geoelectric precursors to earthquakes

sensitivity of the telluric monitoring array in parkfield california to changes of resistivity parkfield is the site of characteristic earthquakes which repeat every 22 plus minus 5 years so that the next one is due between 1983 and 1993 the authors have installed a telluric monitoring array to detect possible changes of resistivity prior to the next characteristic earthquake however the array detects only changes in the telluric response and an independent estimate of the geoelectrical structure is needed in order to locate the perturbed regions and to determine the magnitude of the change in resistivity they have developed a three dimensional electrical model for parkfield based on 12 shallow 1 500 m schlumberger soundings and 31 deep soundings using their array the model is complex but shows that rock adjacent to and southwest of the san andreas fault is conductive less than 10 ohm m to depths of at least 10 km the authors infer that these low resistivities are due to brecciation from intense shearing along the fault they have also used this geoelectric structure to predict the sensitivity of their telluric array to changes in resistivity along the fault changes in resistivity beneath the array at depths from 1 5 to 6km produce the largest effects at the surface 1 change formore a perturbation of 1 at depth changes of resistivity from depths of 6 12 km yielded lower sensitivities but are still detectable because the top of the seismogenic zone in parkfield is at 5 km the array should be sensitive to changes of resistivity prior to the next earthquake less

determining landslide susceptibility in central taiwan from rainfall and six site factors using the analytical hierarchy process method this work provides a landslide susceptibility assessment model for rainfall induced landslides in central taiwan based on the analytical hierarchy process method the model considers rainfall and six site factors including slope geology vegetation soil moisture road development and historical landslides the rainfall factor consists of 10 day antecedent rainfall and total rainfall during a rainfall event landslide susceptibility values are calculated for both before and after the beginning of a rainfall event the 175 landslide cases with detailed field surveys are used to determine a landslide susceptibility threshold value of 9 0 when a landslide susceptibility assessment value exceeds the threshold value slope failure is likely to occur three zones with different landslide susceptibility levels below slightly above and far above the threshold are identified the 9149 landslides caused by typhoon toraji in central taiwan are utilized to validate the study s result approximately 0 2 0 4 and 15 3 of the typhoon caused landslides are located in the three landslide susceptibility zones respectively three villages with 6 6 0 4 and 4 9 of the landslides respectively are used to validate the accuracy of the landslide susceptibility map and analyze the main causes of landslides the landslide susceptibility assessment model can be used to evaluate susceptibility relative to accumulated rainfall and is useful as an early warning and landslide monitoring tool

seventeen years of the la clapiere landslide evolution analysed from ortho rectified aerial photographs we present a new method of digital elevation model dem calculation from aerial photographs and apply this method to the la clapiere landslide in the mercantour massif in eastern france the method uses new techniques of image correlation and of restitution of camera parameters the calculated dems are used to ortho rectify three aerial photographs acquired between 1983 and 1999 measurements made from these ortho rectified images show that the average velocity of the landslide was of 1 7 cm day with the rate of the headscarp retreat of 4 1 cm day and the toe of the landslide advancing at 1 7 cm day between 1983 and 1999 within the landslide the velocity field is are relatively homogeneous although their directions are locally heterogeneous scree slopes and scarps develop in an heterogeneous way within the landslide because the headscarp moves faster than the front of the landslide material spreads laterally at the scree slopes and or is eroded at the front of the landslide by the river and or is accumulated within the landslide on a low slope area located above a competent bar called igliere bar d 2002 elsevier science b v all rights reserved

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

a decadal evolution of landslides and debris flows after the wenchuan earthquake abstract the 2008 wenchuan earthquake triggered numerous coseismic landslides the loose materials were retained on steep terrains and deep gullies as well as in river channels which increased higher flooding hazard and geo hazard landslides and debris flows risks in the area in this paper between 2008 and 2016 we monitored landslides and debris flows occurred during rainfall especially the high rainfall amounts in 2013 which caused serious damage to reconstructed villages the changes over time aids in understanding long term landscape evolution in the investigated area impacted by major earthquakes as well as in regions with comparable settings with the aid of a gis platform combined with field investigations we continuously tracked the area and movement paths of the loose deposit materials in all the debris flow gullies and coseismic landslides in the study area and then the spatial and temporal evolutionary patterns of these movements as well as the evolution under different triggering factors were analyzed using the terrain and precipitation information from the past nine years the results showed that both the area and number of coseismic landslides decreased over time and that the deposited materials moved to areas of lower elevation and lower slope in addition the new landslides occurred more easily in areas of low elevation and high slope during periods of normal rainfall under the high rainfall many new landslides and expansion processes occurred easily at high altitudes providing loose materials for debris flows although the overall geoenvironment in the earthquake stricken area has a recovering tendency the outburst of hazards triggered by future extreme rainfalls is still expected and this kind of fluctuating cycle may last for an unexpectedly longer period

a spherical electron channelling pattern map for use in quartz petrofabric analysis correction and verification abstract the recent paper by lloyd ferguson on the use of a spherical electron channelling pattern ecp map in quartz petrofabric analysis contained an unfortunate error due to the incorrect indexing of the quartz single crystal used to construct the map this error can be corrected by a simple 60 rotation of the spherical ecp map and a re definition of the individual ecps specifically those of the positive and negative rhombs and trigonal prisms the verification of this correction and of the technique as a whole is supported by a comparison between pole figure diagrams for a quartzite obtained from the same specimen by ecp analysis and x ray texture goniometry

an illustration of the advantages of a complete texture analysis described by the orientation distribution function odf using quartz pole figure data abstract the preferred orientation of eight crystal directions of quartz was measured with an x ray texture goniometer for selected quartz bearing tectonites with a clear pattern of c axis preferred orientation the advantages of data analysis by means of calculations of the orientation distribution function and other forms of data presentation derived from the odf are demonstrated

improving the measurement accuracy of three dimensional topography changes using optical satellite stereo image data we describe a methodology that allows the more accurate detection and investigation of 3 d terrain changes using digital elevation models dems derived from stereoscopic pushbroom cameras on board satellites repeat 15 m resolution orthorectified images and stereophotogrammetric dems were produced from the advanced spaceborne thermal emission and reflection radiometer for displacement analysis the column and line numbers in the sensor geometry are included to each pixel we reveal that the attitude oscillation of the satellite has a considerable effect on geometric accuracy which is in this paper corrected along the scan lines of pushbroom sensors by destriping in the sensor geometry our results show that the distortion in dems is reduced by about 40 in terms of standard deviation under similar sun elevation conditions by correcting the effect of pitch and yaw oscillations the proposed methodology was applied to the measurement of ground deformation generated by a swarm of earthquakes between september 14 and october 4 2005 which occurred in dabbahu ethiopia we successfully detected the horizontal displacements and dem differences with about 0 1 pixel accuracy

satellite data for a rapid assessment of tsunami inundation areas after the 2011 tohoku tsunami the mw 9 0 earthquake that occurred off the coast of japan s tohoku region produced a great tsunami causing catastrophic damage and loss of life within hours of the tsunami event satellite data were readily available and massive media coverage immediately circulated thousands of photographs and videos of the tsunami satellite data allow a rapid assessment of inundated areas where access can be difficult either as a result of damaged infrastructure e g roads bridges ports airports or because of safety issues e g the hazard at nuclear power plant at fukushima in this study we assessed in a day tsunami inundation distances and runup heights using satellite data very high resolution satellite images from the geoeye1 satellite and from the digitalglobe worldview srtm and aster gdem of the tohoku region northeast japan field survey data by japanese and other international scientists validated our results this study focused on three different locations site selection was based on coastal morphologies and the distance to the tsunami source epicenter study sites are rikuzentakata oyagawahama and yagawahama in the oshika peninsula and the sendai coastal plain sendai city to yamamoto city maximum inundation distance 6 km along the river and maximum runup 39 m at rikuzentakata estimated from satellite data agree closely with the 39 7 m inundation reported in the field here the ria coastal morphology and horn shaped bay enhanced the tsunami runup and effects the sendai coastal plain shows large inundation distances 6 km and lower runup heights natori city and wakabayashi ward on the sendai plain have similar runup values 12 and 16 m respectively obtained from srtm data these are comparable to those obtained from field surveys 12 and 9 5 m however at yagawahama and oyagawahama miyagi prefecture both srtm and aster data provided maximum runup heights 41 to 45 m and 33 to 34 m respectively which are higher than those measured in the field about 27 m this difference in dem and field data is associated with aster and srtm dem s pixel size and vertical accuracy the latter being dependent on ground coverage slope aspect and elevation countries with less access to technology and infrastructure can benefit from the use of satellite imagery and freely available dems for an initial pre field surveys rapid estimate of inundated areas distances and runup and for assisting in hazard management and mitigation after a natural disaster

spatiotemporal characteristics of the geomagnetic diurnal variation anomalies prior to the 2011 tohoku earthquake mw 9 0 and the possible coupling of multiple pre earthquake phenomena abstract xu et al 2013 and han et al 2015 have reported unusual behaviors of geomagnetic diurnal variation gdv in the vertical component prior to the 2011 off the pacific coast of tohoku earthquake mw 9 0 to make a better understanding of this phenomenon temporal spatial analyses of gdv have been applied in this study geomagnetic data of long term observations at 17 stations in japan have been analyzed using the same method in han et al 2015 ratios of diurnal variation range between the reference station kak and the target stations have been computed after removing seasonal variations the 15 day backward running mean values of the ratios in the vertical component shows a clear anomaly exceeding the statistical threshold about 2 months before the mega event at both esa and miz stations in the tohoku region locations of anomalies in spatial distribution show a good correlation with the epicenter of the mw 9 0 earthquake these spatiotemporal results are consistent with those obtained from other independent observations such as groundwater level and gps displacements the coupling of multiple pre earthquake phenomena may help to understand the preparation process of a mega earthquake in the subduction zone

three dimensional topographic mapping with aster stereo data in rugged topography digital elevation models dems were generated from a stereo pair using the advanced spaceborne thermal emission and reflection radiometer aster backward and nadir images with 27 7 spl deg intersection angles b h 0 6 over a high relief area of the canadian rocky mountains fifteen ground control points were a good compromise to compute the stereo bundle adjustment when they are only 25 30 m precise to avoid their error propagation in the modeling it enabled to keep accuracy on the order of one pixel 15 m dem accuracy was then evaluated along the full process and as a function of different parameters applying the calibration of charge coupled devices in order to reduce the striping effects improves the dem accuracy by a factor of 10 the major problems in the image matching were the clouds snow lakes and occluded shadowed areas which generated mismatched areas and artificial relief in the lakes 1000 2000 m during the correlation process and the automatic interpolation method postprocessing the dem with semiautomatic three dimensional tools improved its accuracy by a factor of 10 the final results le68 and le90 of 28 and 51 m respectively were obtained with the interactive correction of lake elevations but without taking into account the large mismatched areas which were specific to this challenging mountainous study site

method for crater detection from martian digital topography data using gradient value orientation morphometry vote analysis slip tuning and calibration recently all the craters from the major currently available manually assembled catalogs have been merged into the catalog with 57 633 known martian impact craters this paper presents a new crater detection algorithm cda for the search of still uncataloged impact craters the cda is based on fuzzy edge detectors and radon hough transform and utilizes digital topography data instead of image data the critical parts of the method providing increased accuracy are as follows 1 gradient value orientation based techniques 2 automated morphometry measurements of depth diameter ratio circularity topographic cross profile rim central peak and radial range where the crater is preserved 3 circularity analysis of votes in parameter space 4 slip tuning of detected craters parameters and 5 calibration which partially compensates differences in morphology between small and large craters using the framework for the evaluation of cdas in comparison with prior work the proposed detector shows the following 1 significantly larger area under the free response receiver operating characteristics auroc and 2 significantly larger number of correct detections using the mars orbiter laser altimeter data as input the cda proposed numerous candidates for gt 57633 catalog extension after the manual survey of all proposed craters and rejection of false detections 57 592 impact craters were confirmed as correct detections the accompanying result to the cda is a new gt 115225 catalog

texture development of recrystallised quartz polycrystals unravelled by orientation and misorientation characteristics abstract the development of microstructures and textures i e crystallographic preferred orientations during recrystallisation of naturally deformed quartz polycrystals has been studied via electron diffraction techniques in the scanning electron microscope in the investigated sample series of quartz rich rocks originating from different deformation regimes the microstructural and textural changes in quartz have been significantly influenced by dynamic recrystallisation based on microstructural observations paired with orientation and misorientation analyses down to the scale of grains and subgrains criteria could be established which characterise the dominant recrystallisation process and its influence on texture development it is shown that the texture development during dynamic recrystallisation is controlled by a differential activation of slip systems in grains of soft and hard orientations the analyses provide further evidence that specific grain orientations are preferred during crystal plastic deformation recrystallisation and grain growth the influence of twinning after the dauphine law was also investigated observations of a progressive reduction in the population of dauphine twin boundaries during recrystallisation and a penetrative deformation in both hosts and twins indicate a generation prior to deformation and recrystallisation a mechanical origin for twinning and possible influence on texture development was therefore discarded

a spherical electron channelling pattern map for use in quartz petrofabric analysis electron channelling patterns ecp s are formed in the scanning electron microscope sem by the interaction between the incident electrons and the lattice of crystalline specimens the patterns are unique for a particular crystallographic orientation and are therefore of considerable potential in petrofabric studies provided they can be accurately indexed indexing requires an ecp map of the crystallographic stereogram or unit triangle covering all possible orientations and hence ecp patterns due to the presence of long range distortions in planar ecp maps it is more convenient to construct the maps over a spherical surface this also facilitates the indexing of individual ecp s a spherical ecp map for quartz is presented together with an example of its use in petrofabric analysis

earthquake triggered increase in sediment delivery from an active mountain belt in tectonically active mountain belts earthquake triggered landslides deliver large amounts of sediment to rivers we quantify the geomorphic impact of the 1999 mw 7 6 chi chi earthquake in taiwan which triggered 20 000 landslides coseismic weakening of substrate material caused increased landsliding during subsequent typhoons most coseismic landslides remained confined to hillslopes downslope transport of sediment into the channel network occurred during later storms the sequential processes have led to a factor of four increase in unit sediment concentration in rivers draining the epicentral area and increased the magnitude and frequency of hyperpycnal sediment delivery to the ocean four years after the earthquake rates of hillslope mass wasting remain elevated in the epicentral area

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

texture analysis of a recrystallized quartzite using electron diffraction in the scanning electron microscope abstract the microstructure and crystallographic preferred orientation texture of a recrystallized quartzite from the bergell alps was quantitatively investigated using automated indexing of electron backscattered patterns ebsp the results are displayed in orientation maps of the microstructure and orientation as well as misorientation distribution functions the orientation distribution function derived from ebsp compares excellently with texture data derived from independent neutron diffraction experiments the misorientation distribution function of next neighbors reveals strong maxima for small angle grain boundaries subgrain boundaries and the dauphine twin correlation the dauphine twins which are generally not detectable optically are not correlated with specific maxima in the orientation distribution function their origin and their role during recrystallization is discussed during recrystallization no other preferred high angle misorientations developed the frequent occurrence of small angle grain boundaries indicates progressive subgrain rotation as a recrystallization mechanism

evaluating volume of coseismic landslide clusters by flow direction based partitioning abstract a strong earthquake can trigger thousands of co seismic landslides the evaluation of the volume of such co seismic landslides is essential for landslide risk assessment and long term post earthquake hazard evaluation empirical volume area power laws are often applied to estimate the landslide volume when several small landslide deposits form a large cluster on the hillslope blurry boundaries of the clustered co seismic landslides may lead to seemingly one large landslide and grossly overestimated landslide volume in this paper we propose a flow direction based method to identify the boundaries of a cluster of landslides and to partition co seismic landslides three watersheds that were severely impacted by co seismic landslides in the wenchuan earthquake region are chosen for case studies each co seismic landslide cluster in these watersheds was interpreted from images taken shortly after the earthquake and partitioned into individual landslides in accordance with a flow direction map that is processed based on a local digital terrain model finally the volume of each individual landslide is calculated using an empirical volume area power law the adopted power law scaling relationship is selected from six widely used empirical relations and verified by 11 local landslide cases the proposed flow direction based partitioning method is further verified by clear boundaries of landslides that were exposed after storms as well as supplementary field survey results the proposed method results in similar landslide boundaries and volumes as the field survey results the uncertainty of this approach is below 19 if no partitioning is conducted the total volume of the landslide cluster can approach twice that from the field investigations

image enhancements of landsat 8 oli and sar data for preliminary landslide identification and mapping applied to the central region of kenya image enhancements lead to improved performance and increased accuracy of feature extraction recognition identification classification and hence change detection this increases the utility of remote sensing to suit environmental applications and aid disaster monitoring of geohazards involving large areas the main aim of this study was to compare the effect of image enhancement applied to synthetic aperture radar sar data and landsat 8 imagery in landslide identification and mapping the methodology involved pre processing landsat 8 imagery image co registration despeckling of the sar data after which landsat 8 imagery was enhanced by principal and independent component analysis pca and ica a spectral index involving bands 7 and 4 and using a false colour composite fcc with the components bearing the most geologic information the sar data were processed using textural and edge filters and computation of sar incoherence the enhanced spatial textural and edge information from the sar data was incorporated to the spectral information from landsat 8 imagery during the knowledge based classification the methodology was tested in the central highlands of kenya characterized by rugged terrain and frequent rainfall induced landslides the results showed that the sar data complemented landsat 8 data which had enriched spectral information afforded by the fcc with enhanced geologic information the sar classification depicted landslides along the ridges and lineaments important information lacking in the landsat 8 image classification the success of landslide identification and classification was attributed to the enhanced geologic features by spectral textural and roughness properties

dynamic lithospheric response to megathrust and precursory seismicity features of megathrust abstract temporal variations of seismic properties in inner trench regions before and after three megathrusts with magnitudes greater than or equal to 8 8 since 2004 are investigated to understand the nature of megathrust earthquakes the seismicity was increased significantly and the fault type compositions changed after megathrusts the seismicity displays characteristic fault type dependent distribution on rupture planes the postseismic thrustal events were populated around the down dip rupture margins due to the concentration of shear stress after coseismic ruptures normal faulting earthquakes increased after the megathrusts particularly in shallow depth regions with large slips which may be associated with lithospheric rebound and development of splay faults the earthquake occurrence rate b value displays a characteristic slip dependent feature the earthquake occurrence rates decrease with the slip amount of forthcoming megathrust which may be caused by continuous accumulation of plate driven stress and tectonic loading around the future rupture planes on the slab surface the slip dependency of earthquake occurrence rates is enhanced with time until the occurrence of megathrust the level of seismicity after megathrust is inversely proportional to that before megathrust yielding comparable average seismicity over the rupture zone it was also observed that the dynamic lithospheric response is highly correlated with slip distribution on the rupture plane the tension axes of the normal faulting earthquakes for 100 days after the tohoku oki earthquake focus to an apparent pole suggesting a radial viscoelastic deformation of lithosphere the temporal changes of slip dependent b values fit well with an exponential function suggesting an exponential increase of normal stress on the locked region with time until the occurrence of the megathrust this observation suggests that the temporal variation of slip dependent b values may be useful for prediction of forthcoming megathrusts at least several tens years beforehand

texture analysis of a muscovite bearing quartzite a comparison of some currently used techniques abstract four well established techniques were applied to determine the mineral textures of a muscovite bearing quartzite 1 directional measurements on an optical u stage 2 x ray 3 neutron and 4 electron diffraction ebsd techniques 1 and 4 are of the single grain type and techniques 2 and 3 of the statistical or volume type experimental pole density diagrams were compared by means of the construction of pole figure differences difference pole figures which led to the observation that ebsd and u stage derived pole figures agree well even in detail in contrast pole figures derived from x ray and neutron diffraction are clearly different from pole figures derived from the single grain techniques visible as pronounced preferred orientation in the difference pole figures specific properties of the applied techniques may be responsible for the observed differences such as 1 missing proportionality to the grain volume in the single grain methods 2 the accessible sample volume 3 erroneous data correction or 4 statistical errors also the method of data treatment which is basically different for the single grain and statistical methods should be considered when pole figures are evaluated apart from purely economical constraints and availibility of equipment the decision on the most suitable method for a texture determination should be based on the scientific goals and specific properties of particular techniques texture measurements of the statistical type are well suited for determination of bulk textures of rocks e g as required for the calculation of anisotropic physical properties of rocks whereas single grain measurements are advantageous for the investigation of local textures and texture forming mechanisms

monitoring shallow resistivity changes prior to the 12 may 2008 m 8 0 wenchuan earthquake on the longmen shan tectonic zone china abstract an active source measurement of shallow resistivity using fixed electrode quasi schlumberger arrays has been conducted at pixian jiangyou and wudu stations on the longmen shan tectonic zone in western china with the hope of detecting earthquake associated changes for the duration of the monitoring experiment a gradual decrease of apparent resistivity of up to 6 7 several years prior to the 12 may 2008 m 8 0 wenchuan earthquake had been recorded clearly at pixian station approximately 35 km from the epicenter the change of apparent resistivity was monitored with a fixed schlumberger array of ab mn spacings of 736 m 226 m in the direction of n57 5 e giving precisions in measured daily averages of 0 16 or less a coseismic resistivity drop of up to 5 3 was observed at jiangyou station using a schlumberger array of ab mn spacings of 710 m 90 m in the direction of n10 e no fluctuation of resistivity was detected at wudu station at the time of the wenchuan mainshock while the focus of this paper is on monitoring or tracking resistivity variations prior to during and after the wenchuan earthquake we also aim to compare resistivity records of the wenchuan earthquake to those of the m 7 8 tangshan and m 7 2 songpan earthquakes of 1976 attempts to explain the observed resistivity variations have been made the results show that the resistivity variations observed at all three stations are in approximate agreement with resistivity stress behavior deduced from in situ experiments focal mechanisms a simplified dynamical model static stress analyses and field investigations from along the longmen shan fault zone