determination of mmax from background seismicity and moment conservation we describe a simple method to determine the probability distribution function of the magnitude m max and return period t r of the maximum plausible earthquake on crustal faults the method requires the background seismicity rate estimated from instrumental data and the rate of interseismic moment buildup the method assumes that the moment released by the seismic slip is in balance with the moment deficit accumulated in between earthquakes it also assumes that the seismicity obeys the gutenberg richter gr law up to m max we took into account the aftershocks of large infrequent events that were not represented in the instrumental record so that we could estimate the average seismicity rate over the entire fault history we extrapolated the instrumental record using the gr law to model the frequency of larger events and their aftershocks this increased the frequencies of smaller events on average when these smaller events were newly extrapolated they predicted a higher frequency of larger events we iterated this process until stability was reached and then we assumed moment balance when we found the maximum magnitude we have found this method to be appropriate in applications involving examples of fault with good historical catalogs we then showed examples of applications to faults with no historical catalogs we present results from nine cases for the san andreas fault system we find m max 8 1 0 3 with t r380 950 120 yrs for the north anatolian fault m max 8 0 0 3 with t r275 650 135 yrs for the main himalayan thrust m max 9 0 0 2 with t r1200 2700 550 yrs for the japan trench m max 9 3 0 3 with t r520 1200 220 yrs for the sumatra andaman trench m max 9 0 0 3 with t r200 450 80 yrs for the bocono fault m max 7 3 0 3 with t r160 360 70 yrs for the altyn tagh fault m max 8 0 0 3 with t r900 2000 400 yrs for the dead sea transform m max 7 8 0 3 with t r1000 2400 450 yrs and for the kunlun fault m max 8 0 0 3 with t r1000 2000 450 yrs

changes in seismicity and stress loading on subduction faults in the kanto region japan 2011 2014 seismic activity has increased in the kanto region japan following the 2011 m9 0 tohoku earthquake we here reassess this increase up to june 2014 to show that normal omori like relaxation characterizes the activity on crustal faults as well as on the philippine sea plate but not on the deeper pacific plate there repeating earthquakes display a twofold rate of occurrence still ongoing in june 2014 as compared to the pre tohoku rate suggesting enhanced creep we compute the coulomb stress changes on the upper locked portion of the philippine sea plate which last ruptured in 1923 we find that this fault was little affected by either the coseismic the postseismic the accelerated creep or the 2011 boso silent slip event

distal degassing of radon and carbon dioxide on galeras volcano colombia abstract diffuse degassing at galeras volcano colombia was studied during three consecutive field seasons from 1993 to 1995 measurements of222rn and co2 were made at 30 stations which were distributed on the volcano and on regional faults intersecting the edifice time series data show a decline of radon soil gas of up to 50 prior to a m 2 8 earthquake on 12 august 1993 at stations located near the epicenter and on the volcano near the location of earthquake swarms which occurred in april 1993 november december 1993 and march 1995 the onset of volcanic seismic activity tornillos on 9 august 1994 was preceded by anomalous soil gas increases at six stations located on the flanks of the volcano on the southwestern flank radon increased from 51 to 130 pci 1 between 7 and 14 august while on the northern flank radon concentrations began to increase 19 days before the appearance of tornillos in general stations close to the crater showed the largest radon increases soil gas distributions and carbon isotope data suggest that diffuse degassing on the volcano is structurally controlled and that the abundance of co2 in soil gas on the edifice cannot be taken as an indicator for the presence of magmatic gases radon soil gas concentrations and the222rn emanating226ra concentration increase near faults whereas co2 concentrations are more variable but commonly are higher on the volcano than near faults 13c values in soil co2 vary between 8 5 and 23 2 with 13c values more enriched than 15 found only in the vicinity of faults or sites prone to earthquake swarms this suggests a magmatic origin of co2 soil gas only near faults and an almost impermeable edifice in unfractured areas the observed correlations between seismic activity and soil degassing provide further evidence that soil gas studies especially when correlated to other methods of volcano surveillance such as seismicity and deformation may be useful in forecasting volcanic and seismic events

landslide hazard and risk assessment using semi automatically created landslide inventories landslide inventories prepared manually from remote sensing data or through field surveys have shown to be useful for preparation of landslide susceptibility and hazard maps recent literatures show several studies have been carried out to prepare landslide inventories from satellite data by automatic methods however almost no attempt has been made to validate the effect of such inventories on landslide hazard and risk assessment in this paper we have shown how landslide inventories prepared by semi automatic methods from post event satellite images can be used in the assessment of landslide susceptibility hazard and risk in the high himalayan terrain in india a susceptibility map was made using the weights of evidence method wherein weights were derived using the semi automatically prepared historical landslide inventories combined with a series of pre disposing factor maps seven evidence layers were used for the calculation of weights selected in such a way that the majority could be derived from satellite data validation was done using the test data created through a temporal subsetting of the inventories temporal probability was calculated through gumbel frequency distribution analysis using daily rainfall data of a 13 year period for which landslide inventories were prepared from satellite data spatial probability was determined by calculating landslide density for the inventories per susceptibility class that represent a given return period elements at risk such as buildings and roads were interpreted from a high resolution cartosat 1 2 5 m image absolute vulnerability of the buildings and roads were multiplied with landslide spatial probability to derive the total loss for different return period scenarios and shown in a risk curve this study has shown that the inventories prepared semi automatically can be used for landslide hazard and risk assessment in a data poor environment

thermal convection of soil air on hillsides although diffusion is usually considered to be the main transport process for volatile constituents in the unsaturated zone of soils and other surficial materials an alternative process of thermally driven convection may be significant especially on hillsides and over irregular bedrock convection in this mode is driven by buoyancy forces arising from differences in soil air density in a temperature gradient for bodies with sloping boundaries the conventional rayleigh criterion is not directly applicable so that flow of air is possible in a wide variety of situations numerical simulations for several simple cases show that air convection is expected within relatively permeable materials such as sandy soils gravel deposits and talus on slopes

the coulomb stress changes and seismicity rate due to the 1990 mw 7 3 rudbar earthquake we investigate correlation between the coulomb stress changes and the spatial distribution of the aftershocks of the 1990 m w 7 3 rudbar earthquake that occurred on and off the rudbar fault the coulomb stress changes indicate that the rudbar mainshock encouraged parts of the kelishom and kashachal strike slip faults located east of the main rupture as well as parts of the manjil thrust fault located south of the main rupture the central part of the manjil thrust which is sandwiched between two stress shadow zones experienced an increase in coulomb stress we observe that the events before and after the rudbar mainshock have different spatial distribution patterns we find that most of the aftershocks occurred in an area between the kabateh and zardgeli segments where the static coulomb stress is high while few aftershocks occurred in the stress shadow zone that extends to the northwest and southeast of the rudbar rupture the aftershocks that occurred in the stress shadow zones northwest of the baklor segment were related to the continuation of the background seismicity after the mainshock a burst of seismicity following the rudbar earthquake south of the zardgeli segment provides evidence for dynamic stress triggering for the aftershocks that affected these regions for the first 1 3 months after the mainshock we also compare the coulomb stress changes with the seismicity rate and find that the regions with high seismicity rate are in good agreement with the high stress such as the western end of the baklor and an area between the kabateh and zardgeli segments to validate the effects of the coulomb stress on the seismicity rate we resolved stress changes on the aftershock nodal planes and recognize that the aftershocks located between the kabateh and zardgeli segments and the surrounding areas were brought closer to failure

a procedure for landslide susceptibility zonation by the conditional analysis method numerous methods have been proposed for landslide probability zonation of the landscape by means of a geographic information system gis among the multivariate methods i e those methods which simultaneously take into account all the factors contributing to instability the conditional analysis method applied to a subdivision of the territory into unique condition units is particularly straightforward from a conceptual point of view and particularly suited to the use of a gis in fact working on the principle that future landslides are more likely to occur under those conditions which led to past instability landslide susceptibility is defined by computing the landslide density in correspondence with different combinations of instability factors the conceptual simplicity of this method however does not necessarily imply that it is simple to implement especially as it requires rather complex operations and a high number of gis commands moreover there is the possibility that in order to achieve satisfactory results the procedure has to be repeated a few times changing the factors or modifying the class subdivision to solve this problem we created a shell program which by combining the shell commands the gis geographical research analysis support system grass commands and the gawk language commands carries out the whole procedure automatically this makes the construction of a landslide susceptibility map easy and fast for large areas too and even when a high spatial resolution is adopted as shown by application of the procedure to the parma river basin in the italian northern apennines

factors affecting exhalation of radon from a gravelly sandy loam measurements of radon exhalation from a gravely sandy loam have been made in a semi arid climate by using a combination of closed accumulation flow through accumulation and 222rn and 210pb soil profiles the meteorological factors that most affected the instantaneous value of exhalation of 222rn were atmospheric pressure and rain effects due to other parameters such as wind or temperature were either comparatively small or undetectable no evidence was seen for migration of radon from distant 10m sources or for an effect on exhalation due to limited nearby seismic activity measurements for 220rn indicated its exhalation was also sensitive to pressure variation but to a lesser extent than for 222rn while instantaneous exhalation of 222rn could easily vary by a factor of 2 or more time averaged exhalation was found to be close to that expected for pure diffusion there is thus some indication that the time averaged effect of cyclic environmental variables is small for this soil comparison with transport equations indicates that it is difficult to explain the observed variation in surface flux density solely in terms of the radon concentration gradient in the top few decimeters of soil a contribution to transport from direct flow perhaps through inhomogeneities such as cracks or channels is one possible explanation

mapping the suitability for ice core drilling of glaciers in the european alps and the asian high mountains ice cores from mid latitude mountain glaciers provide detailed information on past climate conditions and regional environmental changes which is essential for placing current climate change into a longer term perspective in this context it is important to define guidelines and create dedicated maps to identify suitable areas for future ice core drillings in this study the suitability for ice core drilling sicd of a mountain glacier is defined as the possibility of extracting an ice core with preserved stratigraphy suitable for reconstructing past climate morphometric and climatic variables related to sicd are selected through literature review and characterization of previously drilled sites a quantitative weight of evidence method is proposed to combine selected variables i e slope local relief temperature and direct solar radiation to map the potential drilling sites in mid latitude mountain glaciers the method was first developed in the european alps and then applied to the asian high mountains model performances and limitations are discussed and first indications of new potential drilling sites in the asian high mountains are provided results presented here can facilitate the selection of future drilling sites especially on unexplored asian mountain glaciers towards the understanding of climate and environmental changes

debris flow susceptibility mapping using frequency ratio and seed cells in a portion of a mountain international route dry central andes of argentina abstract debris flow and floods represent one of the main natural hazards that impact transport infrastructure causing serious damage economic losses and hinder regional economic development these processes are eventually associated with massive traffic cuts and direct damage to road structures to enable the prevention of such consequences this paper employs statistical modeling techniques various instability factors and geomorphological mapping to generate debris flow susceptibility maps in a portion of an important route on the dry andes of san juan in the agua negra river basin argentina a debris flows inventory map was prepared using satellite images and field checks the debris flows inventory was randomly divided into a model dataset 80 47 debris flows and remaining 20 12 debris flows data was used for validation purpose the instability factors chosen that influence debris flows occurrence were elevation slope angle slope aspect solar radiation topographic wetness index stream power index topographic position index melton ruggedness number terrain ruggedness index sediment transport capacity index plan curvature profile curvature lithology distance to road and proximity to stream using these factors six different models of debris flow susceptibility were calculated by frequency ratio fr lithology igneous complex was found to be important debris flows related factor in the study area the precision of the results was evaluated by receiver operating characteristic roc analysis according to the area under the curve auc the models of all flow track and natural breaks and all flow track and geometrical interval were 0 83 and 0 84 respectively showing a practically identical predictive capacity

a country wide spatial assessment of landslide susceptibility in romania abstract this paper proposes a brief spatial analysis of landslides in romania completed by a landslide susceptibility model landslides constitute a very common geomorphic hazard in this country mainly in the hilly regions which occupy around 30 of romania s territory the landslide susceptibility assessment at national level was accomplished using a landslide susceptibility index lsi computed in gis which considers and weights the main factors that control landslide activity lithology slope gradient maximum rainfall in 24 h land use seismicity and local relief each factor was classified into 7 18 classes which were rated from 1 to 10 by means of expert judgement a formula was devised to compute the landslide susceptibility index over each 100 m 100 m pixel and the resulting values were ranked into 5 landslide susceptibility classes this synthetic method of landslide susceptibility assessment applied to the whole country is a useful tool to evaluate the distribution of landslide prone areas as well as to validate and to enhance some results obtained in previous studies based on field research and map interpretation the most landslide prone areas correspond to the subcarpathians an outer fringe of hilly terrain accompanying the carpathians as well as to the moldavian plateau in the east the semi quantitative approach has been validated with satisfactory results in a particular sector using independent cartographic landslide inventories

heterogeneity of direct aftershock productivity of the main shock rupture the epidemic type aftershock sequence etas model is widely used to describe and analyze the clustering behavior of seismicity instead of regarding large earthquakes as point sources the finite source etas model treats them as ruptures that extend in space each earthquake rupture consists of many patches and each patch triggers its own aftershocks isotropically we design an iterative algorithm to invert the unobserved fault geometry based on the stochastic reconstruction method this model is applied to analyze the japan meteorological agency jma catalog during 1964 2014 we take six great earthquakes with magnitudes 7 5 after 1980 as finite sources and reconstruct the aftershock productivity patterns on each rupture surface comparing results from the point source etas model we find the following 1 the finite source model improves the data fitting 2 direct aftershock productivity is heterogeneous on the rupture plane 3 the triggering abilities of m5 4 events are enhanced 4 the background rate is higher in the off fault region and lower in the on fault region for the tohoku earthquake while high probabilities of direct aftershocks distribute all over the source region in the modified model 5 the triggering abilities of five main shocks become 2 6 times higher after taking the rupture geometries into consideration and 6 the trends of the cumulative background rate are similar in both models indicating the same levels of detection ability for seismicity anomalies moreover correlations between aftershock productivity and slip distributions imply that aftershocks within rupture faults are adjustments to coseismic stress changes due to slip heterogeneity

landslide susceptibility assessment using a novel hybrid model of statistical bivariate methods fr and woe and adaptive neuro fuzzy inference system anfis at southern zagros mountains in iran the aim of landslide susceptibility mapping lsm is to produce the most important and basic information required for overall landslide disaster planning and mitigation different statistical bivariate methods such as frequency ratio fr and weights of evidence woe have been widely used for lsm although results of these aforementioned statistical methods are generally acceptable however they can be improved further by fine tuning the conditioning factor s classes the purpose of this paper is to overcome some drawbacks of the bivariate models by developing a novel hybrid method using adaptive neuro fuzzy inference system anfis and statistical bivariate methods fr and woe in geographical information system the provinces of southern zagros mountains iran are chosen as a case study to implement the proposed method first landslide inventory map was produced using various data source such as historical landslides locations remote sensing images and land surveying techniques second the inventory data were divided into a ratio 70 30 for training and testing the models third twelve landslide conditioning and triggering factors such as altitude slope aspect plan and profile curvatures distance to roads distance to streams distance to faults rainfall seismicity land use and lithology were selected and categorized in two groups consisting of numerical and nominal values then each conditioning factor was classified and the weight of each class was determined by using fr and woe models the outputs of individual statistical and hybrid methods were applied to determine nominal and continuous numerical data respectively in the hybrid approach the calculated weights of each class were allocated to the center of each class and the rest of the weights were determined by anfis landslide locations which were not used in training the models were used for validation the produced susceptibility maps were validated and compared using area under the curve auc results indicated that predictive performances of hybrid models fr anfis and woe anfis have better performance than the statistical models fr and woe the aucs of success rates are 85 86 87 and 87 and the aucs of predicted rates are 82 82 85 and 84 for fr woe fr anfis and woe anfis respectively additionally frequency ratio plots frp and seed cells area index scai methods were also employed for a second round of validation the frp and scai graphs illustrated higher performance for the hybrid lsm models the proposed approach can be applied in other types of natural hazard modeling such as flood land subsidence and gully erosion

a study of the coulomb stress and seismicity rate changes induced by the 2008 m w 7 9 wenchuan earthquake sw china abstract correlations between the calculated coulomb stress changes and observed seismicity rate changes after the wenchuan earthquake are investigated in this article three improvements are made in the calculation of static stress change including employing a dislocation method with triangular elements rather than traditional rectangular elements setting up a more realistic source slip model and a more complete receiver fault model and resolving stress changes on assumed receiver faults with spatially variable focal mechanisms based on well determined focal mechanisms at different calculation points the recorded aftershocks are mapped for comparison with the spatial distribution of stress changes the results indicate that the wenchuan earthquake encourages not only three major fault systems the east kunlun south of xianshuihe and west of qinling southern frontal but also several other regions including tazang north of min jiang north of pingwu qingchuan and west of chongqing in particular the eastern segment of longriba is shown to be quite dangerous with dramatic stress increase the influence of depth and frictional coefficient is analyzed the depth of calculation beyond the depth range of the source model will make a significant difference to the stress change map and thus cannot be neglected many aftershocks occurring in the stress shadow zone near the main rupture can be attributed to dynamic stress triggering and the fractal structure of the main fault the observed seismicity rate changes are compared with the static stress changes the results show that high background seismicity rates will amplify the effect of stress change the observed seismicity rate changes support the forecast rate of 10 year seismicity after the wenchuan earthquake based on the rate and state dependent friction model coulomb stresses increase on the focal mechanisms away from the main rupture which demonstrates the influence of the wenchuan earthquake over a wide range especially the focal mechanism for lushan earthquake undergoes a stress increase by more than 2 0 bars which suggests that the lushan earthquake has been effectively promoted by the wenchuan earthquake

frequency ratio model based landslide susceptibility mapping in lower mae chaem watershed northern thailand the purpose of this study is to produce a landslide susceptibility map for the lower mae chaem watershed northern thailand using a geographic information system gis and remotely sensed images for this purpose past landslide locations were identified from satellite images and aerial photographs accompanied by the field surveys to create a landslide inventory map ten landslide inducing factors were used in the susceptibility analysis elevation slope angle slope aspect lithology distance from lineament distance from drainage precipitation soil texture land use land cover lulc and ndvi the first eight factors were prepared from their associated database while lulc and ndvi maps were generated from landsat 5 tm images landslide susceptibility was analyzed and mapped using the frequency ratio fr model that determines the level of correlation between locations of past landslides and the chosen factors and describes it in terms of frequency ratio index finally the output map was validated using the area under the curve auc method where the success rate of 80 06 and the prediction rate of 84 82 were achieved the obtained map can be used to reduce landslide hazard and assist with proper planning of lulc in the future

exhalation of radon and thoron the question of the effect of thermal gradients in soil abstract experimental measurements show no evidence for diurnal variation in exhalation of radon and thoron from soil due to convection induced by thermal gradients in the top few decimeters of soil as suggested by several authors estimates based on convective calculations indicate that even in the unlikely event of either vertical temperature gradients large enough to cause vertical instability or horizontal gradients sufficient to cause significant convection any effect would be too small to be detected these same calculations suggest that it is difficult to conceive of cases involving typical thermal gradients in unfractured porous media such as soil where thermally induced convection would play an important role in transport of radon or thoron

the m w 6 7 12 october 2013 western hellenic arc main shock and its aftershock sequence implications for the slab properties the 12 october 2013 m w6 7 earthquake offshore crete island is one of the few strong earthquakes to have occurred in the last few decades in the southwestern part of the hellenic subduction zone hsz providing the opportunity to evaluate characteristics of the descending slab the hsz has experienced several strong m 7 0 earthquakes in historical times with the largest one being the 365 ad m w 8 4 earthquake the largest known ever occurred in the mediterranean region the 2013 main shock occurred in close proximity with the 365 event on an interplate thrust fault at a depth of 26 km onto the coupled part of the overriding and descending plates gcmt solution shows a slightly oblique rake 130 thrust faulting with downdip compression on a nearly horizontal dip 3 northeast dipping fault plane with strike 340 parallel to the subduction front with the compression axis being oriented in the direction of plate convergence the subduction interface can be more clearly resolved with the integration of aftershock locations and cmt solution for this scope the aftershocks were relocated after obtaining a v p v s ratio equal to 1 76 a one dimensional velocity model and time delays that approximate the velocity structure of the study area and the employment of double difference technique for both phase pick data and cross correlation differential times the first day relocated seismicity alike aftershocks in the first 2 months shows activation of an area at the upper part of the descending slab with most activity being concentrated between 13 and 27 km where the main shock is also encompassed aftershocks are rare near to the main shock implying homogeneous slip on a large patch of the rupture plane based on the aftershock distribution the size of the activated area estimated is about 24 km long and 17 km wide coulomb stress changes resolved for transpressive motion reveal negligible off fault aftershock triggering evidencing a comparatively stable regime in the downdip part of the slab or different fault mechanism

shallow dynamic overshoot and energetic deep rupture in the 2011 mw 9 0 tohoku oki earthquake strong spatial variation of rupture characteristics in the moment magnitude mw 9 0 tohoku oki megathrust earthquake controlled both the strength of shaking and the size of the tsunami that followed finite source imaging reveals that the rupture consisted of a small initial phase deep rupture for up to 40 seconds extensive shallow rupture at 60 to 70 seconds and continuing deep rupture lasting more than 100 seconds a combination of a shallow dipping fault and a compliant hanging wall may have enabled large shallow slip near the trench normal faulting aftershocks in the area of high slip suggest dynamic overshoot on the fault despite prodigious total slip shallower parts of the rupture weakly radiated at high frequencies whereas deeper parts of the rupture radiated strongly at high frequencies

crustal block kinematics and seismic potential of the northernmost philippine sea plate and izu microplate central japan inferred from gps and leveling data 1 we clarify the contemporary deformation observed by gps and leveling for the greater tokyo kanto eastern tokai and the izu islands region where the izu ogasawara bonin arc is subducting and colliding with the central part of the japan arc from these data we develop a kinematic model of fault sources with variable components of seismic and aseismic slip under the assumption that the contemporary deformation during 1995 2000 is representative of the long term interseismic strain field the geodetic data are inverted to estimate the rotation poles of the crustal blocks the degree of elastic strain accumulation on faults and the volumetric inflation sources beneath volcanoes the present crustal movements are explained by four crustal blocks the izu microplate the central japan block the pacific plate and the philippine sea plate along the suruga and sagami margins of the philippine sea plate lie strongly coupled faults which include sites of the 1854 m 8 4 tokai 1923 m 7 9 kanto and 1703 m 8 2 genroku kanto earthquakes in contrast the philippine sea plate boundary immediately north of the izu peninsula site of m 7 5 collisional earthquakes is only weakly coupled the boundary between the izu microplate and the philippine sea plate experiences left lateral motion with the rate of 30 mm yr most of this boundary is locked and thus has a large potential of future earthquakes the izu microplate is found to rotate rapidly clockwise at 10 myr with a rotation pole relative to the central japan block located just north of its northern boundary the pole and angular velocity of the izu microplate depends however on the assumed location of the boundary with the exception of the site of the 1938 m 7 earthquake swarm which we infer has the current potential to produce a m 8 1 earthquake the pacific megathrust has a very low seismic potential although the geodetic data have little resolving power for much of the pacific plate interface east of tokyo

sensitivity of coulomb stress change to the parameters of the coulomb failure model a case study using the 2008 mw 7 9 wenchuan earthquake the coulomb stress change has been widely employed to interpret mainshock mainshock and mainshock aftershock triggering as well as interactions amongst earthquake faults and volcanoes this quantitative index is computed based on the coulomb failure criterion and is a function of fault parameters including the source and receiver fault geometries the friction coefficient on the receiver fault and skempton s coefficient of the host rock thus for the robust determination of the coulomb stress change the sensitivity of the coulomb stress change to these model parameters should be thoroughly assessed however notwithstanding numerous case studies almost no systematic investigation of the sensitivity of the coulomb stress change has been performed here we present an error estimator for the coulomb stress change and then quantitatively investigate the sensitivity of the coulomb stress change to the fault model parameters for the 2008 mw 7 9 wenchuan earthquake our results indicate that for this case the coulomb stress change is the most sensitive to the uncertainty in the dip angle of the receiver fault while the influences of the uncertainties in the slip model of the source fault the strike and rake angles of the receiver fault and the friction and skempton s coefficients cannot be neglected accordingly it is crucial to perform a realistic estimate of the uncertainty in the coulomb stress change by performing such calculation future coulomb stress analyses such as the stress triggering of earthquake sequence and the likelihoods of potential earthquakes could be based on more robust coulomb stress change maps

a gis based landslide susceptibility evaluation using bivariate and multivariate statistical analyses bivariate and multivariate statistical analyses were used to predict the spatial distribution of landslides in the cuyahoga river watershed northeastern ohio u s a the relationship between landslides and various instability factors contributing to their occurrence was evaluated using a geographic information system gis based investigation a landslide inventory map was prepared using landslide locations identified from aerial photographs field checks and existing literature instability factors such as slope angle soil type soil erodibility soil liquidity index landcover pattern precipitation and proximity to stream responsible for the occurrence of landslides were imported as raster data layers in arcgis and ranked using a numerical scale corresponding to the physical conditions of the region in order to investigate the role of each instability factor in controlling the spatial distribution of landslides both bivariate and multivariate models were used to analyze the digital dataset the logistic regression approach was used in the multivariate model analysis both models helped produce landslide susceptibility maps and the suitability of each model was evaluated by the area under the curve method and by comparing the maps with the known landslide locations the multivariate logistic regression model was found to be the better model in predicting landslide susceptibility of this area the logistic regression model produced a landslide susceptibility map at a scale of 1 24 000 that classified susceptibility into four categories low moderate high and very high the results also indicated that slope angle proximity to stream soil erodibility and soil type were statistically significant in controlling the slope movement

transport of radon from fractured rock the transport of 222rn from fractured rock has been studied in an abandoned mine pressure induced flow both natural and artificial is quite important and can easily cause an order of magnitude increase in the instantaneous transport of radon into the tunnel airspace compared to that due to flowfree diffusion permeability studies indicate that large scale cracks of surface density of the order of several cracks per square meter dominate flow in first order effective flux due to natural pressure variation follows an approximate dp dt dependence in higher order there exists an enhancement of time averaged flux by typically a factor of 2 due to natural pressure variation mathematical modeling indicates that the relation between pressure and the strength and time dependence of the radon transport is difficult to explain solely with conventional models for semi infinite homogeneous porous media a model of cul de sac chambers is proposed to account for some of this dependence

landslide susceptibility assessment by bivariate methods at large scales application to a complex mountainous environment statistical assessment of landslide susceptibility has become a major topic of research in the last decade most progress has been accomplished on producing susceptibility maps at meso scales 1 50 000 1 25 000 at 1 10 000 scale which is the scale of production of most regulatory landslide hazard and risk maps in europe few tests on the performance of these methods have been performed this paper presents a procedure to identify the best variables for landslide susceptibility assessment through a bivariate technique weights of evidence woe and discusses the best way to minimize conditional independence ci between the predictive variables indeed violating ci can severely bias the simulated maps by over or under estimating landslide probabilities the proposed strategy includes four steps i identification of the best response variable rv to represent landslide events ii identification of the best combination of predictive variables pvs and neo predictive variables npvs to increase the performance of the statistical model iii evaluation of the performance of the simulations by appropriate tests and iv evaluation of the statistical model by expert judgment the study site is the north facing hillslope of the barcelonnette basin france affected by several types of landslides and characterized by a complex morphology results indicate that bivariate methods are powerful to assess landslide susceptibility at 1 10 000 scale however the method is limited from a geomorphological viewpoint when rvs and pvs are complex or poorly informative it is demonstrated that expert knowledge has still to be introduced in statistical models to produce reliable landslide susceptibility maps

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

radon 222 emanometry a relevant methodology for water well siting in hard rock aquifers to improve the understanding of soil gas emanations with the aim of groundwater prospecting in fractured substrates radon anomalies were mapped in a tropical region french guyana where the structural features of a potential gas source are masked owing to the thick regolith cover two anomalies were located two probes were then installed one bl on the border of the north anomaly and the second b2 at the center of the south anomaly as well as a meteorological station and monitoring was carried out for 6 months extending from the dry to the rainy season signal processing of radon signal atmospheric pressure time series allowed us to determine the physical processes causing migration of the gases in the soil and the subsoil the radon anomalies are very probably associated with the presence in the hard rock substratum of a permeable structure that permits the transit of deep origin gas to the surface this transport by advection disturbs the radon diffusion profile from the first meters of soil into the atmosphere the radon thus behaves as a marker of deeper gases percolating through the regolith cover indeed in such a context with low permeability weathered formations because of its short half life 3 8 days the radon measured in the first decimeters of the soil displays an exclusively superficial origin hence the measurement of the radon content in soil at an identical depth from one sampling site to another helps locate the zones affected by advective gas transfers which explains why the radon anomalies in soil gases identified at the scale of a hydrogeological prospecting site located in a hard rock context usually coincide vertically in hydraulically active fracture zones this fully justifies the use of this method to site water wells provided some precautions are observed particularly pertaining to the spatial and temporal variability of the signal associated with different types of soils and changes in the meteorological parameters and soil moisture contents the methodology is simple since only robust equipment is required the estimation of gas transport parameters also helped identify the extent of advection areas during the dry season they are characterized by low gas velocity these zones shrink with the early rains and the advection area is confined vertically up the fault where a channeling effect occurs soil gas preferably follows the less constricted pores and the increased pressure gradient offsets the decrease in permeability

landslide hazard zonation using analytical hierarchy process along national highway 3 in mid himalayas of himachal pradesh india landslide zonation studies emphasize on preparation of landslide hazard zonation maps considering major instability factors contributing to occurrence of landslides this paper deals with geographic information system based landslide hazard zonation in mid himalayas of himachal pradesh from mandi to kullu by considering nine relevant instability factors to develop the hazard zonation map analytical hierarchy process was applied to assign relative weightages over all ranges of instability factors of the slopes in study area to generate landslide hazard zonation map layers in geographic information system were created corresponding to each instability factor an inventory of existing major landslides in the study area was prepared and combined with the landslide hazard zonation map for validation purpose the validation of the model was made using area under curve technique and reveals good agreement between the produced hazard map and previous landslide inventory with prediction accuracy of 79 08 the landslide hazard zonation map was classified by natural break classifier into very low hazard low hazard moderate hazard high hazard and very high landslide hazard classes in geographic information system depending upon the frequency of occurrence of landslides in each class the resultant hazard zonation map shows that 14 30 of the area lies in very high hazard zone followed by 15 97 in high hazard zone the proposed model provides the best fit classification using hierarchical approach for the causative factors of landslides having complex structure the developed hazard zonation map is useful for landslide preparedness land use planning and social economic and sustainable development of the region

cohesion versus friction in controlling the long term strength of a self healing experimental fault the coulomb s failure criterion which postulates that failure occurs along a fault plane when the applied shear stress overcomes a resistance made of two parts of different nature cohesion and friction remains the standard conceptual framework of faulting mechanics more recently rate and state friction laws became the main modelling tool of the seismic cycle these laws implicitly assume that only frictional resistance sets the fault strength and its evolution we therefore raise the question of the role of cohesion and related healing sealing mechanisms on fault mechanics we designed an original laboratory experiment based on a model material an ice thin layer sitting on top of a water tank and mechanically deformed at various rates with a circular couette like geometry this allowed sliding along the fault plane over arbitrarily large slip distances and analyzing the competition between faulting and cohesion healing rates whereas frictional resistance resulting from the fault roughness is limited in magnitude we show that cohesion healing plays an essential role in the time evolution of the interface strength under constant loading rate in particular the magnitudes of shear stress fluctuations are observed to be temperature and velocity weakening the present experiment shares several properties similar to that of active faults during seismic cycles suggesting that cohesive healing could control some of these features scale invariance properties gutenberg richter law of rupture events size distribution omori s law of energy dissipation at least after major ruptures time asymmetry in energy dissipation and periods of creep under high shear stress alternating with major earthquake like ruptures

landslides and climatic conditions in the barcelonnette and vars basins southern french alps france research into the climatic causes behind the triggering and reactivation of landslides has been carried out in two basins in the southern french alps where a great many landslides have occurred over more than a century correlations between landslides and climate are sometimes precise and closely related in time at other times imprecise and more distant the better known the type of landslide and the date of its occurrence the greater the correlation may appear be this as it may climate is never the sole cause this paper deals with the limits of the effects of climate

aftershocks halted by static stress shadows the role of permanent versus transient crustal stress changes in triggering earthquakes is debated analysis of the stress imparted by the joshua tree and nearby landers earthquakes in california in 1992 implies that a permanent drop in stress can halt aftershocks so such static stress changes should be incorporated into seismic hazard assessments

landslide susceptibility mapping using frequency ratio analytic hierarchy process logistic regression and artificial neural network methods at the inje area korea every year the republic of korea experiences numerous landslides resulting in property damage and casualties this study compared the abilities of frequency ratio fr analytic hierarchy process ahp logistic regression lr and artificial neural network ann models to produce landslide susceptibility index lsi maps for use in predicting possible landslide occurrence and limiting damage the areas under the relative operating characteristic roc curves for the fr ahp lr and ann lsi maps were 0 794 0 789 0 794 and 0 806 respectively thus the lsi maps developed by all the models had similar accuracy a cross tabulation analysis of landslide occurrence against non occurrence areas showed generally similar overall accuracies of 65 27 64 35 65 51 and 68 47 for the fr ahp lr and ann models respectively a correlation analysis between the models demonstrated that the lr and ann models had the highest correlation 0 829 whereas the fr and ahp models had the lowest correlation 0 619

the 2011 m 9 0 tohoku oki earthquake more than doubled the probability of large shocks beneath tokyo 1 the kanto seismic corridor surrounding tokyo has hosted four to five m 7 earthquakes in the past 400 years immediately after the tohoku earthquake the seismicity rate in the corridor jumped 10 fold while the rate of normal focal mechanisms dropped in half the seismicity rate decayed for 6 12 months after which it steadied at three times the pre tohoku rate the seismicity rate jump and decay to a new rate as well as the focal mechanism change can be explained by the static stress imparted by the tohoku rupture and postseismic creep to kanto faults we therefore fit the seismicity observations to a rate state coulomb model which we use to forecast the time dependent probability of large earthquakes in the kanto seismic corridor we estimate a 17 probability of a m 7 0 shock over the 5 year prospective period 11 march 2013 to 10 march 2018 two and a half times the probability had the tohoku earthquake not struck

coulomb stress changes and secondary stress triggering during the 2003 mw 6 6 bam iran earthquake abstract the 26 december 2003 mw 6 6 bam earthquake is one of the most destructive events in the recorded history of iran good variable slip fault models and precise aftershock data enabled us to calculate coulomb stress changes on the surrounding faults optimally oriented faults and the aftershock nodal planes to learn whether they were brought closer to failure we also test the role of secondary stress on the aftershocks triggering calculated stress on the surrounding faults showed that the southern part of the gowk fault and middle part of the dalfard and bam faults received positive stress changes stress also increases at the ends of the ruptured fault plane to expand it our calculations showed that deeper part of the bam fault planes received positive stress changes due to slipping on the shallow depth it can lead to the occurrence of aftershocks and enhance the probability of large events in the future that represent a substantial remaining seismic hazard to the reconstructed city of bam by imparting stress on optimally oriented faults the correlation between coulomb stress changes and aftershock distribution is investigated obtained results showed good correlation between coulomb stress change and seismicity from 331 well located aftershock hypocenters about 270 events 81 are located in the positive stress changes area the imparted stress due to the main shock and secondary aftershocks on the nodal planes of the 158 aftershocks is calculated the results show that the imparted stress due to main shock encouraged about 60 1 of nodal planes and 77 8 of the chosen nodal planes of aftershocks and added secondary aftershock encouraged about 81 6 of chosen nodal planes in other word by adding secondary triggering stress coulomb index for chosen nodal planes increased from 0 778 to 0 816 and about 80 of aftershocks receive greater positive stress changes

a new 1649 1884 catalog of destructive earthquakes near tokyo and implications for the long term seismic process 1 in order to assess the long term character of seismicity near tokyo we construct an intensity based catalog of damaging earthquakes that struck the greater tokyo area between 1649 and 1884 models for 15 historical earthquakes are developed using calibrated intensity attenuation relations that quantitatively convey uncertainties in event location and magnitude as well as their covariance the historical catalog is most likely complete for earthquakes m 6 7 the largest earthquake in the catalog is the 1703 m 8 2 genroku event seismicity rates from 80 years of instrumental records which include the 1923 m 7 9 kanto shock as well as interevent times estimated from the past 7000 years of paleoseismic data are combined with the historical catalog to define a frequency magnitude distribution for 4 5 m 8 2 which is well described by a truncated gutenberg richter relation with a b value of 0 96 and a maximum magnitude of 8 4 large uncertainties associated with the intensity based catalog are propagated by a monte carlo simulation to estimations of the scalar moment rate the resulting best estimate of moment rate during 1649 2003 is 1 35 1026 dyn cm yr 1 with considerable uncertainty at the 1 level 0 11 0 20 1026 dyn cm yr 1 comparison with geodetic models of the interseismic deformation indicates that the geodetic moment accumulation and likely moment release rate are roughly balanced over the catalog period this balance suggests that the extended catalog is representative of long term seismic processes near tokyo and so can be used to assess earthquake probabilities the resulting poisson or time averaged 30 year probability for m 7 9 earthquakes is 7 11

a slab fragment wedged under tokyo and its tectonic and seismic implications a three dimensional evaluation of earthquake hypocentres beneath the kanto basin in japan reveals the presence of a distinct 25 km thick and 100 km wide body its fast seismic velocity and the presence of a double seismic zone suggest that it is a fragment of the pacific slab rather than an extension of the philippine sea slab this implies that the penetration of the philippine sea slab is much shallower beneath the kanto basin than was previously thought the philippine sea and pacific plate slabs both subduct beneath tokyo and so their configuration and seismic potential have been subject to intensive study1 2 3 4 5 6 7 8 previous work suggests that the philippine sea slab extends up to 100 km northwest of tokyo and subducts to a depth of 90 km beneath the kanto basin where it is folded against the underlying pacific slab here we evaluate seismic data in three dimensions and delineate a distinct 25 km thick and 100 km wide body beneath the kanto basin that has hitherto been considered to be part of the philippine sea slab we find that several of its characteristics such as its high seismic velocity and the presence of a double seismic zone point instead to an affinity with the pacific slab implying that the philippine sea slab penetrates to depths of only 35 40 km beneath the kanto basin we propose that the body is a fragment of pacific lithosphere that formed by the collision of two intersecting seamount chains with the japan trench 2 3 million years ago we suggest that such slab fragments may not be uncommon especially where seamount subduction deforms trenches and near triple junctions

pre and postseismic slow slip surrounding the 2011 tohoku oki earthquake rupture abstract slow aseismic slip that accommodates part of the long term plate motion on subduction megathrusts is thought to be strongly related to the occurrence of large earthquakes on the same fault zone however the temporal evolution and spatial distribution of the aseismic slip before major earthquakes and of accelerated postseismic afterslip are largely unconstrained we estimate cumulative offsets of small repeating earthquakes that are interpreted to reflect the in situ aseismic slip history on the subduction zone offshore northeastern japan these data reveal contrasting aseismic slip patterns between the coseismic rupture area of the mw 9 0 tohoku oki earthquake and surrounding portions of the subduction thrust the rupture area is characterised by low and variable slip rates before 2008 and the slip stopped almost completely after the earthquake the region surrounding the rupture area exhibited higher aseismic fault slip rates before the earthquake and clear postseismic slip of up to 1 6 m within 9 months following the main shock the frictional fault properties and complete relief of ambient stress in the central rupture zone of the main shock probably control the observed distribution the postseismic slip shows a more abrupt increase in the region closer to the source suggesting outwards propagation of afterslip small but distinct increases in the slip rate in the 3 yr before the earthquake near the area of large coseismic slip suggests preseismic unfastening of the locked area in the last stage of the earthquake cycle

combining spatial data in landslide reactivation susceptibility mapping a likelihood ratio based approach in w belgium a key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction various combinations of high resolution predictor variables and possibilities of selecting them from a larger dataset are analysed the scarp reactivation of several landslides in a hilly region of w belgium is investigated at the pixel scale the susceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m resolution related to topography hydrology land use and lithology as potential independent variables the modelling uses a likelihood ratio approach based on the comparison for each independent variable between two empirical distribution functions edfs respectively for the reactivated and non reactivated areas it uses these edfs as favourability values to build membership values and combine them with a fuzzy gamma operator five different data combinations are tested and compared by analysing the prediction rate curves obtained by cross validation the geomorphological value of the resulting susceptibility maps is also discussed this research shows relevant results for predicting the susceptibility to scarp reactivation we highlight the need for testing several data combinations and underline that combining quantitative criteria with expert opinion is an asset for reliable predictions

static stress increase in the outer forearc produced by m w 8 2 september 8 2017 mexico earthquake and its relation to the gravity signal an mw 8 2 earthquake affected on september 8 2017 the cocos plate beneath the caribbean plate next to the transform contact with the north american plate across the tehuantepec gap one of the two gaps that exist along the mexican subduction zone offshore chiapas the epicenter occurred at a depth of 47 km and was associated with a highly steep normal fault parallel to the trench the origin can be related to slab pull forces dehydration processes and reactivation of outer rise faults this earthquake produced positive changes in the coulomb static stress which would favor the development of thrust displacements along the interplate contact across the tehuantepec gap instead of liberating tensions accumulated on it for decades in the case that stresses were not released steadily in the future a thrusting related event with a magnitude of mw 7 9 or higher could be expected after the september 8 2017 chiapas earthquake however the differential weight of the forearc offshore that contains a region with a high positive gravity gradient could inhibit rupture propagation to the coast precluding higher magnitudes combined and satellite only earth gravity field models show a highly heterogeneous density structure along the forearc of the north america caribbean plates and in particular at the studied zone maximum displacements in the rupture zone correlate to minimum gravity derived anomalies showing a probable relationship between the differential weight of the forearc structure and the extensional faulting affecting the bending of the cocos plate at depth in this sense variable sediment thicknesses over the forearc and a high gravity gradient zone parallel to the trench in the outer forearc could be reflecting physical heterogeneities that influence the propagation of the rupture zone additionally to the north a highly positive gradient signal related to the subducted tehuantepec fz projection beneath the north american plate marks the ending of the main slip patch acting as a barrier to the seismic rupture propagation this event exemplifies 1 how extensional ruptures in the downgoing slab of a subduction zone can increment accumulated elastic strain across a seismic gap instead of liberating tensions 2 that rupture propagation for this intraplate event was probably controlled at shallow depths by the density structure of the forearc similarly to recent interplate earthquakes along the chilean margin 3 how a low gravity gradient signal and low density structures identified from the inversion model in the region of the outer forearc where the normal stress increased after the main seismic event suggest a higher risk of occurrence of a great megathrust earthquake

preceding coseismic and postseismic slips of the 2011 tohoku earthquake japan 1 we estimated the spatial and temporal evolution of the preceding aseismic slip from january 2003 to january 2011 the coseismic slip of the tohoku earthquake and the postseismic slip after the earthquake based on global positioning system gps data time dependent analysis indicates aseismic slip offshore of miyagi and fukushima prefectures from 2004 associated with a series of subduction earthquakes that overlap the aseismic slip area these preceding aseismic and coseismic slip areas are centered between the centers of the coseismic and afterslip areas of the tohoku earthquake offshore of miyagi prefecture while they overlap the coseismic and afterslip areas of the tohoku earthquake off fukushima prefecture the timing of moment magnitude nine mw9 class earthquakes appears to be controlled by multiple preceding slip events smaller earthquakes and their afterslip the preceding aseismic and coseismic slip decreased the coupling rate off the tohoku coast suggesting the possibility that the preceding slip represented a precursive stage of the tohoku earthquake the afterslip of the tohoku earthquake occurred in an area where the coseismic slip was not large complementing the large coseismic slip zone the afterslip along iwate miyagi extends up to 80 km in depth and is currently the sole mechanism of strain release in this depth range the source region of the anticipated miyagi oki earthquake shows small postseismic slip after the tohoku earthquake reflecting the energy release at the time of the earthquake aftershock activity is roughly governed by an afterslip process

acceleration of regional plate subduction beneath kanto japan after the 2011 tohoku oki earthquake two oceanic plates the pacific pa and philippine sea ph subduct beneath the land plate and they forms deeper ph pa and shallower land ph plate boundaries beneath kanto remarkably enhanced seismicity was observed in the densely populated area after the 2011 tohoku oki earthquake which cannot simply be explained by the southern expansion of the postseismic slip of the earthquake we examine interplate repeating earthquakes to constrain the relative plate motion across aseismically slipping faults the repeater slip rates show creep rates in the deeper and shallower boundaries respectively increased to 2 4 6 6 times and 1 3 6 2 times the pre tohoku oki rates in addition the repeater slip directions show no change larger than 4 degree in the deeper boundary the interplate creep rates and slip directions suggest regional movements of both the two plates had accelerated they probably caused the seismicity increase frequent slow slips on the shallower boundary and enhanced probability of larger earthquakes

forecasting the evolution of seismicity in southern california animations built on earthquake stress transfer 1 we develop a forecast model to reproduce the distribution of main shocks aftershocks and surrounding seismicity observed during 1986 2003 in a 300 310 km area centered on the 1992 m 7 3 landers earthquake to parse the catalog into frames with equal numbers of aftershocks we animate seismicity in log time increments that lengthen after each main shock this reveals aftershock zone migration expansion and densification we implement a rate state algorithm that incorporates the static stress transferred by each m 6 shock and then evolves coulomb stress changes amplify the background seismicity so small stress changes produce large changes in seismicity rate in areas of high background seismicity similarly seismicity rate declines in the stress shadows are evident only in areas with previously high seismicity rates thus a key constituent of the model is the background seismicity rate which we smooth from 1981 to 1986 seismicity the mean correlation coefficient between observed and predicted m 1 4 shocks the minimum magnitude of completeness is 0 52 for 1986 2003 and 0 63 for 1992 2003 a control standard aftershock model yields 0 54 and 0 52 for the same periods four m 6 0 shocks struck during the test period three are located at sites where the expected seismicity rate falls above the 92 percentile and one is located above the 75 percentile the model thus reproduces much but certainly not all of the observed spatial and temporal seismicity from which we infer that the decaying effect of stress transferred by successive main shocks influences seismicity for decades finally we offer a m 5 earthquake forecast for 2005 2015 assigning probabilities to 324 10 10 km cells

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

prediction of landslide susceptibility using rare events logistic regression a case study in the flemish ardennes belgium abstract in this article a statistical multivariate method i e rare events logistic regression is evaluated for the creation of a landslide susceptibility map in a 200 km2 study area of the flemish ardennes belgium the methodology is based on the hypothesis that future landslides will have the same causal factors as the landslides initiated in the past the information on the past landslides comes from a landslide inventory map obtained by detailed field surveys and by the analysis of lidar light detection and ranging derived hillshade maps information on the causal factors e g slope gradient aspect lithology and soil drainage was extracted from digital elevation models derived from lidar and from topographical lithological and soil maps in landslide affected areas however we did not use the present day hillslope gradient in order to reflect the hillslope condition prior to landsliding the pre landslide hillslope was reconstructed and its gradient was used in the analysis because of their limited spatial occurrence the landslides in the study area can be regarded as rare events rare events logistic regression differs from ordinary logistic regression because it takes into account the low proportion of 1s landslides to 0s no landslides in the study area by incorporating three correction measures the endogenous stratified sampling of the dataset the prior correction of the intercept and the correction of the probabilities to include the estimation uncertainty for the study area significant model results were obtained with pre landslide hillslope gradient and three different clayey lithologies being important predictor variables receiver operating characteristic roc curves and the kappa index were used to validate the model both show a good agreement between the observed and predicted values of the validation dataset based on a qualified judgement the created landslide susceptibility map was classified into four classes i e very high high moderate and low susceptibility if interpreted correctly this classified susceptibility map is an important tool for the delineation of zones where prevention measures are needed and human interference should be limited in order to avoid property damage due to landslides

tsunami earthquake can occur elsewhere along the japan trench historical and geological evidence for the 1677 earthquake and tsunami since the 11 march 2011 tohoku earthquake the mechanisms of large earthquakes along the japan trench have been intensely investigated however characteristics of tsunami earthquakes which trigger unusually large tsunami remain unknown the earthquake of 4 november 1677 was a tsunami earthquake striking the southern part of the japan trench its source mechanism remains unclear this study elucidates the fault slip and moment magnitude of the 1677 earthquake and tsunami based on integrated analyses of historical documents tsunami deposits and numerical simulation geological survey results the analytical results of thickness and grain size distributions and diatoms revealed that tsunami deposits in a small pond at 11 m elevation were probably formed by the 1677 event this finding and historical descriptions are useful as important constraint conditions to estimate unusually large fault slips and moment magnitude of the 1677 earthquake numerical simulation results reveal that 8 34 8 63 moment magnitude with the large 11 16 m slip area is necessary to satisfy the constraint conditions this fault slip and magnitude are equivalent to those of the 1896 sanriku earthquake a well known tsunami earthquake in the northern part of the japan trench we therefore conclude that a tsunami earthquake of moment magnitude 8 3 8 6 with unusually large slip can occur elsewhere along the japan trench this point should be considered for future tsunami risk assessment along the japan trench and along any trench having similar tectonic settings to those of the japan trench

the use of predictive modeling techniques for optimal exploitation of spatial databases a case study in landslide hazard mapping with expert system like methods a case study is presented in which different probabilistic prediction models bayesian probability fuzzy logic and or sum product gamma operations and certainty factors are used to produce landslide hazard maps for a hilly and mountainous region in the northern apennines italy seven data layers are exploited to detect most vulnerable areas lithology distance from the geological lineaments annual rainfall amount land cover type topographic slope and aspect and the distance from hydrographic network segments the results of the different predictions are compared using the prediction rate index and critically discussed to evaluate the possibility of using readily available databases for land planning

estimating the quality of landslide susceptibility models we present a landslide susceptibility model for the collazzone area central italy and we propose a framework for evaluating the model reliability and prediction skill the landslide susceptibility model was obtained through discriminant analysis of 46 thematic environmental variables and using the presence of shallow landslides obtained from a multi temporal inventory map as the dependent variable for statistical analysis by comparing the number of correctly and incorrectly classified mapping units it is established that the model classifies 77 0 of 894 mapping units correctly model fitting performance is investigated by comparing the proportion of the study area in each probability class with the corresponding proportion of landslide area we then prepare an ensemble of 350 landslide susceptibility models using the same landslide and thematic information but different numbers of mapping units this ensemble is exploited to investigate the model reliability including the role of the thematic variables used to construct the model and the model sensitivity to changes in the input data by studying the variation of the model s susceptibility estimate the error associated with the susceptibility assessment for each mapping unit is determined this result is shown on a map that complements the landslide susceptibility map prediction skill of the susceptibility model is then estimated by comparing the forecast with two recent event inventory maps the susceptibility model is found capable of predicting the newly triggered landslides a general framework for testing a susceptibility model is proposed including a scheme for ranking the quality of the susceptibility assessment

geometry and relative motion of the philippine sea plate and pacific plate beneath the kanto tokai district japan the recent acquisition of high density and improved seismic data by the kanto tokai k t observational network of the national research institute of earth science and disaster prevention requires the revision of conventional plate configuration models for the k t district we propose a new interpretation of the configuration and relative motion of the philippine sea phs plate pacific pac plate and eurasian eur plate on the basis of the distribution of hypocenters velocity structure and focal mechanisms in the k t district the new model for the configuration of the phs and pac slabs clearly delineates the phs slab subducting northwestward beneath the k t district from the sagami and suruga troughs and the pac slab subducting westward beneath the phs slab from the japan trench the thickness of the descending phs slab is estimated to be 30 5 km the proposed configuration of the phs slab is significantly different from those obtained by other researchers including our own previous study the new model is fully consistent with global plate motion data the new model leads to an interpretation of the tectonic processes taking place beneath the k t district for the sagami trough wing of the phs slab the northeastern portion of the slab is dipping northwestward in direct contact with the upper surface of the pac slab the southwestern portion carrying the izu peninsula has been bent upward because of its buoyancy producing the observed contorted shape for the suruga trough wing the dip direction of the phs slab gradually changes from northwestward at the eastern portion to northward at the western portion the new model also indicates the presence of offset within the phs slab between the sagami and suruga trough wings this area is characterized by a low level of seismic activity the absence of a high velocity structure and the presence of quaternary volcanoes it seems reasonable to speculate that the distribution of quaternary volcanic edifice construction is controlled by the location of the offset within the phs slab in view of this new model the tectonic processes of large earthquakes which occurred recently in the studied area are also reexamined

estimating the topographic predictability of debris flows abstract the norwegian traffic network is impacted by about 2000 landslides avalanches and debris flows each year that incur high economic losses despite the urgent need to mitigate future losses efforts to locate potential debris flow source areas have been rare at the regional scale we tackle this research gap by exploring a minimal set of possible topographic predictors of debris flow initiation that we input to a weights of evidence wofe model for mapping the regional susceptibility to debris flows in western norway we use an inventory of 429 debris flows that were recorded between 1979 and 2008 and use the terrain variables of slope total curvature and contributing area flow accumulation to compute the posterior probabilities of local debris flow occurrence the novelty of our approach is that we quantify the uncertainties in the wofe approach arising from different predictor classification schemes and data input while estimating model accuracy and predictive performance from independent test data our results show that a percentile based classification scheme excels over a manual classification of the predictor variables because differing abundances in manually defined bins reduce the reliability of the conditional independence tests a key and often neglected prerequisite for the wofe method the conditional dependence between total curvature and flow accumulation precludes their joint use in the model slope gradient has the highest true positive rate 88 although the fraction of area classified as susceptible is very large 37 the predictive performance i e the reduction of false positives is improved when combined with either total curvature or flow accumulation bootstrapping shows that the combination of slope and flow accumulation provides more reliable predictions than the combination of slope and total curvature and helps refining the use of slope area plots for identifying morphometric fingerprints of debris flow source areas an approach used outside the field of landslide susceptibility assessments

background seismicity in boso peninsula japan long term acceleration and relationship with slow slip events slow slip events sses in subduction zones can trigger earthquake swarms especially at shallow depth the monitoring of seismicity rates has therefore the potential to help detect and characterize sses and transient changes in coupling however the relationship between seismicity rate and slow slip rate during a sse is unknown and made complicated by aftershock triggering within the swarm here we propose to complement geodetic methods with an objective measure of the seismicity rate that is directly associated with changes in slip rate we show that this measure applied to known occurrences of sses in the boso area japan yields an estimate albeit indirect of their seismic moment hence their slip rate we finally prove that the background rate in boso has been accelerating since 1990 this explains previous observations of the shortening of the recurrence time between sses in boso that clearly predate the 2011 mw9 0 tohoku oki earthquake

seismotectonics of the 6 february 2012 mw 6 7 negros earthquake central philippines abstract at 03 49 utc on the 6th of february 2012 negros island in the visayan region of central philippines was struck by a magnitude mw 6 7 earthquake causing deaths of over 50 people and tremendous infrastructure damage leaving hundreds of families homeless the epicenter was located in the vicinity of the eastern coastal towns of la libertad and tayasan of the province of negros oriental earthquake induced surface deformation was mostly in the form of landslides liquefaction ground settlement subsidence and lateral spread there were no clear indications of a fault surface rupture the earthquake was triggered by a fault that has not been previously recognized earthquake data including epicentral and hypocentral distributions of main shock and aftershocks and focal mechanism solutions of the main shock and major aftershocks indicate a northeast striking northwest dipping nodal plane with a reverse fault mechanism offshore seismic profiles in the tanon strait between the islands of negros and cebu show a northwest dipping reverse fault consistent in location geometry and mechanism with the nodal plane calculated from earthquake data the earthquake generator is here proposed to be named the negros oriental thrust not geologic transects established from structural traverses across the earthquake region reveal an east verging fold thrust system in the latitude of guihulngan this fold thrust system is represented by the razor back anticline negros oriental thrust pair and by the pamplona anticline yupisan thrust pair in the latitude of dumaguete to the south together these active fold thrust systems are causing active deformation of the western section of the visayan sea basin under a compressional tectonic regime this finding contradicts previous tectonic models that interpret the tanon strait as a graben bounded on both sides by normal faults supposedly operating under an extensional regime the negros earthquake and the active fold thrust systems that were discovered in the course of the structural analysis provide strong arguments for basin inversion processes now affecting the visayan sea basin albeit under very slow strain rates derived from previous gps campaigns the occurrence of the earthquake in an area where no active faults have been previously recognized and characterized by slow present day strain rates underscores the necessity of paying more attention to and exerting more effort in the evaluation of earthquake hazards of regions that are seemingly seismically quiet especially when they underlie highly urbanized areas

different landslide sampling strategies in a grid based bi variate statistical susceptibility model abstract this study had three aims the first was to assess the performance of the weights of evidence wofe landslide susceptibility model in areas that are very different in terms of size geoenvironmental settings and landslide types the second was to test the appropriate strategies to sample the mapped landslide polygon the final aim was to evaluate the performance of the method to changes in the landslide sample size used to train the model the method was applied to two areas the fella river basin eastern italian alps containing debris flows and buzau county romanian carpathians with shallow landslides the three landslide sampling strategies used were 1 the landslide scarp centroid 2 points populating the scarp on a 50 m grid and 3 the entire scarp polygon the highest success rates were obtained when sampling shallow landslides as 50 m grid points and debris flow scarps as polygons prediction rates were highest when using the entire scarp polygon method for both landslide types the sample size test using the landslide centroids showed that a sample of 104 debris flow scarps was sufficient to predict the remaining 941 debris flows in the fella river basin while 161 shallow landslides was the minimum required number to predict the remaining 1451 scarps in buzau county below these landslide sample thresholds model performance was too low however using more landslides than the threshold produced a plateau effect with little to no increase in the model performance rates

a constitutive law for rate of earthquake production and its application to earthquake clustering seismicity is modeled as a sequence of earthquake nucleation events in which the distribution of initial conditions over the population of nucleation sources and stress ing history control the timing of earthquakes the model is implemented using solutions for nucleation of unstable fault slip on faults with experimentally derived rate and state dependent fault properties this yields a general state variable constitutive formulation for rate of earthquake production resulting from an applied stressing history to illustrate and test the model some characteristics of seismicity following a stress step have been explored it is proposed that various features of earthquake clustering arise from sensi tivity of nucleation times to the stress changes induced by prior earthquakes the model gives the characteristic omori aftershock decay law and interprets aftershock parameters in terms of stress change and stressing rate earthquake data appear to support a model prediction that aftershock duration defined as the time for rates to return to the back ground seismicity rate is proportional to mainshock recurrence time observed spatial and temporal clustering of earthquake pairs arises as a consequence of the spatial depen dence of stress changes of the first event of the pair and stress sensitive time dependent nucleation applications of the constitutive formulation are not restricted to the simple stress step models investigated here it may be applied to stressing histories of arbitrary complexity the apparent success at modeling clustering phenomena suggests the possibil ity of using the formulation to estimate short to intermediate term earthquake probabil ities following occurrence of other earthquakes and for inversion of temporal variations of earthquake rates for changes in driving stress

instability conditions of marly hillslopes towards landsliding or gullying the case of the barcelonnette basin south east france abstract black marl hillslopes in the french alps are strongly affected either by mass movements or by gully erosion due to their susceptibility to weathering processes this paper presents experimental data geomorphological geotechnical geomechanical and hydrological on the parameters of the material of three well known earthflows and of the two stratigraphic parts of the callovo oxfordian black marl the main objectives are to define the geomechanical behaviour of the various formations using different characterisations grain size distribution mineralogy retention capacity consolidation test direct shear test and triaxial test and to demonstrate how such soils can affect the stability of natural slopes particular care must be taken when interpreting the geomechanical tests on this evolving and very heterogeneous clay rich material there are strong relationships between the parent rock and the landslide materials this paper presents a conceptual model of the development of strength over a period of time and investigates the parameters of the material for use in slope stability analysis and risk assessment

comparison of landslide susceptibility based on a decision tree model and actual landslide occurrence the akaishi mountains japan abstract this paper proposes a statistical decision tree model to analyze landslide susceptibility in a wide area of the akaishi mountains japan the objectives of this study were to validate the decision tree model by comparing landslide susceptibility and actual landslide occurrence and to reveal the relationships among landslide occurrence topography and geology landslide susceptibility was examined through ensemble learning with a decision tree decision trees are advantageous in that estimation processes and order of important explanatory variables are explicitly represented by the tree structures topographic characteristics elevation slope angle profile curvature plan curvature and dissection and undissection height and geological data were used as the explanatory variables these topographic characteristics were calculated from digital elevation models dems the objective variables were landslide occurrence and reactivation data between 1992 and 2002 that were depicted by satellite image analysis landslide susceptibility was validated by comparing actual data on landslides that occurred and reactivated after the model was constructed between 2002 and 2004 this study revealed that from 2002 to 2004 landslides tended to occur and reactivate in catchments with high landslide susceptibility the landslide susceptibility map thus depicts the actual landslide occurrence and reactivation in the akaishi mountains this result indicates that the decision tree model has appropriate accuracy for estimating the probabilities of future landslides the tree structure indicates that landslides occurred and reactivated frequently in the catchments that had an average slope angle exceeding ca 29 and a mode of slope angle exceeding 33 which agree well with previous studies a decision tree also quantitatively expresses important explanatory variables at the higher order of the tree structure

the association between ground gas radon variations and geologic activity in hawaii soil gas radon activities have been recorded at 10 stations on kilauea volcano for approximately 5 years long term average radon activities were found to vary substantially among the sites monitored spatial variations appear to be controlled predominantly by 1 near surface hydrothermal activity 2 thickness and permeability of soil cover and 3 the presence of subsurface fracturing temporal changes in radon activity show minor correlation with meteorological changes but a strong correlation with seismic and volcanic events on kilauea magmatic intrusions were associated with contemporaneous changes in radon concentrations whereas seismic events were associated with precursory radon anomalies such changes may be caused by release of trapped radon from rocks by microfracturing under broadly distributed stress changes associated with intrusion events and preceding seismic events

widespread seismicity excitation throughout central japan following the 2011 m 9 0 tohoku earthquake and its interpretation by coulomb stress transfer 1 we report on a broad and unprecedented increase in seismicity rate following the m 9 0 tohoku mainshock for m 2 earthquakes over inland japan parts of the japan sea and izu islands at distances of up to 425 km from the locus of high 15 m seismic slip on the megathrust such an increase was not seen for the 2004 m 9 1 sumatra or 2010 m 8 8 chile earthquakes but they lacked the seismic networks necessary to detect such small events here we explore the possibility that the rate changes are the product of static coulomb stress transfer to small faults we use the nodal planes of m 3 5 earthquakes as proxies for such small active faults and find that of fifteen regions averaging 80 by 80 km in size 11 show a positive association between calculated stress changes and the observed seismicity rate change 3 show a negative correlation and for one the changes are too small to assess this work demonstrates that seismicity can turn on in the nominal stress shadow of a mainshock as long as small geometrically diverse active faults exist there which is likely quite common