2014 mainshock aftershock activity versus earthquake swarms in west bohemia czech republic a singular sequence of three episodes of m l 3 5 4 4 and 3 6 mainshock aftershock occurred in the west bohemia vogtland earthquake swarm region during 2014 we analysed this activity using the webnet data and compared it with the swarms of 1997 2000 2008 and 2011 from the perspective of cumulative seismic moment statistical characteristics space time distribution of events and prevailing focal mechanisms for this purpose we improved the scaling relation between seismic moment m 0 and local magnitude m l by webnet the total seismic moment released during 2014 episodes m 0 mathrm tot approx 1 58 times 10 15 nm corresponded to a single m l 4 6 event and was comparable to m 0 mathrm tot of the swarms of 2000 2008 and 2011 we inferred that the m l 4 8 earthquake is the maximum expected event in nov kostel nk the main focal zone despite the different character of the 2014 sequence and the earthquake swarms the magnitude frequency distributions mfds show the b values approx 1 and probability density functions pdfs of the interevent times indicate the similar event rate of the individual swarms and 2014 activity only the a value event productivity in the mfd of the 2014 sequence is significantly lower than those of the swarms a notable finding is a significant acceleration of the seismic moment release in each subsequent activity starting from the 2000 swarm to the 2014 sequence which may indicate an alteration from the swarm like to the mainshocks aftershock character of the seismicity the three mainshocks are located on a newly activated fault segment asperity d in out notation of the nk zone situated in the transition area among fault segments a b c which hosted the 2000 2008 and 2011 swarms the segment d appears to be predisposed to an oblique thrust faulting while strike slip faulting is typical of segments a b and c in conclusion we propose a basic segment scheme of the nk zone which should be improved gradually

the prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models the accuracy of the predictions of distributed hydrological models must depend in part on the proper specification of flow pathways this paper examines some of the problems of deriving flow pathways from raster digital terrain data in the context of hydrological predictions using topmodel distributed moisture status is predicted in topmodel on the basis of spatial indices that depend on flow path definition the sensitivity of this index to flow path algorithm and grid size is examined for the case where the surface topography is a good indicator of local hydraulic gradients a strategy for the case where downslope subsurface flow pathways may deviate from those indicated by the surface topography is described with an example application

effects of dem resolution on the calculation of topographical indices twi and its components summary a variety of landscape properties have been modelled successfully using topographic indices such as the topographic wetness index twi defined as ln a tan where a is the specific upslope area and is the surface slope previous studies have shown the influence of scale on twi values when converting standard resolution dems to coarser resolutions in this study a high resolution digital elevation model dem with a 5 m grid size derived from lidar light detection and ranging data was used to investigate the scale dependency of twi values when converting from high resolution elevation data to standard resolution dems first a set of dems was generated from an initial dem by thinning to resolutions of 10 25 and 50 m grid sizes to study the effects of lower grid size and decreased information content next to investigate the impact of different information content on dems with the same grid size the three lower resolution dems were all interpolated to the original 5 m grid size in addition to comparing index distribution functions a second objective was to evaluate differences in spatial patterns thus the values of twi and its components as computed for the seven different dems were compared in three different ways 1 distribution functions and their statistics 2 cell by cell comparison of four dems with the same resolution but different information content and 3 comparison of blocks of cells within different resolution dems with different information content like previous twi studies the computed specific upstream area decreased on average for higher resolution dems while computed slope values followed a narrower distribution twi variation between neighbouring cells in 50 50 m areas decreased largely with increasing grid size a cell by cell comparison of the twi values of the four 5 m dems with different information content showed a clear decrease in correlation with the twi based on the original dem with decreasing information content the results showed considerable differences between topographic indices computed for dems of different grid resolution interpolating the dems to a higher resolution i e a smaller grid size provided more similar twi distributions but the pixel by pixel comparison showed that different information contents caused clearly different twi maps

spatial autocorrelation of topographic index in catchments summary spatial autocorrelation represents the association of a spatial parameter around neighborhoods and it usually distorts the statistics of the distribution of the parameter topographic spatial autocorrelation is rooted with the distribution of land surface elevation using moran s i statistics originating from geographic studies this paper presents a method to quantify the spatial autocorrelation of topographic index ti in catchments derived from digital elevation models dem positive autocorrelation similarity or homogeneity of ti is found over a wide range of spatial extents it declines with the increasing of spatial extents but becomes relatively static beyond a threshold area of approximately 1 km 2 the analysis of the effect of dem grid size resolution on the spatial autocorrelation shows that the effect is characterized by a similar pattern and critical grid size for selected catchments with different terrains based on these analyses further discussions address some issues in catchment hydrology such as the appropriate dem sizes for deriving ti and the causes for the empirical linear or log linear relation between mean ti and dem grid size

physical interpretation and sensitivity analysis of the topmodel the topmodel is a variable contributing area conceptual model in which the predominant factors determining the formation of runoff are represented by the topography of the basin and a negative exponential law linking the transmissivity of the soil with the distance to the saturated zone below the ground level although conceptual this model is frequently described as a physically based model in the sense that its parameters can be measured directly in situ in line with the analysis of various conceptual rainfall runoff models conducted by franchini and pacciani j hydrol 122 161 219 1991 a detailed analysis of the topmodel is performed to arrive at a closer understanding of the correspondence of the assumptions underpinning the model with the physical reality and in particular the role that topographic information expressed by the topographic index curve and the nature of the soil expressed by saturated hydraulic conductivity and its decay with soil depth have within the model itself also investigated is the extent to which the model parameters actually reflect the physical properties to which they refer and how far their values offset the inevitable schematisation of the model the various applications to real situations include the sieve basin river arno tributary which was used for the comparison of conceptual rainfall runoff models described in the above mentioned study by franchini and paccini this allows that analysis to be extended to the topmodel

coseismic traveling ionospheric disturbances during the mw 7 8 gorkha nepal earthquake on 25 april 2015 from ground and spaceborne observations coseismic travelling ionospheric disturbances ctids and their propagation characteristics during mw 7 8 gorkha earthquake in nepal on 25 april 2015 have been investigated using a suite of ground based gps receivers and broad band seismometers along with the space borne radio occultation observations over the indian subcontinent region depletion in vertical total electron content vtec a so called ionospheric hole is observed near the epicenter 9 11 minutes after the onset of earthquake a positive pulse preceding the depletion similar to n shaped perturbation propagating with an apparent velocity of 2 4 km s is observed on the south further the ctids in the southward direction are found to split in to fast 2 4 1 7 km s and slow 680 520 m s propagating modes at epicentral distances greater than 800 km however the velocities of fast mode ctids are significantly smaller than the surface rayleigh wave velocity 3 7 km s indicating that they are not the true imprint of rayleigh wave instead can probably be attributed to the superimposed wave front formed by the mixture of acoustic waves excited by main shock and propagating rayleigh wave the southward ctids are found to propagate at f2 region altitudes of 300 440 km captured by cosmic radio occultation observations the ctids with periods of 4 6 minutes are observed in all directions with significantly larger amplitudes and faster propagation velocities in south and east directions the observed azimuthal asymmetry in the amplitudes and velocities of ctids are discussed in terms of the alignment with geomagnetic field and nature of surface crustal deformation during the earthquake

the effect of directivity in a psha framework summary we propose a method to introduce a refined representation of the ground motion in the framework of the probabilistic seismic hazard analysis psha this study is especially oriented to the incorporation of a priori information about source parameters by focusing on the directivity effect and its influence on seismic hazard maps two strategies have been followed one considers the seismic source as an extended source and it is valid when the psha seismogenetic sources are represented as fault segments we show that the incorporation of variables related to the directivity effect can lead to variations up to 20 per cent of the hazard level in case of dip slip faults with uniform distribution of hypocentre location in terms of spectral acceleration response at 5 s exceeding probability of 10 per cent in 50 yr the second one concerns the more general problem of the seismogenetic areas where each point is a seismogenetic source having the same chance of enucleate a seismic event in our proposition the point source is associated to the rupture related parameters defined using a statistical description as an example we consider a source point of an area characterized by strike slip faulting style with the introduction of the directivity correction the modulation of the hazard map reaches values up to 100 per cent for strike slip unilateral faults the introduction of directivity does not increase uniformly the hazard level but acts more like a redistribution of the estimation that is consistent with the fault orientation a general increase appears only when no a priori information is available however nowadays good a priori knowledge exists on style of faulting dip and orientation of faults associated to the majority of the seismogenetic zones of the present seismic hazard maps the percentage of variation obtained is strongly dependent on the type of model chosen to represent analytically the directivity effect therefore it is our aim to emphasize more on the methodology following which all the information collected may be easily converted to obtain a more comprehensive and meaningful probabilistic seismic hazard formulation

topographic parameterization in continental hydrology a study in scale digital elevation models dems are useful and popular tools from which topographic parameters can be quickly and efficiently extracted for various hydrologic applications dems coupled with automated methods for extracting topographic information provide a powerful means of parameterizing hydrologic models over a wide range of scales however choosing appropriate dem scales for particular hydrologic modelling applications is limited by a lack of understanding of the effects of scale and grid resolution on land surface representation the scale effects of aggregation on square grid dems of two continental scale basins are examined base dems of the mackenzie and missouri river basins are extracted from the hydro1k dem of north america successively coarser grids of 2 4 8 64 km were generated from the base dems using simple linear averaging topaz topographic parameterization was applied to the base and aggregated dems using constant critical source area and minimum source channel length values to extract topographic variables at varying scales or resolutions the effects of changing dem resolution are examined by considering changes in the spatial distribution and statistical properties of selected topographic variables of hydrological importance the effects of increasing grid size on basin and drainage network delineation and derived topographic variables tends to be non linear in particular changes in overall basin extent and drainage network configuration make it impractical to apply a simple scaling function to estimate variable values for fine resolution dems from those derived from coarse resolution dems results also suggest the resolution to which a dem can be reduced by aggregation and still provide useful topographic information for continental scale hydrologic modelling is that at which the mean hydraulic slope falls to approximately 1 in this study that generally occurred at a resolution of about 10 km

estimation of ground motion in mexico city from a repeat of the m 7 0 acambay earthquake of 1912 abstract the acambay earthquake of 1912 m 7 0 which occurred in the central trans mexican volcanic belt ctmvb about 100 km west northwest of mexico city has been thought to be a critical scenario event in the estimation of seismic hazard of the city we use seismograms of two small earthquakes located near actopan 15 december 2003 18 may 2010 and recorded at station cuig a hill zone site in mexico city as empirical green s functions egfs for the acambay region because actopan like acambay is situated in the ctmvb and both are located at about the same distance from cuig the use of the recordings of the actopan earthquakes as egfs is partly justified we first analyze data of the two small earthquakes at a local station dhig to estimate their seismic moment and stress drop as there is considerable uncertainty in the estimated stress drops of the two events we choose a reasonable range of values for them and apply a technique of random summation of egfs to simulate ground motion at cuig from a postulated m w 7 earthquake the estimated geometric mean horizontal peak ground acceleration pga and peak ground velocity pgv at cuig range from 2 7 to 9 7 cm s 2 and from 1 1 to 3 0 cm s respectively ground motion maps for the entire city are presented using a simulated trace at cuig and the known transfer functions of many sites within the city the results are consistent with reported seismic intensities in mexico city and pga and peak ground displacement pgd at a 2 s period at the seismic station of tacubaya during the acambay earthquake estimated ground motions suggest that a repeat of the event does not present significant hazard to mexico city

diminishing high frequency directivity due to a source effect empirical evidence from small earthquakes in the abruzzo region italy the aim of this study is to investigate the directivity effects of 250 aftershocks magnitudes 3 5 5 of the mw 6 1 2009 l aquila earthquake central italy to this end we estimate the apparent source spectra at each station removing path and site effects inferred by standard generalized inversion technique then we evaluate the residuals between the apparent source spectra and the event mean source spectrum at selected frequencies we investigate azimuthal and frequency dependence of the residuals for 40 events with the best station coverage for most of events with the strongest directivity effect mw 3 4 4 0 we observe a remarkable decrease of the directivity amplification at high frequencies which has not yet been documented for such relatively small magnitude events since there is negligible distance dependence we ascribe this observation to a source phenomenon such as significant small scale rupture propagation complexity

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

estimating finite source properties of small earthquake ruptures many of the most fundamental questions in earthquake science are currently limited by a lack of knowledge about small earthquake ruptures small earthquakes are difficult to study owing to the poor constraints placed on many of the interesting physical parameters by bandlimited far field seismic data traditionally dynamic models such as an expanding circular crack have been utilized to bridge the gap between the easily measurable quantities for small earthquakes and more interesting physical parameters such as stress drop and rupture velocity here i present a method for estimating the basic finite source properties of a rupture that is independent of any a priori model and utilizes the description of a finite source the second moments that far field waves are inherently sensitive to application to two magnitude 5 events in southern california demonstrates the ability of an empirical green9s function approach to estimating the second moments to resolve the fault plane ambiguity rupture length and overall directivity additional results are presented for two example m 2 7 events from the creeping section of the san andreas fault to examine the likely lower bound on event size that can be studied with surface seismometers the creeping section earthquakes have very similar rupture areas but would be improperly interpreted as significantly different using the traditional methodology one of these events presents a relatively clear interpretation of the velocity of rupture front propagation which is about 0 8 of the rayleigh speed suggesting little difference in rupture velocity between it and typical large earthquakes

sequential formation of subsolidus and anatectic migmatites in response to thermal evolution eastern scotland two groups of migmatites represent the thermal culmination of the classic area of barrovian metamorphism in the eastern highlands of scotland group a are spatially and temporally associated with kyanite grade metamorphism while group b are spatially and temporally associated with sillimanite grade metamorphism and structurally overprint group a structural textural modal and mineral chemical arguments indicate that group a migmatites are the products of subsolidus differentiation whereas group b migmatites apparently were formed by anatexis kyanite metamorphism and group a migmatites probably result from conductive heating related to regional scale nappe emplacement locally modified by advection during synmetamorphic folding sillimanite metamorphism and group b migmatites on the other hand result from local and transient fluid advection the relative importance of conductive vs advective heat transfer has apparently varied in both space and time over a relatively small 50 km 2 area

experimental and numerical evidence of the clustering effect of structures on their response during an earthquake a case study of three identical towers in the city of grenoble france in this article interpretation of an equivalent to a macroseismic intensity survey performed in three identical stand alone buildings located in grenoble france after an m l 4 1 earthquake reveals a clustering effect resulting in different levels of perception of seismic loading by inhabitants the clustering effect is confirmed using numerical simulation the variation of the seismic response of the building in the middle of the cluster depends on the azimuth of the seismic source relative to the building cluster the major effect is the splitting of its resonance frequency accompanied by a decrease in vibration amplitude we conclude that clustering has an impact on urban effects calling into question the validity of seismic design which considers buildings in urban areas as stand alone constructions and the interpretation of macroseismic intensity surveys conducted in dense urban areas

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

empirical green s function analysis of recent moderate events in california i use seismic data from portable digital stations and the broadband terrascope network in southern california to investigate radiated earthquake source spectra and discuss the results in light of previous studies on both static stress drop and apparent stress applying the empirical green s function egf method to two sets of m 4 6 1 events i obtain deconvolved source spectra estimates and corner frequencies the results are consistent with an 2 source model and constant brune stress drop however consideration of the raw spectral shapes of the largest events provides evidence for a high frequency decay more shallow than 2 the intermediate f 1 slope cannot be explained plausibly with attenuation or site effects and is qualitatively consistent with a model incorporating directivity effects and a fractional stress drop rupture process as suggested by haddon 1996 however the results obtained in this study are not consistent with the model of haddon 1996 in that the intermediate slope is not revealed with egf analysis this could reflect either bandwidth limitations inherent in egf analysis or perhaps a rupture process that is not self similar i show that a model with an intermediate spectral decay can also reconcile the apparent discrepancy between the scaling of static stress drop and that of apparent stress drop for moderate to large events

simulating ground motion directivity using stochastic empirical green s function method first strong motion recordings from an m w 4 4 earthquake with symmetrical rupture were regarded as empirical green s functions egfs to simulate ground motions produced by the 2013 m w 6 6 lushan mainshock using the two step stochastic egf method proposed by kohrs sansorny et al 2005 in this simulation the source of the lushan mainshock was set to consist only of an asperity in the vicinity of the hypocenter which was determined according to the statistical properties of asperity the good agreement between the simulated ground motions and the observed recordings at short periods 2 0 s validates this method furthermore recordings from an m w 4 5 earthquake with significant rupture directivity were used as egfs to simulate ground motions of the lushan mainshock the rupture directivity mainly exerts significant effects on the simulated short period ground motions which result in large discrepancies with the observed recordings simulated ground motions are much higher than the observed ones at directive stations but lower at antidirective stations more significant effects are observed at directive stations than antidirective stations using the azimuthal apparent corner frequency to consider the rupture directivity in the two step stochastic egf method the good reproductions of the observed recordings are obtained at short periods which indicates that the rupture directivity at short periods can be simulated well finally ground motions from a series of lushan like earthquakes assuming various rupture directivities were simulated by adjusting the apparent corner frequency the simulated ground motions show significant directivity effects the two step stochastic egf method provides an effective approach to predicting ground motions for future earthquakes because far fewer source parameters are required

analysis of the ground accelerations radiated by the 1980 livermore valley earthquakes for directivity and dynamic source characteristics the strong motion accelerograph recordings of the 24 january 1980 main shock and the 27 january 1980 aftershock of the livermore valley earthquake sequence are analyzed for systematic variations with azimuth or station location the variation of the peak accelerations with epicentral azimuth is apparently reversed for the two events the main shock accelerations are larger to the south and the aftershock accelerations are larger to the northwest we eliminate the site effects by forming the ratio of the peak accelerations recorded at the same station after correcting for the epicentral distance this analysis indicates that source directivity caused a total variation of a factor of 10 in the peak accelerations comparison of this variation with the spatial extent of the aftershock sequences suggests that the strong directivity in the radiated accelerations is the result of unilateral ruptures in both events the accelerograms recorded at 10 stations within 35 km of the events were digitized to analyze the azimuthal variation of the rms acceleration the peak velocity and the radiated energy flux the variation of rms acceleration correlates almost exactly with the variation of the peak accelerations this correlation is analyzed using both deterministic and stochastic models for the acceleration waveforms the peak velocities corrected for epicentral distance vary with azimuth by a factor of 5 for both events while the radiated energy flux varies by a factor of 30 for the main shock and 15 for the aftershock the peak velocities are strongly correlated with the radiated energy flux the radiated seismic energies are estimated to be 2 6 0 9 1020 dyne cm for the main shock and 1 5 0 3 1020 dyne cm for the aftershock

fluid induced swarms and coseismic stress transfer a dual process highlighted in the aftershock sequence of the 7 april 2014 earthquake ml 4 8 ubaye france

differences in topographic characteristics computed from 100 and 1000 m resolution digital elevation model data topographic characteristics computed from 100 and 1000 m resolution digital elevation model dem data are compared for 50 locations representing varied terrain in the conterminous usa the topographic characteristics are three parameters used extensively in hydrological research and modelling slope s specific catchment area as and a wetness index computed as the logarithm of the specific catchment area divided by slope ln as s slope values computed from 1000 m dems are smaller than those computed from 100 m dems specific catchment area and the wetness index are larger for the 1000 m dems compared with the 100 m dems most of the differences between the 100 and 1000 m resolution dems can be attributed to terrain discretization effects in the computation of the topographic characteristics and are not the result of smoothing or loss of terrain detail in the coarse data in general the terrain discretization effects are greatest on flat terrain with long length scale features and the smoothing effects are greatest on steep terrain with short length scale features for the most part the differences in the average values of the topographic characteristics computed from 100 and 1000 m resolution dems are predictable that is biases in the mean values for the characteristics computed from a 1000 m dem can be corrected with simple linear equations copyright 2000 john wiley sons ltd

effects of digital elevation model map scale and data resolution on a topography based watershed model the effects of digital elevation model dem map scale and data resolution on watershed model predictions of hydrologic characteristics were determined for topmodel a topography based watershed model the effects of topography on watershed hydrology are represented in topmodel as the distribution of ln a tan b where ln is the napierian logarithm a is the upslope area per unit contour length and tan b is the gravitational gradient the minimum maximum mean variance and skew values of the ln a tan b distribution were computed from 1 24 000 scale 24k dems at 30 and 90 m resolutions and from 1 250 000 scale 250k dems at 90 m resolution for 71 areas in pennsylvania new york and new jersey an analysis of topmodel showed that model predictions of the depth to the water table the ratio of overland flow to total flow peak flow and variance and skew of predicted streamflow were affected by both the dem map scale and data resolution further topmodel analyses showed that the effects of dem map scale and data resolution on model predictions were due to the sensitivity of the predictions to the mean of the ln a tan b distribution which was affected by both dem map scale and data resolution dem map scale affected the mean of the ln a tan b distribution through its influence on the mean of the ln a distribution which characterizes land surface shape and the mean of ln 1 tan b distribution which characterizes land surface slope dem resolution in contrast affected the mean of the ln a tan b distribution primarily by its influence on the mean of the ln a distribution

high frequency directivity effect for an mw 4 1 earthquake widely felt by the population in southeastern france abstract we document a moderate earthquake in the french alps 26 february 2012 m w 4 1 that has been much more distinctly felt south of the event than north of it this discrepancy was especially clear in the two large cities of nice and grenoble both situated at 100 km from the epicenter this observation was confirmed by ground motion measurements that were eight times larger in one city than in the other one for the same site conditions using a time domain deconvolution between the broadband recordings of the mainshock and an aftershock used as empirical green s functions we show that the rupture process of this event had a strong directivity effect toward a direction of n155 5 on an 2 km long fault detectable only at frequencies higher than 1 hz the fault size and direction are in good accordance with the location of the aftershocks despite the various possible contributions leading to high frequency amplification we show here that this simple directivity effect controlled the intensity felt by the population and the acceleration measured in the cities

active deformation at the southwestern alps ligurian basin junction france italy boundary evidence for recent change from compression to extension in the argentera massif abstract several hundred earthquakes of small and moderate magnitude occur each year at the southwestern alps ligurian basin junction in addition the historical seismicity data attests for earthquakes of magnitude close to 6 5 despite the seismic hazard and the vulnerability of this region the present day driving mechanism of deformation and the major structures accommodating these deformations remain unclear this littoral area presents a strong topographic gradient from 3000 masl on the argentera alpine massif to 2500 m u s l in the ligurian basin and a strong structural inheritage resulting from 50 my geological evolution combining different processes such as continental collision and ocean basin opening we present new results about the kinematics of the corsica sardinia continental block with respect to the western alpine belt from 7 years of continuous gps measurements we show that a small part of the nubia eurasia convergence is certainly transferred northward of the maghrebides deformation belts to the corsica sardinia block in the southwesternmost alps from torino to the mediterranean coast the baselines reveal differential motions of lengthening between the po plain and the argentera and shortening between the argentera and the ligurian domain in a region where few focal solutions are available we determine seven new focal mechanisms located in the argentera massif these new data underline a quaternary change from compression to extension in that part of the western alpine belt the focal mechanisms calculated attest for extensional faulting at shallow level between 1 and 11 km depth we add 7 focal mechanisms from the literature to calculate the stress tensor a homogeneous solution indicates a direction of extension broadly perpendicular to the topographic axis culmination of the argentera in contrast the earthquakes recorded below 15 km at the northwestern margin of the po plain testify reverse faulting and a compressional state of stress in the deep crust thus we point out that the stress field is vertically heterogeneous in the crust of the argentera area the ligurian domain is mainly characterized by reverse and strike slip faulting the major earthquakes are located in the northern margin and at the ocean continent transition these earthquakes are assumed to result from the reactivation in a compressional state of stress of the structures formed during the oligo miocene opening of the ligurian basin finally we propose three hypotheses to explain the current deformation at the alps ligurian basin junction taking into account the far field kinematics between the nubia and the eurasia plates the topographic gradient between the argentera massif and the ligurian oceanic floor and the distribution of the deformations

saturation regions in catchments and their relations to soil and topographic properties abstract criteria are derived for the existence of saturated areas on draining hillslopes in natural catchments these are given in terms of soil transmissivity the hillslope gradient and its wetness state characterised by the baseflow discharge from the catchment analyses are made for idealised hillslopes with uniform soils to obtain expression for the width of the saturated zone the size of saturated zones on undulating hillslopes with gradiational soils is shown to depend strongly on topographic convergence or divergence the effects of soil transmissivity hillslope geometry and drainage flux density are lumped into a dimensionless parameter whose value determines the location of seepage boundaries on slopes of specified geometry scaling relations for seepage area in catchments of different size are shown to be generally nonlinear and depend primarily on local hillslope gradients relative predictions of seepage zone size are confirmed by observed hydrographs from three catchments with different physical characteristics

site effect study in urban area experimental results in grenoble france three methods are used to determine the site effect in the town of grenoble located in the western alps first we use the classical spectral ratio method in 14 sites to calculate the transfer function of the basin we find an amplification of 10 in the frequency range of 0 25 to 10 hz second we compare these results with the h over v spectral ratio method and propose a map of resonance frequency of the basin we find a lower resonance frequency in the center of the basin than on the edge that is consistent with the structure deduced from a gravity bouguer anomaly map finally we use the empirical green s function method to simulate a m w 5 5 earthquake at a distance of 20 km from the town the simulated acceleration reaches the level of 2 m s2 in the center of the basin compared to 0 2 m s2 on the edges the simulated ground motion we compute is smaller than the french seismic codes on the edge of the valley but significantly larger in the center

simulation of the basin effects in the po plain during the emilia romagna seismic sequence 2012 using empirical green s functions the two main earthquakes that occurred in 2012 may 20 and 29 in the reggio emiliano region northern italy were relatively small mw 6 1 and mw 5 9 but they generated unexpected damages in a large area around the epicenter on some stations the observed seismic levels exceeded design levels recommended by the ec8 seismic code for buildings and civil engineering works the ground motions generated by the two mainshocks have specific characteristics the waveforms are mainly controlled by surface waves generated by the deep sedimentary po plain by local site effects and also on some stations by non linear behaviors in this particular context we test the ability of an empirical green s function egf simulation approach to reproduce the recorded seismograms in a large frequency band without any knowledge of the underground medium we focus on the possibility to reproduce the strong surface waves generated by the basin at distances between 25 and 90 km we choose to work on the second mainshock of the sequence mw 5 9 which occurred on may 29 2012 because it is better recorded by the seismological networks than the may 20th first mainshock we use a k 2 kinematic source model to generate a set of 100 slip distributions on the fault plane and choose the recordings of a close by mw 3 9 event as egf we then generate a set of broad band seismograms from 0 2 to 35 hz and compare them to the mainshock signals at 15 stations seismograms fourier spectra pga pgv duration stockwell transforms at epicentral distances from 5 to 160 km we find that the main specific features of the signals are very well reproduced for all the stations within and beyond the basin nevertheless at nearby stations the pga values are over evaluated which could be explained by the fact that non linear effects are not taken into account in the simulation process a better fit was found for a position of the nucleation point to the bottom west of the fault that suggest a directivity effect of the rupture process of the may 29th event towards the north east

re scaling the topographic index to improve the representation of physical processes in catchment models abstract the assignment of hydrological model parameters from physically measurable catchment attributes remains an unsolved problem several authors have shown that for the hydrological model topmodel there is a relationship between the scale of the digital elevation model dem and the saturated hydraulic conductivity parameter used to calculate water table position and baseflow for models that use dem data from pixels measured in tens of metres the value of the corresponding saturated hydraulic conductivities for satisfactory flow reproduction are often much larger than measured values and this causes most surface flow to be generated by the saturation excess mechanism this is undesirable in environments where infiltration excess runoff can also occur this paper presents a way to objectively compensate for the distorting effect of dem scale on the value of the saturated hydraulic conductivity so that its measured value can be used in topmodel simulations the method described links the distribution of topographic index ln a tan to a spatial variability measure svm based on the shannon and weaver information content equation for a digital signal by maximising the svm an optimum adjustment to the mean of the distribution of topographic index can be made so that the distribution represents what would have been calculated had a dem been available at the spatial resolution at which the saturated hydraulic conductivity was measured the method is applied to a topmodel of the mahurangi basin in new zealand and it is shown that physically reasonable simulations are achieved with the adjusted distribution of topographic index

the persistence of directivity in small earthquakes abstract we derive a simple inversion of peak ground acceleration pga or peak ground velocity pgv for rupture direction and rupture velocity and then test this inversion on the peak motions obtained from seven 3 5 m 4 1 earthquakes that occurred in two clusters in november 2002 and february 2003 near san ramon california these clusters were located on two orthogonal strike slip faults so that the events share the same approximate focal mechanism but not the same fault plane three earthquakes exhibit strong directivity but the other four earthquakes exhibit relatively weak directivity we use the residual pgas and pgvs from the other six events to determine station corrections for each earthquake the inferred rupture directions unambiguously identify the fault plane for the three earthquakes with strong directivity and for three of the four earthquakes with weak directivity the events with strong directivity have fast rupture velocities 0 63 v 0 87 the events with weak directivity either rupture more slowly 0 17 v 0 35 or bilaterally the simple unilateral inversion cannot distinguish between slow and bilateral ruptures adding a bilateral rupture component degrades the fit of the rupture directions to the fault planes by comparing pgas from the events with strong and weak directivity we show how an up dip rupture in small events can distort the attenuation of peak ground motion with distance when we compare the rupture directions of the earthquakes to the location of aftershocks in the two clusters we find than almost all the aftershocks of the three earthquakes with strong directivity occur within 70 of the direction of rupture

aftershocks triggered by fluid intrusion evidence for the aftershock sequence occurred 2014 in west bohemia vogtland the west bohemia vogtland region central europe is well known for its repeating swarm activity however the latest activity in 2014 although spatially overlapping with previous swarm activity consisted of three classical aftershock sequences triggered by ml3 5 4 4 and 3 5 events to decode the apparent system change from swarm type to mainshock aftershock characteristics we have analyzed the details of the major ml4 4 sequence based on focal mechanisms and relocated earthquake data our analysis shows that the mainshock occurred with rotated mechanism in a step over region of the fault plane unfavorably oriented to the regional stress field most of its intense aftershock activity occurred in plane with classical characteristics such as i the maximum magnitude of the aftershocks is significantly less than the mainshock magnitude and ii the decay can be well fitted by the omori utsu law however the absolute number of aftershocks and the fitted omori utsu c and p parameters are much larger than for typical sequences by means of the epidemic type aftershock sequence model we show that an additional aseismic source with an exponentially decaying strength triggered a large fraction of the aftershocks corresponding pore pressure simulations with an exponentially decreasing flow rate of the fluid source show a good agreement with the observed spatial migration front of the aftershocks extending approximately with log t thus we conclude that the mainshock opened fluid pathways from a finite fluid source into the fault plane explaining the unusual high rate of aftershocks the migration patterns and the exponential decrease of the aseismic signal

seismic stereometry reveals preparatory behavior and source kinematics of intermediate size earthquakes although moderate size earthquakes are poorly studied by lack of near fault observations they can provide key information about larger damaging earthquakes here we propose a new approach inspired by double difference relocation that uses high coherency waveforms recorded at neighboring sensors to study the preparation phase and dynamics of moderate size earthquakes we validate this technique by analyzing the 2016 m w 5 2 borrego springs earthquake in southern california and find consistent rupture velocities of 2 km s highlighting two main rupture asperities the analysis of the 2019 ml5 2 le teil earthquake in france reveals slow nucleation at depth that migrates to the surface and propagates northward with a velocity of 2 8 km s highlighting two main rupture events also imaged by insar by providing unprecedented resolution in our observation of the rupture dynamics this approach will be useful in better understanding the preparation phase and rupture of both tectonic and induced earthquakes plain language summary small and moderate size earthquakes are much more numerous yet studied in much less detail than large and damaging earthquakes this is because to study small earthquakes precisely one needs seismometers very close to the rupture which is rarely the case it is still unclear if small and large earthquakes start the same way thus studying more systematically small earthquakes could help to answer this question here we show that we can use two close by seismometers as we would do with 3 d glasses to observe with a stereoscopic effect the evolution of intermediate size earthquakes when they rupture along a fault we can retrieve the direction of rupture the speed at which the fault breaks and the length of the rupture important parameters that help to characterize the earthquakes using this new method we can sometimes also observe the behavior of the fault before the main rupture which will be useful to better understand how earthquakes start

rupture properties of the giant sumatra earthquake imaged by empirical green s function analysis empirical green s function egf analysis has remained little used to image the rupture properties of the giant 26 december 2004 sumatra earthquake the 2 november 2002 foreshock m w 7 2 close to the mainshock epicenter gives us the opportunity to use its waveforms to empirically simulate the rayleigh wave propagation of the sumatra earthquake we first show that the exceptional size of the sumatra earthquake does not prevent use of the egf technique four aftershocks m w 5 9 6 1 distributed along the sumatra andaman trench are shown to have consistent rayleigh waves for periods between 100 and 200 sec at a lower frequency we present two large earthquakes of the mexican subduction zone m w 7 2 7 3 close to the selected egf magnitude for which long period green s functions 100 2000 sec remain very similar even if event epicenters are separated by about 650 km this justifies the possibility of using the 2002 foreshock as an egf for the whole rupture process of the sumatra earthquake and shows more generally the very broad range of application of egf technique then a specific analysis reveals that seismic moment magnitude is close to 9 1 seismic moment equal to 5 6 10 22 n m moment release analysis along the sumatra andaman trench shows two main slip episodes one next to the northern extremity of sumatra 20 m slip and the other one along the nicobar islands 10 m slip with a global extent of 1150 1200 km rupture velocity varies between values around 2 5 km sec in the first half of the rupture and values closer to 2 km sec in the second half total duration imaged by rayleigh waves is 580 sec 20 sec and no activity of the fault is found in the time scale between 600 and 2000 sec in the hypothesis of even longer timescale slip this phenomenon would be of the order of 10 20 of the global moment and likely restricted to the andaman islands

models for the tectonothermal evolution of the eastern dalradian of scotland the preserved array of pressures in the eastern dalradian indicates that considerable syn to post metamorphic differential uplift has occurred this inferred differential uplift suggests that buchan sillimanite zone rocks originally lay at higher structural levels than presently adjacent cooler kyanite zone rocks to the west a number of features are believed to coincide with the western margin of the sillimanite zone these are a maximum in temperature sharp thermal features a high strain zone and a train of metabasites these features are explained by invoking syn metamorphic movement between the buchan sillimanite zone and the kyanite zone to its west involving some horizontal component of movement it is suggested that the lateral now eroded equivalents of the buchan area once provided part of the required tectonic thickening for other parts of the dalradian areas surrounding the buchan area suffered tectonic burial followed by metamorphism during uplift relative to the buchan area

rupture complexity of a moderate intraplate earthquake in the alps the 1996 m5 epagny annecy earthquake summary the magnitude 5 epagny annecy earthquake of 1996 july 15 is the largest seismic event to have occurred in the alps since the introduction of modern digital instrumentation this strike slip event was located on the vuache fault near the town of annecy in the northern french alps the aim of our work was to retrieve the main parameters of the rupture process of this earthquake from seismograms recorded at local and regional distances 20 300 km to eliminate path and site evects from the seismograms we compared the main shock recordings at each station with those of the largest aftershocks nearby we used a combination of techniques including pulse width measurements and cross correlation of velocity traces comparison of p wave displacement pulses and empirical green s function deconvolution to retrieve the apparent duration of the rupture process as seen at each station our results demonstrate that in the absence of on scale data p wave pulse width measurements on clipped signals can be misleading if the rupture process is complex in the case of the annecy earthquake comparisons of on scale p wave displacement seismograms and the empirical green s function deconvolutions show that the rupture process consisted of at least two subevents separated by 0 2 0 3 s and with a total duration of about 0 5 s the systematic azimuthal dependence of both the shape and duration of the apparent source time function is consistent with a nearly unilateral propagation of the main rupture phase in a southeast direction along the fault plane and parallel to the direction of slip an isochron analysis reveals that the first subevent occurred slightly to the northwest of the nucleation point but that the second subevent was located further to the southeast thus confirming the overall rupture directivity towards the southeast an interpretation of our results in light of the previously documented aftershock distribution and of observations of ground cracks in the epicentral area suggests that the main shock occurred on the vuache fault and that rupture in a northwest direction was inhibited by a right lateral stepover in the fault accordingly the vast majority of the subsequent aftershocks which include several magnitude 3 4 events occurred on a fault segment that is slightly ovset from the inferred surface trace of the vuache fault and that was activated by the main shock

resolution of rupture directivity in weak events 1 d versus 2 d source parameterizations for the 2011 mw 4 6 and 5 2 lorca earthquakes spain resolving robustly source parameters of small moderate magnitude earthquakes is still a challenge in seismology we infer directivity from apparent source time functions astfs at regional distance and quantify the associated uncertainties astfs are used for i modeling a propagating 1d line source from the duration data and ii inverting the 2d slip distribution from the full signals slip inversion is performed through a popperian scheme where random trial models are either falsified on account of large misfit or else become members of the solution set of the inverse problem we assess the resolution of rupture directivity representing centroid shifts from the solution set in a rose diagram using as example an event with well studied rupture directivity the 2011 mw 5 2 lorca spain earthquake 1d and 2d parameterizations yield similar estimates for direction n213 e and n220 e respectively and asymmetry 67 33 65 35 of rupture propagation as well as rupture length 2 1 km 2 7 km and speed 3 5 km s 3 25 km s the high rupture velocity 90 vs may be held primarily responsible for the strong directivity effect of this earthquake we show that inversion of apparent source durations is intrinsically unable to resolve highly asymmetric bilateral ruptures while inversion of full astfs misses part of the signal s complexity suggesting the presence of deconvolution artifacts we extend the analysis to the mw 4 6 foreshock of the lorca earthquake inferring similar directivity parameters and slip pattern as for the mainshock the rupture towards sw of both earthquakes suggests that this direction could be inherent to the fault segment