a crack like rupture model for the 19 september 1985 michoacan mexico earthquake evidence supporting a smooth crack like rupture process of the michoacan earthquake of 1985 is obtained from a major earthquake for the first time digital strong motion data from three stations caleta de campos la villita and la union recording near field radiation from the fault show unusually simple ramped displacements and permanent offsets previously only seen in theoretical models the recording of low frequency 0 to 1 hz near field waves together with the apparently smooth rupture favors a crack like model to a step or haskell type dislocation model under the constraint of the slip distribution obtained by previous studies a crack like rupture characterized by an approximated dynamic slip function and systematic decrease in slip duration away from the point of rupture nucleation produces the best fit to the simple ramped displacements observed spatially varying rupture duration controls several important aspects of the synthetic seismograms including the variation in displacement rise times between components of motion observed at caleta de campos ground motion observed at caleta de campos can be explained remarkably well with a smoothly propagating crack model however data from la villita and la union suggest a more complex rupture process than the simple crack like model for the south eastern portion of the fault

detection of anomalous seismic phases by the wavelet transform summary strong motion data at la union one of three near fault stations of the michoacan mexico earthquake in 1985 are analysed by a wavelet transform in order to identify a clear later energy arrival whose frequency content and particle motion are quite different from the main part of the seismograms we used an orthonormal set of analysing wavelets a discrete wavelet transform proposed by meyer and yamada with which an efficient computational procedure can be achieved utilizing the fast fourier transform results of an application of the above wavelet transform to three component velocity data of la union are summarized as follows a vertical seismogram does not contain any distinguishable later energy arrivals for the entire frequency range recorded the major energy arrives in the time interval between 10 and 30 s in contrast an east west component seismogram shows a peculiar later arrival more than 10 s later than the main energy arrival and our wavelet analysis shows that this later phase is characterized by an arrival time of 38 s and a frequency range from 0 1 to 1 hz where the amplitude of the later phase is even larger than the main part this example clearly demonstrates the potential of wavelet transforms to identify objectively any phase in seismograms localized in both time and frequency from the information on its particle motion the above phase corresponds to a heterogeneous and delayed break of one stronger portion on a fault on which the rupture was very smooth or crack like elsewhere

seismic source modeling seismic source modeling is taken to mean the modeling of seismograms to investigate kinematic properties of the earthquake source current trends such as the use of other data types e g geodetic measurements of coseismic deformation and the explicit consideration of source dynamics when modeling seismograms are beginning to blur this definition but i will adhere to it in this review i have divided seismic source modeling into teleseismic regional and near source modeling teleseismic modeling has the advantage of global coverage for earthquakes of magnitude 5 5 and larger but does not provide much more than point source parameters regional distance modeling has the advantage of a more rapid assessment of earthquake source properties but is complicated by relatively complex wave propagation the coverage is also limited to areas of broadband regional networks typically continental areas of developed countries near source modeling has the potential for detailed imaging of source properties but very few earthquakes occur in regions with sufficient instrumentation to allow this i have also included a section on historical earthquakes because of the additional issues that seismologists face in working with pre wwssn data and because of the important issues such as earthquake recurrence that require historical data in addition to reviewing the progress in seismic source modeling during the last four years i have also briefly reviewed some of the progress in understanding earthquake physics and hazards that has come about because of basic research in earthquake source modeling

high rates of erosion and rapid weathering in a plio pleistocene mudstone badland taiwan abstract the badlands of southwest taiwan are characterized by sharp ridges and are located in a tropical monsoon area that experiences contrasting rainy and dry seasons surface erosion predominates and subsurface erosion by piping is rather limited to accumulation of mud in valley bottoms erosion rates on plio pleistocene mudstone slopes measured using erosion pins over a period of 4 years averaged up to 9 cm y which is considerably faster than the rates of a few cm y typical in arid or semi arid areas mudstone sample cores recovered from the slopes in the dry season april and in the early rainy season july prior to the extensive erosion that occurs later in the rainy season suggested the following mechanism for weathering and erosion near surface layers

factors underlying piping in the basilicata region southern italy abstract piping tunnelling erosion is a widely spread process in the plio pleistocene marine clays of the basilicata region in southern italy the pipes are often closely concentrated along the surface drainage networks at different depths with a tunnel length and a diameter varying from just a few centimetres to some metres the formation and evolution of pipes in the badlands can be explained through 1 geo structural characteristics of the clay 2 material properties such as a high exchangeable sodium percentage 3 favourable climatic conditions and 4 hydraulic gradient along the path controlled by the gully or ravine bottom that is acting as a local drain the exposure and the extension of joints at the surface and in the bedrock along the slope are the main factors required for development of the pipes the absence of the piping erosion on the slopes where a reasonably thick layer of the soil material covers the open joints shows that although certain material properties and climatic conditions play an important role they are not sufficient to develop extensive piping erosion in the area

morphological analysis and erosion rate evaluation in badlands of radicofani area southern tuscany italy abstract since 1988 geomorphologic research based on field surveys and photo geological analysis has been conducted in southern tuscany italy in areas characterised by very rapid morphological evolution in the area outcrop pliocene marine claystones uplifted during the quaternary up to 750 m above sea level now undergoing intense erosion processes leading to considerable badlands formation morphodynamic analysis conduced by direct and indirect measurements in a sample area were taken in order to quantify the erosion rate in badland areas the torrente piantrafolla sample area was chosen as representative of the study area it was most recently monitored during the period nov 2000 feb 2004 at this time morphographic and morphometric analyses carried out in selected measurement stations located on slopes identified gravity as the main morphogenetic process responsible for slope shaping the calanchi badland areas are characterised by constant and rapid shrinking of their edges resulting from landslides which occur in autumn and winter as a consequence of intense rainstorms selected measurement stations indicate an erosion rate value range from 5 to 7 5 cm y the comparison between 1976 and 1994 digital elevation models dem obtained from photogrammetric restitution indicated a mean erosion rate of about 5 cm y in a nineteen year period this value considerably higher than the values measured in other italian basins indicate a very rapid evolution of the slopes due mainly to small earth flows inside calanchi badlands

a modeling study of oceanic nitrous oxide during the younger dryas cold period 1 the marine production cycling and air sea gas exchange of nitrous oxide n2o are simulated in a coupled climate biogeochemical model of reduced complexity the model gives a good representation of the large scale features of the observed oceanic n2o distribution and emissions to the atmosphere the transient behavior of the model is tested for the younger dryas y d cold period 12 700 11 550 bp which is simulated by releasing a freshwater pulse into the north atlantic causing a temporary collapse of the model s atlantic thermohaline circulation thc a temporary drop in atmospheric n2o of about 10 ppb results while ice core measurements show a total drop of 25 to 30 ppb this suggests that terrestrial changes have also contributed to the observed variations the main cause of the modeled reduction in atmospheric n2o is increased oceanic storage in the short term and a reduction of new production in the long term due to increased stratification

space time variability of denudation rates at the catchment and hillslope scales on the tyrrhenian side of central italy studies on denudation rates can provide insight into the influence of climate change tectonics and human activities on landscape evolution research performed in central italy has shown considerable spatial variability of denudation rates in the major river basins these studies have focused mainly on the tyrrhenian side of the italian peninsula where plio pleistocene marine deposits filling nw se elongated sedimentary basins have been uplifted during the quaternary up to several hundreds of meters above present sea level small sub catchments developed on clays are affected by sharp and or rounded edged badlands i e calanchi and biancane representing denudation hot spots in the present day morphoclimatic framework in this paper we analyze the relationships between indirectly estimated denudation rates at the catchment scale and field monitoring data at the hillslope scale we attempt to better understand and quantify all hillslope processes that contribute to seasonal variability of denudation to help with predicting the net input from hot spots to the overall estimated sediment yield at the basin outlets at the hillslope scale we discuss in particular the variability of denudation rates at calanchi and biancane badlands as a function of their different morphoevolution

msi morphometric slope index for analyzing activation and evolution of calanchi in italy article i nfo the calanchi singular calanco are a typical example of italian badlands widespread in areas with hills of clay rich sediments and rocks they appear as a very dense and rapidly evolving drainage system characterized by an alternating pattern of narrow furrows and sharp crests the calanchi can be considered as small hydrographical basins characterized by two possible drainage patterns parallel and dendritic the two patterns show both linear and areal erosion processes in this study calanchi with dendritic drainage patterns were analyzed in three different areas representative of the italian peninsular atri in the abruzzi region mount ascensione in the marche region and orcia valley in the tuscany region for each calanchi the pre erosion topographic surface was reconstructed and the value of msi morphometric slope index was calculated for the surface the volume of eroded material was estimated by comparing the pre calanchi and present surfaces we assumed that slope morphometry influences the type of erosion processes and the efficacy of these processes with respect to the amount of eroded material is a func tion of their duration we deduced that calanchi inception was contemporaneous because the duration of the processes was common to all landforms and probably due to a common climate input moreover the relations among msi eroded volume and erosion processes indicate that over a long period areally distributed surface processes contribute more to total sediment yields than channel flows

spatial variation of bed roughness in eroding rills and gullies when overland flow concentrates rill and gully channels can be formed if a series of thresholds are exceeded these thresholds are more or less explicitly linked to the erosion resistance of the topsoil moreover flow velocity and channel width depend on total flow discharge more recently also bed roughness in eroding channels has been attributed to the eroding effect of flow discharge while channel width was shown to be the result of the interplay between erosion resistance of the topsoil and flow discharge see channel junction approach torri et al 2006 which could be described by a modified leopold and maddock s relationship the objective of this paper is to investigate the spatial variability of channel bed roughness in rills and gullies using an approach based on these findings field data confirm the various aspects reported so far hence these were used to develop a new equation allowing one to predict bed roughness in eroding rill and gully channels each of the new aspects introduced into the channel width flow discharge equation by the channel junction approach is discussed and verified with new data the validity of this approach is tested against channel data from mars finally an equation predicting bed roughness and based on stream power is developed and compared with measured rill and gully bed roughness successfully confirming that 1 bed roughness if generated by concentrated flow increases with stream power 2 channel width local bed slope topsoil cohesion at saturation and grain size are all important factors controlling channel bed roughness and 3 these variables as well as soil characteristics all measurable in the field after a rill or gully forming event are sufficient to determine channel bed roughness therefore one may expect that bed roughness of an eroded channel and consequently hydraulic roughness or friction will generally increase with bed gradient erosion resistance of the soil and grain size following a logic which is best expressed by the final equations described in this paper

the role of the hillside in determining the morphometric characteristics of calanchi the example of adriatic central italy abstract a typical example of badlands in the italian peninsula is the calanchi plural of calanco which may be defined as rapidly evolving very dense and hierarchical drainage systems whose genesis is controlled by mineralogical characteristics the granulometric composition of local lithotypes structural conditions hillside gradient and climate in this work some of the morphometric characteristics of the hillside were compared on a statistical basis with those of the drainage network of the calanchi for two large sample areas in adriatic central italy it was possible to demonstrate how the hillside environment strongly affects the activation of the process and the characteristics of the calanchi depending on their morphometric morphometric characteristics in particular the length inclination ratio of the hillside conditions the hydrographic pattern of the calanco system

a typical calanchi landscape on the eastern apennine margin atri central italy geomorphological features and evolution abstract the surroundings of the town of atri abruzzo region central italy situated about 10 km from the adriatic shoreline can be considered as representative of most part of the italian seaward peninsular landscape the subject of this research the calanchi landscape often generally considered as badlands by non italian authors is in fact made up of many singular landforms each of which calanco corresponds to a more or less extended hydrographic unit the dynamics are mainly the result of the action of the particularly aggressive climatic factors such as the mediterranean rainfall regime on weak substrata clay silt and sand of the plio pleistocene marine cycles the morphogenetic activity is not only limited to channel erosion but it is also due to repeated superficial slides so that it should in fact be better to consider the calanco as the result of a combined erosion process sensu zachar d 1982 soil erosion elsevier amsterdam since the mechanism regulating this process remains unclear this work wants to offer a contribution to this research field multitemporal geomorphological analysis has helped us to distinguish the different areas in which the calanchi evolution has been more or less important in the past in such a way it has been possible to characterize the landscape evolution as a function of the parameters that influence soil loss especially in areas such as that of atri where calanchi like landforms are highly developed moreover this analysis coupled with the processing of 40 years rainfall data also taking into account the concurrent land use changes has clearly shown that the areas affected by calanchi erosion on the eastern apennine margin still tectonically active are progressively diminishing

effects of land use changes on badland erosion in clayey drainage basins radicofani central italy abstract hillslopes of the radicofani area in the upper valley of the orcia river southern tuscany region italy consist mainly of early pliocene clayey sediments and are widely affected by frequent badland erosion reforestation with frugal conifers has been carried out in the area over the last 50 years the goal of the present study is to evaluate the impact of reforestation and land use change on erosion rates in nine small drainage basins through a multidisciplinary approach geological geomorphological hydrological and land use characteristics were analyzed by a diachronic confrontation between pre reforestation 1954 and post reforestation 2007 situations aerial photo interpretation and processing in gis allowed us to quantify changes in areas affected by badland erosion land use and variations in erosion rates moreover dendrometric data were gathered from 18 circular sample plots in forest stands of 40 years old this allowed us to evaluate both the adaptability of different forest species to the clayey substrate and reforestation fragmentation the differences between the pre and post reforestation situations led to increases in arable land and forest areas and considerable decreases in erosion rates and badland areas however no significant correlation between the erosion rates and the forest area emerged due to the excessive fragmentation of reforestation cores and relatively small reforested surfaces land reclamation seems to have played a more important role in reducing erosion in the clayey substrate the integrated method presented here is an important tool useful to understand the morphological dynamics of badlands in relation to forest vegetation and for land planning and management

detachment and infiltration variations as consequence of regolith development in a pyrenean badland system the araguas experimental catchment has been monitored to study badland dynamics in the central pyrenees previous studies of weathering processes within the catchment reported strong regolith dynamics associated with seasonal variations in the temperature and moisture regimes a preliminary analysis of hydrological response and suspended sediment transport data recorded at a gauging station also demonstrated seasonal trends the main objective of the present study is to understand the effect of regolith dynamics on sediment detachment and infiltration processes based on field studies using simulated rainfall the experiment design was based on seasonal differences in the physical conditions of surface regolith and the general trends of hydro sedimentological responses rainfall simulations were conducted on small plots using a pressure nozzle similar experimental rainfall conditions were set for all plots rainfall intensity around 45 mm h 1 the results showed strong variations in the infiltration and detachment responses closely associated with the regolith conditions and crusting development infiltration showed seasonal differences in time lag and intensity average infiltration rates ranged from very low 2 05 mm h 1 to moderated high values 44 04 mm h 1 associated to regolith development conditions maximum sediment concentration as an indicator of particles produced by detachment also ranged from moderate 3 g l 1 to extreme values 145 g l 1 mean and minimum infiltration rates showed negative correlations with initial moisture content sediment concentration showed a positive correlation with time lag ponding and sealing time and a negative correlation with initial moisture in terms of seasonal trends infiltration and erosion responses were relatively stable during spring and autumn whereas wide variations were recorded in infiltration rates and sediment detachment during summer and winter as a general conclusion the obtained results indicate that seasonal differences in detachment and infiltration depend on the nature of regolith development copyright 2009 john wiley sons ltd

n2o and ch4 variations during the last glacial epoch insight into global processes 1 greenhouse gas measurements along polar ice cores provide important insight into the former composition of the atmosphere its natural variations and the responses to fast climatic changes in the past we present high resolution nitrous oxide n2o and methane ch4 records measured along two ice cores from central greenland covering part of marine isotope stages 3 and 4 in the last glacial epoch the n2o data confirm the hypothesis that n2o shows variations in phase to fast climatic changes observed in the northern hemisphere the so called dansgaard oeschger d o events variations exist not only for events with a long duration 1500 years and more but also for the shorter ones the comparison with ch4 unveils interesting differences between the response of ch4 and n2o to d o events while the average amplitudes of ch4 oscillations associated with d o events are similar to those of the northern hemisphere summer insolation the magnitude of the n2o concentration change instead correlates with the duration of the d o events the records give further insight into the timing of concentration changes at the beginning of d o events they show that for long lasting events the n2o concentration starts to increase before both the sharp increase in the ch4 concentration and the temperature reconstructed for greenland

micropiping processes and biancana evolution in southeast tuscany italy abstract biancane badlands consisting of small domes dissected by rills and micropipes with rough disordered microrehef can be found along the apennines in italy the dominant processes forming biancane differ from those of badlands formed on smectite rich mudrocks as micropipes associated with pseudokarstic enlargement of pores and cracks predominate and form the main routes for evacuation of eroded material biancana evolution is controlled by water infiltration into intact bedrock producing an erodible weathering rind which is more porous than intact rock this rind is easily removed by rill or micropipe flow and erosion is therefore weathering controlled depending on rind production by infiltrating water infiltration is initially slow and stepped due to slow water movement through very small capillary pores in intact rock alternating with rapid filling of macropores and cracks this occurs due to rapid matrix pore enlargement by dispersion and or dissolution the infiltration pattern is accurately reproduced by a model built on progressive development of weathering layers by moisture penetration model results are consistent with weathering rind depths and erosion observed in the field and show that a pipe network can be generated on newly exposed rock by the rainfall of one year propagation of the pipe network diverts a progressively larger proportion of runoff into micropipes expanding weathering rind production within the biancana as well as on the surface internal weathering and flow progressively dominate with few unweathered corestones and the biancana gradually collapses into a penultimate souffle like form

strong ground motion from the michoacan mexico earthquake the network of strong motion accelerographs in mexico includes instruments that were installed under an international cooperative research program in sites selected for the high potenial of a large earthquake the 19 september 1985 earthquake magnitude 8 1 occurred in a seismic gap where an earthquake was expected as a result there is an excellent descripton of the ground motions that caused the disaster

pliocene quaternary transpressional evolution of the anzi calvello and northern s arcangelo basins basilicata southern apennines italy as a consequence of deep seated fault reactivation abstract in this paper we report the results of a study of the plio pleistocene anzi calvello basin and the northern sector of the s arcangelo basin southern apennines italy our work suggests that the evolution of the anzi calvello basin is related to the activity of a deep seated roughly nne trending dextral transpressional fault zone camastra transcurrent fault zone ctfz structural control of sedimentation by this structure is indicated by the geometry of the unconformity bounded stratigraphic units as well as by the deformation of the basin fill en echelon n s trending thrusts n to ne trending dextral transpressional faults and nw to nnw striking folds affecting the substratum constitute the surface response to lateral displacement along the ctfz the s arcangelo basin is bounded to the north by a deep seated roughly wnw nw trending sinistral transpressional structure valsinni lateral ramp vlr that terminates northwestward against the ctfz at the surface the vlr is dominated by back thrusts and by transpressional fault zones the vlr has been interpreted as the sinistral lateral ramp of the large scale valsinni thrust anticline and it is inferred to have strongly controlled local deposition within the s arcangelo basin the deep seated structures ctfz and vlr probably represent reactivated pre existing normal and transfer faults affecting the rigid apulian platform that were generated during passive margin evolution as well as during the flexural bending of the apulian lithosphere during the pliocene pleistocene these structures were reactivated as lateral ramps accommodating the thrusting within the apulian platform transpression along the lateral ramps in the apulian platform propagated upwards through the nappe pile giving rise to a complex surface structural pattern and the local development of flower like structures

soil erodibility and processes of water erosion on hillslope abstract the importance of the inherent resistance of soil to erosional processes or soil erodibility is generally recognized in hillslope and fluvial geomorphology but the full implications of the dynamic soil properties that affect erodibility are seldom considered in canada a wide spectrum of soils and erosional processes has stimulated much research related to soil erodibility this paper aims to place this work in an international framework of research on water erosion processes and to identify critical emerging research questions it focuses particularly on experimental research on rill and interrill erosion using simulated rainfall and recently developed techniques that provide data at appropriate temporal and spatial scales essential for event based soil erosion prediction results show that many components of erosional response such as partitioning between rill and interrill or surface and subsurface processes threshold hydraulic conditions for rill incision rill network configuration and hillslope sediment delivery are strongly affected by spatially variable and temporally dynamic soil properties this agrees with other recent studies but contrasts markedly with long held concepts of soil credibility as an essentially constant property for any soil type properties that determine erodibility such as soil aggregation and shear strength are strongly affected by climatic factors such as rainfall distribution and frost action and show systematic seasonal variation they can also change significantly over much shorter time scales with subtle variations in soil water conditions organic composition microbiological activity age hardening and the structural effect of applied stresses property changes between and during rainstorms can dramatically affect the incidence and intensity of rill and interrill erosion and therefore both short and long term hillslope erosional response similar property changes linked to climatic conditions may also significantly influence the stability and resilience of plant species and vegetation systems full understanding of such changes is essential if current event based soil erosion models such as wepp and eurosem are to attain their full potential predictive precision the complexity of the interacting processes involved may however ultimately make stochastic modelling more effective than physically based modelling in predicting hillslope response to erodibility dynamics

geomorphic features of a badland biancane area central italy characterisation distribution and quantitative spatial analysis abstract the biancana landscapes rather common in several italian areas have a very complex morphology different geomorphic features often occur along the same hillslope from a morphological survey of an experimental site in southern tuscany the forms were classified and their distribution analysed spatial analysis of the biancane provided insights into the range of forces responsible for their formation and evolution the results confirm an evolutionary trend from an original gently sloping surface to a complex biancana landform emphasising a trend from the taller bean forms to the terminal souffle like and cone forms the presence of scarp and sliding forms in the most sloping areas and along the residual surfaces supports the hypothesis of a process influenced by base level acting initially by small mass movements spatial analysis did not reveal any systematic trend in the variability of the erosional features along the slopes variographic analysis showed that selected morphological attributes are spatially auto correlated over a short range suggesting that the erosive processes responsible for morphogenic evolution of biancane act mostly on a local scale the strong geometric anisotropy detected in directions parallel to the main jointing systems also indicated a broader scale tectonic control of biancane evolution probably in an early stage of their formation

unstable younger dryas climate in the northeast north atlantic the younger dryas stadial greenland stadial 1 has long been recognized in proxy records throughout the north atlantic region as a stable cool period that started and ended abruptly however modeling experiments in which the younger dryas cooling was forced by meltwater predict much more unstable climatic conditions compared to the proxy records here we present evidence of a climatically unstable younger dryas based on a decadal resolution marine proxy record from the norwegian continental shelf this record shows that the north atlantic was characterized in the early younger dryas by arctic water and an increasing accumulation of fresh surface water that peaked at 12 500 calendar yr b p for 300 yr during the late younger dryas the sea surface temperatures fluctuated between glacial values 2 c and interglacial values 10 c on a subdecadal to multidecadal time scale this period of extreme instability preceded the more stable and warm holocene starting ca 11 500 calendar yr b p these results are consistent with modeling experiments that link the younger dryas climate changes to fluctuations of the north atlantic thermohaline circulation

tectonic forcing of evolution and holocene erosion rate of ravines in the marginal ganga plain india abstract understanding the processes of ravine formation and estimates of specific sediment yields ssy of these regions help in formulating mitigation policies significantly upto now in the ganga plain the work done on ravine formation erosion and ssy estimates has been speculative here utilizing i high resolution digital elevation models dems prepared from real time kinematic rtk survey and cartosat images of ravined zones and ii luminescence chronology we provide the first estimate of ssy from the ravines the results indicate that ssy in the marginal ganga plain mgp ravines may range between 600 100 t km 2 yr and 1600 200 t km 2 yr the correspondence between the orientations of fractures and that of first order ravine suggests that the ravine growth is genetically related to extensional stress regime of the peripheral forebulge further the clay sedimentology indicates that besides regional tectonics action of swelling clays may have accelerated development of the badlands the geomorphic relationship between the length of ravined catchments and incision in the trunk channels indicates that the river incision associated base level change is not playing an overarching role in the ravine formation in the mgp

linearized inversion for fault rupture behavior application to the 1984 morgan hill california earthquake we present a technique to infer the rupture history of an earthquake from near source records of ground motion unlike most previous studies each point on the fault is assumed to slip only once when the rupture front passes with a spatially variable slip intensity in this parameterization the data are linearly related to slip intensity but nonlinearly related to rupture time we perform a linearized inversion for slip intensity and rupture time by iteratively perturbing an assumed starting model the inverse problem for the model perturbation is solved using a tomographic back projection technique smoothing and inequality constraints are applied to ensure that the resulting solution is stable and feasible asymptotic ray theory is used to calculate theoretical seismograms and partial derivatives with respect to model parameters in test cases with noisy synthetic data sets we found that it is possible to distinguish between rupture models having variable slip amplitude and models having variable rupture velocity provided the station coverage is adequate we apply the technique to recordings of the april 24 1984 morgan hill earthquake the results indicate that slip amplitude on the fault plane was extremely variable and that the rupture front did not propagate uniformly away from the hypocenter in particular rupture was delayed on a 12 km2 section of the fault approximately 14 km to the southeast of the hypocenter the rupture front surrounded the region which subsequently failed with a component of rupture propagation back toward the hypocenter similar behavior has been observed in dynamic rupture models with stress or strength inhomogeneities this segment of the fault ruptured with a large slip amplitude releasing 12 of the total seismic moment from 4 of the total area of the aftershock zone the surface trace of this section of the fault is characterized by a complex left step that could act to increase the normal stress acting across the fault however the distribution of aftershocks suggests that the fault at depth is simpler and that it may bend to the right in either case our rupture model suggests that this segment of the fault represents an asperity which initially resisted rupture but eventually ruptured massively we estimate the shear fracture energy for this earthquake to be 2 106 j m2

methane emission from the mud volcanoes of sicily italy 1 mud volcanoes represent the largest expression of natural methane release into the atmosphere however the gas flux has never been investigated in detail methane output from vents and diffuse soil degassing is herewith reported for the first time measurements were carried out at 5 mud volcano fields around sicily italy each mud volcano is characterized by tens of vents and bubbling pools in the quiescent phase methane emission from single vents ranges between 0 01 and 6 8 kg day diffuse soil leakage around the vents is in the order of 102 104 mg m 2 d 1 an exceptional flux of 106 mg m 2 d 1 was recorded close to an everlasting fire soil ch4 flux is positive even at large distances from the mud volcano fields suggesting a diffuse microseepage over wider areas a total of at least 400 tons ch4 per year can be estimated over the area investigated alone 1 5 km2

a very broad band analysis of the michoacan mexico earthquake of september 19 1985 long period seismograms from the gdsn rstn and ida network are used in a centroid moment tensor analysis of the september 19 1985 michoacan mexico earthquake ms 8 1 the long period data are also used together with broad band displacement p waveforms in a joint very broad band inversion for the moment tensor and the moment rate distribution in time and space results are that the earthquake had a total scalar moment of 1 1 1028 dyne cm and that the moment release occurred mainly in two subevents the second of which was located approximately 70 km southeast of the first observations of earth s normal modes at ultra long periods 600 to 2000 sec are shown to be consistent with the obtained scalar moment and source mechanism

investigation of relationships between measured field indicators and erosion processes on badland surfaces at petrer spain abstract indicators were obtained to measure and predict rill erosion and mass wasting in biancana and calanchi like badland areas rainfall simulation experiments were used to find a relationship between soil moisture change and sediment concentration behaviour this relationship appeared to be able to show in its role as indicator differences between materials affected by various degrees of rill erosion or mass wasting indicators explaining this relationship are surface characteristics runoff and infiltration characteristics and chemical and mineralogical soil properties from the experimental study it was concluded that the high infiltration capacity in materials affected by mass wasting resulted in an unstable soil and a high degree of erodibility the materials which were more affected by rill erosion or had a continuous crust at the surface were saturated earlier during the experiment than the other materials this saturation caused an increase in runoff the mechanism is explained as the system crossing a threshold after which flow hydraulics at the surface are more important for erosion processes than dynamic soil properties and infiltration characteristics

structural evolution of the lucanian apennines southern italy abstract in this paper we present a study of an entire segment of the southern apennines of italy extending from the pollino mountain range to the south to the agri valley to the north in which all the units of the chain are represented combining regional information with detailed structural data obtained from the different tectonic units forming the orogenic belt the structure as well as the tectonic evolution of this portion of the orogenic belt are proposed the overall architecture of this segment of the southern apennines mountain chain represents the result of a complete orogenic cycle in which oceanic subduction syn collisional and post collisional events are well recorded structurally this segment of the orogenic belt exhibits two distinct structural levels separated by a major detachment surface the sole thrust of the accretionary wedge that occur at the surface in the allochthonous nappes and at depth in the adria continental margin the upper level is characterized by an imbricated fan system affecting the allochthonous terranes emplaced during oceanic subduction and the first stages of continent continent collision the lower level is represented by a duplex geometry that has developed in the post collisional stage during evolution of the foreland migrating thrust system involving the carbonate platform basin system of the adria block during the last stages of the mountain building process when the foreland thrust migration was locked by the thickening of the colliding continental crusts the southern apennines were thus affected by a severe strike slip tectonics that dissects the entire mountain belt deeply modifying the previous thrust geometry

relationships between a new slope morphometric index and calanchi erosion in northern sicily italy the italian badlands or calanchi are common landforms in mediterranean areas including central and southern italy calanchi landforms may be compared to small hydrographic basins these landforms are characterised by dense hierarchical and rapidly evolving drainage systems carved into steep clayey slopes and by a sharply alternating pattern of furrows and narrow generally sharp crests this work presents a study of morphometric characteristics and a statistical analysis for two sites in northern sicily italy on outcrops of silty clay deposits affected by active erosion processes which give this area a typical calanchi landscape in particular factors closely linked to the characteristics of the hydrographic network and slope morphometry were considered and analysed the initial geometry of the slopes was reconstructed and statistically compared with that of the current calanchi slopes including the drainage network a new morphometric index morphometric slope index msi was defined to represent the initial slope geometry as a whole this index was found to be effective in defining the structure of hydrographic networks summarising the characteristics and type of slope evolution and quantifying the rate of soil erosion the rate was determined based on both linear gully erosion and areal landslides sheet and rill erosion morphogenetic processes and our analysis based on msi indicates the dominance of areal erosion msi could also be used for basins larger than calanchi to represent the characteristics of geomorphic processes

pleistocene strike slip tectonics in the lucanian apennine southern italy structural studies carried out in the lucanian apennines southern italy show that strike slip faulting was the principal mode of deformation of this area during middle upper pleistocene time w nw to e se trending left strike slip fault systems dissect the entire apennine mountain belt and affect the preexisting thrust geometry strike slip faults activated by a roughly e w shortening are characterized by different geometries representing the surface response to lateral motion occurring along deep seated structures the occurrence of different structural patterns which characterize different segments of strike slip system is related to 1 the depth of a major decoupling surface which separates the upper tectonic multilayered horizon apennines thrust belt system from the lower rigid horizon apulian belt in which strike slip structures have originated and 2 the geometric relationships between the strike slip faults and the thrust belt pattern which characterize the upper horizon the different segments of the strike slip system are interpreted as internal deformation developed within a crustal shear zone this zone which corresponds to the boundary between the apulian block and the apennine chain is characterized by sinistral movement as a response to the northwesterly convergent motion of the african plate with respect to europe

source mechanism of the september 19 1985 michoacan earthquake and its implications moment tensor inversion of low frequency teleseismic data for the september 19 1985 michoacan mexico earthquake gave an average strike 298 slip 268 and seismic moment 10 3 1027 dyne cm low frequency body waves clearly show the complex nature of this event cross correlation of the september 19 p wave with that of the smaller and colocated october 25 1981 playa azul earthquake show that the michoacan earthquake consisted of two subevents separated in time by 25 s and located approximately 30 km northwest and 40 km southeast respectively of the playa azul epicenter body wave inversion of the first subevent gave strike 298 slip 266 and seismic moment 3 0 1027 dyne cm the second subevent had a comparable seismic moment the cumulative moment for large earthquakes occurring along the michoacan northwest guerrero coast indicate that seismic displacement along this segment of the mexican subduction zone is similar to that occurring on other portions indicating that the former michoacan gap was not anomalously aseismic

testing gis morphometric analysis of some sicilian badlands abstract calanchi badlands are erosion landforms characterized by areas with scarce or absent vegetation steep slopes knife edge divides and high erosion rates they are originated by a combination of morphogenetic processes partly similar to those shaping bigger fluvial landforms and therefore can be considered as field laboratories this paper presents the results of an investigation carried out in two badland sites located in sicily where the geometry of 25 calanchi has been characterized using digital elevation models having a mesh size equal to 2 m for each landform a power length volume relationship is established this relationship demonstrates that length of calanchi channels can be used as a reliable predictor of eroded volume as already verified for smaller linear erosion landforms such as rills ephemeral and permanent gullies moreover length volume width and depth of calanchi are combined into two dimensionless groups allowing to establish a morphological similarity between rills ephemeral permanent gullies and the studied badlands furthermore the hack s law which relates channel length to drainage basin area is applied to the 25 calanchi basins obtaining an exponent of this power law smaller than 0 5 this result indicates that basins do not become necessarily more elongate with increasing size finally the relationships between maximum length and width of the landforms are analyzed demonstrating that calanchi basins become wider and not longer and narrower when evolving and increasing their size

source characteristics of earthquakes in the michoacan seismic gap in mexico we investigated the source characteristics of large earthquakes which occurred in the michoacan mexico seismic gap during the period from 1981 to 1986 in relation to historical seismicity in the region the rupture pattern of the michoacan gap during this period can be characterized by a sequential failure of five distinct asperities before 1981 the michoacan gap had not experienced a large earthquake since 1911 when an m s 7 8 earthquake occurred the recent sequence started in october 1981 with the playa azul earthquake which broke the central part of the gap body wave modeling indicates that the playa azul earthquake is 27 km deep with a seismic moment of 7 2 10 27 dyne cm it is slightly deeper than the recent michoacan earthquakes and its stress drop is higher suggesting a higher stress level at depths in the michoacan gap the seismic moment of the 19 september 1985 m w 8 1 earthquake was released in two distinct events with the rupture starting in the northern portion of the seismic gap and propagating to the southeast with low moment release through the area already broken by the 1981 playa azul earthquake the rupture propagated further southeast with an m w 7 5 event on 21 september 1985 another aftershock occurred on 30 april 1986 to the northwest of the 19 september main shock body wave modeling indicates that this event has a simple source 10 sec long at 21 km depth and fault parameters consistent with subduction of the cocos plate 280 12 and 70 and m 0 2 0 to 3 1 10 26 dyne cm m w 6 8 to 6 9 although this distribution of asperities is considered characteristic of the michoacan gap whether the temporal sequence exhibited by the 1981 to 1986 sequence is also characteristic of this gap or not is unclear it is probable that depending on the state of stress in each asperity the entire gap may fail in either a single large event with a complex time history or a sequence of moderate to large events spread over a few years the seismic moment and the time since the last earthquake in michoacan in 1911 fit an empirical relation between moment and recurrence time found for the guerrero oaxaca region of the mexico subduction zone

the role of some site geochemical processes in the development and stabilisation of three badland sites in almeria southern spain samples of both surface and subsurface soils were collected on various surfaces in three badland areas of differing ages tabernas vera and mocatan in almeria province southern spain data were explored with the aim of identifying any diagnostic geochemical relationships between site ec ph sediment size and sar which might constitute typical signatures for site materials with some success data for the three sites are further used to explore the hypothesis that changes in site geochemistry through time are involved in badland stabilisation it was found that 1 the physico chemical properties of the three sites can be differentiated by the functional relationship between ec and sar and this may represent a useful tool in characterising sites where piping predominates 2 there is some equivocal evidence that sediment size distribution may play an additional role in site diagnosis and evolution and 3 surfaces appear to lose sodium over time the suggestion being that sodium is either progressively buffered by calcium during leaching or exchanges with hydrogen on the cation exchange sites under a vegetation cover since other research suggests that smectite can also relocate down the profile on some marl sites reducing hydraulic conductivity and suppressing pipes we argue that the surface at tabernas may be capable of long term autostabilisation in which piping intensity progressively reduces however this possibility really applies only to fine grained densely structured materials and evidence from the silty triassic rich unit in the mocatan basin suggests that without a high clay content piping may be expected to increase through time from this standpoint contemporary badland morphology at mocatan does not represent an early stage of the forms seen in vera and tabernas

mapping badland areas using landsat tm etm satellite imagery and morphological data abstract soil erosion is the most influential component of land degradation for its strong impacts on both natural and agricultural environments in order to support effective intervention and recovery policies for eroded areas monitoring techniques should take into account the space time variability of the processes involved and make use of assessed mapping methodologies as baseline criteria for studying the dynamics of landform development when using multispectral data for mapping eroded areas low spectral separability is a significant limit in areas with complex features where soil materials are frequently remixed by surface runoff since multispectral satellite images are a valuable data source for multi temporal analyses of erosion processes at the medium scale we assessed how accurately a badland area can be identified from landsat tm and etm data a protocol for an optimal mapping was built up by testing the performance of different supervised algorithms and input layers spectral and morphological tests were carried out in a well known badland area of basilicata italy with an extension of 8000 ha results obtained from the use of spectral bands with and without thermal channel and principal components returned an overall accuracy ranging from 53 for classification on first three components to 72 for classification on all bands from tm with low values for the kappa coefficient 0 30 0 50 showing that the spectral information alone are insufficient to accurately identify badland areas in order to improve mapping we found that the integration of slopes and aspects derived from a digital elevation model dem can overcome problems inherent to the low separability of spectral signatures the use of morphological data was tested for different classification algorithms and integration approaches in discriminating badlands the better performing algorithm was mlc maximum likelihood classifier and the best results were obtained by integrating all seven bands including tir with slope and aspect maps as input within the classifier a 0 85 and k 0 75 for both the sensors we selected such parameters because they play an important role in characterising badlands of study area from a morphological perspective but the proposed approach is also conceptually simple and can be easily exported to other areas the obtained results support the hypothesis that the combined use of remote sensing imagery and auxiliary morphological data significantly improves the mapping of badlands over large areas with heterogeneous features thus providing a useful methodology for long term studies on soil erosion processes

soil loss rates due to piping erosion compared with surface soil erosion by water subsurface erosion piping is generally less studied and harder to quantify however wherever piping occurs it is often a significant or even the main sediment source in this study the significance of soil loss due to piping is demonstrated through an estimation of soil volume lost from pipes and pipe collapses n 560 in 137 parcels under pasture on loess derived soils in a temperate humid climate belgium assuming a period of 5 to 10 years for pipe collapse to occur mean soil loss rates of 2 3 and 4 6 t ha 1 yr 1 are obtained which are at least one order of magnitude higher than surface erosion rates 0 01 0 29 t ha 1 yr 1 by sheet and rill erosion under a similar land use the results obtained for the study area in the flemish ardennes correspond well to other measurements in temperate environments they are however considerably smaller than soil loss rates due to subsurface erosion in semi arid environments although local slope gradient and drainage area largely control the location of collapsed pipes in the study area these topographic parameters do not explain differences in eroded volumes by piping hence incorporation of subsurface erosion in erosion models is not straightforward copyright 2011 john wiley sons ltd

physical chemical and mineralogical properties of parent materials and their relationship with the morphology of badlands abstract badlands are present throughout the world but not everywhere do they have the same morphology the main objective of this study is to try to understand why these different morphologies occur by analysing the physical chemical and mineralogical characteristics of the parental material in which badlands have developed the study was carried out in three areas of the region of murcia south east spain abanilla mula and gebas several analyses were carried out i field analysis orientation slope length and shape of the slope presence and characteristics of the rills vegetation vegetation pedestals exposed roots stoniness physical and biological crusts saline efflorescence cracks popcorn piping processes sedimentation areas and mass movements ii physical chemical analysis of the soils colour texture aggregate stability bulk density organic matter ph electrical conductivity cations and cation exchange capacity total or equivalent calcium carbonate sodium absorption ratio and exchangeable sodium percentage and iii mineralogical analysis the results of the analyses reveal how the rounded shapes in the badlands that appear in abanilla have significant differences with respect to the angled shapes of mula and gebas which could explain the different morphologies in general abanilla has very small amount of sand higher bulk density small amount of organic matter lower cation exchange capacity and very high salinity as shown in the values of electrical conductivity sodio sar and esp on the other hand similarities were found between the badlands of the region of murcia with the calanchi angled shapes and biancane rounded shapes of italy

irregular glacial interstadials recorded in a new greenland ice core the greenland ice sheet offers the most favourable conditions in the northern hemisphere for obtaining high resolution continuous time series of climate related parameters profiles of 18o 16o ratio along three previous deep greenland ice cores1 3 seemed to reveal irregular but well defined episodes of relatively mild climate conditions interstadials during the mid and late parts of the last glaciation but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate rather than artefacts due to disturbed stratification here we present results from a new deep ice core drilled at the summit of the greenland ice sheet where the depositional environ ment and the flow pattern of the ice are close to ideal for core recovery and analysis the results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt according to a preliminary timescale based on stratigraphic studies the interstadials lasted from 500 to 2 000 years and their irregular occurrence suggests complexity in the behaviour of the north atlantic ocean circulation

root tensile strength relationships and their slope stability implications of three shrub species in the northern apennines italy abstract the role of root strength is important in stabilising steep hillslopes which are seasonally affected by storm induced shallow landslides in the italian apennines steep 25 40 slopes underlain by mudstone are generally stable if they are covered by shrubs whose roots anchor into the soil mantle to quantify the mechanical reinforcement of roots to soil the root tensile breaking force and the root tensile strength of three autochthonous shrub species commonly growing on stiff clay soils of the northern italian apennines rosa canina l inula viscosa l and spartium junceum l were measured by means of field and laboratory tests for each test approximately 150 root specimens were used the tensile force increases with increasing root diameter following a second order polynomial regression curve the tensile strength decreases with increasing root diameter following a power law curve the field in situ tensile force required to break a root is always smaller than that obtained from laboratory tests for the same root diameter although their difference becomes negligible if the root diameter is smaller than 5 mm the influence of root tensile strength on soil shear strength was verified based on the infinite slope stability model the root reinforcement was calculated using the number and mean diameter of roots the factor of safety was calculated for three different soil thickness values 0 1 0 3 and 0 6 m and topographic slopes between 10 and 45 the factor of safety for the combination of 0 6 m soil thickness slopes smaller than 30 and vegetation of i viscosa l or s junceum l is always larger than 1 if a slope is steeper the factor of safety may be smaller than 1 for i viscosa l although it is still larger than 1 for s junceum l in the stiff clayey areas of the northern italian apennines i viscosa l mainly colonizes fan cone taluses and stabilises these zones up to a topographic gradient

three dimensional finite difference simulation of fault dynamics rectangular faults with fixed rupture velocity we analyze three dimensional finite difference solutions for a simple shear crack model of faulting to determine the effects of fault length and width on the earthquake slip function the fault model is dynamic with only rupture velocity fault dimensions and dynamic stress drop prescribed the numerical solutions are accurate for frequencies up to 5 hz and are combined with asymptotic results for shear cracks in order to characterize the slip function at higher frequencies near the hypocenter the slip velocity exhibits a square root singularity whose intensity increases with hypocentral distance at distances greater than the fault width w growth of the velocity intensity ceases and the slip function becomes nearly invariant with distance along the fault length closed form expressions are developed for the dependence of static slip s slip rise time tr and slip velocity intensity v on fault geometry along the center line of a long narrow fault at hypocentral distances exceeding w these expressions reduce to s w tr 0 5 w vr and v w 2 vr where is the dynamic stress drop the shear modulus and vr the rupture velocity the numerical results imply that uniform dislocation kinematic earthquake models in which slip is represented by a ramp time function will underpredict high frequency ground motion relative to low frequency ground motion a further implication of the numerical solutions is that the nature of inelastic processes at the advancing edge of a long fault will depend on fault width but will be independent of rupture length

the impact of the farming practice of remodelling hillslope topography on badland morphology and soil erosion processes abstract badland landforms created in plio pleistocene clay landscapes of the basilicata region of southern italy form marginal features in a semi arid landscape dominated by the widespread cultivation of subsidised cereals these badland features are high relative relief forms exhibiting a high drainage density and steep slopes with slope angles typically in excess of 35 economic incentives to increase agricultural productivity have resulted in the practice of remodelling these marginal areas using heavy earth moving equipment remodelling the badland features creates longer slopes at lower angles which can be cultivated using conventional farm machinery these changes in hillslope morphology have altered the degree to which soil erosion processes operating in these areas are spatially coupled in the badland areas erosion and deposition are strongly localised with minimal sediment delivery to ephemeral or perennial channel systems the economically driven change in land use from visually striking badland areas to newly remodelled fields for agricultural use results in an increase in the coupling of drainage networks and a net increase in soil erosion

piggyback basin development and thrust belt evolution structural and palaeostress analyses of plio quaternary basins in the southern apennines abstract in southern italy structural analysis of the intramontane pliocene quaternary terrigenous basins of sant arcangelo and ofanto shows that they are piggyback basins the recent uplift of the southern apennines provides good conditions for carrying out detailed studies of palaeostresses in relation to structure and sediment accumulation in such piggyback basins we demonstrate that in the pleistocene sant arcangelo marine basin a single n70 compression induced a complex pattern of folds and strike slip faults in contrast the older pliocene ofanto basin reveals a polyphase history characterized by successive tilts and palaeostresses according to different compressions in both basins compressional stresses are syn depositional the geometry of the sedimentary infill of these basins provides information on the thrusting activity in terms of location geometry and age we point out that in addition to sedimentary and structural studies including interpretation of seismic reflection data palaeostress analyses provide a valuable tool for deciphering development and evolution of compressional basins in a fold and thrust belt

control of climate and local topography on dynamic evolution of badland from southern italy calabria abstract this work deals with an integrated geomorphological and chemical physical study of calanchi landforms in site caulonia of se calabria southern italy developed on of late pliocene quaternary clay deposits the aim of this paper is to investigate how topography and rainfall quantity may affect runoff and slope processes in calanchi landforms by influencing the physical chemical and mineralogical properties of clayey sediments to this purpose a comparison has been made among the physical chemical and mineralogical features of calanchi materials sampled after a rainy period precipitation mean annual rainfall of 709 6 mm wet year with those sampled after relatively dry period mean annual rainfall of 431 4 mm dry year and in different topographic settings opposite flanks of a catchment exhibiting different steepness and lengths i e w to nw facing and e to ne facing slopes using a multivariate statistic approach which adopts the principal component analysis pca method to extract factors it has been possible to make a hypothesis of the main processes responsible for dynamic evolution of the study area the rainfall quantity coupled with topography has to be considered as the main control factor inducing changes in the physical chemical mineralogical parameters

the influence of groundwater on surface flow erosion processes during a rainstorm surface erosion rates on a disturbed natural soil in a 10 m indoor flume increased by an order of magnitude when a water table developed at a 10 cm depth during simulated rainstorms erosion rate increases did not correlate well with surface hydraulic flow conditions and all significant erosion increases began before the full soil depth was saturated before the water table reached the soil surface and before seepage was possible groundwater influenced erosion processes primarily by increasing unsaturated pore water pressures and decreasing soil shear strength in surface rainflow rather than through the direct entrainment of soil particles by seepage flow there was no unique morphologic expression of the influence of groundwater during a rainstorm subsurface processes influencing surface erosion were detected only by appropriate subsurface instrumentation which included micropiezometers tensiometers and time domain reflectometry erosion rate increases occurred all along the slope and were not concentrated at the base of slope due to a seepage zone soil depth was crucial to determining surface erosion increase it is likely that confusing trends in surface flow erosion rates in past studies have occurred due to unrecorded groundwater development or an emphasis on seepage effects groundwater must be monitored along hillslopes under all moisture and soil conditions in order to avoid misleading and inconsistent conclusions derived solely from surface flow or seepage data copyright 2002 john wiley sons ltd

fine structure of a postfailure wadati benioff zone the hypocentral distribution of locally recorded aftershocks of the great ms 8 1 michoacan mexico earthquake of september 19 1985 defines a narrow wadati benioff zone structure roughly 10 km thick dipping 14 at n23 e this is in good agreement with the source geometry obtained by waveform modeling of the 1985 michoacan mainshock and the large 1979 petatlan earthquake in the adjoining region we inverted for the crustal velocity structure in the epicentral region by applying the levenberg marquardt non linear least squares algorithm to our local aftershock data the velocity model consists of a layer with linearly increasing velocity in depth overlying a dipping constant velocity halfspace our hypocentral location program uses a velocity model of the same form together with ray tracing the earthquake hypocentral resolution obtained with this program is significantly better than that from conventional approaches hypo and looks very promising for use in velocity structures with an important dipping interface like subduction zones

how mudrock and soil physical properties influence badland formation at vallcebre pre pyrenees ne spain abstract soils regoliths and their parent materials were investigated in relation to the development of badlands in the pre pyrenees in ne spain on late cretaceous mudrocks under a mountain mediterranean climate whilst all the soils in the area which are developed on mudrocks show a good structure and support a dense plant cover the bare parent materials slake very rapidly giving rise to badlands characterized by high erosion rates several physical chemical mineralogical and micromorphological properties of soils regoliths and related parent materials were analyzed in order to explain their different susceptibility to erosion and to determine which of all these properties are better related to such erosive behaviour only micromorphological and porosity properties were able to explain the erosion susceptibility whilst mineralogical chemical and physico chemical specific surface area properties were not among the aggregate stability tests performed to estimate the relationships of soil components with the susceptibility to erosion the emerson test for macroaggregate evaluation was particularly well suited although no good correlation was found between the emerson test classes and organic matter content we observed that the degree of slaking in organic rich horizons was always lower than in subsurface horizons and regoliths consequently as far as organic rich aggregates are present in the soil surface the influence of water in producing slaking swelling and then erosion will be minimum however when regoliths and rocks are uncovered the influence of water in these particular materials through freeze drying and swell shrinking will give rise to mudrock desintegration leading to accelerated erosion

the influence of physico chemical material properties on erosion processes in the badlands of basilicata southern italy piping tunnelling appears to be one of the more significant methods of erosion in the badlands in the plio pleistocene marine sourced clays of the basilicata area in southern italy a detailed field investigation of the pedological textural mineralogical and geochemical properties of the clay rich terrains widely outcropping in two selected badland field sites the fossa bradanica area and the bacino di sant arcangelo was undertaken to further elucidate process variability across the complex site paralleling findings from other piped badlands certain physico chemical properties of the clays were found to influence the different erosional processes in fundamental ways the very dispersive nature of the materials enhances pipe enlargement so that subsurface flow rapidly becomes the dominant process causing pipe enlargement by a process of positive feedback the paper speculates on the progressive role of surface and subsurface processes in the genesis of all evolutional badland forms calanchi calanchi mammellonari and biancane in an early stage the calanchi mammellonari are produced as slope mounds become increasingly separated by a dense network of small inclined pipes in the intermediate part of the slopes a site which is presumed to favour elevated subsurface flow when the overburden collapses many cones are isolated in these portions of the slope a second stage follows in which overland flow dominates with the water canalizing into small gullies generated by the collapsed crust at the base of many slopes this same mechanism produces biancane as residual cones because of the structural weakness of piped materials mass movements cannot be ruled out in a few locations landsliding may be involved especially in the formation of calanchi mammellonari in this case the intersection of the vertical pipes with the impermeable substratum focuses subsurface flow and collapse of the surface along this failure plane subsequent remodelling occurs by surface processes since the catchment volume for large pipes no longer exists this interpretation differs from that of others who have argued that in other locations the biancane formation is linked to the development of large vertical pipes along tectonic joints

preliminary study of the erosion mechanisms in a biancana badland tuscany italy abstract italian badlands are present along the appennini mountains with an annual precipitation which ranges from 400 to 1200 mm the genesis of these badlands has often been studied whereas current processes and erosion rates have only rarely been examined and measured this paper describes a preliminary study on a badland developed in temperate mediterranean climate and located in sw tuscany italy the selected site is characterized by biancane dome shaped features a few meters in height generally having a vegetated nne aspect and severely eroded ssw slope with a sub horizontal basal pediment field rainfall and runoff experiments were carried out field results were substantiated by data collected in specially devised laboratory tests it was concluded that near surface pipes which develop at the point of contact between a surficial layer of weathered and severely fractured regolith and the less fractured and weathered regolith underneath are the main drainage channels while rills play a secondary role soil detachment is largely due to mechanical and chemical slaking of the regolith during infiltration the role of runoff is almost solely transport in particular it was found that the runoff detachment rate is limited by the rate at which the water front penetrates into the regolith

mineralogical and grain size composition of clays developing calanchi and biancane erosional landforms abstract clayey terrains outcropping in many parts of italy are frequently affected by accelerated erosion processes producing landforms known as calanchi and biancane the calanchi are intensely dissected landscapes presenting rill and gully landforms and a dense dendritic drainage network the biancane are landforms characterized by bare cones and hummocks separated by flatter areas of surface wash deposits the factors controlling the development of these two landforms are still poorly understood this study was undertaken to identify the material properties of calanchi and biancane the data suggest a biancane tend to develop in very fine sediments such as silty clays with a very high clay content 65 70 b calanchi tend to occur in relatively coarser sediments such as clayey silts and sandy clayey silts having a notable sand fraction 6 18 c both biancane and calanchi may develop in intermediate textures such as silty clays and clayey silts made up of approximately equal quantities of silt and clay d no strong trend in clay mineralogy can be correlated with the landforms the swelling phyllosilicate contents are roughly equivalent in the parent materials of biancane and calanchi e pore water chemistry seems to play a very important role in the development of these landforms the biancane have high concentrations of sodium relative to other cations essentially calcium and magnesium in pore water all the analysed calanchi pore waters have low concentrations of sodium relative to divalent cations

slip distribution of the 19 september 1985 michoacan mexico earthquake near source and teleseismic constraints we simultaneously invert the strong motion velocity records and the long and intermediate period teleseismic p waveforms of the 19 september 1985 michoacan mexico earthquake to recover the distribution of slip on the fault using a point by point constrained and stabilized least squares inversion method a fault plane with strike fixed at 300 and dip fixed at 14 is placed in the region of the earthquake hypocenter and divided into 120 subfaults rupture is assumed to propagate at a velocity of 2 6 km sec away from the hypocenter synthetic near source ground motions and teleseismic p waveforms for pure strike slip and dipslip dislocations are calculated for each subfault the observed data are then inverted to obtain the amount of strike slip and dip slip displacement required of each subfault we also invert the data sets using a time window procedure where the subfaults are allowed to slip up to three times this approach relaxes the constraint of fixed subfault rupture time imposed by a constant rupture velocity inversion of the strong motion data alone yields a slip model similar to the solution previously obtained using only teleseismic waveforms this result supports the use of teleseismic waveform data for the derivation of fault dislocation models in the absence of strong motion recordings our simultaneous inversion of both data sets suggests that rupture during the michoacan earthquake was controlled largely by the failure of three major asperities located along the length and down the dip of a 150 km segment of the cocos north america plate boundary the solution contains three major source regions including an 80 km by 55 km source near the hypocenter with a peak slip of 6 5 meters two additional sources are present on the southeast portion of the fault about 70 km away from the hypocenter one of these sources with a peak slip of 5 meters covers a 45 km by 60 km area and extends downdip from a depth of about 10 km to 24 km the third source region is somewhat smaller 30 km by 60 km area 3 1 meters peak slip and extends further downdip at depths between 27 km and 39 km aftershock activity following the earthquake was associated mainly with the two shallow sources these two sources are separated by the aftershock zone of the 1981 playa azul earthquake

origin of biancane and calanchi in east aliano southern italy abstract areas underlain by plio pleistocene marine mudstone in south italy are severely affected by denudation processes and have been transformed into badlands with two well defined types of landform biancane and calanchi in this paper factors that contributed to the development of the aliano badlands and particularly to the geneses of biancane and calanchi have been studied based on aerospace data field observations on geomorphic processes and geological structure laboratory measurements of soil and bedrock samples and morphometric analysis several maps and spatial data were prepared to describe factors which are thought to be related with landform formations such as lineament distribution elevation slope and pipe distribution morphometric characteristics of biancane and calanchi steepness and slope length dominant active processes and the dip orientation of beddings joints and fault planes were investigated and 71 samples of soils and bedrock were taken to characterise their properties the results of the analyses of the soil bedrock samples show no significant differences in their properties between biancane and calanchi field observations do not support the idea that biancane are the final product of calanchi development but support the hypothesis that biancane and calanchi are formed under different terrain conditions related to structural patterns and denudation processes of highly erodible materials the origin of biancane is associated with highly dissected surfaces along a reticular system of small joints in contrast calanchi are formed on steep wall like slopes along larger lineaments where the rate of incision into the slopes surpasses the denudation of the densely vegetated back slope

geomorphological chemical and physical study of calanchi landforms in nw sicily southern italy abstract this work deals with an integrated geomorphological and chemical physical study of calanchi landforms in two sites ottosalme and catalfimo of nw sicily southern italy developed on dominant silty clay deposits the calanchi fronts are characterized by different morphological features and dominant geomorphic processes sharp knife edged ridges and concentrated water runoff dominate at ottosalme and smoother landforms affected by mass movements mud flows and translational slides prevail at catalfimo we focused on some geochemical and physical parameters such as ph total dissolved salts sodium adsorption ratio sar porosity plastic and liquid limits as possible causes of the above differences with special emphasis on their role in discriminating the behavior of peculiar microforms such as a weathered outer crust and the corresponding inner massive portion unweathered substrate our results show that the main chemical physical features of calanchi morphologies and microforms often display no clear correlations with respect to those reported in the existing literature pointing to a higher complexity of patterns and behaviors in particular all samples consist of dispersive material sar values 10 but a more plastic and liquid behavior at catalfimo can explain a higher occurrence of landslides and smoother morphology than at ottosalme higher sar values at ottosalme well explain the dominance of concentrated water erosion the chemical behavior of the studied microforms is better described by ph being alkaline with higher values in the inner substrate than the outer crust and appears to minimize the effects of all other parameters and their responses to other external controlling factors lower sar values in the crust suggest that clay dispersivity is not the prominent factor controlling its surface detachment and mobility downslope which is more likely promoted by its higher porosity and consequent water absorption than the inner portion with changes in the saturation state shear strength and water pressure

destructive strong ground motion in mexico city source path and site effects during great 1985 michoacan earthquake simultaneous consideration of source path and site effects on ground motion during the michoacan earthquake of 1985 allows us to draw coherent conclusions regarding the roles played for the disaster in mexico city by the rupture process the mode of propagation of the waves between the epicentral zone and mexico city and the local amplification in contrast to the horizontal component which showed dramatic amplification for the 2 to 3 sec motion at lake sediment sites we observe almost identical vertical displacement seismograms containing ripples with 2 to 3 sec period throughout the mexico city valley whether the recording site is on the lake sediments or on hard rock we therefore conclude that the 2 to 3 sec motion responsible for the destruction of mexico city was present in the incident field after performing a phase analysis we interpret the signal as the superposition of long period rayleigh waves and short period lg with a dominant period of about 3 sec the analysis of the teleseismic records indicates that the radiation of this event is enhanced for waves around the 3 sec period except in the case of stations for which an anomalous path effect is suspected the records present ripples appearing a few seconds after the beginning of the signal the characteristics of near fault records show that the rupture process consists of the growth of a smooth crack the numerical simulation indicates that the 3 sec period ripples can be explained by a series of changes of the rupture front velocity we examine two alternative source models associated with different crustal models to explain the characteristics of the vertical displacements recorded in mexico city our preferred model attributes the cause of the enhanced 3 sec motion to the irregularity in the rupture propagation in addition to the effect of the local conditions in mexico city this interpretation leads to a very coherent scenario of what happened from the start of the failure on the fault up to the destruction in mexico city this example illustrates the need to consider simultaneously source path and site effects in order to understand strong ground motions

connectivity as a crucial determinant of badland morphology and evolution the way in which threshold behaviour landscape sensitivity and connectivity1 operate together at the meso and macro scale in badlands is initially considered from a theoretical energy utilisation perspective the argument is developed that intrinsic changes to process domain dominance can result in progressive shifts in process connectivity without the need to invoke external climatic or tectonic change from this premise a meso scale closed system model for the evolution of connected states in regionally isolated badlands is developed applicable to systems evolving towards a fixed base level within a less erosive host landscape the model shows how badlands disconnected from regional drainage can develop from a wide range of initial states into a convergent quasi equilibrium followed by a period of complex response as energy is dissipated across thresholds giving rise to a range of equifinal maximum entropy landscapes this classification is illustrated using a range of global badland examples longer term macro scale interruptions to this semi deterministic model of badland relief degradation are also considered from this longer term larger scale perspective it is argued that extrinsic changes to relative relief can be driven by base level changes tectonically isostatically or eustatically induced in which case the continuity and linkages of information within the system are modified by effects which move up through the system bottom up control macro scale climatic changes also alter connectivity by changing the power distribution of prevailing events and by causing long term changes in mean precipitation temperature and e p ratio which affect vegetation and therefore runoff resistance all across the landscape from this perspective longer term climatic change operates in a top down manner the interplay between these two larger scale controls will inevitably determine the pattern of connected states that the landscape experiences through time the top down and bottom up combinations that can lead to either rejuvenation and a return to the stages described for the closed system model or stabilisation enhanced phases of both morphological and geochemical stabilisation are discussed

regional variation in the number of aftershocks mb 5 of large subduction zone earthquakes mw 7 0 it is reasonable to expect that the number of aftershocks following a large earthquake should reflect the degree of heterogeneity on and near the fault plane to investigate this question we plot n the number of aftershocks with mb 5 0 occurring within the next 30 days after large subduction zone thrust faulting earthquakes mw 7 0 versus the magnitude mw of the main shock only earthquakes that occurred after the installation of the world wide standard seismographic network stations are considered because the detection threshold of aftershocks in many regions is greater than mb 5 0 n is obtained by fitting the data to gutenberg and richter s relation log n a b mb for the same mw n varies by a factor of about 40 in different regions n is less than expected in the eastern pacific including alaska and is greater than expected in the western pacific relative lack and excess of n correlates well with regions of supposedly strong and weak coupling respectively while small and large n also show some correlation with the expansion rate of aftershock area with time the variation in n is much larger than would be expected from the mere increase of aftershock areas in some cases it appears that the number of aftershocks n for earthquakes of similar mw may also reflect the complexity and enrichment of the p wave amplitude spectra from 1 to 10 sec for example the valparaiso chile earthquake of 1985 mw 8 0 generated n 46 earthquakes whereas for the michoacan mexico event of 1985 mw 8 1 n is only equal to 5 furthermore for the valparaiso earthquake p waveforms are much more complex and the spectra are more energetic at 1 to 10 sec as compared to the 1985 michoacan event

modelling the concentration of atmospheric co2 during the younger dryas climate event the younger dryas yd dated between 12 7 11 6 ky bp in the grip ice core central greenland is a distinct cold period in the north atlantic region during the last deglaciation a popular but controversial hypothesis to explain the cooling is a reduction of the atlantic thermohaline circulation thc and associated northward heat flux as triggered by glacial meltwater recently a ch4 based synchronization of grip 18o and byrd co2 records west antarctica indicated that the concentration of atmospheric co2 coatm2 rose steadily during the yd suggesting a minor influence of the thc on coatm2 at that time here we show that the coatm2 change in a zonally averaged circulation biogeochemistry ocean model when thc is collapsed by freshwater flux anomaly is consistent with the byrd record cooling in the north atlantic has a small effect on coatm2 in this model because it is spatially limited and compensated by far field changes such as a warming in the southern ocean the modelled southern ocean warming is in agreement with the anti phase evolution of isotopic temperature records from grip northern hemisphere and from byrd and vostok east antarctica during the yd 13c depletion and po4 enrichment are predicted at depth in the north atlantic but not in the southern ocean this could explain a part of the controversy about the intensity of the thc during the yd potential weaknesses in our interpretation of the byrd co2 record in terms of thc changes are discussed

alpine gullies system evolution erosion drivers and control factors two examples from the western italian alps abstract denudation processes affecting mountain slopes may vary according to different factors e g lithology and structural setting of bedrock climate relief features which may be very diverse at the local scale gully complex systems characterised by morphological features similar to those developing in other climate contexts i e pseudo badlands are also becoming common at higher altitudes and latitudes the selected study cases of gran gorgia susa valley and saint nicolas aosta valley in the western italian alps are sites of geomorphological interest as they are specifically relevant for their scientific features the aims of this work are i reconstructing the morphometric evolution of gully systems and vegetation colonisation time by means of multitemporal spatial analysis on surface morphological changes under water erosion ii reconstructing in detail through dendrogeomorphological analysis the progressive spatial surface denudation and changes in erosion rates by analysing trees and exposed roots and using different indicators i e compression wood traumatic resin ducts iii obtaining data on successive aggradation degradation episodes along slopes surrounding such hotspots through geopedological investigations and iv identifying which control factors exert a predominant role on denudation patterns in such contexts multidisciplinary analyses regarding the study sites allowed for detailing of erosional history of the studied slopes detecting the prevailing drivers of their evolution according to the results and considering the common climate and bedrock conditions the structural background seems to have more influence on slope evolution at the saint nicolas site while superficial geomorphic processes seem to be more relevant at the gran gorgia site because the sites have already been recognised as part of geoheritage by local authorities the data obtained in the present research on their genesis evolution and local drivers affecting the rates of denudation i e scientific relevance of the site suggests that description of the sites for dissemination purposes should include links to the entire slope history

a faulting model for the 1979 imperial valley earthquake by comparing synthetic particle velocities with the near source strong motion data we have constructed by trial and error a faulting model for the 1979 imperial valley earthquake the calculation of the synthetic seismograms takes into account the vertical inhomogeneity of the elastic parameters in the imperial valley and the spatial variation of the slip rate parameters on the fault plane the independent slip rate parameters are 1 the strike slip rate amplitude 2 the dip slip rate amplitude 3 the duration that slip rate is nonzero the rise time of the slip function and 4 the rupture time which determines when the slip rate is initiated our faulting model has the following principal features 1 faulting occurred on the imperial fault and on the brawley fault rupture on the brawley fault being triggered by rupture on the imperial fault 2 the imperial fault is a plane 35 km long and 13 km wide with a strike of 323 measured clockwise from north and a dip of 80 ne the brawley fault is a 10 km long and 8 km wide plane with a strike of 360 and a dip of 90 3 faulting on the imperial fault is primarily right lateral strike slip with a small component of normal dip slip in the sediments at its northern end the larger strike slip rates are generally confined between depths of 5 and 13 km with maximum values of about 1 0 m s the duration varies on the fault with a maximum of 1 9 s which is considerably shorter than the total time for the rupture to take place 4 the rupture velocity on the imperial fault is highly variable locally it exceeds the shear wave velocity and in one instance the compressional wave velocity the average rupture velocity though is less than the shear wave velocity 5 although the slip on the brawley fault contributes only about 4 of the total moment it greatly affects the ground motion at nearby stations 6 the total seismic moment is 6 7 1018 n m where the imperial fault contributes 6 4 1018 n m and the brawley fault contributes 2 7 1017 n m in the process of trying almost 300 faulting models we found that given the elastic parameters of the medium the synthetic seismograms were most sensitive to the specification of the rupture time although the slip rate amplitudes are linearly related to the data the rupture time and the duration are not the parameterization of the nonlinear variables has a strong effect on the generation of synthetic seismograms from a finite fault

badlands denudation hot spots the role of parent material properties on geomorphic processes in 20 years monitored sites of southern tuscany italy abstract some monitoring stations have been recording for 20 years the geomorphic processes acting on calanchi and biancane badlands located in the tyrrhenian side of central italy field monitoring was aimed at studying the dynamics of surface processes such as sheet rill and gully erosion shallow landsliding piping and tunneling considering their space time variability as a consequence of both natural factors and human pressure this paper shows the results of grain size geochemical and mineralogical composition of parent materials from upper orcia valley sites southern tuscany to further elucidate the role of their properties on processes acting on both bare and vegetated surfaces parent materials properties are discussed with respect to the initiation and development of different badlands processes in particular clay dispersivity at different depths in the sample sites is examined as a well known controlling factor of accelerated erosion thus providing some interesting clues for understanding the spatial variability of denudation rates in the considered badlands sites

crack like rupture processes observed in near fault strong motion data strong motion data observed directly above a rupture zone of the michoacan mexico earthquake in 1985 provide for the first time clear evidence for crack like rupture process in a major earthquake the observed simple ramp function type displacements cannot be explained by dislocation models such as a step function dislocation but require a crack like slip function which grossly satisfies stress conditions on the fault i e stress drops to some finite level after a passage of rupture front this conclusion is required because the records contain sufficient near field terms to distinguish between the two models

a new empirical model for estimating calanchi erosion in sicily italy abstract calanchi plural of calanco are typical badland landforms of the italian landscape they consist of dense networks of v shaped valleys with a sparse or absent vegetation cover which frequently develop on unconsolidated or poorly consolidated clayey deposits in this paper the dimensional analysis and the incomplete self similarity theory were used to deduce a model relating the volume of sediments eroded from the calanchi area to a set of geometric attributes of their tributary areas the morphometric characteristics of 209 calanchi basins were used to calibrate and validate the model the predictive skill of the model was assessed by calculating the mean square error and the nash sutcliffe model efficiency coefficient the model was found to provide a reliable prediction of eroded volume from basins entirely covered by calanchi landforms as well as from basins only partially affected by badland erosion processes furthermore as the residuals between the calculated and the measured volume of the eroded material are normally distributed the deterministic model may be considered complete meaning that no other variables are necessary to explain the studied physical process in other words the model is able to predict erosion volume in calanchi landforms from a deterministic point of view

coastal uplift and mortality of intertidal organisms caused by the september 1985 mexico earthquakes coastal uplift associated with the great mexican earthquake of 19 september 1985 and its principal aftershock produced widespread mortality of intertidal organisms along the coast of the states of michoacan and guerrero mexico measurements of the vertical extent of mortality at ten sites provided estimates of the magnitude of the vertical component of deformation along the coast within the affected area uplift ranged from about 12 centimeters to about 1 meter and no subsidence was observed the observations are consistent with models of the tectonic deformation that results from buried slip on a shallow dipping underthrust fault

erosion processes in calanchi in the upper orcia valley southern tuscany italy based on multitemporal high resolution terrestrial lidar and uav surveys a 125 000 m2 calanchi badland in the province of siena tuscany was monitored with an unmanned aerial vehicle uav and terrestrial laser scanning over the period of one year tls terrestrial laser scanning was carried out on two sample slopes whereas the image acquisition of the uav covered the entire catchment in combination with ground control points the uav images were used to create orthophotos and 3d point clouds using the structure from motion sfm software photoscan the tls surface models indicate seasonal differences in erosion and deposition the surface change measured with sfm showed nearly 6 700 m3 of net material loss resulting from 8 700 m3 erosion and 2 000 m3 deposition these values reveal a mean annual surface lowering of 5 3 cm for the catchment additionally several geomorphological processes such as rill erosion slope wash and translational slides could be detected in the one year monitoring period a comparison of tls and sfm results showed differences in the calculated volumes of mobilised material these discrepancies resulted from shadowing effects and low point densities of the tls point clouds

the temporal and spatial evolution of the 19 september 1985 michoacan earthquake as inferred from near source ground motion records abstract a frequency domain inversion technique is employed to image the rupture process of the 19 september 1985 michoacan mexico earthquake a linear system is derived from the elastodynamic representation theorem and is solved for the spatial slip velocity distribution in the frequency bandwidth 0 0 to 0 32 hz the temporal behavior of slip velocity on the fault plane is then recovered by fourier synthesis model complexity is penalized by seeking a solution that propagates with the most nearly constant rupture velocity and that produces the most nearly constant spatial slip distribution at 0 hz the inversion of surface static displacements as inferred from strong motion recordings of the guerrero accelerograph array gives an estimate of the static offset on the fault plane coastal uplift data inferred from the mortality of intertidal organisms bodin and klinger 1986 is also used to further constrain the spatial slip distribution a low frequency image of the rupture process of the earthquake has been obtained using full space green9s functions two areas of large slip amplitude are discernible one located downdip of the reported hypocenter and the other updip of the projection on the fault plane of station la union their separation is approximately 100 km assuming that full space green9s functions underestimate static offset values at the surface of a half space by a factor of 0 5 the inferred seismic moment is 10 6 10 27 dyne cm 90 per cent of which is released in these two areas sustaining the largest slip the total inferred rupture duration is approximately 56 sec from the hypocenter the rupture front proceeds with an average velocity estimated at 2 8 km sec there are indications of bilateral propagation both from the hypocentral area and from an area surrounding the projection on the fault plane of the strong motion station la union an upper bound on rupture duration at the two principal subevents is 8 sec

the response of atmospheric nitrous oxide to climate variations during the last glacial period detailed insight into natural variations of the greenhouse gas nitrous oxide n2o in response to changes in the earth s climate system is provided by new measurements along the ice core of the north greenland ice core project ngrip the presented record reaches from the early holocene back into the previous interglacial with a mean time resolution of about 75 years between 11 and 120 kyr bp atmospheric n2o concentrations react substantially to the last glacial interglacial transition termination 1 and millennial time scale climate variations of the last glacial period for long lasting dansgaard oeschger do events the n2o increase precedes greenland temperature change by several hundred years with an increase rate of about 0 8 1 3 ppbv century which accelerates to about 3 8 10 7 ppbv century at the time of the rapid warming in greenland within each bundle of do events the new record further reveals particularly low n2o concentrations at the approximate time of heinrich events this suggests that the response of marine and or terrestrial n2o emissions on a global scale are different for stadials with and without heinrich events