local atmospheric forcing during the coastal ocean dynamics experiment 1 a description of the marine boundary layer and atmospheric conditions over a northern california upwelling region as part of the coastal ocean dynamics experiment code meteorological instruments were deployed on buoys and at coastal stations and instrumented aircraft flights and coastal soundings were made to study the three dimensional structure of the marine boundary layer over the continental shelf off northern california during the 1981 and 1982 upwelling seasons these measurements show that after the atmospheric spring transition the airflow in the marine layer is dominated by the north pacific high and the surface wind field over the shelf is characterized by periods of strong 7 15 m s upwelling favorable alongshelf winds lasting for up to 30 days interrupted by shorter periods of much weaker winds directed either equatorward or poleward these periods of weak or reversed winds typically last several days and are called wind relaxations even though they are primarily associated with coastally trapped perturbations of the marine layer along the central and northern california coast and not with a large scale weakening of the north pacific high the atmospheric boundary layer measurements made in code suggest a simple conceptual model which can explain much of the physiology or structure of the marine layer and associated surface wind field during periods of persistent upwelling favorable winds during these periods which represent the quasi steady state regime during the upwelling season the inversion base of the marine layer drops eastward toward the coast until it intersects the coastal mountain range at a height of several hundred meters and the associated thermal wind produces an alongshelf wind jet which has a maximum speed just below the inversion base turbulent mixing tends to homogenize any stratification in the marine layer beneath the jet and couple the jet to the ocean surface producing strong upwelling favorable winds over the shelf day night heating cooling over the narrow coastal strip beneath the marine layer generates a weak cross coast secondary circulation which causes the core of the alongshelf jet to drop in elevation and shift onshore this diurnal change in the marine layer structure explains both the daytime acceleration of the surface winds observed over and near the coast and its offshore decay and the associated offshore increase in the subdiurnal alongshelf wind thus the quasi steady component of the wind stress has a significant curl over the inner shelf during periods of active upwelling this mean summer atmospheric boundary layer regime is occasionally interrupted by synoptic and or mesoscale events or anomalous conditions analysis of the code observations suggests five types of events two primarily synoptic scale conditions which lead to stronger than normal upwelling favorable winds over the shelf and three primarily mesoscale events which lead to wind relaxation about half of the wind relaxation events observed in 1981 and 1982 are believed to be associated with either coastal trapped gravity currents or internal kelvin waves which propagate north ward in the marine layer along the central and northern california coastal mountain range

effects of wind stress and wind stress curl variability on coastal upwelling abstract aircraft measurements during the winter 1989 shelf mixed layer experiment smile and summer 1982 coastal ocean dynamics experiment code were used to characterize the spatial variation of the low level wind and wind stress over the northern california shelf the curl of the wind stress was calculated from directly measured turbulent stress components the accuracy of the computed curl was estimated to be adequate to map the spatial structure wintertime measurements showed a concentration of large positive curl over 1 pa 100 km 1 west of point arena regardless of wind direction due to the effects of the coastal topography on the wind fields results from summertime measurements showed a similar local maximum of positive curl west of point arena larger curl values over 3 5 pa 100 km 1 however were observed across a hydraulic jump propagating from stewarts point for highly supercritical marine boundary layer flow a two layer vertically integrated numerical model of coastal upwellin

seven landslide dams of old seismic origin in southeastern sicily italy this paper focuses on origin morphology and evolution of seven landslide dams in southeastern sicily these landforms are part of a set of 146 landslides recently recognised in this area which was hitherto considered to have little or no slope instability southeastern sicily consists of a plateau the hyblaean mountains incised by canyons and surrounded by lower lands it is underlain mostly by subhorizontal moderately to well lithified carbonate rocks relief is low several lines of evidence justify the assumption of a seismic trigger for the landslides in this area 1 the geo climatic environment is not favourable to landsliding 2 low angle basal shear surfaces are very frequent 3 landslide distribution is consistent with the known magnitude distance relationships for earthquake induced landslides 4 historical documents testify to earthquake triggered slope instability and 5 a specific landslide can be exactly dated the phenomena illustrated here include six rock slides one with a debris flow component and one rock fall slip surfaces are mostly non circular landslide volume ranges from about 5010 3 to 3410 6 m 3 with reference to the costa and schuster geol soc am bull 100 1988 1054 classification of landslide dams five cases belong to type ii spanning the entire valley and two to type iv failures from both valley sides with frontal or side contact between failed masses with reference to crozier and pillans catena 18 1991 471 classification of landslide lakes all cases show a main valley lake while tributary valley back and supra lakes are sporadically present one damming is attributable to the 1693 earthquake with certainty another damming to the same earthquake with high probability three dams were reincised one breached or reincised one is slightly reincised and two more or less intact correspondingly five silting up deposits were reincised one is being reincised at present and two are still under formation d 2002 elsevier science b v all rights reserved

a review on natural and human induced geohazards and impacts in karst karst environments are characterized by distinctive landforms related to dissolution and a dominant subsurface drainage the direct connection between the surface and the underlying high permeability aquifers makes karst aquifers extremely vulnerable to pollution a high percentage of the world population depends on these water resources moreover karst terrains frequently underlain by cavernous carbonate and or evaporite rocks may be affected by severe ground instability problems impacts and hazards associated with karst are rapidly increasing as development expands upon these areas without proper planning taking into account the peculiarities of these environments this has led to an escalation of karst related environmental and engineering problems such as sinkholes floods involving highly transmissive aquifers and landslides developed on rocks weakened by karstification the environmental fragility of karst settings together with their endemic hazardous processes have received an increasing attention from the scientific community in the last decades concurrently the interest of planners and decision makers on a safe and sustainable management of karst lands is also growing this work reviews the main natural and human induced hazards characteristic of karst environments with specific focus on sinkholes floods and slope movements and summarizes the main outcomes reached by karst scientists regarding the assessment of environmental impacts and their mitigation

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

effect of slope failures on river network pattern a river piracy case study from the flysch belt of the outer western carpathians abstract landslides are important geomorphic agents in various mountainous settings we document here a case of river piracy from the upper part of the mala brodska valley in the vsetinske mts czech republic raca unit of the flysch magura group of nappes flysch belt of the outer western carpathians controlled by mass movement processes based on the field geological geomorphological and geophysical data we found out that the landslide accumulations pushed the more active river of out of two subparallel river channels with different erosion activity westwards and forced intensive lateral erosion towards the recently abandoned valley apart from the landslide processes the presence of the n striking fault accentuated by higher flow rates of the eastern channel as a result of its larger catchment area were the most critical factors of the river piracy as a consequence of the river piracy intensive retrograde erosion in the elbow of capture and also within the upper portion of the western catchment occurred deposits of two landslide dams document recent minimum erosion rates to be 18 8 mm ky 1 in the western captured catchment and 3 6 mm ky 1 in the eastern catchment respectively the maximum age of the river piracy is estimated to be of the late glacial and or the early holocene

giant landslide triggerings and paleoprecipitations in the central western andes the aricota rockslide dam south peru abstract the central part of the western andes holds an exceptional concentration of giant paleolandslides involving very large volumes of rock material v km3 while those gravitational slope failures are interpreted consensually as an erosional response to the geodynamic activity of the andes relief formation and tectonic activity the question of their triggering mechanisms remains enigmatic to clarify the respective roles of climatic versus seismic forcing on the andean landslides new temporal constraints on paleo movements are essential here we focus on one of those giant slope failures the aricota giant rockslide that damned the locumba valley in southern peru we conducted fieldwork high resolution dem analysis and cosmogenic nuclide dating to decipher its development history and failure mechanisms our results point to the occurrence of two successive events a giant failure mobilizing a rock volume of ca 2 km3 first produced a dam at 17 9 0 7 ka considering its height of ca 600 m the aricota rockslide dam is one of the three largest landslide dams worldwide at 12 1 0 2 ka a second event produced ca 0 2 km3 of material and the rock avalanche debris spread out over the dam as the chronology of those two events is pointing to the two main paleoclimatic pluvial periods in this region heinrich stadial 1a and younger dryas we favor the interpretation of a climatic forcing at a regional scale the concomitant aggradation of alluvial terraces and fan systems along the nearby valleys highlights higher regional erosion sediments supply and mass wasting events during those paleoprecipitation events and strengthens this conclusion

satellite measurements reveal persistent small scale features in ocean winds four year averages of 25 kilometer resolution measurements of near surface wind speed and direction over the global ocean from the quikscat satellite radar scatterometer reveal the existence of surprisingly persistent small scale features in the dynamically and thermodynamically important curl and divergence of the wind stress air sea interaction over sea surface temperature fronts throughout the world ocean is evident in both the curl and divergence fields as are the influences of islands and coastal mountains ocean currents such as the gulf stream generate distinctive patterns in the curl field these previously unresolved features have important implications for oceanographic and air sea interaction research

winter dynamics on the northern portuguese shelf part 1 physical processes results of a program of observations carried out on the northern portuguese shelf and slope between july 1996 and june 1999 are used to characterise the main physical processes of the winter regime the data set includes time series of waves and currents at mid shelf 86 m depth and of winds atmospheric pressure and sea level at the coast as well as hydrographic and suspended particle matter spm observations carried during three multidisciplinary surveys the wave regime was found to be characterised by highly energetic conditions during the winter with storm events leading to waves of significant heights exceeding 5 m with mean periods of over 10 s prevailing southerly winds force a downwelling regime over the shelf with poleward flow at mid shelf 10 20 cm s and offshore transport in the bottom ekman layer episodic strong upwelling events can occur during this period leading to important changes in the near bottom stratification at mid shelf tidal currents at mid shelf are dominated by the contribution of the m2 tide 3 cm s and are polarised in the cross shelf direction reflecting the guiding effect of the porto canyon

wind forcing of the coastal circulation off north and northwest iberia comparison of atmospheric models 1 comparisons between observed winds and winds from reanalysis national centers for environmental prediction ncep reanalysis 1 and 2 and forecast meteorological models high resolution limited area model hirlam agencia estatal de meteorologia 0 2 and atmospheric research mesoscale model version 5 meteogalicia with 30 km and 10 km resolution have been performed for the coastal region around northwest and north iberia during a typical autumn downwelling period september december 2002 observations at buoys and coastal stations and quikscat derived winds were employed the analyzed period was dominated by southerly and southwesterly winds associated to the passage of low pressure systems our results show that the westward component is higher on the north coast than on the west coast and that winds are intensified at the western north coast in this situation the performance is similar in all model products in general terms but only hirlam represents the reduction of winds in the cantabrian sea and ncep and mm5 overestimate the magnitude of south southwest winds spatial differences in winds are also obtained for upwelling favorable events associated either with a high pressure system north from iberia at the beginning of the autumn transition northeasterly winds or with conditions after the passage of a low pressure system northwesterly winds the existence of sea surface temperature sst gradients in the coastal region implies that higher resolution boundary sst products for meteorological models are necessary finally the effect of these wind products on the coastal circulation was assessed with a 3 d numerical simulation differences in the expansion confinement of river plumes and the surface speed of the slope current are induced by differences in wind patterns over the shelf and slope area among atmospheric models

wind driven upwelling in the vicinity of cape finisterre spain observations and numerical simulations of upwelling along the galician coast of spain during april 1982 are presented in situ measurements include shipboard determinations of hydrographic and biological parameters from a grid of stations covering the continental shelf from cape finisterre to ria de vigo sea level data from vigo and la coruna and wind stress estimates derived from the ship winds and from surface pressure charts sea surface temperature information and pigment concentration information have been obtained from a sequence of satellite images from the noaa 7 advanced very high resolution radiometer and the nimbus 7 coastal zone color scanner respectively since the cape finisterre sector of the iberian peninsula is characterized by an abrupt change in coastline orientation wind driven upwelling can occur in that region over a 270 range of wind direction these data document the evolution of upwelling and the resultant coastal circulation in response to two wind events that occurred over a 10 day period salient features of the circulation include a southward coastal jet and a northward flow further offshore along the western coast numerical simulations of the coastal currents the vertical excursion of a density interface from a static equilibrium position and coastal sea level are conducted using a wind patch characterized by constant direction and negative curl the simulations show that during these wind events the greatest upwelling will occur either at cape finisterre or along the northern coast as was observed in this case and as has been reported by others it is suggested on the basis of the analysis of the sea level records and on the numerical simulations that wave disturbances propagate northward along the coast at a speed of 120 160 km day finally it is speculated that much of the organic material formed during upwelling events north of the cape finisterre is advected out to sea northwest of the cape

formation of landslide dammed lakes during a wet period between 40 000 and 25 000 yr b p in northwestern argentina abstract new ams radiocarbon data from the deposits of landslide dammed lakes in the santa maria basin 26 s 66 w and the quebrada del toro 25 s 66 w in the eastern argentine cordillera show that important mass movements occurred during a wet period between 40 000 and 25 000 yr b p in addition to increased humidity during this time detailed analysis of annual layered lacustrine strata suggests enhanced inter and intra annual fluctuations in precipitation as compared to the present variations in sediment characteristics and diatom assemblages with mean periodicities of 2 to 5 and 10 to 14 years respectively suggest an influence of the el nino southern oscillation enso and the atlantic sea surface temperature dipole the atlantic dipole slightly increased rainfall every 10 14 years as at present in contrast the weak modern enso influence in this area differs from the past situation where rainfall increased significantly with enso type periodicities both increased humidity and seasonality are believed to have reduced thresholds for the generation of catastrophic mass movements in northwestern argentina

forecasting where larger crustal earthquakes are likely to occur in italy in the near future a forecast of future occurrences of larger m 5 9 crustal earthquakes in italy is made on the basis of historic and instrumental seismicity and following a seismotectonic regionalization recently derived on the basis of geological evidence combined with earthquake epicenters and focal mechanisms completeness problems in the seismic catalog allow one to study only 20 regions out of 58 large crustal seismicity within each seismogenic region is modeled as either a periodic gauss process or a random poisson process according to the experimental coefficient of variation of the series of past occurrences in each region return times are estimated directly from the series of m 4 5 earthquakes if they are sufficient in number or from the gutenberg richter law applied to lower magnitude seismicity m 4 5 otherwise the immediate probability of an m 5 9 crustal seismic event is esti mated to be very low in all regions except southeastern sicily and appennino abrnz zese in the near future next 20 yr the estimated probability is high above 65 also in the appennino forlivese and naso capo d orlando regions in addition to detailed seismic risk reevaluations these regions represent the best bet for a program of intensive monitoring to gather a record of the process of strain accumulation and seismic release

developments in a non destructive method of determining rock strength material strength is an important variable for any study of the relationships between rock mass geomechanical characteristics and landform development standard field and laboratory tests for measuring strength present a variety of problems to the geomorphologist recent studies allison 1988 have described a laboratory based non destructive method for indirectly determining material strength by measuring dynamic young s modulus data presented here suggest that the same apparatus can be used as a field technique tests have been conducted on the devonian limestone of the napier range western australia laboratory results obtained using the non destructive ultrasonic apparatus have a high correlation with triaxial hoek cell tests results from on site tests have much greater accuracy than data collected using the schmidt hammer which is currently the most widely used geomorphological field technique for determining rock strength

stability of landslide dams and development of knickpoints the wenchuan earthquake triggered many landslides and numerous avalanches and created 100 odd quake lakes the quake lakes may be removed or preserved the removal strategy was applied to several large landslide dams which were dangerous because massive amounts of water pooled up in the quake lakes the dams could eventually fail under the action of dam outburst flooding potentially endangering the lives of people in the downstream reaches this paper studied the stability of landslide dams and the development of knickpoints by field investigations and experiments and analyzing satellite images the study concluded that if landslide dams were preserved they would develop into knickpoints and act as a primary control of riverbed incision and thus reduce the potential of new landslide the stability of landslide dams depends mainly on the development of the step pool system and stream power of the flood flow if a landslide dam consists of many boulders a step pool system may develop on the spillway channel of the dam which would maximize the resistance consume most of the flow energy and consequently protect the dam from incision the development degree of the step pool system is represented by a parameter s p which was measured with a specially designed instrument a preservation ratio of landslide dams is defined as the ratio of preserved height after flood scouring to the original height of the dam for streams with peak flood discharge lower than 30 m3 s the preservation ratio is linearly proportional to s p for rivers with a peak flood discharge higher than 30 m3 s 30 30 000 m3 s the minimum s p value for stable channel increases with log p in which p is the unit stream power for a landslide dam with a poorly developed step pool system s p is smaller than the minimum value and the outburst flood incises the spillway channel and causes failure of the dam for preserved landslide dams sediment deposits in the quake lakes a landslide dam may develop into a knickpoint if it is stabilized by long term action of the flow large knickpoints can totally change the fluvial processes and river morphology uplift of the qinghai tibetan plateau has caused extensive channel bed incision along almost all rivers for many rivers the incision has been partly controlled by knickpoints upstream reaches of a knickpoint have a new and unchanging base level this brings about a transition from degradation to aggradation and from vertical bed evolution to horizontal fluvial process multiple and unstable channels are prominent in the reaches upstream of the knickpoints if hundreds of landslide dams occurred simultaneously on a reach of a mountain river the potential energy of bank failure and the slope erosion would be greatly reduced and sediment yield from the watershed may be reduced to nearly zero the quake lakes may be preserved long term and become beautiful landscapes streams with long term unfilled quake lakes have good aquatic ecology

ocean currents evident in satellite wind data satellite mounted radar scatterometers designed to quantify surface winds over the ocean actually measure the relative motion between the air and the ocean surface estimates of the wind stress from conventional surface wind measurements are usually derived neglecting ocean currents however when the relative motion is used the differences in the estimated stress can be as large as 50 near the equator and may even reverse sign during an el nino this assertion is supported by the strong relationship between the surface currents measured by the tropical atmosphere ocean tao array in the pacific ocean and the differences between the winds estimated from scatterometer data and those measured by tao anemometers the fact that the scatterometer measures relative motion and not wind alone makes scatterometer derived stress a more accurate representation of the boundary condition needed for both atmospheric and oceanic models than stress fields derived neglecting ocean currents

crack propagation by differential insolation on desert surface clasts abstract in the southwest u s cracks in alluvial fan surface clasts have a preferred orientation independent of rock fabric and shape in this paper we show that differential insolation of incipient cracks of random orientations predicts a distribution of crack orientations consistent with field observations in this model crack growth by hydration and or thermal weathering is primarily a function of local water content at the crack tip crack tips that experience minimal solar insolation maintain a greater average moisture and hence weather more rapidly than cracks that experience greater solar insolation to show this we used a numerical radiative transfer code to quantify the solar insolation of rectangular cracks at 35 n latitude with a range of depths and orientations the amount of solar energy reaching the bottom of each crack was calculated at 5 min intervals over the day for several days of the year to determine hourly daily seasonal and annual energy deposition as a function of crack depth and orientation by assuming that only crack orientations that effectively shield their interiors and minimize their water loss are able to grow the pattern of cracks produced by the model is consistent with field observations the annual average insolation which controls water retention is associated with the two primary modes of crack orientation the effect of daily recharge by summer rains of the north american monsoon system is consistent with the observed deviations from these primary modes model results suggest that both the annual average insolation and the daily pattern of rainfall is recorded in the preferred crack orientations of surface clasts in the southwest u s

complex weathering in drylands implications of stress history for rock debris breakdown and sediment release abstract weathering studies have often sought to explain features in terms of a prevailing set of environmental conditions however it is clear that in most present day hot desert regions the surface rock debris has been exposed to a range of weathering environments and processes these different weathering conditions can arise in two ways either from the effects of long term climate change acting on debris that remains relatively static within the landscape or through the spatial relocation of debris from high to low altitude consequently each fragment of rock may contain a unique weathering related legacy of damage and alteration a legacy that may greatly influence its response to present day weathering activity experiments are described in which blocks of limestone sandstone granite and basalt are given stress histories by subjecting them to varying numbers of heating and freezing cycles as a form of pre treatment these imposed stress histories act as proxies for a weathering history some blocks were used in a laboratory salt weathering simulation study while others underwent a 2 year field exposure trial at high mid and low altitude sites in death valley california weight loss and ultrasonic pulse velocity measurements suggest that blocks with stress histories deteriorate more rapidly than unstressed samples of the same rock type exposed to the same environmental conditions laboratory data also indicate that the result of imposing a known weathering history on samples by pre stressing them is an increase in the amount of fine sediment released during salt weathering over a given period of time in comparison to unstressed samples

river patterns and their meaning abstract rivers are largely responsible for shaping the earth s continental landscapes river patterns the spatial arrangements of channels in the landscape are determined by slope and structure at site and sector scale channel morphology varies spatially and in time but river patterns and drainage texture or the frequency of stream lines per unit area together determine the intricacy or otherwise of topography most river patterns evolve through natural selection slope induces the formation of such patterns as parallel radial and distributary while structure produces straight angular trellis and annular arrangements once established patterns tend to persist nevertheless at many sites the usual patterns have been disturbed and patterns that are anomalous in terms of slope and structure have been produced by diversion tectonism volcanism glaciation mass movements and human activities by antecedence superimposition inheritance or underprinting by the persistence of deeply eroding rivers which encounter alien structures and by climatic change river patterns provide clues to underlying structure and to the chronology of events they have also proved significant in the search for minerals

earthquake dammed lakes in new zealand eleven small lakes were formed by landslides caused by the 1929 buller earthquake four others were formed by other historic earthquakes in new zealand at least nine other new zealand lakes are also dammed by landslides and were probably formed by prehistoric earthquakes when recognized by morphology synchronous age and areal distribution earthquake dammed lakes could provide an estimate of paleoseismicity for the past few hundred or thousand years

the formation and impact of landslide dams state of the art abstract the blocking of river courses by mass movements is very common in mountainous areas with deep and narrow valleys landslide dams may pose serious threats to people and their livelihoods downstream in the case of abrupt dam failure since the publication of benchmark reviews of costa and schuster 1988 and korup 2002 there is a growing number of studies focusing on the formation stability and short term impacts of landslide dams this review combines the insights of all these studies builds on current concepts of landslide dams and suggests ways to unify terminologies and classifications we furthermore present a new worldwide database compiled from literature data it contains 410 landslide dams 1 million m3 in volume that were formed since 1900 since these have the most complete data entries these data show that dam longevity is among other factors correlated with the type of landslide forming the dam those formed by rock debris avalanches and rockslides have longest lifespans however the influence of landslide type or material on dam longevity decreases with time after dam formation to ensure consistency in the next database generation we suggest guidelines for data collection to provide a solid basis for evaluating dam stability and governing factors a preliminary classification matrix for landslide dam stability that combines topographic setting and the internal structure of the dam body is another outcome of our review furthermore an evaluation of the various geomorphic stability indices proposed in the literature regarding their suitability and limitations in assessing dam formation and stability shows that they predict the probability of dam formation reasonably well but that their application to longevity estimates requires further assessment the geomorphic impacts of landslide dams in the short medium and long term are summarized and illustrated with key examples finally for a better understanding of the factors controlling dam stability we recommend to 1 include dam composition and sedimentary structures in future case studies 2 maintain and update the worldwide database for sound statistical analyses 3 refine landslide dam stability indices and test them for different landslide types and 4 study hazard cascades related to multiple dams in one watershed for long term landscape evolution studies we suggest to 5 quantify terrestrial sediment flux related to landslide dams 6 detect ancient landslide dams in river profiles and 7 further exploit the sediment archives in former impoundment areas

sea surface temperature fronts in the california current system from geostationary satellite observations 1 sea surface temperature sst fronts are determined for the 2001 2004 time period from geostationary operational environmental satellites goes data in the california current system ccs the probability of detecting a sst front at an individual pixel location in the ccs is presented as a bi monthly climatology fronts clearly indicate the seasonal evolution of coastal upwelling as well as meanders and filaments that are often linked with irregularities in coastline geometry winter is characterized by low frontal activity along the entire coast fronts first appear close to the coast during spring particularly south of cape blanco where upwelling favorable winds are already persistent the area of high frontal activity continues to increase during summer especially between monterey bay and cape blanco extending more than 300 km from the coast the region with high frontal activity widens at 2 6 km day 1 off northern baja california a band with persistent fronts is found close to the coast year round but there is no evidence of a seasonal widening of the area of higher activity during fall the weakening of upwelling favorable winds leads to a gradual decrease in frontal activity an empirical orthogonal function eof decomposition reveals the development of sst fronts associated with seasonal upwelling for locations north of monterey bay with less summer intensification to the south the first appearance of fronts close to the coast during spring and the occurrence of the fronts offshore later in the season are represented by additional statistically significant eof modes

turbidite paleoseismology in the calabrian arc subduction complex ionian sea 1 the calabrian arc subduction system is part of the africa eurasia plate boundary is one of the most seismically active regions in the mediterranean sea and has been struck repeatedly by destructive historical earthquakes in this study we investigate the effects of historical earthquakes on abyssal marine sedimentation through the analysis of the turbidite record we collected gravity cores in tectonically controlled basins where the eastern mediterranean pelagic sequence is interbedded with resedimented units textural micropaleontological geochemical and mineralogical signatures reveal three turbidite events in the last millennium we dated the turbidite sequences from two different cores using different radiometric methods whereas the average time interval between successive turbidite beds was estimated from pelagic sediment thickness and sedimentation rates chronologies were refined through age modeling that provided age ranges 2 of each turbidite bed the results suggest that turbidite emplacement was triggered by three historical earthquakes recorded in the area i e the 1908 1693 and 1169 events their magnitude epicentral location and associated tsunamis support causative faults located in the ionian sea the source for all the turbidites as inferred from their mineralogy is the metamorphic basement outcropping in southern calabria and or northeastern sicily turbidite composition and cable breaks for the 1908 event have been used to infer likely traveling paths and seismogenic faults in the subduction system our findings suggest that ionian sea turbidites represent more than 80 of sedimentation and may be seabed archives of paleo earthquakes capable of reconstructing seismicity back in time during several earthquake cycles

simulating weathering of basalt on mars and earth by thermal cycling physical weathering induced by heating and cooling may cause rock breakdown on mars and earth we report results from parallel weathering simulations on basalt blocks exposed to diurnal cycles representing mars like two simulation runs from 55 to 20 oc and 75 to 10 oc 1 100 relative humidity 4 8 mbar pressure co 2 atmosphere and hot arid earth 23 72o c 30 100 relative humidity conditions under earth conditions thermally pre stressed blocks showed measurable strength declines whilst salt pre treated blocks showed strength gains under mars like conditions pre stressed blocks recorded greater or similar strength declines and salt pre treated blocks showed more muted strength declines than under earth conditions the results imply that on earth and mars diurnal cycling of temperature alone can cause deterioration of basalt with a pre existing stress history the type of stress history is important with salt pre treatment affecting the response of thermally pre stressed blocks under both earth and mars conditions

rapid salt weathering in the coastal namib desert implications for landscape development data on the rate and style of breakdown on naturally occurring rock types are important to improving geomorphological understanding of landscape development in arid environments two years exposure of rock blocks cut from an english limestone bath stone as well as locally relevant namibian rocks karibib marble and damara granite within four distinctive microenvironments in and around a coastal salt pan environment reveals high rates of breakdown in the bath stone blocks observable breakdown in the marble blocks and weight gains and strength increases in the granite blocks breakdown is associated with high conductivities and large amounts of halite and gypsum within the surface sediments frequency of wetting and drying appears to be a major control on the resultant breakdown rates these findings can be compared with recent data from further inland in the namib desert which suggest very slow rates of breakdown of similar blocks of damara granite and karibib marble even where salts are readily available high rates of rock breakdown within coastal salt pans appear to contribute to dust production and the effective flattening of relief along the coastal strip

impact of mass movements on geo and biodiversity in the polish outer flysch carpathians complex research was simultaneously done on the geological geomorphological and biocenotic features of landslide areas in the polish outer flysch carpathians the research allowed us to define the relations between the diversity of the landslide originating landforms and the biotopes occurring within them high geodiversity diversity of landforms soil and water of landslide areas allows for a mosaic network of extremely diversified natural habitats all of these natural habitats together are characterized by a specific biodiversity dependence between geo and biodiversity in landslide areas is connected with a specific co evolution which is related to the adaptation of the ecosystems to landforms comprehensive research of this relation to landslide areas would promote the necessity to protect the landslide areas unfortunately such research done in the carpathians is still sporadic the comprehensively documented landslide areas are especially valuable elements of the nature protection network within the carpathian euro region if made reasonably accessible they may be used for didactic purposes and in geotourism

wind stress curl forcing of the coastal ocean near point conception california near point conception california the atmospheric flow separates from the coast and a large wind stress curl results direct spatial wind field observations from 20 aircraft overflights in the spring of 1983 suggest that ekman pumping of on average 4 m day21 contributes to the local dynamics during strong and persistent upwelling events the curl driven ekman pumping reaches up to 20 m day21 a single complex empirical orthogonal function explains more than 72 of the spatial and temporal wind stress variance it reveals large wind stress curl at the center of the western santa barbara channel entrance this dominant mode correlates strongly r 2 5 0 79 with the wind stress observed at a moored buoy the location of largest ekman pumping in the ocean indicated by this mode coincides with the location of a laterally sheared cyclonic flow cold upwelled waters enter the santa barbara channel along its southern perimeter while warm and thus buoyant waters from the southern california bight exit the channel along its northern perimeter buoy wind stress and lateral current shear at 30 m depth correlate significantly at periods of about 3 5 and 6 days with phase lags of about 0 5 and 2 days respectively hydrographic observations from 1983 do not however indicate effects of ekman pumping on the internal mass field as winds vary in speed and direction at daily timescales this contrasts with 1984 observations that do indicate strong doming of isopycnals over the center of the channel at its western entrance winds prior to and during hydrographic observations in the spring of 1984 were both stronger and more steady than they were in 1983 cyclonic shears reach 0 4 f at the entrance of the santa barbara channel near point conception here f is the planetary vorticity the thermal wind balance explains the lateral shear of the alongchannel surface flow rather well

morphometric evidences of recent tectonic deformation along the southeastern margin of the hyblean plateau se sicily italy abstract the present work focuses on the tectonic characterization of the southeastern portion of the hyblean plateau se sicily italy along the southeastern margin of this raised crustal block a clear recent antiformal deformation coupled with diffuse landscape rejuvenation affects the summit surface many studies using merely qualitative geomorphological approach refer the recent morphotectonic evolution of this region to motion along an active border fault located at the base of the well developed arc shaped avola mountain front this paper provides new insights resulting from the morphometric analysis across the avola region in order to detail on the relationships between the landscape geomorphic unsteadiness and the long term tectonic deformation we perform both drainage system and relief investigations consisting of the exploration of different geomorphic indices e g hypsometric integral topographic relief and dissection sl index ksn long profile analysis marine terraces age model definition field based geomorphological and structural surveys the results and the spatial distribution of morphometric indexes evidence the occurrence of two incipient nne trending en echelon fault segments here named cassibile noto fault responsible for the relief building along the southeastern border of the hyblean plateau the northern fault segment directly controls the northern portion of the avola mountain front whereas the southern segment diverges from the main scarp cutting through the low standing areas of the coastal plain in addition the centrifugal arrangement of fluvial captures and the half elliptical envelope of the downstream projections of coeval paleo long profiles as well as the distribution of pleistocene marine terraces well evidence the long term wnw ese trending low amplitude bow shaped deformation affecting the footwall of the cassibile noto normal fault we relate this convex upward trend to the late pleistocene

inconsistent patterns of historical seismicity and earthquake triggered landsliding in southeastern sicily an alarm bell in southeastern sicily the distribution pattern of earthquake triggered landslides is inconsistent with historically known seismic activity in particular historical seismicity has been stronger in the eastern sector while earthquake triggered landsliding is much more developed in the western sector and this contrasts with expectations this paper describes the patterns of seismicity and landsliding and tackles the problem of whether greater landsliding in the western sector may be due a to seismicity of the eastern sector or b to a high magnitude low recurrence seismicity generated in the western sector itself it is statistically shown that lithostructural characteristics of rock masses and geometry of hillslopes cannot justify either singly or jointly greater landsliding in the western sector if triggering earthquakes are generated in the eastern sector as a consequence it is possible that landsliding of the western sector is due to earthquakes generated locally but having higher magnitude and longer recurrence intervals than historically observed

geomorphic events and landform response in south eastern taranaki new zealand abstract south eastern taranaki is a tectonically rising area of hill country and marine terraces cut into plio pleistocene marine sediments in the north island of new zealand it is argued that the geomorphic development of the region is more satisfactorily explained with resort to concepts of dynamic metastable equilibrium and unsteady behaviour than by concepts of steady equilibrium behaviour the region is constantly adjusting in part or in whole to a spectrum of geomorphic events including sea level change tectonic uplift aeolian deposition large landslide triggering earthquakes deforestation and landslide triggering rainstorms the record of these events in terms of frequency and magnitude is established and the consequential landform response is discussed twelve high sea level events within the last 700 ka are recorded in the landscape each with associated phases of aeolian deposition large earthquakes with terrain forming capability occur on average once every 1000 to 10 000 years as a result of slope destabilization by recent deforestation erosion rates appear to have increased by three times their previous rate the agents involved in this process are rainstorms with a return period of about 10 years which during a single event can strip the regolith from 5 to 15 percent of hillslopes over areas of up to 100 km2