landslides and climate change in the italian dolomites since the late glacial abstract the paper deals with the relationship between the temporal occurrence of landslides and climatic changes in the italian dolomites since the late glacial after an introduction on the state of the art with particular reference to the alpine region the results of recent investigations in the two study sites are illustrated at cortina d ampezzo several landslides were dated mainly by the radiocarbon method the most ancient landslide event there involved large rock slides which affected the dolomitic slopes following the withdrawal of glaciers after the last glacial maximum lgm and also slides and flows mainly occurring in pelitic materials of the valley floors from 13 000 to 10 000 cal bp a later series of flows occurred between 5500 and 2500 cal bp in the upper badia valley alta badia the most ancient events go back to 10 000 and 9000 cal bp and correspond with earth flows that followed vast rotational slides affecting the bedrock up to a depth of about 50 m more recent earth flows involving more modest amounts of material took place between 6500 and 2300 cal bp by analysing the dates from the two study areas it was possible to correlate the recorded increase of landslide activity with the climatic changes occurring at the boundary between the late glacial and the holocene and between the atlantic and the subboreal and to compare the results with those derived from other european regions the types and causes of landslides taking place in these two periods were substantially different reflecting the different morphoclimatic conditions that existed in the two areas when these mass movements were triggered finally notwithstanding the importance of non climatic causes such as geological structural factors and possible human influences it is concluded that many of the dated landslides can be considered as indicators of climatic change

pollen and lignin records of late quaternary vegetation lake washington analyses of lignin oxidation products and pollen for an 11 meter core from lake washington provide independent but similar reconstructions of the late quaternary vegetation in the puget lowland an exception is in sediments of the late pleistocene where pollen percentages and influx values suggest conifer forest whereas lignin compositions suggest a treeless source region this dissimilarity appears to result from different major provenances eolian transport of pollen to the lake from adjacent or downstream drainage basins as opposed to fluvial transport of lignified plant debris only from the lake washington drainage basin

synchroneity of meltwater pulse 1a and the bolling warming new evidence from the south china sea a twofold decrease in long chain n alcane n nonacosane concentrations in a downcore record from the northern south china sea indicates a rapid drop in the supply of terrigenous organic matter to the open south china sea during the last deglaciation paralleled by an equally rapid increase in sea surface temperatures corresponding with the bolling warming at 14 7 ka the sudden drop in terrigenous organic matter delivery to this marginal basin is interpreted to reflect a short term response of local rivers to rapid sea level rise strongly implying that the bolling warming and the onset of meltwater pulse mwp 1a are synchronous this phase relation contrasts with the widely cited onset of this mwp 1a ca 14 ka and implies that previous studies postulating a weakening of deep water formation in the north atlantic due to massive meltwater discharge during mwp 1a need to be reevaluated

wellen radar wera a new ground wave hf radar for ocean remote sensing hf radars can be used to measure surface currents and wave spectra the coastal radar codar used by the university of hamburg was designed for current mapping only it has been operated for 15 field experiments during the past 15 years recently a new hf radar called wellen radar wera has been developed at the university of hamburg one main advantage of the system is the possibility of connecting different configurations of receive antennas when operated with a linear array information on the sea state can be obtained via second order spectral bands a further advantage is the flexibility in range resolution between 0 3 and 1 2 km instead of the fixed resolution of about 2 km of codar this is achieved by transmitting frequency modulated continuous wave fmcw chirps instead of continuous wave cw pulses in addition this technique avoids the blind range of about 3 km in front of the codar the technical design of wera is described and first experimental results are presented

holocene history of deep seated landsliding in the north fork stillaguamish river valley from surface roughness analysis radiocarbon dating and numerical landscape evolution modeling documenting spatial and temporal patterns of past landsliding is a challenging step in quantifying the effect of landslides on landscape evolution while landslide inventories can map spatial distributions lack of dateable material landslide reactivations or time access and cost constraints generally limit dating large numbers of landslides to analyze temporal patterns here we quantify the record of the holocene history of deep seated landsliding along a 25 km stretch of the north fork stillaguamish river valley washington state usa including the 2014 oso landslide which killed 43 people we estimate the ages of more than 200 deep seated landslides in glacial sediment by defining an empirical relationship between landslide deposit age from radiocarbon dating and landslide deposit surface roughness we show that roughness systematically decreases with age as a function of topographic wavelength consistent with models of disturbance driven soil transport the age roughness model predicts a peak in landslide frequency 1 000 ybp with very few landslide deposits older than 7 000 ybp or younger than 100 ybp likely reflecting a combination of preservation bias and a complex history of changing climate base level and seismic shaking in the study area most recent landslides have occurred where channels actively interact with the toes of hillslopes composed of glacial sediments suggesting that lateral channel migration is a primary control on the location of large deep seated landslides in the valley

spectral signatures of characteristic spatial scales and nonfractal structure in landscapes 1 landscapes are sometimes argued to be scale invariant or random surfaces yet qualitative observations suggest that they contain characteristic spatial scales we quantitatively investigate the existence of characteristic landscape scales by analyzing two dimensional fourier power spectra derived from high resolution topographic maps of two landscapes in california in both cases we find that spectral power declines sharply above a frequency that corresponds roughly to hillslope length implying that the landscape is relatively smooth at finer scales the spectra also show that both landscapes contain quasiperiodic ridge and valley structures and we derive a robust measure of the ridge valley wavelength by comparing the spectra with the statistical properties of spectra derived from randomly generated topography we show that such uniform valley spacing is unlikely to occur in a random surface we describe several potential applications of spectral analysis in geomorphology beyond the identification of characteristic spatial scales including a filtering technique that can be used to measure topographic attributes such as local relief at specific scales or in specific orientations

catastrophic rock avalanche 3600 years bp from el capitan yosemite valley california large rock slope failures from near vertical cliffs are an important geomorphic process driving the evolution of mountainous landscapes particularly glacially steepened cliffs the morphology and age of a 2 19 106 m3 rock avalanche deposit beneath el capitan in yosemite valley indicates a massive prehistoric failure of a large expanse of the southeast face geologic mapping of the deposit and the cliff face constrains the rock avalanche source to an area near the summit of 8 5 104 m2 the rock mass free fell 650 m reaching a maximum velocity of 100 m s 1 impacted the talus slope and spread across the valley floor extending 670 m from the base of the cliff cosmogenic beryllium 10 exposure ages from boulders in the deposit yield a mean age of 3 6 0 2 ka the 13 kyr time lag between deglaciation and failure suggests that the rock avalanche did not occur as a direct result of glacial debuttressing the 3 6 ka age for the rock avalanche does coincide with estimated late holocene rupture of the owens valley fault and or white mountain fault between 3 3 and 3 8 ka the coincidence of ages combined with the fact that the most recent ad 1872 owens valley fault rupture triggered numerous large rock falls in yosemite valley suggest that a large magnitude earthquake m7 0 centered in the south eastern sierra nevada may have triggered the rock avalanche if correct the extreme hazard posed by rock avalanches in yosemite valley remains present and depends on local earthquake recurrence intervals published in 2010 by john wiley sons ltd

automated landslide mapping using spectral analysis and high resolution topographic data puget sound lowlands washington and portland hills oregon abstract landslide inventory maps are necessary for assessing landslide hazards and addressing the role slope stability plays in landscape evolution over geologic timescales however landslide inventory maps produced with traditional methods aerial photograph interpretation topographic map analysis and field inspection are often subjective and incomplete the increasing availability of high resolution topographic data acquired via airborne light detection and ranging lidar over broad swaths of terrain invites new automated landslide mapping procedures we present two methods of spectral analysis that utilize lidar derived digital elevation models of the puget sound lowlands washington and the tualatin mountains oregon to quantify and automatically map the topographic signatures of deep seated landslides power spectra produced using the two dimensional discrete fourier transform and the two dimensional continuous wavelet transform identify the characteristic spatial frequencies of deep seated landslide morphologic features such as hummocky topography scarps and displaced blocks of material spatial patterns in the amount of spectral power concentrated in these characteristic frequency bands highlight past slope instabilities and allow the delineation of landslide terrain when calibrated by comparison with detailed independently compiled landslide inventory maps our algorithms correctly classify an average of 82 of the terrain in our five study areas spectral analysis also allows the creation of dominant wavelength maps which prove useful in analyzing meter scale topographic expressions of landslide mechanics past landslide activity and landslide modifying geomorphic processes these results suggest that our automated landslide mapping methods can create accurate landslide maps and serve as effective objective and efficient tools for digital terrain analysis

comparative analysis of surface roughness algorithms for the identification of active landslides abstract parameters correlated to surface roughness are quite commonly used to describe landslide activity in quantitative geomorphology previous studies proved that topographic roughness is closely related to both landslide mechanics and features a number of different techniques have emerged over the years to describe quantitatively the great variety of landforms and processes that affect unstable slopes in this work we perform a comparative analysis of several methods used in literature to compute surface roughness root mean square applied to elevation and slope grids eigenvalue ratios semivariance discrete fourier transform continuous wavelet transform and wavelet lifting scheme in order to evaluate quantitatively which algorithms are best suited to discriminate active landslides and to predict them for automated mapping purposes a first test was carried out on artificial surfaces simulating different roughness patterns encountered in nature so to highlight advantages and limits in controlled conditions then the algorithms were applied to lidar datasets of two earth flow case studies in the northern apennines italy results obtained by using effect size statistical test to objectively quantify the capability of the different algorithms of discriminating active landslide slopes from other slope types showed that most algorithms perform reasonably well and that simple techniques rms based and wavelet lifting scheme achieve equal or sometimes even better results that more complex ones results from the use of roughness indexes for the prediction of landslide slopes in automated mapping showed that non forested active slopes could be predicted by most methods with an accuracy greater than 85 and that most methods had a 15 drop in prediction accuracy in forested active slopes results also proved that increasing the size of the moving window has minor beneficial effects in predictive capability suggesting that small size of pixels and moving windows should be used to retain a full resolution of surface conditions in slopes

remote sensing of wind speed at sea surface level using hf skywave echoes from decametric waves using an hf skywave radar to study the decametric sea waves it appears that their amplitudes do not saturate as the wind speed increases a measurement method based on the kahma sea wave spectrum is proposed and radar estimations of the wind speed are compared with in situ measurements performed on board a ship the rms difference between the two measurements is 2 5m s and is probably mainly due to the spatial variability in the wind speed

a tsunami about 1000 years ago in puget sound washington water surged from puget sound sometime between 1000 and 1100 years ago overrunning tidal marshes and mantling them with centimeters of sand one overrun site is 10 kilometers northwest of downtown seattle another is on whidbey island some 30 kilometers farther north neither site has been widely mantled with sand at any other time in the past 2000 years deposition of the sand coincided to the year or less with abrupt probably tectonic subsidence at the seattle site and with landsliding into nearby lake washington these findings show that a tsunami was generated in puget sound and they tend to confirm that a large shallow earthquake occurred in the seattle area about 1000 years ago

responses of soil mantled hillslopes to transient channel incision rates 1 channel incision drives hillslope morphology in humid soil mantled landscapes when channel incision rates change numerous hillslope soil properties e g erosion rates soil thickness and soil production adjust in response to this change here we investigate the timescales of adjustment of hillslope soil properties when channel incision rates change in time an idealized soil mantled hillslope linear sediment flux law and soil density equal to bedrock density is investigated and the transient evolution of this hillslope is determined analytically this analysis reveals two dominant adjustment timescales the longer of these two timescales determines the rate at which the entire hillslope adjusts to a change in channel incision rates and is proportional to 4 2 2d where is the length of the hillslope and d is the sediment diffusivity numerical simulations are then used to examine responses of hillslopes that involve nonlinear behavior e g hillslopes that experience nonlinear sediment transport or have soil thicknesses that respond to the soil production function using these numerical models we show that the ratio between the soil density s and the density of the soil parent material can alter the long term response of the hillslope such that the characteristic timescale becomes 4 2 2d s in addition we show that the adjustments of the soil erosion rate the soil production rate and the soil thickness have different characteristic response timescales hillslopes that experience sediment flux that is proportional to the depth slope product respond on longer timescales than hillslopes that experience a linear sediment flux law when channel incision rates increase we illustrate how the spatial pattern of hillslope response to changes in channel incision rates can be used to constrain either channel incision histories or hillslope response timescales if the hillslope response timescale is known the pattern of hillslope disturbance can be used to constrain the celerity of a incision wave as it moves upstream through a channel if the channel incision history is known the hillslope response timescale may be evaluated on the basis of the spatial pattern of hillslope disturbance

landslide inventory maps new tools for an old problem landslides are present in all continents and play an important role in the evolution of landscapes they also represent a serious hazard in many areas of the world despite their importance we estimate that landslide maps cover less than 1 of the slopes in the landmasses and systematic information on the type abundance and distribution of landslides is lacking preparing landslide maps is important to document the extent of landslide phenomena in a region to investigate the distribution types pattern recurrence and statistics of slope failures to determine landslide susceptibility hazard vulnerability and risk and to study the evolution of landscapes dominated by mass wasting processes conventional methods for the production of landslide maps rely chiefly on the visual interpretation of stereoscopic aerial photography aided by field surveys these methods are time consuming and resource intensive new and emerging techniques based on satellite airborne and terrestrial remote sensing technologies promise to facilitate the production of landslide maps reducing the time and resources required for their compilation and systematic update in this work we first outline the principles for landslide mapping and we review the conventional methods for the preparation of landslide maps including geomorphological event seasonal and multi temporal inventories next we examine recent and new technologies for landslide mapping considering i the exploitation of very high resolution digital elevation models to analyze surface morphology ii the visual interpretation and semi automatic analysis of different types of satellite images including panchromatic multispectral and synthetic aperture radar images and iii tools that facilitate landslide field mapping next we discuss the advantages and the limitations of the new remote sensing data and technology for the production of geomorphological event seasonal and multi temporal inventory maps we conclude by arguing that the new tools will help to improve the quality of landslide maps with positive effects on all derivative products and analyses including erosion studies and landscape modeling susceptibility and hazard assessments and risk evaluations

bedrock incision rock uplift and threshold hillslopes in the northwestern himalayas the topography of tectonically active mountain ranges reflects a poorly understood competition between bedrock uplift and erosion dating of abandoned river cut surfaces in the northwestern himalayas reveals that the indus river incises through the bedrock at extremely high rates 2 12 mm yr 1 in the surrounding mountains the average angles of hillslopes are steep and essentially independent of erosion rate suggesting control by a common threshold process in this rapidly deforming region an equilibrium is maintained between bedrock uplift and river incision with landsliding allowing hillslopes to adjust efficiently to rapid river down cutting

an inversion method for extraction of wind speed from high frequency ground wave radar oceanic backscatter a new approach to extracting sea surface wind speed from high frequency radar doppler spectra is presented based on certain appropriate approximations associated with the doppler region close to the first order bragg peaks the second order radar cross section equation is differentiated once doppler shifts due to ocean currents are removed from the data an expression that relates the wind speed to the frequency position of the second order peak is derived the method is applied to simulated noisy data as well as to field data obtained from a seasonde a product of codar oceans sensors in breezy point ny in the latter case the retrieved wind speeds are then compared to ground truth data measured by an anemometer from a national oceanic and atmospheric administration weather station located in the vicinity of the illuminated patch of ocean subject to certain constraints as detailed in the manuscript the algorithm shows significant promise

long term kinematics and sediment flux of an active earthflow eel river california although earthfl ows are the dominant erosion mechanism in many mountainous landscapes estimates of long term earthfl ow driven sediment fl ux remain elusive because landslide displacement data are typically limited to contemporary time periods combining high resolution topography from airborne lidar light detection and ranging total station surveying orthorectifi ed historical aerial photographs and inventories of meteoric 10 be in soil pits we quantifi ed 150 years of slope movement on a 1 5 km long earthfl ow in the eel river catchment northern california united states using lidar derived topography we mapped the upper half of the earthfl ow into three distinct kinematic zones an upslope source area a long narrow transport zone and a mid slope compressional zone from our air photo analysis 1944 2006 average velocities are fastest in the transport zone 1 7 m a slowest in the source zone 1 m a and decrease monotonically over the past 30 years in all three zones meteoric 10 be inventories systematically increase with distance downslope of the source area consistent with the notion that the elongate transport zone acts like a relatively undeformed soil conveyor that can be used to quantify long term displacement because our 10 be derived transport zone velocity of 2 1 m a averages over the past 150 years pre 1944 velocities likely approached 2 5 m a suggesting that twentieth century land use practices have not increased rates of sliding although our results reveal a progressive decline in velocity that may refl ect exhaustion of readily mobilized source material velocities temporarily increased in the midtwentieth century due to major hydrologic events given an average velocity of 2 m a the kekawaka earthfl ow is defl ating its source area over 20 times faster than the regional erosion rate emphasizing the localized and vigorous role of active earthfl ows in landscape evolution

finding concealed active faults extending the southern whidbey island fault across the puget lowland washington 1 the southern whidbey island fault zone swif as previously mapped using borehole data potential field anomalies and marine seismic reflection surveys consists of three subparallel northwest trending strands extending 100 km from near vancouver island to the northern puget lowland east of puget sound the swif makes landfall between the cities of seattle and everett but is concealed beneath a thick mantle of young glacial deposits and vegetation a 20 km wide northwest trending swath of subparallel low amplitude aeromagnetic anomalies crosses this region of the puget lowland and is on strike with the swif the most prominent aeromagnetic anomaly the cottage lake lineament extends at least 18 km and lies approximately on strike with the swif on whidbey island subtle scarps and topographic lineaments on pleistocene surfaces visible on high resolution lidar topography at a number of locations along the swif lie on or near these magnetic anomalies in the field scarps exhibit northeast side up and vertical relief of 1 to 5 m excavations across several lidar scarps lying on or near magnetic anomalies show evidence for multiple folding and faulting events since deglaciation most likely above buried reverse oblique faults excavations in areas away from magnetic anomalies do not show evidence of tectonic deformation in total paleoseismological evidence suggests that the swif produced at least four earthquakes since deglaciation about 16 400 years ago the most recent less than 2700 years ago

hf radar wave and wind measurement over the eastern china sea high frequency hf radar can be employed to measure sea surface state parameters such as waveheight wind field and surface current velocity this paper describes the application of the hf ground wave radar in remote sensing the surface conditions over the eastern china sea in october 2000 the radar referred to as the osmar2000 was developed by wuhan university preliminary wave spectra waveheights and wind fields estimated from the collected data are presented and compared with ship recorded measurements where such are available the range for wind direction sensing is up to 200 km wave information and wind speed can be provided up to a range of 120 km the mean difference between radar and ship measured significant waveheight is 0 323 m wind direction is measured within 20 spl deg and wind speed to within 0 6 m s with such agreement being fairly reasonable the feasibility of the inversion algorithm and the ocean state real time sensing capability of osmar2000 are demonstrated

prehistoric rock avalanches in the olympic mountains washington rock avalanches blocked streams in the olympic mountains southwest of puget sound during the past few thousand years limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter most of the dates were from the outer preserved rings of trees drowned behind avalanche dams these three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western washington no rock avalanches in the olympic mountains are known to have resulted from storms or earthquakes during the past century the avalanches strengthen the case that a large prehistoric earthquake occurred in the puget sound region

abrupt uplift within the past 1700 years at southern puget sound washington shorelines rose as much as 7 meters along southern puget sound and hood canal between 500 and 1700 years ago evidence for this uplift consists of elevated wave cut shore platforms near seattle and emerged peat covered tidal flats as much as 60 kilometers to the southwest the uplift was too rapid for waves to leave intermediate shorelines on even the best preserved platform the tidal flats also emerged abruptly they changed into freshwater swamps and meadows without first becoming tidal marshes where uplift was greatest it adjoined an inferred fault that crosses puget sound at seattle and it probably accompanied reverse slip on that fault 1000 to 1100 years ago the uplift and probable fault slip show that the crust of the north america plate contains potential sources of damaging earthquakes in the puget sound region

great earthquakes of variable magnitude at the cascadia subduction zone comparison of histories of great earthquakes and accompanying tsunamis at eight coastal sites suggests plate boundary ruptures of varying length implying great earthquakes of variable magnitude at the cascadia subduction zone inference of rupture length relies on degree of overlap on radiocarbon age ranges for earthquakes and tsunamis and relative amounts of coseismic subsidence and heights of tsunamis written records of a tsunami in japan provide the most conclusive evidence for rupture of much of the plate boundary during the earthquake of 26 january 1700 cascadia stratigraphic evidence dating from about 1600 cal yr b p similar to that for the 1700 earthquake implies a similarly long rupture with substantial subsidence and a high tsunami correlations are consistent with other long ruptures about 1350 cal yr b p 2500 cal yr b p 3400 cal yr b p 3800 cal yr b p 4400 cal yr b p and 4900 cal yr b p a rupture about 700 1100 cal yr b p was limited to the northern and central parts of the subduction zone and a northern rupture about 2900 cal yr b p may have been similarly limited times of probable short ruptures in southern cascadia include about 1100 cal yr b p 1700 cal yr b p 3200 cal yr b p 4200 cal yr b p 4600 cal yr b p and 4700 cal yr b p rupture patterns suggest that the plate boundary in northern cascadia usually breaks in long ruptures during the greatest earthquakes ruptures in southernmost cascadia vary in length and recurrence intervals more than ruptures in northern cascadia

characterizing arid region alluvial fan surface roughness with airborne laser swath mapping digital topographic data 1 range front alluvial fan deposition in arid environments is episodic and results in multiple fan surfaces and ages these distinct landforms are often defined by descriptions of their surface morphology desert varnish accumulation clast rubification desert pavement formation soil development and stratigraphy although quantifying surface roughness differences between alluvial fan units has proven to be difficult in the past high resolution airborne laser swath mapping alsm digital topographic data are now providing researchers with an opportunity to study topography in unprecedented detail here we use alsm data to calculate surface roughness on two alluvial fans in northern death valley california we define surface roughness as the standard deviation of slope in a 5 m by 5 m moving window comparison of surface roughness values between mapped fan surfaces shows that each unit is statistically unique at the 99 confidence level furthermore there is an obvious smoothing trend from the presently active channel to a deposit with cosmogenic 10be and 36cl surface exposure ages of 70 ka beyond 70 ka alluvial landforms become progressively rougher with age these data suggest that alluvial fans in arid regions smooth out with time until a threshold is crossed where roughness increases at greater wavelength with age as a result of surface runoff and headward tributary incision into the oldest surfaces

the stratigraphic filter and bias in measurement of geologic rates 1 erosion and deposition rates estimated from the stratigraphic record frequently exhibit a power law dependence on measurement interval this dependence can result from a power law distribution of stratigraphic hiatuses by representing the stratigraphic filter as a stochastic process called a reverse ascending ladder we describe a likely origin of power law hiatuses and thus rate scaling while power law hiatuses in certain environments can be a direct result of power law periods of stasis no deposition or erosion they are more generally the result of randomness in surface fluctuations irrespective of mean subsidence or uplift autocorrelation in fluctuations can make hiatuses more or less heavy tailed but still exhibit power law characteristics in addition we show that by passing stratigraphic data backward through the filter certain statistics of surface kinematics from their formative environments can be inferred

a record of late quaternary vegetation from davis lake southern puget lowland washington abstract pollen and macrofossil analyses of a core spanning 26 000 yr from davis lake reveal late pleistocene and holocene vegetational patterns in the puget lowland the core ranges lithologically from a basal inorganic clay to a detritus gyttja to an upper fibrous peat and includes eight tephra units the late pleistocene pollen sequence records two intervals of tundra parkland vegetation the earlier of these has high percentages of picea gramineae and artemisia pollen and represents the vegetation during the evans creek stade fraser glaciation ca 25 000 17 000 yr b p the later parkland interval is dominated by picea tsuga mertensiana and gramineae it corresponds to the maximum ice advance in the puget lowland during the vashon stade fraser glaciation ca 14 000 yr b p an increase in pinus ontorta pollen between the two tundra parkland intervals suggests a temporary rise in treeline during an unnamed interstade after 13 500 yr b p a mixed woodland of subalpine and lowland conifers grew at davis lake during a period of rapid climatic amelioration in the early holocene the prolonged expansion of pseudotsuga and alnus woodland suggests dry temperate conditions similar to those of present rainshadow sites in the puget lowland more mesic forests of tsuga eterophylla thuja plicata and pseudotsuga similar to present lowland vegetation appeared in the late holocene ca 5500 yr b p

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

could surface roughness be a poor proxy for landslide age results from the swabian alb germany the potential of surface roughness to quantify geomorphological landforms and processes has been enhanced with the availability of high resolution digital terrain models dtm recent studies that attempt to identify landslide features with surface roughness have suggested that this measure of topographic heterogeneity may also be applied to estimate the relative age of landslides this is a provisional study that explores the potential of this relationship by assessing the ability of surface roughness to act as a proxy for relative landslide age the surface roughness for a set of 12 dated landslides in the swabian alb that occurred between 1789 and 1985 was calculated from a 1 m2 spatial resolution lidar dtm with three algorithms root mean square height rmsh standard deviation of slope sds and direction cosine eigenvalue ratios dce scale dependence was analysed by calculating surface roughness for a range of moving window sizes 3 3 5 5 9 9 and 15 15 and surface roughness for each landslide was summarized by the median and upper quartile only weak correlations best spearman s rho 0 58 were present between landslide age and surface roughness this correlation becomes weaker with increasing moving window size given weak observed associations and discussed challenges pertaining to the complexities of landslide morphology change over time we currently find that surface roughness alone may not be justifiable to act as a proxy for landslide age for our study region furthermore we recommend future studies should focus on addressing possible natural and anthropogenic factors such as land use change that may alter surface roughness these studies may focus on one of the three roughness measures used here as they are strongly correlated copyright 2014 john wiley sons ltd

temporal occurrence and activity of landslides in the area of cortina d ampezzo dolomites italy abstract this article shows the results of research on landslides carried out in the area of cortina d ampezzo dolomites italy within the framework of the epoch project of the european community the investigated area where tourism activities and infrastructures are highly developed has been affected by several landslides since the retreat of the wurnian glaciers and is at present still affected by active slides and flows which endanger some villages after a geological and geomorphological description the distribution in space and time of landslides which occurred in the surroundings of cortina d ampezzo is presented the type activity frequency and when possible the age of mass movements have been outlined furthermore special attention is focused on the landslides active at present which are reactivations of ancient movements the results from the monitoring systems which were installed in order to survey kinematic and hydrogeologic parameters and define the movement rate are shown the research enables the reconstruction of the post wurmian geomorphological evolution of a site in the dolomites that appears to be very peculiar both on account of the wide distribution of landslides and the intense human activity

landslide mobility and hazards implications of the 2014 oso disaster abstract landslides reflect landscape instability that evolves over meteorological and geological timescales and they also pose threats to people property and the environment the severity of these threats depends largely on landslide speed and travel distance which are collectively described as landslide mobility to investigate causes and effects of mobility we focus on a disastrous landslide that occurred on 22 march 2014 near oso washington usa following a long period of abnormally wet weather the landslide s impacts were severe because its mobility exceeded that of prior historical landslides at the site and also exceeded that of comparable landslides elsewhere the 8 10 6 m 3 landslide originated on a gently sloping

late holocene earthquakes on the toe jam hill fault seattle fault zone bainbridge island washington five trenches across a holocene fault scarp yield the first radiocarbon measured earthquake recurrence intervals for a crustal fault in western washington the scarp the first to be revealed by laser imagery marks the toe jam hill fault a north dipping backthrust to the seattle fault folded and faulted strata liquefaction features and forest soil a horizons buried by hanging wall collapse colluvium record three or possibly four earthquakes between 2500 and 1000 yr ago the most recent earthquake is probably the 1050 1020 cal calibrated yr b p a d 900 930 earthquake that raised marine terraces and triggered a tsunami in puget sound vertical deformation estimated from stratigraphic and surface offsets at trench sites suggests late holocene earthquake magnitudes near m7 corresponding to surface ruptures 36 km long deformation features recording poorly understood latest pleistocene earthquakes suggest that they were smaller than late holocene earthquakes postglacial earthquake recurrence intervals based on 97 radiocarbon ages most on detrital charcoal range from 12 000 yr to as little as a century or less corresponding fault slip rates are 0 2 mm yr for the past 16 000 yr and 2 mm yr for the past 2500 yr because the toe jam hill fault is a backthrust to the seattle fault it may not have ruptured during every earthquake on the seattle fault but the earthquake history of the toe jam hill fault is at least a partial proxy for the history of the rest of the seattle fault zone

controls on large landslide distribution and implications for the geomorphic evolution of the southern interior columbia river basin large landslides 0 1 km 2 are important agents of geomorphic change while most common in rugged mountain ranges large landslides can also be widespread in relatively low relief several 100 m terrain where their distribution has been relatively little studied a fuller understanding of the role of large landslides in landscape evolution requires addressing this gap since the distribution of large landslides may affect broad regions through interactions with channel processes and since the dominant controls on landslide distribution might be expected to vary with tectonic setting we documented 400 landslides between 0 1 and 40 km 2 across 140 000 km 2 of eastern oregon in the semiarid southern interior columbia river basin the mapped landslides cluster in a nw se trending band that is 50 100 km wide landslides predominantly occur where even modest local relief 100 m exists near key contacts between weak sedimentary or volcaniclastic rock and coherent cap rock fault density exerts no control on landslide distribution while 10 of mapped landslides cluster within 3 10 km of mapped fold axes landslide occurrence is curtailed to the ne by thick packages of coherent basalt and to the sw by limited local relief our results suggest that future mass movements will localize in areas stratigraphically preconditioned for landsliding by a geologic history of fluviolacustrine and volcaniclastic sedimentation and episodic capping by coherent lava flows in such areas episodic landsliding may persist for hundreds of thousands of years or more producing valley wall slopes of 7 13 and impacting local channels with an evolving array of mass movement styles

measurement of sea surface wind direction using bistatic high frequency radar a method for extracting sea surface wind direction information from bistatic high frequency hf radar doppler spectra is presented by analogy to the monostatic case the ratio of the intensities of the positive and negative bistatic bragg peaks is used to derive the ambiguous wind direction for bistatic operation the reference is taken with respect to the scattering ellipse normal rather than the radar beam direction the method is shown to be valid based on simulated bistatic hf radar doppler spectra wind direction is also extracted from the bistatic radar data collected on the southern china coast comparison between the radar measured wind directions and those obtained from the advanced scatterometer shows good agreement