analyzing rockfall activity 1600 2002 in a protection forest a case study using dendrogeomorphology for the first time dendrogeomorphology has been used to investigate spatial and temporal variations of rockfall activity in a protection forest we report results of 564 cores from 135 severely injured larix decidua mill trees on the west facing taschgufer slope swiss alps while trees sampled reached an age of 297 years on average the oldest one attained breast height in ad 1318 for reasons of sample depth the analysis was limited to the period 1600 2002 in total we reconstructed 741 growth disturbances gd during the last four centuries impacts were most commonly found in trees located in the southern part of the slope where gd recurred more than once per decade in contrast trees in the northern part were less frequently disturbed by rockfall and define recurrence intervals of more than 150 years throughout the last four centuries rockfall has caused gd to the trees sampled on the taschgufer slope most frequently in the form of low magnitude high frequency events in addition we identified one high magnitude low frequency event in 1720 which displaced the forest fringe of the northern sector a considerable distance downslope and eliminated an entire forest stand to analyze past rockfall activity we introduce a brateq defined as the number of impacts per meter width of all tree surfaces sampled per decade results clearly demonstrate that this rockfall brateq continually decreased in both sectors after the large 1720 rockfall event significantly low rockfall bratesq can be observed during the 1850s 1960s and 1970s in the northern and during the 1820s in the southern sector in contrast high rockfall bratesq were identified during the 1870s and 1990s in the northern and during the 1770s in the southern sector reconstructed data further show that the forest recolonizing the southern sector after the 1720 event gradually improved its protective function reducing bratesq by a factor of 13 between the 1740s and the 1990s in the recent past bratesq oscillated around 0 7 gd 1 meter width 1 10 years 1 in the well established forest of the northern sector the efficacy of the protective forest was temporarily reduced by the rockfalls in 1720 resulting in increased rockfall bratesq since then the protective

event frequency and landscape stability on the floodplain systems of arid central australia abstract central australian floodplains contain landforms suggesting activity at three scales a set of large sand sheets sand threads and megaripple covered channels related to a few enormous floods the contemporary floodplain which consists of channels and levees floodouts unchannelled floodplains and floodbasins and erosion cell mosaics which result from local redistribution of sediment classical floodplain models do not fit these systems which behave more like low angle alluvial fans because they continue to accumulate sediment the sedimentary history of the central australian floodplains suggests that deposition in the last 10 000 years has been dominated by a few gigantic floods these events are not represented in the published slackwater deposit record but morphological evidence for them can be found in bedrock gorges as well as on floodplains since the last major flood channel levee systems have been growing slowly upwards and outwards and outwards from the mountain ranges away from these systems sediment supply is limited and the dominant process is local reworking this has intensified since the arrival of europeans 100 years ago and also as a result of increased flooding due to variations in rainfall

spatial analysis of rockfall activity bounce heights and geomorphic changes over the last 50 years a case study using dendrogeomorphology article i nfo tree ring series have been used to reconstruct 50 years of rockfall behavior on a slope near saas balen swiss alps a total of 796 cores and 141 cross sections from 191 severely injured conifer trees larix decidua mill picea abies l karst and pinus cembra l combined with a series of aerial photographs were used to investigate the evolution of the forest stand so as i to reconstruct past rockfall rates ii to analyze the spatial behavior of maximum bounce heights and iii to analyze the spatial comportment of rockfall activity over the last five decades tree ring analysis permitted the reconstruction of the age distribution at the study site results were in perfect agreement with the afforestation process shown in the aerial photographs the oldest are located in the lower central part of the study site the youngest individuals at its uppermost lateral boundaries reconstructed rockfall rates reveal strong interannual variations and single event years with increased activity namely in 1960 1961 and 1995 spatial analysis of the maximum bounce heights indicate highest values at the lateral boundaries and lowest heights in the lower central part of the forest stand where a big boulder seems to shield trees growing below it the spatial analysis of past rockfall activity shows high active zones at the uppermost north facing boundaries of the forest and least active zones in the lowermost central part of the studied stand the high rockfall activity at the slope is expressed by a mean rockfall rate of n1 event m 1 y 1

assessment of the recurrence intervals of rockfall through dendrogeomorphology and counting scar approach a comparative study in a mixed forest stand from the vercors massif french alps as direct observations of rockfalls are rare and difficult to obtain over long timescales stem injuries and their dating with dendrogeomorphic techniques have been applied frequently in the past to reconstruct process activity however the analysis of tree ring samples requires considerable temporal efforts which can be detrimental in applied research and expert opinions to compensate for this shortcoming several studies have lately explored the potential of the counting of visible scars as an alternative method to dendrogeomorphology as it requires much less time and human efforts to reconstruct spatial patterns of rockfall activity yet to date both approaches have not been compared at the same site in this paper based on the extensive analysis of 278 conifer and broadleaved trees from which 1097 tree ring cores were extracted from a mixed forest plot of the vercors massif french alps we demonstrate that both methods provide similar spatial patterns of rockfall activity with a strong increase of recurrence intervals down the talus slope and a clear lateral zonation of activity despite this apparent convergence between both approaches our study also evidences that rockfall frequencies strongly differ with tree species and diameter the visual inspection of conifer stems and the analysis of tree ring signals in large diameter broadleaved trees typically lead to an overestimation of recurrence intervals based on these findings we recommend giving priority to the scar counting approach on small diameter 15 cm broadleaved stems and to restrict tree ring analysis to old conifers that are more susceptible through the identification of tangential rows of traumatic resin ducts to provide reliable estimations of long recurrence intervals as generally observed in the lower portions of the slope these guidelines should help to improve the reliability of recurrence interval maps of rockfall process activity in forests further but also to improve cost benefit ratios of future studies

tree ring based reconstruction of rockfalls at cofre de perote volcano mexico in this study dendrogeomorphic techniques are employed to analyse the temporal frequency and spatial distribution of rockfalls on a talus slope of la teta valley located on the nw slopes of cofre de perote volcano at 4000 m above sea level based on the interpretation of disturbance signals in growth rings of old growth pinus hartwegii lindl trees we identify 100 growth disturbances related with rockfall events dated between 1780 and 2011 with slightly more than half of these events being dated to the last 50 years the sectors most susceptible to rockfall correspond with the young rock lobes located at the foot of scarps roughly three in ten events has been triggered by regional m 6 earthquakes whereas half of the events activity coincides with periods characterized by severe prolonged summer rainfalls such as the ones occurred in 1995 1998 2005 and 2011

hydrology of lake eyre australia el nino link abstract all major ephemeral rivers of australia lie in the lake eyre basin dry for years on occasions they carry enormous floods with annual volumes of 40 km 3 and instantaneous discharges of the order of 30 000 m 3 s 1 mean annual runoff of the basin is 4 km 3 or 3 5 mm significantly less than the 57 mm for the whole of australia this paper examines lake eyre and its drainage basin describing the historical hydrology of the catchment both in terms of instrument records and inflows hindcast using a model based on the technique of coral fluorescence palaeohydrological reconstruction coral fluorescence is a function of nearby river discharge and can be used to reconstruct annual river outputs reconstruction coral fluorescence is a function of nearby river discharge and can be used to reconstruct annual river outputs beyond the instrument period the burdekin river catchment runoff history is strongly paralleled by the volumes of lake eyre inflows during the period of common reliable instrument gaugings the burdekin runoff data have been extended back to 1735 a d using the correlation between river discharge and annual growth band fluorescence in an old coral from pandora reef off the north queensland coast for the instrument period 1952 to 1980 73 of the variance between coral fluorescence and burdekin discharge is common during the period 1949 1980 41 of the variance between coral fluorescence and lake eyre inflow data is common modelled inflows to lake eyre for the period 1885 1948 are based on the latter data set

potential of two submontane broadleaved species acer opalus quercus pubescens to reveal spatiotemporal patterns of rockfall activity long term records of rockfalls have proven to be scarce and typically incomplete especially in increasingly urbanized areas where inventories are largely absent and the risk associated with rockfall events rises proportionally with urbanization on forested slopes tree ring analyses may help to fill this gap as they have been demonstrated to provide annually resolved data on past rockfall activity over long periods yet the reconstruction of rockfall chronologies has been hampered in the past by the paucity of studies that include broadleaved tree species which are in fact quite common in various rockfall prone environments in this study we test the sensitivity of two common yet unstudied broadleaved species quercus pubescens willd qp and acer opalus mill ao to record rockfall impacts the approach is based on a systematic mapping of trees and the counting of visible scars on the stem surface of both species data are presented from a site in the vercors massif french alps where rocks are frequently detached from valanginian limestone and marl cliffs we compare recurrence interval maps obtained from both species and from two different sets of tree structures i e single trees vs coppice stands based on cohen s k coefficient and the mean absolute error a total of 1230 scars were observed on the stem surface of 847 a opalus and q pubescens trees both methods yield comparable results on the spatial distribution of relative rockfall activity with similar downslope decreasing recurrence intervals yet recurrence intervals vary significantly according to tree species and tree structure the recurrence interval observed on the stem surface of q pubescens exceeds that of a opalus by n20 years in the lower part of the studied plot similarly the recurrence interval map derived from a opalus coppice stands dominant at the stand scale does not exhibit a clear spatial pattern differences between species may be explained by the bark thickness of q pubescens which has been demonstrated to grow at twice the rate of a opalus thus constituting a mechanical barrier that is able to buffer low energy rockfalls and thus can avoid damage to the underlying tissues the reasons for differences between tree structures are related to the clustered coppice specific spatial stem distribution in clumps that could result on one hand in bigger gaps between clumps which in turn decreases the probability of tree impacts for traveling blocks on the other hand data also indicate that several scars on the bark of coppice stands may stem from the same impact and thus may lead to an overestimation of rockfall activity

major episodes of quaternary activity in the lower neales river northwest of lake eyre central australia abstract the lake eyre basin australia s largest internal drainage system represents a key site in unravelling the complexities of terrestrial climate change the basin covering one sixth of the australian continent spans a number of climatic zones including the tropical monsoon system to the north and the mid latitude westerly circulation to the south this study describes four major episodes of quaternary fluvial lacustrine and aeolian activity in the neales river a western catchment of lake eyre the first phase is represented by coarse grained fluvial aggradation which dates to at least 170 ka the depocentre of lake eyre is believed to have been located further to the east during this phase the second episode is a phase of high lake level lacustrine deposition which occurred before 103 ka the deltaic margin of the lake at this time was approximately 20 km west of the present playa the third phase was characterised by significant base level lowering and channel incision after 50 ka but before 31 ka lake level lowering induced fluvial incision of up to 9 m scouring several metres into the basal silicified miocene sediments some time after 50 ka the final phase was a period of aeolian and ephemeral fluvial deposition which peaked between 20 ka and 18 ka coincident with the last glacial maximum these episodes are compared with chronostratigraphic data from the monsoon dominated catchments of the cooper and diamantina rivers the nature and record of fluvial and lacustrine deposition are correlated throughout the basin during the penultimate and last interglacial cycles the late quaternary record is more ambiguous and further studies are required to elucidate the precise nature of climate change in the basin over the last 30 ka

visual dating of rockfall scars in larix decidua trees dating past mass wasting with growth disturbances in trees is widely used in geochronology as the approach may yield dates of past process activity with up to subannual precision past work commonly focused on the extraction of increment cores wedges or stem cross sections however sampling has been shown to be constrained by sampling permissions and the analysis of tree ring samples requires considerable temporal efforts to compensate for these shortcomings we explore the potential of visual inspection of wound appearance for dating purposes based on a data set of 217 wood penetrating wounds of known age inflicted to european larch larix decidua mill by rockfall activity we develop guidelines for the visual noninvasive dating of wounds including i the counting of bark rings ii a visual assessment of exposed wood and wound bark characteristics such as the color and weathering status of wounds and iii the relationship between wound age and tree diameter a characterization of wounds based on photographs randomly selected from the data set reveals that young wounds typically can be dated with high precision whereas dating errors gradually increase with increasing wound age while visual dating does not reach the precision of dendrochronological dating we clearly demonstrate that spatial patterns of and differences in rockfall activity can be reconstructed with both approaches the introduction of visual dating approaches will facilitate fieldwork especially in applied research assist the conventional interpretation of tree ring signals and allow the reconstruction of geomorphic processes with considerably fewer temporal and financial efforts

parameterization of rockfall source areas and magnitudes with ecological recorders when disturbances in trees serve the calibration and validation of simulation runs on forested talus slopes which have been build up by rockfall a strong interaction exists between the trees and the falling rocks while the presence and density of vegetation have a profound influence on rockfall activity the occurrence of the latter will also exert control on the presence vitality species composition and age distribution of forest stands this paper exploits the interactions between biotic tree growth and abiotic rockfall processes in a mountain forest to gather and obtain reliable input data on rockfall for the 3d process based simulation model rockyfor3d we demonstrate that differences between the simulated and observed numbers of tree impacts can be minimized through i a careful definition of active source areas and ii a weighted distribution of block sizes as observed in the field as a result of this field based optimized configuration highly significant values can be obtained with rockyfor3d for the number of impacts per tree so that results of the model runs can be converted with a high degree of certainty into real frequencies the combination of the field based dendrogeomorphic with the modeling approaches is seen as a significant advance for hazard mapping as it allows a reliable and highly resolved spatial characterization of rockfall frequencies and a realistic representation of past rockfall dynamics at the slope scale

genesis of the kangshan au polymetallic deposit xiong ershan district north china craton constraints from fluid inclusions and c h o s pb isotopes abstract the kangshan au polymetallic deposit in the xiong ershan district of china lies on the southern margin of the north china craton the orebodies are hosted in e ne w sw trending brittle faults formed during the mesozoic which crosscut neoarchean metamorphic rocks and mesoproterozoic volcanic rocks the ore forming process can be divided into three stages a quartz pyrite stage stage 1 a quartz polymetallic sulfide stage stage 2 and a quartz calcite stage stage 3 stage 2 includes two substages a quartz pyrite chalcopyrite electrum substage stage 2 1 the main au mineralization stage and a galena sphalerite pyrite ankerite ag bearing tetrahedrite chalcopyrite electrum substage stage 2 2 the main pb zn ag mineralization stage four types of fluid inclusions have been identified in the kangshan deposit three phase co2 rich inclusions two phase aqueous inclusions one phase vapor inclusions and one phase aqueous inclusions inclusion microthermometric laser raman and c h o s pb isotope analyses were undertaken to clarify the properties of the ore forming fluids sources of these fluids and ore forming materials and mineral precipitation mechanisms laser raman spectroscopic analysis indicate that the ore forming fluids were formed in a nacl h2o co2 system inclusion homogenization temperatures and salinities are 130 c 359 c and 0 53 11 46 wt nacl equivalent eqv respectively 18ofluid values calculated from the 18osmow and d values of the inclusions in auriferous quartz veins are 1 0 9 0 and 92 to 67 respectively 13cpdb and 18osmow values of ankerite are 4 89 to 3 67 and 12 0 13 9 respectively fluid c h o isotopic compositions indicate that the ore forming fluids originated mainly from magmas with minor addition of meteoric water 34s values of the ore sulfides are 4 8 7 4 206pb 204pb 207pb 204pb and 208pb 204pb ratios of the ore sulfides are 17 625 17 889 15 543 15 620 and 38 389 38 740 respectively s pb isotopic compositions indicate that the ore forming materials of the deposit originated from granitic magmas and host rocks the kangshan au polymetallic deposit is a medium low temperature hydrothermal deposit its mineralization may be related toearly cretaceous granite formed in an extensional tectonic setting caused by craton destruction on the southern margin of the north china craton

tree ring based assessment of rockfall frequency on talus slopes at sola d andorra eastern pyrenees abstract the determination of the frequency of rockfall events continues to challenge quantitative hazard assessments in most mountain areas dendrogeomorphological analysis was used to assess rockfall frequency on talus slopes at sola d andorra eastern pyrenees andorra rockfall events were dated at two sites one at the outlet of a chute and the other below a rock wall the impact wounds visible on the tree surface were analyzed with a seasonal temporal resolution at each site trees were sampled in three forest strips 15 to 30 m wide located at different heights on the talus all the trees with visible injuries in the strips were sampled rockfall frequency cannot be assessed by a simple analysis of time series of tree damage a satisfactory assessment requires a prior interpretation of the location of the damaged trees in relation to a number of rockfall events at sola d andorra the rockfall chronology was reconstructed for the last 25 years by dating visible wounds for older periods the tree wound record of rockfalls is incomplete owing to progressive closure of wounds wounds exceeding 40 years in age had already disappeared from the tree surface in the study area our results show a clear reduction of the rockfall frequency down the talus a noticeable lateral change in frequency and an influence of source morphology chute or wall on rockfall activity on the talus

wetting and drying of australia over the past 300 ka alternately dry and wet climatic episodes across central and eastern australia during the past 300 ka have greatly affected australia9s rivers lakes and dune fields evidence of widespread climate and flow regime changes has been provided by 75 thermoluminescence tl dates and 18 u th dates from alluvial and eolian sediments fluvial conditions dominated part of the last two interglacials stage 5 and 7 resulting in large sand loads in rivers in the present simpson desert and southeastern australia during the last interglacial fluvial activity in central australia peaked at 110 ka stage 5 pluvial probably 5 10 ka behind world temperature and sea level maxima following the last late interglacial wet phase aridity associated with dune building spread from central australia toward its margins achieving greatest intensity during the last glacial maximum a less widespread wet phase identified at about 55 35 ka stage 3 subpluvial is associated with high lake levels and paleochannel activity in southeastern australia this tl record of variable continental aridity in australia correlates well with global changes including the variable eolian dust flux into central china the northern pacific ocean and antarctica

mass movements and tree rings a guide to dendrogeomorphic field sampling and dating abstract trees affected by mass movements record the evidence of geomorphic disturbance in the growth ring series and thereby provide a precise geochronological tool for the reconstruction of past activity of mass movement the identification of past activity of processes was typically based on the presence of growth anomalies in affected trees and focused on the presence of scars tilted or buried trunks as well as on apex decapitation for the analyses and interpretation of disturbances in tree ring records in contrast clear guidelines have not been established with largely differing or no thresholds used to distinguish signal from noise at the same time processes with a large spatial footprint e g snow avalanches landslides or floods will likely leave growth anomalies in a large number of trees whereas a falling rock would only cause scars in one or a few trees along its trajectory based on the above considerations we examine issues relating to the interpretation and dendrogeomorphic dating of mass movements particular attention is drawn to sampling in terms of sample distribution across a study site the actual selection of trees as well as to sample size i e number of trees sampled based on case studies from snow avalanche debris flow and landslide sites we demonstrate that thresholds can indeed improve dating quality and at the same time minimize noise in time series we also conclude that different thresholds need to be used for different processes and different periods of the reconstruction especially for the early stages of the reconstruction when the number of potentially responding trees will be much smaller this paper seeks to set standards for dendrogeomorphic fieldwork analysis and interpretation for different processes of mass movements

seven centuries of avalanche activity at echalp queyras massif southern french alps as inferred from tree rings the purpose of this study was to reconstruct spatiotemporal patterns of avalanche events in a forested avalanche path of the queyras massif echalp avalanche path southeast french alps analysis of past events was based on tree ring series from 163 heavily affected multicentennial larch trees larix decidua mill growing near or next to the avalanche path a total of 514 growth disturbances such as tangential rows of traumatic resin ducts the onset of compression wood as well as abrupt growth suppression or release were identified in the samples indicating 38 destructive snow avalanches between 1338 and 2010 the mean return period of snow avalanches was 22 years with a 4 probability that an avalanche occurs in a particular year on a temporal plan three maxima in snow avalanche frequency were reconstructed at the beginning of the 16th and 19th centuries and around 1850 correlating with below average winter temperatures and glacier advances analysis of the spatial distribution of disturbed trees contributed to the determination of four preferential patterns of avalanche events the comparison of dendrogeomorphic data with historical records demonstrate that at least 18 events six of which were undocumented reached the hamlet of echalp during the last seven centuries but no significant temporal trend was detected concerning the frequency of these extreme events

thermoluminescence dating study of quartz in aeolian sediments from southeastern australia abstract using 90 125 m grains of quartz extracted from sediments the equivalent dose absorbed since burial was derived by exposing aliquots of quartz to a sunlamp regenerating the tl growth curve by artificial irradiation and comparing the natural tl of the sample being dated as well as that of an adjacent surface sample to this curve the age can then be calculated once the dose rate is known the method is tested successfully on known age aeolian sediments retaining their original bedding but reveals some difficulties in trying to use tl to date aeolian sediments for which the original bedding has been destroyed anomalous fading of tl in quartz is reported this latter difficulty was circumvented by using a delay of several weeks between the irradiation and heating of the quartz

defining sample size and sampling strategy for dendrogeomorphic rockfall reconstructions optimized sampling strategies have been recently proposed for dendrogeomorphic reconstructions of mass movements with a large spatial footprint such as landslides snow avalanches and debris flows such guidelines have by contrast been largely missing for rockfalls and cannot be transposed owing to the sporadic nature of this process and the occurrence of individual rocks and boulders based on a data set of 314 european larch larix decidua mill trees i e 64 trees ha growing on an active rockfall slope this study bridges this gap and proposes an optimized sampling strategy for the spatial and temporal reconstruction of rockfall activity using random extractions of trees iterative mapping and a stratified sampling strategy based on an arbitrary selection of trees we investigate subsets of the full tree ring data set to define optimal sample size and sampling design for the development of frequency maps of rockfall activity spatially our results demonstrate that the sampling of only 6 representative trees per ha can be sufficient to yield a reasonable mapping of the spatial distribution of rockfall frequencies on a slope especially if the oldest and most heavily affected individuals are included in the analysis at the same time however sampling such a low number of trees risks causing significant errors especially if nonrepresentative trees are chosen for analysis an increased number of samples therefore improves the quality of the frequency maps in this case temporally we demonstrate that at least 40 trees ha are needed to obtain reliable rockfall chronologies these results will facilitate the design of future studies decrease the cost benefit ratio of dendrogeomorphic studies and thus will permit production of reliable reconstructions with reasonable temporal efforts

centennial scale process activity in a complex landslide body in the qilian mountains northeast tibetan plateau china abstract mass movements in china typically encompass landslides rockfalls and debris flows and these processes affect almost 70 of all mountain areas of china an improved understanding of geomorphic process dynamics and their drivers and process histories are important prerequisites for a proper assessment and a sustainable management of mountain hazards tree rings have on varied occasions proven to be a reliable tool for the acquisition of data on past mountain hazards here we present the first reconstruction of past landslide activity on a slope in the qilian mountains northeast tibetan plateau china to this end a total of 543 qilian juniper sabina przewalskii kom samples were selected from 239 trees growing on or next to a complex landslide body with the aim to reconstruct past landslide histories at the site the dataset of disturbed trees was complemented with 174 increment cores from 84 reference qilian juniper trees growing on three adjacent yet undisturbed sites based on the dating of the samples and the interpretation of growth disturbances gd in the tree ring series of affected trees we provide the first reconstruction of past landslides as retrieved from a dendrogeomorphic record covering more than a millennium 956 2011 ce results show that the first detectable gd occurred as early as in 1042 ce followed by seven major landslide reccurrences in 1703 1816 1848 1863 1913 1970 and 1982 comparison between our landslide record and a dendroclimatic precipitation reconstruction points to the crucial role of major longer term wet precipitation anomalies on landslide occurrence

dendrogeomorphic reconstruction of lahar activity and triggers shiveluch volcano kamchatka peninsula russia lahars are highly concentrated water saturated volcanic hyperconcentrated flows or debris flows containing pyroclastic material and are a characteristic mass movement process on volcanic slopes on kamchatka peninsula russian federation lahars are widespread and may affect remote settlements historical records of past lahar occurrences are generally sparse and mostly limited to events which damaged infrastructure on the slopes or at the foot of volcanoes in this study we present a tree ring based reconstruction of spatiotemporal patterns of past lahar activity at shiveluch volcano using increment cores and cross sections from 126 larix cajanderi trees we document 34 events covering the period ad 1729 2012 analyses of the seasonality of damage in trees reveal that 95 of all lahars occurred between october and may and thus point to the predominant role of the sudden melt of the snow cover by volcanic material these observations suggest that most lahars were likely syn eruptive and that lahar activity is largely restricted to periods of volcanic activity by contrast rainfall events do not seem to play a significant role in lahar triggering

achieving a more realistic assessment of rockfall hazards by coupling three dimensional process models and field based tree ring data sound knowledge of the spatial and temporal patterns of rockfalls is fundamental for the management of this very common hazard in mountain environments process based three dimensional simulation models are nowadays capable of reproducing the spatial distribution of rockfall occurrences with reasonable accuracy through the simulation of numerous individual trajectories on highly resolved digital terrain models at the same time however simulation models typically fail to quantify the real frequency of rockfalls in terms of return intervals the analysis of impact scars on trees in contrast yields real rockfall frequencies but trees may not be present at the location of interest and rare trajectories may not necessarily be captured due to the limited age of forest stands in this article we demonstrate that the coupling of modeling with tree ring techniques may overcome the limitations inherent to both approaches based on the analysis of 64 cells 40 m 40 m of a rockfall slope located above a 1631 m long road section in the swiss alps we illustrate results from 488 rockfalls detected in 1260 trees we illustrate that tree impact data cannot only be used i to reconstruct the real frequency of rockfalls for individual cells but that they also serve ii the calibration of the rockfall model rockyfor3d as well as iii the transformation of simulated trajectories into real frequencies calibrated simulation results are in good agreement with real rockfall frequencies and exhibit significant differences in rockfall activity between the cells zones along the road section real frequencies expressed as rock passages per meter road section also enable quantification and direct comparison of the hazard potential between the zones the contribution provides an approach for hazard zoning procedures that complements traditional methods with a quantification of rockfall frequencies in terms of return intervals through a systematic inclusion of impact records in trees