analyzing earthquake clustering features by using stochastic reconstruction 1 on the basis of the epidemic type aftershock sequence etas model and the thinning procedure this paper gives the method about how to classify the earthquakes in a given catalogue into different clusters stochastically the key points of this method are the probabilities of one event being triggered by another previous event and being a background event making use of these probabilities we can reconstruct the functions associated with the characteristics of earthquake clusters to test a number of important hypotheses about the earthquake clustering phenomena we applied this reconstruction method to the shallow seismic data in japan and also to a simulated catalogue the results show the following assertions 1 the functions for each component in the formulation of the space time etas model are good enough as a first order approximation for describing earthquake clusters 2 a background event triggers less offspring in expectation than a triggered event of the same magnitude 3 the magnitude distribution of the triggered event depends on the magnitude of its direct ancestor 4 the diffusion of the aftershock sequence is mainly caused by cascades of individual triggering processes while no evidence shows that each individual triggering process is diffusive and 5 the scale of the triggering region is still an exponential law as formulated in the model but not the same one for the expected number of offspring

the effect of selected physiographic factors on dissolved gypsum transport by simulated runoff on gypsiferous soils summary simulated rainfall with intensities of 48 and 58 mmh 1 representing those found in heavy storm events in the middle ebro valley have been applied to gypsiferous soils of varying characteristics and slope an attempt to assess the effect of selected physiographic factors on the transport of dissolved gypsum by runoff is presented in this paper the 51 field experiments carried out on1 25m 1 25m plots have shown high variability in the gypsum yield among the diverse situations tested the gypsum load transported by runoff ranges from 5 to 40 gm 2 per hour transport of dissolved gypsum is positively related to rock outcrop and slope and rainfall intensity produces a small dilution effect dry soil conditions and higher percentages of plant cover favour higher gypsum concentrations runoff is undersaturated in gypsum with values ranging from 1 4 to 0 3 the highest gypsum yields are recorded in dystric leptosols followed by gypsic calcisols lithic phase and then gypsic calcisols

the reconstruction and climatic implication of an independent palaeo ice cap within the andean rain shadow east of the former patagonian ice sheet santa cruz province argentina abstract this paper describes the reconstruction of the previously undocumented meseta cuadrada palaeo ice cap on south west meseta del lago buenos aires santa cruz province patagonia based on theoretical surface profiles the reconstruction of the meseta cuadrada palaeo ice cap indicates an ice mass covering at least 78 km2 with a total ice volume around 9 2 km3 the inferred equilibrium line altitude ela of the palaeo ice cap 2031 m asl represents a drop of 286 m compared to the ela of the current meseta cuadrada glacier 2317 m asl we explain this small change in ela with reference to the flat hypsometry of the palaeo ice cap and an enhanced aridity to the west of the patagonian andes caused by the existence of the last glacial maximum lgm patagonian ice sheet calculated annual accumulation values of ca 402 to 957 mm a at the ela of the meseta cuadrada palaeo ice cap derived by a degree day model ddm during the last local glacial maximum extent are low compared with estimations of the current accumulation at the ela of the remaining glacierized area of around 3789 mm a this strongly supports the existence of increased aridity and seasonality east of the patagonian andes during the last glacial maximum provided both maximum extents were synchronous

positive degree day factors for ablation on the greenland ice sheet studied by energy balance modelling ice ablation is related to air temperature by the positive degree day factor variations of the positive degree day factor in west greenland are studied using an energy balance model to simulate ablation under different conditions degree day factors for simulated and measured ice ablation at nordbogletscher and qaman rssup sermia agree well with values around 8 mm d 1 c 1 degree day factors for snow are less than half those for ice energy balance modelling shows that degree day factors vary with summer mean temperature surface albedo and turbulence but there is only evidence of large positive degree day factors at lower temperatures and with low albedo 0 3 the greatest effect of albedo variations 0 3 0 7 is at lower temperatures while variations in turbulence have greater effect at higher temperatures current models may underestimate runoff from the greenland ice sheet by several tenths because they use a degree day factor for melting ice that is too small for the colder parts of the ice sheet i e the upper ablation area and the northerly margin

space time etas models and an improved extension for sensitive detection of anomalous seismicity such as quiescence and activation in a given region we need a suitable statistical reference model that represents a normal seismic activity in the region the regional occurrence rate of the earthquakes is modeled as a function of previous activity the specific form of which is based on empirical laws in time and space such as the modified omori formula and the utsu seki scaling law of aftershock area against magnitude respectively this manuscript summarizes the development of the epidemic type aftershock sequence etas model and proposes an extended version of the best fitted space time model that was suggested in ogata ogata y 1998 space time point process models for earthquake occurrences ann inst statist math 50 379 402 this model indicates significantly better fit to seismicity in various regions in and around japan d 2005 elsevier b v all rights reserved

a study on the background and clustering seismicity in the taiwan region by using point process models 1 this paper investigates the shallow seismicity occurring in the taiwan region during the 20th century using a stochastic declustering method that has been developed on the basis of the theory of the epidemic type aftershock sequence model it provides a probability based tool to objectively separate the space time occurrences of earthquakes into a background and a clustering component on the basis of the background and clustering seismicity rates we discuss the correlation between the distribution of the cluster ratio and the regional seismotectonic structures specifically we find that the areas of the highest clustering ratio correspond to the major strike slip fault traces in and around taiwan additionally in the taiwan inland region during the period 1960 1990 the outputs for the stochastically declustered catalogue show a clear quiescence in background seismicity preceding the recovery of activation and the occurrences of the 1999 chi chi earthquake of ml7 3 while the other active regions show stationary background activity this could be interpreted as an effect of the aseismic slip in the chi chi rupture fault whereby the inland region around the chi chi source becomes a stress shadow

linking glacier extent and summer temperature in ne russia implications for precipitation during the global last glacial maximum abstract it is generally assumed that during the global last glacial maximum glgm i e 18 24 ka bp dry climatic conditions in ne russia inhibited the growth of large ice caps and restricted glaciers to mountain ranges however recent evidence has been found to suggest that glacial summers in ne russia were as warm as at present while glaciers were more extensive than today as a result we hypothesize that precipitation must have been relatively high in order to compensate for the high summer temperatures and the resulting glacial ablation we estimate precipitation abundance by mass balance calculations for the palaeo glaciers on kamchatka and in the kankaren range using a degree day modelling ddm approach and find that precipitation during the glgm was likely comparable to or even exceeded the modern average we suggest that stronger than present southerly winds over the northwest pacific may have accounted for the abundant precipitation the ddm results imply that summer temperature rather than aridity limited glacier extent in the southern pacific sector of ne russia during the glgm

fundamental questions of earthquake statistics source behavior and the estimation of earthquake probabilities from possible foreshocks abstract estimates of the probability that an m l 4 8 earthquake which occurred near the southern end of the san andreas fault on 24 march 2009 would be followed by an m 7 mainshock over the following three days vary from 0 0009 using a gutenberg richter model of aftershock statistics reasenberg and jones 1989 to 0 04 using a statistical model of foreshock behavior and long term estimates of large earthquake probabilities including characteristic earthquakes agnew and jones 1991 i demonstrate that the disparity between the existing approaches depends on whether or not they conform to gutenberg richter behavior while gutenberg richter behavior is well established over large regions it could be violated on individual faults if they have characteristic earthquakes or over small areas if the spatial distribution of large event nucleations is disproportional to the rate of smaller events i develop a new form of the aftershock model that includes characteristic behavior and combines the features of both models this new model and the older foreshock model yield the same results when given the same inputs but the new model has the advantage of producing probabilities for events of all magnitudes rather than just for events larger than the initial one compared with the aftershock model the new model has the advantage of taking into account long term earthquake probability models using consistent parameters the probability of an m 7 mainshock on the southernmost san andreas fault is 0 0001 for three days from long term models and the clustering probabilities following the m l 4 8 event are 0 00035 for a gutenberg richter distribution and 0 013 for a characteristic earthquake magnitude frequency distribution our decisions about the existence of characteristic earthquakes and how large earthquakes nucleate have a first order effect on the probabilities obtained from short term clustering models for these large events

correction to space time model for regional seismicity and detection of crustal stress changes 2 in paragraph 12 in the first sentence the n should be italic ti xi yi mi si mi mc i 1 n 3 in paragraph 39 in the first sentence the magnitude values should be switched this procedure is applied to the long term strong earthquake data in and around japan m 5 and the small earthquakes m 2 5 in the central japan area 4 in paragraph 41 time t should be italic 5 in paragraph 46 in the second sentence the equals are missing

temperature and precipitation climate at the equilibrium line altitude of glaciers expressed by the degree day factor for melting snow several authors relate accumulation or precipitation at the glacier equilibrium line altitude ela to summer mean temperature using exponential or power law functions i analyze the accumulation temperature relation at the ela with a degree day model using data from the 1992 paper by a ohmura and others the dataset includes estimates at the ela of winter balance and of winter balance plus summer precipitation which represent respectively low and high estimates of annual accumulation which is seldom measured the ohmura dataset only lists summer mean temperature but i recover monthly temperatures for the whole year for 66 of the glaciers by assuming sinusoidal temperature variation through the year and using annual temperature range from a gridded climatology monthly degree day sums are then estimated from monthly mean temperature and summed to give annual totals so degree day factors for melting snow at the ela are obtained the degree day factors fall close to those reported in the literature for glacier snowmelt with averages of 3 5 1 4 and 4 6 1 4 mm d 1 k 1 for low and high accumulation estimates on the 66 glaciers the degree day model gives a family of accumulation temperature curves that depend upon the annual temperature range representing the contrast between maritime and continental climates

glaciological conditions in seven contrasting regions estimated with the degree day model we apply the degree day model to seven glacial regions that offer contrasting conditions and are well documented in the world glacier inventory the regions are axel heiberg island in arctic canada svalbard northern scandinavia southern norway the alps the caucasus and new zealand we estimate the average equilibrium line altitude ela for each half degree latitude longitude grid square from the median elevations of glaciers within the square and we extrapolate temperature from the uea cru climate research unit of the university of east anglia gridded climatology using the degree day model we calculate annual accumulation at the ela equal to ablation at the ela and other quantities like summer mean temperature length of melt season balance gradients and the sensitivity of mass balance to temperature and or precipitation changes glaciers can be characterized on a scale from cold dry axel heiberg island to warm wet new zealand corresponding to the contrast between maritime and continental climates mass balance sensitivities to temperature and or precipitation changes are relatively small for dry cold climate and relatively high for warm wet climate we could extend the approach to other glacier regions but we note that there are large areas for which ela data are not available as they are still not covered by the world glacier inventory

the foreshock sequence of the february 4 1975 haicheng earthquake m 7 3 we have examined the locations and radiation patterns of the foreshocks of the february 4 1975 haicheng earthquake m 7 3 using arrival times from six local seismic stations the foreshocks and mainshock were located relative to a master event the foreshocks occurred in a tight cluster that elongated with time before the largest foreshock the activity was located within a small approximately equidimensional volume with a diameter of about 2 km after the largest foreshock the activity spread northwest and southeast forming a 6 km long northwest trending zone first motions and ratios of p to s amplitudes indicate that two different faulting mechanisms occurred during the foreshock sequence the two radiation patterns can tentatively be correlated with different parts of the zone the hypocenter of the mainshock was not located on the same fault as that defined by the foreshocks hypocenters but rather was located 6 km south of and several kilometers shallower than the foreshock cluster we think this large separation between foreshocks and mainshock in a direction perpendicular both to the plane of rupture of the mainshock and to the trend of the foreshocks might be the result of an en echelon step in the fault that slipped during the mainshock an analysis of the change in stress due to slip during the foreshocks shows that the increase in shear stress on the mainshock fault caused by the foreshocks is very small and that direct triggering of the mainshock by the foreshocks is unlikely

statistical features of foreshocks in comparison with other earthquake clusters summary when earthquakes occur in a cluster the probability that they will be foreshocks of a forthcoming significantly larger earthquake appears dependent on the magnitude differences origin time spans and distances between several of the earliest events in a cluster the earthquake catalogue of the japan meteorological agency jma 1926 91 mj 2 4 is decomposed into numbers of clusters in time and space to compare statistical features of foreshocks with those of swarms and main shockaftershock sequences since the number of foreshocks in individual earthquake clusters is usually small two types of data stacking are considered first we consider the spatial and temporal distribution of events relative to the location and time of the coming main shock for the foreshocks a relative doughnut shaped pattern which converges in time to the main shock s epicentre is seen while this pattern is weak for swarms next we consider the temporal spatial and magnitude distributions of events relative to the time location and magnitude of earlier events in every sequence then a statistical discrimination of foreshocks from earthquakes of other types of clusters is explored the search for significant trends of relative frequency of foreshocks in comparison with other cluster types revealed the following features of foreshocks 1 their relative frequency is high when the inter event time span is less than several days but the maximum is attained at about several hours span 2 their relative frequency is high at short distances between epicentres especially within 10 km and then decreases as the distance gets larger and 3 their relative frequency increases as the magnitude increases among the earliest shocks in a cluster the stability of the results is confirmed by finding similar trends using different cluster identification methods and different threshold magnitudes further microearthquakes in the japan university network data file 1983 87 m 2 2 and moderate to large earthquakes in the international seismological centre world catalogue isc 1979 90 mh 2 5 are examined to see some effects of the magnitude thresholds of these catalogues similar features to those obtained in the jma catalogue are also found for these catalogues

foreshock rates from aftershock abundance the question whether foreshocks behave like mainshocks that happen to have larger aftershocks is important for the understanding of earthquake nucleation and the modeling of earthquake clustering many models including the short term earthquake probability step model for forecasting short term earthquake hazard in california and the epidemic type aftershock sequence etas model for the description of earthquake clustering imply that all earthquakes of magnitude m including foreshocks can trigger earthquakes according to a magnitude dependent triggering ability 10 m the magnitudes of the triggered earthquakes are proportional to 10 bm according to the gutenberg richter relation for the magnitude frequency distribution and therefore can be larger than the magnitude of the initiating event however numerous studies observe a lower foreshock occurrence than predicted from aftershock models in this article we show that for homogeneous earthquake catalogs and a consistent definition of foreshocks and aftershocks foreshock rates can be predicted from aftershock characteristics for southern california the probability that the initiating event of an earthquake cluster in the magnitude range 2 0 4 5 is followed by at least one larger event within one day is around 4 this agrees well with corresponding data from the global centroid moment tensor cmt catalog where the probability that the initiating earthquake of a cluster is followed by at least one larger event within 30 days is around 3 these foreshock rates are significantly lower than previously reported and we discuss possible reasons for this

pleistocene ice caps on the coastal mountains of the adriatic sea ice caps once covered large areas of mount orjen 1894 m on the adriatic coast of montenegro bosnia herzegovina croatia the largest ice cap covered an area of c 165 km2 and reached a maximum ice thickness of c 450 m in some areas reaching down to 500 m above modern sea level u series dating of secondary carbonates within moraines indicates that the most extensive glaciation occurred during the middle pleistocene correlating with a major phase of glaciation in greece to the south during mis 12 c 480 430 ka later less extensive glaciations are also recorded in the cirques and valleys and correlate with glaciations during mis 6 190 130 ka and mis 5d 2 110 11 7 ka each phase of glaciation would have required large amounts of snow accumulation under modern precipitation values which at c 5000 mm are some of the highest in europe mean annual temperatures would need to be only c 5 6 c lower in order to form similar sized glaciers today a mean annual temperature depression of 12 13 c would still require 1000 mm of snow accumulation water equivalent to balance ablation suggesting sustained moisture supply during pleistocene cold stages such sustained precipitation supply during pleistocene cold stages is likely to have been facilitated by major temperature contrasts between the european landmass and the mediterranean sea which are likely to have sustained lee side vortices to the south of the alps in the gulf of genoa and adriatic sea forming weak moisture bearing depressions which tracked across the eastern adriatic coastal mountains large ice caps on the dinaric alps would have blocked the inland penetration of these depressions resulting in much drier conditions in the balkan interior creating favourable conditions for the deposition of thick accumulations of loess the last glaciers on orjen formed during the younger dryas 12 9 11 7 ka and confirm the influence of north atlantic ocean circulation on pleistocene climate change in this part of the mediterranean

timing of glaciation and last glacial maximum paleoclimate estimates from the fish lake plateau utah abstract the high plateaus of utah include seven separate mountain ranges that supported glaciers during the pleistocene the fish lake plateau located on the eastern edge of the high plateaus preserves evidence of at least two glacial advances four cosmogenic 3 he exposure ages of boulders in an older moraine range from 79 to 159 ka with a mean age of 129 39 ka and oldest ages of 152 3 and 159 5 ka these ages suggest deposition during the type bull lake glaciation and marine oxygen isotope stage mis 6 twenty boulder exposure ages from four different younger moraines indicate a local last glacial maximum lgm of 21 1 ka coincident with the type pinedale glaciation and mis 2 reconstructed pinedale age glaciers from the fish lake plateau have equilibrium line altitudes ranging from 2950 to 3190 m lgm summer temperature depressions for the fish lake plateau range from 10 7 to 8 2 c assuming no change in precipitation comparison of the fish lake summer temperature depressions to a regional dataset suggests that the fish lake plateau may have had a slight increase 1 5 modern in precipitation during the lgm a series of submerged ridges in fish lake were identified during a bathymetric survey and are likely bull lake age moraines

little ice age glaciers in the balkans low altitude glaciation enabled by cooler temperatures and local topoclimatic controls moraine ridges are present in the highest cirques of the durmitor massif in montenegro and post date the widespread pleistocene moraines of this area lichenometry suggests that at least eight glaciers were present in the 19th century and correlate with the culmination of the little ice age in the european alps cooler temperatures combined with local topoclimatic controls including windblown and avalanching snow as well as shading were crucial for the formation and survival of these glaciers below the regional equilibrium line altitude the resultant regional equilibrium line altitude ela was positioned close to the highest peaks between 2400 and 2500 m with local controls such as avalanche windblown snow and shading depressing the ela in the northern cirques to 2130 2210 m this ela position was very low for this latitude and lower than for most glaciers in the european alps at any time during the holocene and even equivalent to many alpine glaciers during the younger dryas today one glacier still survives in montenegro in a deep northeast facing cirque characterized by the largest combined areas of potential avalanche and windblown snow copyright 2009 john wiley sons ltd

younger dryas glaciers and climate in the mourne mountains northern ireland here we present evidence to suggest that the mourne mountains northern ireland were last occupied by glaciers during the younger dryas stadial the margins of these glaciers are marked by moraines chronologically constrained to the younger dryas by schmidt hammer exposure dating reconstructions indicate that these glaciers had equilibrium line altitudes elas ranging from 356 33 m a s l to 570 9 m a s l with a mean of 475 36 m a s l elas rise from west to east probably reflecting the contribution of windblown snow and ice to the accumulation of younger dryas glaciers in the western mournes taking this into consideration a mean climatic ela of 529 4 m a s l is calculated for the mountains as a whole assuming a mean annual sea level air temperature of 8 c and an annual temperature range of 34 c degree day modelling suggests that during the younger dryas accumulation at the climatic ela of glaciers in the mournes was 846 990 mm a 1 this suggests increased aridity relative to present and is consistent with other parts of nw europe where reduced precipitation alongside notable cooling is thought to reflect increased north atlantic sea ice extent during the younger dryas

using the etas model for catalog declustering and seismic background assessment the concept of background seismicity is strictly related to the identification of spontaneous and triggered earthquakes the definition of foreshocks main shocks and aftershocks is currently based on procedures depending on parameters whose values are notoriously assumed by subjective criteria we propose a method for recognizing the background and the induced seismicity statistically rather than using a binary distinction of the events in these two categories we prefer to assign to each of them a probability of being independent or triggered this probability comes from an algorithm based on the etas model a certain degree of subjectivity is still present in this procedure but it is limited by the possibility of adjusting the free parameters of the algorithm by rigorous statistical criteria such as maximum likelihood we applied the method to the seismicity of southern california and analyzed the sensitivity of the results to the free parameters in the algorithm finally we show how our statistical declustering algorithm may be used for mapping the background seismicity or the moment rate in a seismic area

differences between spontaneous and triggered earthquakes their influences on foreshock probabilities 1 in this study we investigate the foreshock probabilities calculated from earthquake catalogs from japan southern california and new zealand unlike conventional studies on foreshocks we use a probability based declustering method to separate each catalog into stochastic versions of family trees such that each event is classified as either having been triggered by a preceding event or being a spontaneous event the probabilities are determined from parameters that provide the best fit of the real catalogue using a space time epidemic type aftershock sequence etas model the model assumes that background and triggered earthquakes have the same magnitude dependent triggering capability a foreshock here is defined as a spontaneous event that has one or more larger descendants and a triggered foreshock is a triggered event that has one or more larger descendants the proportion of foreshocks in spontaneous events of each catalog is found to be lower than the proportion of triggered foreshocks in triggered events one possibility is that this is due to different triggering productivity in spontaneous versus triggered events i e a triggered event triggers more children than a spontaneous events of the same magnitude however further analysis on simulated data shows that such difference might be caused by the events triggered by smaller events below the magnitude threshold of the catalog even if the physical interpretation is unclear a clustering model where spontaneous events and triggered events have different triggering behaviors can be used to assess the risk of foreshocks and to avoid overpredicting

constraints on the size of the smallest triggering earthquake from the epidemic type aftershock sequence model bath s law and observed aftershock sequences 1 the physics of earthquake triggering together with simple assumptions of self similarity imply the existence of a minimum magnitude m0 below which earthquakes do not trigger other earthquakes noting that the magnitude md of completeness of a seismic catalog is not in general the same as the magnitude m0 of the smallest triggering earthquake we compare observed aftershock sequence parameters with the predictions made by the epidemic type aftershock sequence model to constrain the value of m0 in particular we use quantitative fits to observed aftershock sequences from three previous studies as well as bath s law to obtain four estimates of m0 we show that the branching ratio n average number of triggered earthquakes per earthquake also equal to the fraction of aftershocks in a seismic catalog is the key parameter controlling the estimate of the minimum triggering magnitude m0 conversely physical upper bounds for m0 estimated from rate and state friction indicate that at the very least 55 of all earthquakes are aftershocks

space time model for regional seismicity and detection of crustal stress changes 1 the regional occurrence rate of earthquakes is modeled as a function of previous activity the specific form of which is based on empirical laws in time and space such as the modified omori formula and the utsu seki scaling law of aftershock area against magnitude respectively its parameters including the p value of the aftershock decay rate vary from place to place in such a way that for example the regional p value at the locations around the main shock is similar to the one estimated from the corresponding individual aftershock sequence the estimated space time model is used to visualize features of the regional seismic activity the utility is demonstrated by applying the model to the events of m 5 in and around japan for the period 1926 1995 among the parameters of the model this paper is particularly concerned with the normalized k value of the modified omori function indicating the aftershock productivity this takes high values around the boundaries of asperities that are estimated in the wide area off the east coast of tohoku district japan by the inversion of historical strong motion seismograms furthermore this space time model enables us to identify the anomalous period and regions where the actual occurrence rates deviate systematically from the modeled one such an anomaly activation and quiescence relative to the model could sensitively reveal the change of stresses in the regions we attempt to relate this relative activation and lowering of the seismicity to the pattern of coulomb stress changes due to a rupture or silent slip elsewhere for example such anomalies seen in the seismic activity in the central japan m 2 5 during 1995 1999 and during 2001 are respectively likely the consequence of the coulomb stress changes due to the 1995 kobe rupture and the interplate aseismic slip during 2001 beneath the western tokai region

accumulation at the equilibrium line altitude of glaciers inferred from a degree day model and tested against field observations we extrapolate temperature data from a gridded climatology to the equilibrium line altitude ela of a glacier and tune a degree day model by adjusting precipitation to give zero mass balance at the ela we verify the tuned model by comparing modelled accumulation with winter balance where this has been measured presently for 180 glaciers the modelled accumulation naturally depends upon the vertical lapse rate vlr for temperature and the degree day factor ddf for snowmelt both are somewhat uncertain in high mountain areas but modelled accumulation and measured winter balance are in reasonable agreement for most glaciers the degree day model predicts a non linear relation between accumulation and summer temperature at the ela as assumed by many workers but we find a family of curves rather than a single universal curve maritime glaciers with low annual temperature range have proportionally more accumulation than continental glaciers with high annual temperature range for a similar summer mean temperature averages of winter balance for the five main geographical regions where mass balance data are available agree well with annual accumulation from the degree day model

influence of seasonality on glacier mass balance and implications for palaeoclimate reconstructions climates inferred from former glacier geometries in some areas exhibit discrepancies with regional palaeoclimates predicted by general circulation models gcms and modelling of palaeoecological data possibly as a consequence of their differing treatments of climatic seasonality since glacier based climate reconstructions potentially offer an important tool in the calibration of gcms which themselves need validation if used to predict future climate scenarios we attempt to resolve mismatches between these techniques by 1 investigating the influence of seasonality on glacier mass balance and 2 refining the methodology used for the derivation of glacier based palaeoclimates focussing on the younger dryas stadial glaciation of scotland northeast atlantic we show that sea ice amplified seasonality led to a significantly drier climate than has been suggested by glacier based interpretations this was characterised by a relatively short ablation season and the survival of a more substantial winter snowpack we suggest that if palaeoglaciological studies were to account for changes in seasonal temperature and precipitation variability their results would agree more closely with the cold arid northeast atlantic palaeoenvironment predicted by atmospheric modelling and northwest european pollen studies and would therefore provide more accurate constraints for gcm calibration

modeled patterns of late pleistocene glacier inception and growth in the southern and central rocky mountains usa sensitivity to climate change and paleoclimatic implications abstract high resolution modern climate data for the southern and central rocky mountains provide a starting point for analysis of climate changes necessary to produce regional late pleistocene glaciation a gis based model was used to assess the sensitivity of glaciation in different ranges to climatic change and the combinations of temperature and precipitation change necessary to sustain the last glacial maximum lgm extent of glaciation in each range extensive glaciation initiates first in the wind river range of wyoming under every climate change scenario tested in absence of precipitation change a summer temperature depression of 6 8 c would be necessary to maintain lgm ice extents in colorado and wyoming if precipitation was halved necessary summer temperature depression would be 8 10 c if precipitation was doubled a depression of 3 5 5 5 c would suffice given model uncertainties these values may underestimate necessary temperature depression by as much as 2 c under all scenarios tested lgm glaciation in utah particularly the wasatch range requires either more temperature depression for given precipitation change or more precipitation for a given temperature depression than is required in the colorado wyoming rockies a summer temperature depression of 7 c which would suffice to sustain lgm ice extent with little change from modern precipitation in the colorado wyoming rockies would need to be coupled with a near doubling of precipitation to maintain lgm ice extent in the wasatch range this difference appears to reflect lgm precipitation enhancement in the wasatch range and to a lesser degree the uinta mountains resulting from the presence of lake bonneville immediately upwind of these ranges

bias in fitting the etas model a case study based on new zealand seismicity summary we fit various forms of the etas model to a large region that includes all of the most seismically active areas of new zealand the etas model contains two components a component describing background or immigrant events and a part describing aftershocks of the background events and aftershocks of the aftershocks we refer to the first part as the background part and the second as the etas part generally all of the sophistication and the bulk of the model parameters lies in the etas part of the model the background component is generally treated as a nuisance component and is often very simplistic while the main interest lies in the etas part of the model the poor model description of the background part imposes considerable bias on the etas part of the model for example a poorly specified spatial density of the background events causes many of the background events to be seen as etas events it can also cause the estimated omori power law decay p to be too small and hence the aftershock sequences appear to continue for too long on the other hand the boundary of the observation region can impose a reverse bias which causes aftershocks that are close but within the boundary to be seen as background events in almost all of the large nz event sequences since 1965 the model consistently under fits these sequences consequently it over fits those space time regions where there is normal seismicity with no major events present this may indicate that the space time region of a major event sequence is much closer to criticality in that aftershock events appear to be much more easily initiated the standard etas model does not reflect this observation

on non parametric techniques for area characteristic seismic hazard parameters summary usual techniques for estimating the seismic hazard within a specific geographical area are focused in the theory of extremes of gumbel such kind of techniques suppose the existence of a parametric type of stochastic model for the process of occurrence of earthquakes in this work we will see that the use of non parametric curve estimation techniques represent an interesting alternative to this procedure from the definition of seismic hazard we construct a nonparametric estimate of this function and other related parameters of interest such as the modal annual magnitude the yearly expected number of earthquakes the mean return period and the maximum magnitude applications to earthquakes data of southern spain are made

climate at the equilibrium line of glaciers the relationships between temperature precipitation and radiation on glacier equilibrium lines are investigated using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods it is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months temperature in a free atmosphere annual total precipitation and the sum of global and long wave net radiation all of these are measured at or very near the equilibrium line altitudes then it is shown how the shift of the equilibriumline will occur as a result of a climatic change finally the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations the present results make it possible to identify the altitudes in climate models where glacierization should begin and to evaluate the mass balance changes as a result of possible future changes in the climate

glaciers and climate in pacific far ne russia during the last glacial maximum a combined geomorphological physical model approach is used to generate three dimensional reconstructions of glaciers in pacific far ne russia during the global last glacial maximum glgm the horizontal dimensions of these ice masses are delineated by moraines their surface elevations are estimated using an iterative flowline model and temporal constraints upon their margins are derived from published age estimates the equilibrium line altitudes elas of these ice masses are estimated and glgm climate is reconstructed using a simple degree day melt model the results indicate that during the glgm ice masses occupying the pekulney kankaren and sredinny mountains of pacific far ne russia were of valley glacier and ice field type these glaciers were between 7 and 80 km in length and were considerably less extensive than during pre lgm phases of advance glgm ice masses in these regions had elas of between 575 22 m and 1035 41 m above sea level corresponding to an ela depression of 350 740 m relative to present data indicate that in the pekulney mountains this ela depression occurred because of a 6 48c reduction in mean july temperature and 200 mm a 1 reduction in precipitation relative to present thus reconstructions support a restricted view of glgm glaciation in pacific far ne russia and indicate that the region s aridity precluded the development of large continental ice sheets copyright 2011 john wiley sons ltd

statistical discrimination of foreshocks from other earthquake clusters summary when earthquake activity begins it may be a foreshock sequence to a larger earthquake a swarm or a simple main shock aftershock sequence this paper is concerned with the conditional probability that it will be foreshock activity of a later larger earthquake depending on the occurrence pattern of some early events in the sequence the earthquake catalogue of the japan meteorological agency 1926 1993 m 24 is decomposed into a large number of clusters in time and space in order to compare statistical features of foreshocks with those of swarms and aftershocks using such a data set ogata utsu katsura 1995 revealed some discriminating features of foreshocks relative to the other types of clusters for example the events closer proximity in time and space and a tendency towards chronologically increasing magnitudes which encouraged us to construct models which forecast the probability of the earthquakes being foreshocks specifically the probability is a function of the history of magnitude differences spans between origin times and distances between epicentres within a cluster for purposes of illustration the models were fitted to the early part of the data 1926 1975 and the validity of the forecasting procedure was checked on data from the later period 1976 1993 two procedures for evaluating the performance of the probability forecast are suggested furthermore for the case where only a single event is available i e either it is the first event in a cluster or an isolated event we also forecast the probability of the event being a foreshock as a function of its geographic location then the validity of the forecast is demonstrated in a similar manner finally making use of the multi element prediction formula we show that the forecasting performance is enhanced by the joint use of the information in the location of the first event and that in the subsequent interevent history in the cluster

an improved version of the load unload response ratio method for forecasting strong aftershocks abstract temporal clustering and spatial concentration of aftershock sequences can be observed after the occurrence of most major earthquakes earthquake clustering effects such as the rapid decay of aftershocks and second stage aftershocks cause large fluctuations in the load unload response ratio lurr in order to eliminate the influence of such clustering we introduce a new formula for calculating the lurr taking the epidemic type aftershock sequence etas model as the baseline seismicity model we have applied the new formula retrospectively to the wenchuan earthquake sequence in 2008 in china the results show that the lurr increases slowly to a peak and then decreases sharply before strong aftershocks and that the new lurr performs better than the original lurr

first 36cl cosmogenic moraine geochronology of the dinaric mountain karst velež and crvanj mountains of bosnia and herzegovina abstract this article presents the first attempt to date moraines in the dinaric mountain karst using cosmogenic 36cl surface exposure dating technique twenty samples were collected from moraine boulders from two sets of the lowest and largest lateral moraines on the vele 1965 m asl and crvanj mountains 1920 m asl in bosnia and herzegovina the dated lateral terminal moraine complexes spanning elevations from 980 to 1350 m asl are up to 2 7 km long and rise more than 100 m above the valley floor the moraine boulders yielded 36cl ages spanning from oldest dryas for vele 14 9 1 1 ka to younger dryas for crvanj 11 9 0 9 ka considering the average age of the two oldest samples from each lateral moraine as the most representative time of moraine emplacement the dated moraines mark the largest extent of glaciers in both study areas which have been reconstructed to 28 km2 for vele and 24 km2 for crvanj having a mean equilibrium line altitude at 1388 m and 1541 m respectively under modern precipitation values which account for 2000 mm the temperature depression between 8 and 10 c is required to sustain the palaeoglaciers with reconstructed equilibrium line altitudes glaciers of similar size with such low equilibrium line altitudes during the lateglacial have not been reported until now for the balkan peninsula it is very likely that the boulder ages reflect complex exhumation and denudation histories which at this point do not allow obtaining more precise moraine chronologies for the study areas nevertheless this article delivers new data on the extent and timing of quaternary glaciations in the mediterranean mountains where records of glacier fluctuations seem to be asynchronous amongst different areas it is clear that dating moraines with cosmogenic 36cl surface exposure dating in carbonate lithologies in areas of high precipitation like the dinaric karst remains challenging

variations of near surface firn density in the lower accumulation area of the greenland ice sheet pâkitsoq west greenland firn density variations have been studied in the lower accumulation area of the greenland ice sheet 1440 1620 m a s l near p kitsoq west greenland the main control on density in the near surface firn layer of 5 10 m thickness is the formation of ice layers by the refreezing of meltwater that reaches depths of 2 4 m below the surface the density variations are described by the ratio of annual surface melt m to the annual accumulation c the ratio m c is about 0 6 at the run off limit at about 1400 m a s l in the study area where refreezing of meltwater transforms snow into impermeable ice the mean density of near surface firn decreases with elevation reflecting a decrease in melt with elevation there is a surprising decrease in firn density at depths of more than about 4 m below the 1991 summer surface which reflects lower melt rates and or higher accumulation in the early 1980s and late 1970s when this firn was passing through the surface layer the formation of such low density firn may have partially contributed to the 1978 85 thickening of the ice sheet observed by satellite radar altimetry near surface firn density is therefore very sensitive to climate change and might be an attractive target for climate monitoring

a review of topographic controls on moraine distribution ice marginal moraines are often used to reconstruct the dimensions of former ice masses which are then used as proxies for palaeoclimate this approach relies on the assumption that the distribution of moraines in the modern landscape is an accurate reflection of former ice margin positions during climatically controlled periods of ice margin stability however the validity of this assumption is open to question as a number of additional nonclimatic factors are known to influence moraine distribution this review considers the role played by topography in this process with specific focus on moraine formation preservation and ease of identification topoclimatic controls are not considered published literature indicates that the importance of topography in regulating moraine distribution varies spatially temporally and as a function of the ice mass type responsible for moraine deposition in particular in the case of ice sheets and ice caps 1000 km2 one potentially important topographic control on where in a landscape moraines are deposited is erosional feedback whereby subglacial erosion causes ice masses to become less extensive over successive glacial cycles for the marine terminating outlets of such ice masses fjord geometry also exerts a strong control on where moraines are deposited promoting their deposition in proximity to valley narrowings bends bifurcations where basins are shallow and or in the vicinity of topographic bumps moraines formed at the margins of ice sheets and ice caps are likely to be large and readily identifiable in the modern landscape in the case of icefields and valley glaciers 10 1000 km2 erosional feedback may well play some role in regulating where moraines are deposited but other factors including variations in accumulation area topography and the propensity for moraines to form at topographic pinning points are also likely to be important this is particularly relevant where land terminating glaciers extend into piedmont zones unconfined plains adjacent to mountain ranges where large and readily identifiable moraines can be deposited in the case of cirque glaciers 10 km2 erosional feedback is less important but factors such as topographic controls on the accumulation of redistributed snow and ice and the availability of surface debris regulate glacier dimensions and thereby determine where moraines are deposited in such cases moraines are likely to be small and particularly susceptible to post depositional modification sometimes making them difficult to identify in the modern landscape based on this review we suggest that despite often being difficult to identify quantify and mitigate topographic controls on moraine distribution should be explicitly considered when reconstructing the dimensions of palaeoglaciers and that moraines should be judiciously chosen before being used as indirect proxies for palaeoclimate i e palaeoclimatic inferences should only be drawn from moraines when topographic controls on moraine distribution are considered insignificant

single link cluster analysis as a method to evaluate spatial and temporal properties of earthquake catalogues summary single link cluster analysis is a straightforward method to quantitatively measure the degree of clustering or isolation of groups of elements in a set such as a catalogue of earthquakes to apply single link cluster analysis to a set of n earthquakes individual earthquakes are first linked to their nearest neighbours to form event sub groups the process is then repeated and each sub group linked to its nearest neighbour recursively until n 1 links are found to join all the earthquakes this paper shows how knowledge of these links can be used to divide a group of earthquakes into any number of spatial clusters with various modifications this analysis can identify earthquake nests isolated events aftershock sequences and zones of seismic quiescence to illustrate this method we apply it to i a global data set of 2178 earthquakes having mb of 5 8 or greater reported by the international seismological centre isc between 1964 and february 1986 and ii sets of earthquakes having mb of 4 9 and greater as reported by the isc occurring in central america and in the aleutians to facilitate comparison with real data this study also investigates the distribution of link lengths for synthetic events placed randomly on 1 d circular line 2 d circular area and 3 d spherical volume geometries if we remove links between nuclear explosions from the isc data the resulting link distribution is quite similar to that for synthetic events placed along a 1 d fault for the shortest links the similarity improves markedly if the synthetic fault has a finite width or if relative location errors cause events to be located away from the fault trace with a standard deviation of about 15 km

importance of direct and indirect triggered seismicity in the etas model of seismicity 1 using the simple etas branching model of seismicity which assumes that each earthquake can trigger other earthquakes we quantify the role played by the cascade of triggered seismicity in controlling the rate of aftershock decay as well as the overall level of seismicity in the presence of a constant external seismicity source we show that in this model the fraction of earthquakes in the population that are aftershocks is equal to the fraction of aftershocks that are indirectly triggered and is given by the average number of triggered events per earthquake previous observations that a significant fraction of earthquakes are triggered earthquakes therefore imply that most aftershocks are indirectly triggered by the mainshock

application of a degree day model to reconstruct pleistocene glacial climates there is empirical evidence of a nonlinear relation between annual precipitation or accumulation and summer mean temperature at the equilibrium line altitude ela on glaciers around the world the degree day model gives a similar relation between accumulation and summer temperature although instead of a single universal curve there is a family of curves depending upon the annual temperature range furthermore the degree day model also gives nonlinear relations between accumulation and annual mean temperature thus estimations of accumulation can be made from both summer and annual temperatures at the ela of former reconstructed glaciers such as those in greece this is particularly useful since these climatic variables have major implications for biological proxies such as vegetation history indicated in the pollen record and for periglacial proxies such as permafrost distributions indicated in the geomorphological record the close relationship between glaciers and climate provides one of the most precise methods for reconstructing former climates and offers considerable potential for resolving our understanding of pleistocene cold stage climates

likelihood analysis of earthquake catalogues summary we apply several classes of stochastic multidimensional models to statistical analysis of earthquake catalogues using likelihood methods we investigate the importance of including different earthquake parameters in the model epicentral coordinates hypocentral depth time limits for interearthquake interaction and especially spatial distribution of earthquakes as well as spatial aftershock patterns results of this study combined with other investigations suggest that most distributions controlling earthquake interaction have a fractal or scale invariant form developed models are used for statistical analysis of several earthquake catalogues to evaluate parameters of earthquake occurrence these parameters are shown to be similar for shallow earthquakes of different magnitude ranges and seismogenic regions confirming self similarity of the earthquake process whereas intermediate earthquakes seem to emulate the pattern of shallow earthquake occurrence albeit at a much smaller aftershock rate deep earthquakes differ significantly in their properties predictability of standard shallow earthquake catalogues has been analysed we present evidence that for the best availabfe catalogues the predictability is close to 10 bits per earthquake several synthetic earthquake catalogues have been created and processed through the likelihood inversion scheme the results from likelihood analysis of these catalogues confirm our approach

foreshocks explained by cascades of triggered seismicity 1 the observation of foreshocks preceding large earthquakes and the suggestion that foreshocks have specific properties that may be used to distinguish them from other earthquakes have raised the hope that large earthquakes may be predictable among proposed anomalous properties are the larger proportion than normal of large versus small foreshocks the power law acceleration of seismicity rate as a function of time to the mainshock and the spatial migration of foreshocks toward the mainshock when averaging over many sequences using southern california seismicity we show that these properties and others arise naturally from the simple model that any earthquake may trigger other earthquakes without arbitrary distinction between foreshocks aftershocks and mainshocks we find that foreshock precursory properties are independent of the mainshock size this implies that earthquakes large or small are predictable to the same degree as seismicity rate is predictable from past seismicity by taking into account cascades of triggering the cascades of triggering give rise naturally to long range and long time interactions which can explain the observations of correlations in seismicity over surprisingly large length scales

sensitivity of mass balance of five swiss glaciers to temperature changes assessed by tuning a degree day model a degree day model is used to assess the sensitivity of the mass balance of five swiss glaciers to temperature changes the model uses temperature data extrapolated from nearby climate stations and is tuned by varying precipitation to make the model fit the observed distribution of mass balance with altitude once the model is tuned the effect of temperature change is simulated by recalculating the mass balance with the same parameters as before but with a temperature increase of 1 c throughout the year the largest mass balance changes involving increased ablation of 1 m w e a 1 c 1 occur at the snout with a progressively smaller increase with altitude the area averaged sensitivities for the five glaciers are 0 7 to 0 9 m w e a 1 c 1 if annual precipitation also increased by 20 it would partly offset the effect of the 1 c higher temperatures but could not compensate for it