size distribution of scoria cones within the egrikuyu monogenetic field central anatolia turkey abstract egrikuyu monogenetic field emf is one of the five clusters of monogenetic volcanoes in quaternary central anatolian volcanic province cavp emf consists mainly of scoria cones and a few maars e g kutoren obruk previous studies on monogenetic volcanoes of cavp mainly focused on petrologic evolution of scoria cones rather than the statistical analyses of their morphological parameters using the database compiled by arcasoy 2001 for the morphometric parameters of the scoria cones in the emf we present the power law behavior of their size distribution with respect to basal diameters wco of 77 scoria cones from the whole database both empirical maximum likelihood estimation mle and graphical log log plot methods are used for the estimation of scaling parameter b value of power law for the scoria cones which have basal diameter greater than or equal to 0 36 km however graphical method gives the precise result with the b value of 2 78 0 08 for 77 scoria cones over the width range 0 1 1 23 km herein b value indicates the relative number of the small scoria cones with respect to large ones for a given area the power law behavior of the size distribution of scoria cones in the emf suggests that their occurrence is self organized critical phenomena similar to earthquakes since the size distribution of scoria cones provides information about their eruptive magnitude and occurrence mechanism our results can be directly applied to future risk assessment of the cavp

the role of external environmental factors in changing eruption styles of monogenetic volcanoes in a mio pleistocene continental volcanic field in western hungary abstract the occurrence shape structure and eruption style of monogenetic volcanoes such as maars tuff rings tuff cones and scoria cones are generally governed by several internal composition of the magma magmatic flux ascent rate viscosity volatile contents and external conditions regional and local tectonics topography and the presence of surfacial ground and meteoric water these controlling factors are together responsible for the eruption style distribution pattern volcanic facies architecture and morphology of the monogenetic volcanic landforms the late miocene to pleistocene bakony balaton highland volcanic field bbhvf in western hungary is a typical small sized at least 6 volcanic cycles have been identified by cluster analysis time gap between the cycles were vary from 1 66 up to 0 06 ma while the average eruption recurrence rate was 0 1078 ma event the time volume diagram of the volcanism of bbhvf have shown time predictive behavior combined with low magma flux total preserved volume 2 867 km3 and output rates 0 53 km3 ma for the entire volcanic field and 0 90 km3 ma for the last 5 cycles suggesting that volcanism was largely tectonically controlled and not magmatically controlled furthermore the topographic differences between the northern elevated and southern basin like parts of the volcanic field are also important in local differences in dominant fragmentation style because the elevated part of the field was prone to host large more magmatically evolved volcanoes than on the lower water saturated unconsolidated sediments which favored to the magma water interaction driven phreatomagmatic fragmentation the third controlling parameter which seems to play an important role in controlling the eruptive style of monogenetic volcanism at bbhvf was the paleoclimate fluctuation especially during the time interval of 3 0 to 2 5 ma thus mainly the long term environmental changes e g aridification have been response the shifting fragmentation style from phreatomagmatic to more magmatic ones

morpho chronology of monogenetic scoria cones from their level contour curves applications to the chichinautzin monogenetic field central mexico abstract the genesis distribution and hazards associated with monogenetic volcanic fields pose particular difficulties derived from their dispersed character establishing a relationship between the spatial and the age distributions of volcanic cones is necessary both to understand the nature of monogenetic field formation and evolution and to set supported hazard assessment criteria we present here a new method specifically developed to quantify the degree of age dependent erosion of individual scoria cones aimed to estimate the relative ages of undated scoria cones in a monogenetic volcanic field from a contour level morphometric analysis of the field digital elevation model dem this method is based on the hypothesis that age and the degree and type of erosion causing significant morphological changes on scoria cones are markedly correlated it is assumed that at the time of their formation monogenetic volcanoes have diverse yet smooth shapes which mechanical processes of wearing gradually change in different spatial scales this evolution is largely evidenced both as changes of the volcano slopes and as height dependent undulations of the cone surface generated by the hydrometeorological ablation in the otherwise uniform elevation contour lines here we characterize the time dependence of the shape and size of the altitude isoline undulations by means of the elliptical fourier descriptor spectra of the contour curves of volcanic cones to test the effects of the dem data type and resolution on this morpho chronological dating we analyze the correlations of published radiometric ages of cones with two datasets of contour curves from the sierra chichinautzin monogenetic volcanic field in central mexico scvf one obtained from airborne lidar surveys inegi mexico and the other from a satellite radar mission dlr germany

some remarks about a new last glacial record from the western salzach foreland glacier basin southern germany the amount of glacial advances into the alpine foreland during the pleistocene is still a matter of discussion the big four glaciations of the classical approach were originally derived from outwash sequences from glacial basins only very few long records and studies are known in the context of a geological mapping programme of the bavarian environment agency a research drilling through the salzach foreland glacier area was undertaken continuous coring reached the base of the glacial basin sequence 117 m below surface geological and geophysical logging pollen sampling and dating attempts of core material were conducted while age constraints for the lower part of the sequence are still uncertain the upper part can be ascribed to the last glacial cycle the interpretation of diamictons from the early part of the last glacial cycle is discussed a validation compared to other stratigraphic observations and interpretations from northern alpine quaternary records is presented

computer simulation models of scoria cone degradation abstract long term erosional modifications of the relatively simple morphology of scoria cinder cones are ideally suited for study by field and computer simulation methods a series of temporally distinct cones in the san francisco and springerville volcanic fields of arizona provides the foundation for documenting the degradational evolution of scoria cones in a semi arid climate progressive changes due to erosion are illustrated by the systematic decrease with increasing age of various morphometric parameters including scoria cone height cone height width ratio hco wco crater depth width ratio and slope angle for example holocene latest pleistocene cones in the san francisco field have a mean hco wco value of 0 178 0 041 a mean maximum slope angle of 29 7 4 2 and a mean average slope angle of 26 4 7 3 whereas the group of pliocene cones have values of 0 077 0 024 20 5 5 8 and 8 7 2 7 respectively comparative morphology of scoria cones is a potentially useful dating tool for mapping volcanic fields in order to better understand the degradational modifications of these volcanic landforms we have developed a numerical approach to simulate the surficial processes responsible for the erosion of a typical scoria cone the simulation algorithm can apply either a linear diffusion equation model or a model with a nonlinear transport law using a finite difference formulation the simulation operates upon a three dimensional scoria cone input as a matrix of elevation values utilizing both field and model results the correlation between changing hco wco value cone age and computer time step was expressed graphically to derive comprehensive values of the transport or diffusion coefficient df for both volcanic fields for the san francisco volcanic field df had a calculated value of 21 4 m2 kyr for the linear model and 5 3 m kyr for the nonlinear model while for the springerville volcanic field df had a calculated value of 24 4 m2 kyr for the linear model and 6 3 m kyr for the nonlinear model

lidar based quantification of lava flow susceptibility in the city of auckland new zealand abstract lava flows represent one of the most significant volcanic hazards from basaltic monogenetic volcanoes such as spatter cones scoria cones maars and tuff rings they are common features emanating from parasitic vents on the flanks of polygenetic volcanoes and in dominantly flat lying intraplate volcanic fields the auckland volcanic field avf is a volcanic field that has been active for the last ca 250 ka hosting at least 50 monogenetic volcanoes morphometric parameters of lava flows such as volume length thickness and area were used to quantify the potential lava flow inundation susceptibility to new zealand s most densely populated area the city of auckland based on an airborne light detection and ranging lidar digital surface model dsm the morphometric parameters of fifteen studied flows included average length of 2 5 km range 0 7 6 5 km overall average thickness of 14 8 m range 3 4 43 8 m average of maximum thicknesses of 48 2 m range 18 3 180 5 m average area occupied of 5 1 km 2 range 0 4 25 1 km 2 and average volume of 0 12 km 3 range 0 005 1 km 3 based on these parameters and a lidar derived dsm the present topography was classified into sea topographic depressions low lying areas prone to inundation by an average lava flow buffer zones prone to inundation only by extremely thick lava flows and peaks or ridges which are unlikely to be overtopped in monogenetic fields each new vent occurs in a new location creating uncertainty around the spatial location of the volcanic hazard thus this research provides a general vent location independent approach to describe the lava flow susceptibility for a potentially active monogenetic volcanic field what this analysis reveals is that the city of auckland can be divided into two distinct areas with strongly different susceptibility to lava flow inundation the southern part of the city is predominantly flat without hindrance to lava flow whereas the hilly northern and central part has many ridges that can limit or channelise lavas these contrasting properties must be accounted for in scenario based or probabilistic hazard and risk models developed for the avf

sedimentology eruptive mechanism and facies architecture of basaltic scoria cones from the auckland volcanic field new zealand abstract scoria cones are a common type of basaltic to andesitic small volume volcanoes e g 10 1 10 5 km 3 that results from gas bubble driven explosive eruptive styles although they are small in volume they can produce complex eruptions involving multiple eruptive styles eight scoria cones from the quaternary auckland volcanic field in new zealand were selected to define the eruptive style variability from their volcanic facies architecture the reconstruction of their eruptive and pyroclastic transport mechanisms was established on the basis of study of their volcanic sedimentology stratigraphy and measurement of their pyroclast density porosity scanning electron microscopy 2d particle morphology analysis and visible and near visible infrared spectroscopy collection of these data allowed defining three end member types of scoria cones inferred to be constructed from lava fountaining transitional fountaining and strombolian type and explosive strombolian type using the physical and field based characteristics of scoriaceous samples a simple generalised facies model of basaltic scoria cones for the avf is developed that can be extended to other scoria cones elsewhere the typical avf scoria cone has an initial phreatomagmatic phases that might reduce the volume of magma available for subsequent scoria cone forming eruptions this inferred to have the main reason to have decreased cone volumes recognised from auckland in comparison to other volcanic fields evolved dominantly in dry eruptive condition e g no external water influence it suggests that such subtle eruptive style variations through a scoria cone evolution need to be integrated into the hazard assessment of a potentially active volcanic field such as that in auckland

long term forecasting of the extreme eruptions of etna abstract until now the widely used predictive long term hazard models of the most intense natural phenomena do not yield predictions other than the mean return period to achieve less uncertain estimates an alternative model is proposed the analysis of the eruptions of etna from 1868 to 1993 shows that the time interval d t between consecutive large eruptions is clearly random whereas the total volume of tephra ejected during d t is roughly constant taking into account the above evidence the model yields significant long term forecasts both of the time and of the intensity of future large eruptions the large volume of tephra ejected by the volcano since the last intense eruption in 1980 allows the model to estimate that the next large eruption will not to take place soon

morphometry of scoria cones located on a volcano flank a case study from mt etna italy based on high resolution lidar data abstract by using new high resolution 2 m digital elevation model derived from the 2005 lidar survey of mt etna volcano italy our study measured the classical morphometrical parameters for scoria cones i e w co cone width w cr crater diameter h cone height as well as volume inclination of cone slope and substrate and a number of other parameters for 135 scoria cones of mt etna volume and age distribution of cones shows that there is no direct structural control on their emplacement in terms of etna s rift zones the cones are progressively smaller in size toward summit which can be explained by the large volcano s feeding system and progressively frequent lava burial toward top a careful analysis of h w co ratio determined as 0 18 for other volcanic fields worldwide shows that this ratio strongly depends on 1 the calculation method of h and 2 lava burial of cone for etnean cones applying an improved method for calculating h relative to the dipping substrate results in a significantly lowered standard h w co ratio 0 137 which in turn questions the validity of the classical value of 0 18 in the case of large central volcanoes the reduction of the ratio is not only due to methodology but also to the common lava burial this can be expressed even better if h mean is used instead of h max h mean w co 0 098 using this measure at etna well formed cones have higher ratios than structurally deformed e g double or rifted cones furthermore although the sampled scoria cones at etna have formed in a relatively narrow time interval h w co corresponding to erosional changes detected globally h w co 0 143 0 135 and 0 115 for three age classes of etna s scoria cones corresponding to average slopes of 26 6 23 9 and 23 7 because the morphometrical effect of position on a dipping substrate as well as lava burial exceeds the effect of erosion we call attention to use caution in simply using the h w co ratio of scoria cones for detecting age especially on large active volcanoes

the most complete quaternary record of the swiss alpine foreland abstract the open pit section at thalgut near berne switzerland had already been considered as a quite complete reference section with interglacial lacustrine beds complex glacial sequences and evidence for morphogenetic activity during an earlier interglacial by a drilling operation this section has been extended and completed a long core of a still older interglacial has been recovered containing palynostratigraphic segments characterized by high percentages of pterocarya and fagus pollen assemblages with this discovery the thalgut section has become the most complete quaternary sequence of the northern alpine foreland with two different interglacial lacustrine beds and with a relic paleosoil separated each by complex glacial and glaciolacustrine sediments this record also implies a much older age for maximum erosion in the alpine foreland

plio pleistocene red clay deposits in the pannonian basin a review terrestrial red clays underlying quaternary loess deposits or filling fissures and recently existing caves in limestone are named tengelic red clay formation and kerecsend red clay formation middle pliocene to lower pleistocene they occur in three types in hungary 1 the oldest red clays are mainly in situ weathering crusts rich in kaolinite formed in warm humid subtropical or monsoon climate 2 the younger type is rich in smectite and goethite and 3 illite and chlorite dominant in the youngest part which formed under warm and dry climates in savannah steppe or forest steppe environments and is of wind blown origin representative samples were selected for study from a large number of profiles mineralogical some micromorphological and geochemical investigations of typical samples of red clays in hungary were performed this review focuses on the origin development and distribution in the pannonian basin

long term forecasting of large volcanic eruptions abstract it is shown that the subareal volcanic system of the earth evolves like individual volcanoes preserving a constant average power a simple model that allows the forecasting of extreme eruptions is proposed and discussed

morphological and statistical characterisation of recent mafic volcanism on tenerife canary islands spain abstract tenerife is the largest island of the canarian archipelago and presents a complex volcanic history the construction of a mafic shield and a phonolitic composite volcano represent the main features of the volcanic evolution of the island both volcanic complexes are still active the first through two main rift zones and the second through the teide pico viejo central complex up to 297 mafic monogenetic volcanoes can be recognised on tenerife most of them corresponding to scoria cones that can been grouped into five geographical volcanic fields characterised by similar volcanological features the large number of these edifices compared to the other existing morphological volcano types indicates that they represent the most common eruptive events occurring during tenerife s recent geological past and therefore the type with the shortest recurrence period and the most likely to occur in the near future in this paper the most frequent mafic monogenetic volcano is defined by means of the statistical analysis of its main volcano morphological features cone height cone width ratio crater width crater depth etc we have applied a simple methodology of our own design based on statistical correlations and modal intervals of the morphological and morphometric parameters best defining the volcanoes morphology the most frequently identified mafic monogenetic volcano corresponds to a scoria cone with strombolian to violent strombolian dynamics 100 high and 3 in volume covering an area of 2 by defining this most common mafic volcano or volcano type we may provide key information on the nature of a potential volcanic event on tenerife in the future

explosive volcanic eruptions ix the transition between hawaiian style lava fountaining and strombolian explosive activity the commonest eruption styles of basaltic volcanoes involve hawaiian lava fountaining or intermittent strombolian explosions we investigate the ways in which magma rise speed at depth magma volatile content and magma viscosity control which of these eruption styles takes place we develop a model of the degree of coalescence between gas bubbles in the magma which allows us to simulate the transition between the two extreme styles of activity we find that magma rise speed is the most important factor causing the transition with gas content and viscosity also influencing the rise speed at which the transition occurs counter to intuitive expectations a decrease in gas content does not cause a transition from hawaiian to strombolian activity but instead causes a transition to passive effusion of vesicular lava rather a change from hawaiian to strombolian style requires a significant reduction in magma rise speed

eruptive mechanisms of the puig de la garrinada volcano olot garrotxa volcanic field northeastern spain a methodological study based on proximal pyroclastic deposits abstract an ephemeral and proximal outcrop at the quaternary basaltic puig de la garrinada cinder volcano was studied in order to decipher eruptive mechanism variations in the course of a single eruption once the volcanostratigraphy was established and recorded by photographs a very detailed sampling of underlying lava flows bombs and a large number of fine sized lapilli and ash beds was carried out an ad hoc description card was elaborated for study under stereo microscope in order to identify the different types of materials that form the volcanic cone ten material types were recognised sedimentary accidental clasts massive lava accidental clasts bombs xenoliths xenocrysts and phenocrysts oxidised scoria scoria with oxidised film fluidal pyroclasts non fluidal pyroclasts and coatings subsequent studies under sem eds and basic chemical characterization of the samples whole rock xrf for major and trace elements and empa were conducted all these studies make possible the reconstruction of the eruptive history of the la garrinada volcano which shows a transition from initial strombolian activity to gradually incorporated phreatomagmatic activity this permits the calculation of magma eruption rates magma column oscillations and aquifer interactions with magma column since our general conclusions agree well with the discrimination of eruptive episodes obtained from the stereo microscope description card macroscopic volcanostratigraphy and chemical results it is proposed that a similar study protocol quick volcanostratigraphy logging photographic record detailed sampling description following this card might be useful in the reconstruction of eruptive activity of other cinder cones in the garrotxa region and elsewhere and therefore can provide a good and quick methodological tool especially when rapid field description and sampling is required ephemeral outcrops risky sampling during active eruptive episodes etc moreover the conducted sampling allows for subsequent studies on the same set of pyroclasts

paleogeographic evolution of the late miocene lake pannon in central europe abstract the paleogeographic evolution of lake pannon within the pannonian basin is reconstructed with eight maps ranging from the middle miocene to the early pliocene the maps are based on the distribution of selected biozones and specific fossils and on complementary sedimentological and seismic information our reconstruction shows that the history of lake pannon can be divided into three distinct intervals an initial stage with low water level which resulted in isolation from the sea at about 12 ma and might have led to temporary fragmentation of the lake an interval of gradual transgression lasting until ca 9 5 ma and a long late interval of shrinkage and infilling of sediments that persisted into the early pliocene the deep subbasins of the lake formed during the transgressive interval in more basinward locations than the deep basins of the preceding sarmatian age the southern shoreline running parallel with the sava and danube rivers along the northern foot of the dinarides changed very little during the lifetime of the lake while the northern shoreline underwent profound changes

volcanism and paleoenvironment of the pula maar complex a pliocene terrestrial fossil site in central europe hungary abstract we describe the late pliocene paleoenvironment and paleoclimate of the pula fossil site of the western pannonian basin hungary which occurs within a lacustrine succession deposited in a volcanic crater maar radiometric dating of adjacent volcanic bodies hosting the fossil bearing sedimentary assemblages gives an age of 4 25 0 17 ma k ar to date five articulated rhinoceros skeletons dihoplus sp have been recovered and a few fragmentary remains of artiodactyls and freshwater fishes perca sp leuciscus sp and gobius sp are also present an insect taphocoenosis comprises terrestrial groups that inhabited the former lake margins syrphidae heteroptera chalcidoidea tenebrionidae as well as aquatic insects dytiscidae baetidae and chironomidae deciduous broad leaved woody plants prevailed in and around the pula locality quercus ulmus zelkova acer salicaceae and are associated with some rare floral elements ginkgo sassafras and buxus deposition at the lake bottom seems to have taken place in oxygen depleted layers and taphonomic evidence indicates that fossil material underwent minimal if any weathering 13c values of one rhinoceros tooth suggest that this mammal consumed mixed c3 plants in a wooded environment the climatic conditions inferred from the reconstructed vegetation and stable oxygen isotope data from the tooth enamel support a cf type climate koppen classification with a mean annual temperature of 10 13 c with some dry periods during the year pula is comparable to other maar fossil sites of pliocene age such as camp dels ninots spain and hajnacka i slovakia

geomorphology and spatial distribution of monogenetic volcanoes in the southern puna plateau nw argentina abstract monogenetic volcanoes are the most common volcanic landforms on earth several works have shown that the study of geomorphology and spatial distribution of such small volcanoes reveals important aspects related to the volcanic field from eruption dynamics to tectonic processes the altiplano puna plateau 15 to 27 s central andes comprises the largest non collisional plateau on earth characterized by intensive deformation uplift and volcanism this region is marked by the presence of hundreds of mafic monogenetic volcanoes despite its discrete occurrence the monogenetic volcanoes show a close relationship with large scale lithospheric foundering events in the region in this contribution we applied a geographic information system gis approach in order to build the first complete catalog of monogenetic landforms present in the southern puna plateau 24 30 to 27 00 s nw argentina exploring their evolution and relationship with geotectonic events combining spatial analysis with a geomorphological study of each volcano it was possible to identify the presence of 285 monogenetic volcanoes in the region which could be grouped in seven clusters southern puna shows a predominance of cinder cones and lava domes suggesting a small influence of water in the eruption dynamics despite its high clustering degree southern puna monogenetic vents present a low density 8 3 10 3 vents km2 when compared to other monogenetic fields around the world in addition puna plateau cones show a close relationship with monogenetic cones associated with an extensional environment considering their back arc context based on relative and available absolute ages it was possible to map the volcanism evolution through time the results indicate that the first monogenetic volcanoes appeared in the central region of the plateau sierra de calalaste mainly associated with large scale nne ssw reactivated faults the activity then expanded antofalla and antofagasta regions and finally reached the borders of the plateau pasto ventura and arizaro regions which show volcanoes associated with nw se normal faults

the fekete hegy balaton highland hungary soft substrate and hard substrate maar volcanoes in an aligned volcanic complex implications for vent geometry subsurface stratigraphy and the palaeoenvironmental setting the fekete hegy volcanic complex is located in the centre of the bakony balaton highland volcanic field in the pannonian basin which formed from the late miocene to pliocene period the eruption of at least four very closely clustered maar volcanoes into two clearly distinct types of prevolcanic rocks allows the observation and comparison of hard substrate and soft substrate maars in one volcanic complex the analyses of bedding features determination of the proportion of accidental lithic clasts granulometry and age determination helped to identify and distinguish the two types of maar volcanoes ascending magma interacted with meteoric water in karst aquifers in mesozoic carbonates as well as in porous media aquifers in neogene unconsolidated wet siliciclastic sediments the divided basement setting is reflected by distinct bedding characteristics and morphological features of the individual volcanic edifices as well as a distinct composition of pyroclastic rocks country rocks in hard substrate maars have a steep angle of repose leading to the formation of steep sided cone shaped diatremes enlargement and filling of these diatreme is mainly a result of shattering material by fci related shock waves and wall rock collapse during downward penetration of the explosion locus country rocks in soft substrate maars have much shallower angles of repose leading to the formation of broad bowl shaped structures or irregular depressions enlargement and filling of these diatremes is mainly the result of substrate collapse for example due to liquefaction of unconsolidated material by fci related shock waves and its emplacement by gravity flows the fekete hegy is an important example illustrating that the substrate of a volcanic edifice has to be taken into account as an important interface which can have major control on phreatomagmatic eruptions and the resulting characteristics of the volcanic complex

fracture control on type morphology and distribution of parasitic volcanic cones an example from mt etna italy abstract this paper uses a coupled morphometric and stratigraphic analysis of several tens of parasitic pyroclastic cones of the se flank of mt etna volcano italy to explain the structure of a poorly understood actively deforming zone of the volcano moreover we present a new general classification of pyroclastic cones based on the parameterisation of coeval eruption points along the same magma feeding fracture each cone has been studied in detail in order to define its stratigraphic position morphometric characteristics growth evolution in relation to fracture distribution and orientation stress field and morphology of the substratum end members of this classification are at one side a simple circular or elongated edifice that grew around a single eruption point and can be related to a magma feeding fracture constrained by a relatively high confining stress in the substratum or a low magma pressure the other end member is a multiple rifted strongly elongated cone formed along multiple eruption points of a magma feeding fracture constrained by a relatively low confining stress or a high magma pressure lithostratigraphic and historical analyses demonstrate that the cones in this area developed between 15 ka bp and historical times the most recent one in 1669 ad testifying to a high rate of lateral eruption occurrence in the area these cones show n s elongated maximum crater axes n s trending axis of the depressed points of the crater rim and southward and southeastward breaching directions while coeval cones are n s aligned these morphometric characteristics reflect the geometry of n s magma feeding fractures the area can be regarded as a transitional weakness zone between the n s rift and the releasing system represented by the transtensional trecastagni and mascalucia faults indicating an e w oriented local component of extension possibly related to the interplay between the regional timpe fault system and the eastward gravitational spreading of the volcano the azimuth of breaching is controlled by magma feeding fracture orientation and substrate morphology especially in the eastern part of the area where it is influenced by the scarps related to the timpe regional fault system but it is also sensitive to cone development

post eruptive sediment transport and surface processes on unvegetated volcanic hillslopes a case study of black tank scoria cone cima volcanic field california abstract conical volcanic edifices that are made up from lapilli to block bomb pyroclastic successions such as scoria cones are widespread in terrestrial and extraterrestrial settings eruptive processes responsible for establishing the final facies architecture of a scoria cone are not well linked to numerical simulations of their post eruptive sediment transport using sedimentological geomorphic and 2d fragment morphology data from a 15 ky old scoria cone from the cima volcanic field california this study provides field evidence of the various post eruptive sediment transport and degradation processes of scoria cones located in arid to semi arid environments this study has revealed that pyroclast morphologies vary downslope due to syn eruptive granular flows along with post eruptive modification by rolling bouncing and sliding of individual particles down a slope and overland flow processes the variability of sediment transport rates on hillslopes are not directly controlled by local slope angle variability and the flank length but rather by grain size and morphological characteristics of particles such as shape irregularity of pyroclast fragments and block lapilli ratio due to the abundance of hillslopes degrading in unvegetated regions such as those found in the southwestern usa granulometric influences should be accounted for in the formulation of sediment transport laws for geomorphic modification of volcanic terrains over long geologic time

first results of cosmogenic dated pre last glaciation erratics from the montoz area jura mountains switzerland the jura mountains are a perialpine chain bending from the sw to the nw of switzerland alpine ice reached only marginal areas of this chain during the last glacial maximum lgm but remaining erratic boulders of alpine origin indicate older glaciations of unknown age tentatively correlated either with the classical rissian or with the most extensive glaciation presented here are the first results of dating these pre lgm boulders by using cosmogenic radionuclides 10be and noble gases 21ne both data sets are in good agreement within 1 error with radionuclide apparent exposure ages ranging from 60 to 107 ka and noble gas apparent ages from 73 to 123 ka considering the importance of erosion on older boulders the age of the erratics corresponds most probably to marine isotope stage 6 these results are encouraging for further studies on pre lgm erratic boulders in the mid latitudes

40ar 39ar geochronology of neogene phreatomagmatic volcanism in the western pannonian basin hungary abstract neogene alkaline basaltic volcanic fields in the western pannonian basin hungary including the bakony balaton highland and the little hungarian plain volcanic fields are the erosional remnants of clusters of small volume possibly monogenetic volcanoes moderately to strongly eroded maars tuff rings scoria cones and associated lava flows span an age range of ca 6 myr as previously determined by the k ar method high resolution 40 ar 39 ar plateau ages on 18 samples have been obtained to determine the age range for the western pannonian basin neogene intracontinental volcanic province the new 40 ar 39 ar age determinations confirm the previously obtained k ar ages in the sense that no systematic biases were found between the two data sets however our study also serves to illustrate the inherent advantages of the 40 ar 39 ar technique greater analytical precision and internal tests for reliability of the obtained results provide more stringent constraints on reconstructions of the magmatic evolution of the volcanic field periods of increased activity with multiple eruptions occurred at ca 7 95 ma 4 10 ma 3 80 ma and 3 00 ma these new results more precisely date remnants of lava lakes or flows that define geomorphological marker horizons for which the age is significant for interpreting the erosion history of the landscape the results also demonstrate that during short periods of more intense activity not only were new centers formed but pre existing centers were rejuvenated

the activity of vesuvius in the next millennium abstract the time distribution of the historical eruptions of vesuvius allows the forecasting of the activity of the volcano for the next millennium according to three independent models the next event with volcanic explosivity index vei 4 is likely to occur during the next few decades followed by a decreasing number of smaller eruptions in the successive few centuries and by a very long period of quiescence up to the beginning of the following fourth millennium when the next plinian event vei 5 might occur

volcanism sedimentation interaction in the campo de calatrava volcanic field spain a magnetostratigraphic and geochronological study this work focuses on the influence of cenozoic volcanism of the campo de calatrava volcanic field on the sedimentation of two small continental basins in spain argamasilla and calzada moral basins the volcanism in this area was mainly monogenetic according to the small volume volcanic edifices of scoria cones that were generated and the occurrence of tuff rings and maars a sedimentological analysis of the volcaniclastic deposits led to the identification of facies close to the vents low density dilute pyroclastic surges secondary volcanic deposits and typical maar deposits whole rock k ar dating together with palaeomagnetic constraints yielded an age of 3 11 3 22 ma for the onset of maar formation the deposition finished in the late gauss early matuyana using both techniques and previous paleontological data allowed it to be inferred that the maar formation and the re sedimentation stage that occurred in argamasilla and calzada moral basins were roughly coeval the occurrence of syn eruption volcaniclastic deposits with small thicknesses that were separated by longer inter eruption periods where fluvial and lacustrine sedimentation was prevalent together with the presence of small volume volcanic edifices indicated that there were short periods of volcanic activity in this area the volcanic activity was strongly controlled by previous basement faults that favoured magma feeding and the faults also controlled the location of volcanoes themselves the occurrence of the volcanoes in the continental basins led to the creation of shallow lakes that were related to the maar formation and the modification of sedimentological intra basinal features specifically valley slope and sediment load

syn eruptive morphometric variability of monogenetic scoria cones according to wood s model morphometric parameters such as slope angle can provide valuable information about the age of conical volcanic edifices such as scoria cones assuming that their initial slopes range from 30 to 33 measured manually on topographic maps and assuming that their inner architectures are homogenous this study examines the morphometric variability of nine young a few thousand years old small volume scoria cones from tenerife canary islands using high resolution digital elevation models in order to assess their slope angle variability because of the young age and minimal development of gullies on the flanks their morphometric variability can be interpreted as the result of syn eruptive processes including 1 pre eruptive surface inclination 2 vent migration and lava outflow with associated crater breaching and 3 diversity of pyroclastic rocks accumulated in the flanks of these volcanic edifices results show that slope angles for flank sectors differ by up to 12 among the studied volcanoes which formed over the same period of time this range greatly exceeds the 2 3 indicated by wood the greater than expected original slope range suggests that use of morphometric data in terms of morphometry based relative dating and detection of erosional processes and settings must be done with great care or detailed knowledge about absolute ages and eruption history especially in field scale morphometric investigation

a model for calculating eruptive volumes for monogenetic volcanoes implication for the quaternary auckland volcanic field new zealand abstract monogenetic basaltic volcanism is characterised by a complex array of behaviours in the spatial distribution of magma output and also temporal variability in magma flux and eruptive frequency investigating this in detail is hindered by the difficulty in evaluating ages of volcanic events as well as volumes erupted in each volcano eruptive volumes are an important input parameter for volcanic hazard assessment and may control eruptive scenarios especially transitions between explosive and effusive behaviour and the length of eruptions erosion superposition and lack of exposure limit the accuracy of volume determination even for very young volcanoes in this study a systematic volume estimation model is developed and applied to the auckland volcanic field in new zealand in this model a basaltic monogenetic volcano is categorised in six parts subsurface portions of volcanoes such as diatremes beneath phreatomagmatic volcanoes or crater infills are approximated by geometrical considerations based on exposed analogue volcanoes positive volcanic landforms such as scoria spatter cones tephras rings and lava flow were defined by using a light detection and ranging lidar survey based digital surface model dsm finally the distal tephra associated with explosive eruptions was approximated using published relationships that relate original crater size to ejecta volumes considering only those parts with high reliability the overall magma output converted to dense rock equivalent for the post 250 ka active auckland volcanic field in new zealand is a minimum of 1 704 km3 this is made up of 1 329 km3 in lava flows 0 067 km3 in phreatomagmatic crater lava infills 0 090 km3 within tephra tuff rings 0 112 km3 inside crater lava infills and 0 104 km3 within scoria cones using the minimum eruptive volumes the spatial and temporal magma fluxes are estimated at 0 005 km3 km2 and 0 007 km3 ka the temporal volumetric evolution of auckland is characterised by an increasing magma flux in the last 40 ky which is inferred to be triggered by plate tectonics processes e g increased asthenospheric shearing and backarc spreading of underneath the auckland region

evaluation of morphometry based dating of monogenetic volcanoes a case study from bandas del sur tenerife canary islands morphometry based dating provides a first order estimate of the temporal evolution of monogenetic volcanic edifices located within an intraplate monogenetic volcanic field or on the flanks of a polygenetic volcano two widely used morphometric parameters namely cone height width ratio hmax wco and slope angle were applied to extract chronological information and evaluate their accuracy for morphometry based ordering based on these quantitative parameters extracted from contour based digital elevation models dems two event orders for the bandas del sur in tenerife canary islands were constructed and compared with the existing k ar paleomagnetic and stratigraphic data the results obtained suggest that the commonly used hmax wco ratio is not reliable leading to inappropriate temporal order estimates while the slope angle gives slightly better results the overall performance of such descriptive parameters was however generally poor i e there is no strong correlation between morphometry and age the geomorphic morphometric mismatches could be the result of 1 the diversity of syn eruptive processes i e diverse initial morphologies causing geomorphic morphometric variability 2 contrasting edifice specific degradation that depends partly upon the inner facies architecture of the volcanic edifices 3 various external environmental controls e g tephra mantling from pyroclastic density currents unrelated to the edifice evaluated and 4 differences in the scale resolution of input data the observed degradation trend and changes in morphometric parameters over time do not support a simple degradation model for monogenetic scoria cones volcanoes

structural and morphometric irregularities of eroded pliocene scoria cones at the bakony balaton highland volcanic field hungary abstract scoria cones of the mio pliocene bakony balaton highland volcanic field bbhvf are built up by wide range of volcanic rocks including intercalated lava flows dykes pyroclastic breccias and scoriaceous lapilli with various degrees of welding or agglutination according to k ar and ar ar dating ages of the fourteen scoria cones within the field span between 5 2 and 2 5 ma from these fourteen seven cones were selected which are suitable for morphometric analysis i e visible in the field and have identifiable boundaries the morphometric data were either derived by manual measurement on topographic maps and by digital elevation model based calculations using the same input contour line data from 1 10 000 maps basic cone parameters such as cone height basal and crater width have been measured in order to calculate parameters like h co w co ratio and average slope angle the results of these three parameter based manual calculations have been compared to the dem based results in order to highlight the controls of degradation pitfalls in morphometric parameterization and the differences between these two calculation methods based on the results three main controlling conditions have been identified that are together responsible for the preservation and erosion of the scoria cones located in the bbhvf 1 age of the cone 2 climate during the degradation and the 3 inner architecture of the edifice in terms of morphometric dating the traditional three parameter based method tends to give inaccurate results on 1 scattered and or truncated cones and 2 on the edifices characterised by highly effusive behaviour during the emplacement

geomorphology of the post caldera monogenetic volcanoes at deception island antarctica implications for landform recognition and volcanic hazard assessment abstract deception island is one of the most active volcanoes in antarctica with more than 20 monogenetic eruptions during the holocene the latest episodes of 1967 1969 and 1970 have shown that volcanic activity on deception island can become a concern for tourists scientists and military personnel working on or near the island the objective of this work is to identify eruptive processes and the geomorphic evolution of post caldera monogenetic volcanic edifices at deception island by morphometric analyses supported by field observations morphometric analysis has been used since the 1970s to analyse scoria cones but it has rarely been applied to other monogenetic volcanoes such as tuff cones and tuff rings tuff cones and tuff rings represent the most common landforms during deception island s recent geological past with over 70 scattered eruptive vents inside and along the caldera rim these volcanic landforms have been studied based on field observations and later digital elevation model analyses their geometry ranges from 10 to 100 m in height and diameters vary between 300 and 2500 m the morphometric data suggest that tuff cones have a more circular crater than tuff rings with a significant separation between the two landforms using the height hco and basal width wco parameters tuff cones have hco wco ratios with values between 0 04 and 0 16 and outer slopes between 7 and 34 tuff rings have lower hco wco ratios that are between 0 01 and 0 04 and lower outer slopes between 3 and 21 this study shows that basic shape parameters in combination with slope angle analysis can be used to discriminate among different types of monogenetic volcanoes the initial eruptive related morphometric diversity however prevents correlation of eruption ages with morphometric parameters or constructing a relative chronology of the monogenetic eruptions this work provides a better comprehension of the potential evolution of a future eruption and a broader understanding of volcanic hazards on deception island

long continental records of climate an introduction abstract the symposium on long continental records presented new information on past climates on land it seems that throughout the last 2 5 million years the climate in the middle latitudes changed in the same complex fashion as during the better known late pleistocene and holocene times over 40 interglacial glacial shifts took place during this interval out of those 40 10 12 glacials were markedly stronger and or longer lasting than the others the apparently abrupt shifts from interglacials to glacials were probably gradual oscillatory coolings interrupted by warming episodes in that respect the detailed anatomy of the past climate changes does not differ substantially from the climate oscillations documented by instrumental weather records in the last two centuries the pronounced expansions of dry and cold steppes on land were accompanied by corresponding increases of the ice volume indicated by the oxygen isotope ratio the two exceptions occurred around 1 4 ma ago and 1 6 ma ago the reason for this discrepancy is not known by far the most expressed change of land environments occurred at about 2 4 ma ago

eruptive history of the late quaternary ciomadul csomad volcano east carpathians part ii magma output rates this study which builds on high precision unspiked cassignol gillot k ar age determinations presents an advanced dem based volumetrical analysis to infer long term magma output rates for the late quaternary ciomadul csomad dacitic lava dome complex east carpathians romania the volcanic field of ciomadul developed on the erosional surface of lower cretaceous flysch and 2 ma old andesites and experienced an extended eruptive history from 850 to 30 ka predominantly effusive activity took place during the first stage 850 to 440 ka producing volumetrically minor isolated peripheral domes subsequently after a 250 ky repose interval a voluminous central dome cluster developed in the second stage 200 to 30 ka during the youngest phase of evolution 60 to 30 ka highly explosive eruptions also occurred resulting in the formation of two craters mohos and st ana the calculated 8 00 0 55 km3 total volume of the lava domes which includes the related volcaniclastic 1 57 km3 as well as erosionally removed 0 18 km3 material is in line with dimensions of other medium sized dacitic lava domes worldwide this volume was extruded at an average long term magma output rate of 9 76 km3 my 0 0098 km3 ky however most of the domes 7 53 0 51 km3 were formed in the 200 to 30 ka period implying a significantly increased magma output rate of 37 40 km3 my 0 0374 km3 ky more than 30 times higher than in the first stage within these long term trends individual lava domes of ciomadul e g those with volumes between 0 02 and 0 40 km3 would have been emplaced at much higher rates over a period of years to tens of years the active periods lasting up to hundreds of years would have been followed by repose periods 30 times longer the most recent eruption of ciomadul has been dated here at 27 7 1 4 ka this age which is in agreement with radiocarbon dates for the onset of lake sediment accumulation in st ana crater dates fragmented lava blocks which are possibly related to a disrupted dome this suggests that during the last typically explosive phase of ciomadul lava dome extrusion was still ongoing in a global context the analysis of the volumetric dynamism of ciomadul s activity gives insights into the temporal variations in magma output at lava domes short term day or week scale eruption rates smooth out in long term millenia scale output rates which are tens of times lower

degradation of quaternary cinder cones in the cima volcanic field mojave desert california basaltic cinder cones in the cima volcanic field record a detailed history of progressive erosion in the arid environment of the eastern mojave desert these cones range in age from 0 015 m y to 1 09 0 08 m y as dated by radiocarbon or k ar analyses of the youngest lava flows from each cone cone heights range from 50 to 155 m and basal widths range from 400 to 915 m on younger cones height width ratios average 0 17 and crater width cone width ratios average 0 42 the degradational morphology of these cones displays several trends that are closely related to cone age 1 crater width cone width ratios decrease from 0 48 on the youngest cone to 0 21 on the oldest cone with a preserved crater 2 mean maximum side slopes tan sc decrease from 0 575 on the youngest cone to an average of 0 41 on the oldest cones studied 3 debris apron height cone height ratios increase from 0 10 on the youngest cone to an average of 0 34 on the oldest cones 4 cone drainage evolves from irregularly spaced rills and gullies on the youngest cone to regularly spaced gullies on 0 20 to 0 35 m y old cones to valleys as much as 110 m wide and 10 m deep on cones 0 59 m y old and older these trends form the basis of an empirical model of cinder cone degradation in arid environments this model documents 1 an erosional loss of 15 of cone volume during the first million years 2 progressive decline of cone slope at an average rate of 0 006 103 yr and cone height at an average rate of 2 25 cm 103 yr 3 initial rapid stripping of the loose cinder mantle from upper cone slopes accompanied by rapid debris apron formation and 4 a gradual transition between 0 25 and 0 6 m y from relatively uniform stripping of upper slopes to localized fluvial dissection of both cone slopes and debris apron this transition is apparently controlled by a concomitant change from diffuse subsurface drainage within the pervious cinder mantle to concentrated surface flow across the heterogeneous assemblage of agglutinate layers dikes and ponded flows of the cone interior

wind erosion under cold climate a pleistocene periglacial mega yardang system in central europe western pannonian basin hungary abstract mega yardangs are known to form under extremely arid warm or in some instances moderate climates here we report on the mega yardang field of the pannonian basin hungary which was uniquely formed under periglacial probably semi arid conditions and discuss its implications on factors controlling yardang formation in general the yardang field is composed of advanced streamlined forms and of less aerodynamic ridges separated by well developed corridors the length of the largest features exceeds 60 km their height varies around 150 m together with ventifacts deflation hollows and wind blown sand areas the yardang field is part of an integrated eolian feature system driven by northerly to northwesterly winds dating of ventifact surfaces with in situ produced cosmogenic nuclides places the onset of significant wind erosion to the early pleistocene 1 5 ma osl dated young loess from which well developed yardangs were sculpted and wind blown sands show that eolian action continued until the early holocene the long temporal range of wind erosion compared to average yardang formation rates and the rarity of advanced yardang forms indicate intermittent and relatively short most probably millennial scale deflation periods since the early holocene the system has been inactive and demonstrates that yardangs can persist in a recognizable form for several millennia even under less arid conditions the main control on yardang formation appears to be the existence of strong unidirectional winds in the pannonian basin facilitated mainly by the channeling effect of topographic lows in the surrounding mountain chains yardangs can form even under semi arid climates however the rarity of these occurrences suggests that this requires a special association of environmental conditions yardang formation is facilitated by homogeneous lithology namely by widespread weakly consolidated sandy sediments the distribution of yardang fields is controlled by vertical neotectonic movements which provided uplifted areas to be sculptured and topographic obstacles that sheltered downwind sediments faulting can be excluded as a controlling factor in mega yardang formation nor is the role of jointing supported

the assignment of drainage direction over flat surfaces in raster digital elevation models abstract drainage direction assignment over flat surfaces in raster digital elevation models dem has been a stubborn problem for dem processing methods a new approach that improves upon current methods of flat surface treatment is presented the approach is based on the recognition that in natural landscapes drainage is generally away from higher and towards lower terrain to produce such a drainage dem elevations of a flat surface are modified to impose two gradients one away from higher terrain and one towards lower terrain subsequent processing of the dem produces a drainage pattern over the flat surface that is topographically consistent and exhibits flow convergence properties the proposed approach is not restricted by the shape of the flat surface the number of outlets on its edge or the complexity of the surrounding topography a comparison with the drainage pattern of an established method that displays the parallel flow problem shows significant improvements in producing realistic drainage patterns the proposed approach extends automated dem processing to digital landscapes for which existing methods cannot provide adequate flow directions over flat surfaces to conduct a drainage analysis the necessary algorithmic details for implementation of the approach are provided 1997 elsevier science b v

emplacement conditions of the 1256 ad al madinah lava flow field in harrat rahat kingdom of saudi arabia insights from surface morphology and lava flow simulations abstract lava flow hazard modelling requires detailed geological mapping and a good understanding of emplacement settings and the processes involved in the formation of lava flows harrat rahat kingdom of saudi arabia is a large volcanic field comprising about 1000 predominantly small volume volcanoes most of which have emitted lava flows of various lengths a few eruptions took place in this area during the holocene and they were located in the northern extreme of the harrat rahat a close proximity to critical infrastructure and population living in al madinah city in the present study we combined field work high resolution digital topography and morphometric analysis to infer the emplacement history of the last historical event in the region represented by the 1256 ad al madinah lava flow field these data were also used to simulate 1256 ad type lava flows in the harrat rahat by the magflow lava flow emplacement model which is able to relate the flow evolution to eruption conditions the 1256 ad lava flow field extent was mapped at a scale of 1 1000 from a high resolution 0 5 m light detection and ranging lidar digital terrain model dtm aerial photos with field support the bulk volume of the lava flow field was estimated at 0 4 km3 while the source volume represented by seven scoria cone was estimated at 0 023 km3 the lava flow covered an area of 60 km2 and reached a maximum length of 23 4 km the lava flow field comprises about 20 9 of p hoehoe 73 8 of a and 5 3 of late stage outbreaks our field observation also suggests that the lava flows of the harrat rahat region are mainly core dominated and that they formed large lava flow fields by amalgamation of many single channels these channels mitigated downslope by topography lava flow and channel channel interactions highlighting this typical process that needs to be considered in the volcanic hazard assessment in the region a series of numerical lava flow simulations was carried out using a range of water content 0 1 1 wt solidification temperature 800 600 c and effusion curves simple and complex curves these simulations revealed that the magflow code is sensitive to the changes of water content of the erupting lava magma while it is less sensitive to solidification temperature and the changes of the shape of effusion curve the advance rate of the simulated lava flows changed from 0 01 to 0 22 km h using data and observations from the youngest volcanic event of the harrat rahat as input parameters to magflow code it is possible to provide quantitative limits on this type of hazard

quantitative analysis of land surface topography land surface topography significantly affects the processes of runoff and erosion a system which determines slope aspect and curvature in both the down slope and across slope directions is developed for an altitude matrix also the upslope drainage area and maximum drainage distance are determined for every point within the altitude matrix a fortran 66 program performs the analysis

the al du aythah volcanic cones al madinah city implications for volcanic hazards in northern harrat rahat kingdom of saudi arabia the basaltic al du aythah volcanic cones lie in the northern part of the extensive lava field of harrat rahat and only 13 km from the centre of al madinah city in the kingdom of saudi arabia historical records indicate they may have erupted in ad 641 the four cones are formed by deposits that record a transition from phreatomagmatic to magmatic explosions followed by minor lava effusion three cones display elongated tuff rings at the base and two produced late stage lava flows the cones themselves are symmetrical and constructed mostly by the accumulation of ballistically ejected pyroclasts spherical bombs and lapilli cannonball bombs lapilli occasionally with country rock fragments inside both cored and loaded bombs lapilli are common within the tuff ring deposits lidar data show a total volume of 1 664 10 6 km3 for the four cones 418 10 6 km3 dre whole rock chemical analyses indicate alkali basalt compositions sio2 44 7 45 9 wt with little compositional variation and no relationship between chemistry and eruptive styles small differences in composition may reflect variations in fractional crystallisation of clinopyroxene and olivine a magnetotelluric 2d cross section shows that the cones are located adjacent to a buried sediment filled alluvial channel along a nnw sse fault dipping to the east the al du aythah eruption was related to the ascent of magma through this structure with the first phase of the eruption triggered by the interaction of the magma with water from the northern harrat rahat aquifer that exists in the al madinah basin this initial water source was rapidly exhausted while the eruption progressed roughly from north to south and from west to east the latter motion probably along the fault controlled feeding dyke our work draws attention to the existence of recent explosive phreatomagmatic eruptions in the al madinah basin which despite the hyperarid climate of the area must be considered a potential future eruption hazard