the evolution of early oceanic lithosphere in the southern red sea abstract it seems generally agreed that the red sea has formed by the rotation of arabia from africa about a pole of rotation at 36 5 n 18 0 e but the exact way in which the oceanic lithosphere has evolved between the separating plates remains unclear this paper is concerned with the evolution of the earliest oceanic lithosphere in the southern red sea a combined study is made of gravity magnetic and seismic refraction data for a region on the southeast margin of the red sea between 16 3 n 17 3 n and 41 6 e 43 1 e a model is evolved which satisfies all the geological and geophysical data a feature of this model is that the ocean continent boundary might be 35 km inland from the coast and only 8 km from the exposed precambrian shield in this region the coastal plain being underlain by early oceanic lithosphere this implies that the break in the continental lithosphere was fairly clean

an overview of experimental models to understand a complex volcanic instability application to mount etna italy abstract volcanic edifices are often unable to support their own load triggering the instability of their flanks many analogue models have been aimed especially in the last decade at understanding the processes leading to volcano flank instability general behaviors were defined and the experimental results were compared to nature however available data at well studied unstable volcanoes may allow a deeper understanding of the specific processes leading to instability providing insights also at the local scale etna italy constitutes a suitable example for such a possibility because of its well monitored flank instability for which different triggering factors have been proposed in the last two decades among these factors recent insar data highlight the role played by magmatic intrusions and a weak basement under a differential unbuttressing at the volcano base this study considers original and recently published experimental data to test these factors possibly responsible for flank instability with the final aim to better understand and summarize the conditions leading to flank instability at etna in particular we simulate the following processes a the long term activity of a lithospheric boundary as the malta escarpment separating the ionian oceanic lithosphere from the continental sicilian lithosphere below the most unstable east flank of the volcano b spreading due to a weak basement with different boundary conditions c the pressurization of a magmatic reservoir as that active during the 1994 2001 inflation period d dike emplacement as observed during the major 2001 and 2002 2003 eruptions the experimental results suggest that 1 the long term activity of a lithospheric tectonic boundary may create a topographic slope which provides a differential buttressing at the volcano base a preparing factor to drive longer term 10 5 years instability on the east flank of the volcano 2 volcano spreading 4 years has limited effect on flank instability at etna 3 magmatic intrusions 1 years both in the form of mogi like sources or dikes provide the most important conditions to trigger flank instability on the shorter term

the dead sea transform fault system abstract a new map showing the major features of the dead sea transform fault system based on seismicity satellite imagery geological maps and bathymetric charts is presented special attention is given to the possible northward continuation of the transform system beneath the mediterranean sea near ed damur south of beirut the map shows the dead sea transform system to be a series of offset overlapping left lateral transform faults with a rhombochasm between each pair the system has similarities with the equatorial fracture zones in the atlantic ocean throughout the dead sea transform system is considered in its regional setting i e as extending from the red sea spreading centre in the south to the eurasian collision zone in the north it is suggested that it may intersect the latter somewhere east of cyprus making that area the northernmost termination of the dead sea transform system

integrated 3d density modelling and segmentation of the dead sea transform a 3d interpretation of the newly compiled bouguer anomaly in the area of the dead sea rift is presented a high resolution 3d model constrained with the seismic results reveals the crustal thickness and density distribution beneath the arava araba valley av the region between the dead sea and the gulf of aqaba elat the bouguer anomalies along the axial portion of the av as deduced from the modelling results are mainly caused by deep seated sedimentary basins d 10 km an inferred zone of intrusion coincides with the maximum gravity anomaly on the eastern flank of the av the intrusion is displaced at different sectors along the nnw sse direction the zone of maximum crustal thinning depth 30 km is attained in the western sector at the mediterranean the southeastern plateau on the other hand shows by far the largest crustal thickness of the region 38 42 km linked to the left lateral movement of approx 105 km at the boundary between the african and arabian plate and constrained with recent seismic data a small asymmetric topography of the moho beneath the dead sea transform dst was modelled the thickness and density of the crust suggest that the av is underlain by continental crust the deep basins the relatively large intrusion and the asymmetric topography of the moho lead to the conclusion that a small scale asthenospheric upwelling could be responsible for the thinning of the crust and subsequent creation of the dead sea basin during the left lateral movement a clear segmentation along the strike of the dst was obtained by curvature analysis the northern part in the neighbourhood of the dead sea is characterised by high curvature of the residual gravity field flexural rigidity calculations result in very low values of effective elastic lithospheric thickness te 5 km this points to decoupling of crust in the dead sea area in the central av the curvature is less pronounced and te increases to approximately 10 km curvature is high again in the southernmost part near the aqaba region solutions of euler deconvolution were visualised together with modelled density bodies and fit very well into the density model structures

the december 2002 july 2003 effusive event at stromboli volcano italy insights into the shallow plumbing system by petrochemical studies abstract on 28 december 2002 the persistent strombolian activity at stromboli was interrupted by the sudden onset of lava emission onto the sciara del fuoco slope a horseshoe shaped depression on the nw flank of the volcano the effusive episode went on until 22 july 2003 and produced a cumulative volume of lavas of 11 106 m3 ranking the event as the largest occurred in the past 30 years the eruptive vents were mainly located in the ne sector of the sciara del fuoco depression at an elevation of 550 600 m a s l on 30 december the eastern portion of the sciara del fuoco collapsed producing a tsunamigenic landslide on 5 april 2003 a paroxysmal eruption occurred at the summit craters during which crystal poor pumiceous products were emitted the paroxysm did not interrupt the lava emission the strombolian activity at the summit craters gradually resumed starting from march 2003 and fully recovered by the end of july periodic sampling of the lava at the active vents was carried out during the entire effusive event all the analysed samples are shoshonitic basalts sio2 48 5 50 4 wt k2o 2 1 2 4 wt in the range of composition observed in the products erupted during the past 20 years they bear about 50 vol zoned crystals of plagioclase an90 60 diopside augite and olivine fo70 73 in a compositionally homogeneous shoshonitic groundmass bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations sr and nd isotope ratios are close to those of the crystal rich scoriae erupted in the previous years despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit the data show that the switch from strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 april eruption are likely accounted by limited mixing between the fresh volatile rich crystal poor magma erupted as pumice during the paroxysm and the volatile poor crystal rich magma feeding the lava flow the uniform composition of the erupted lava indicates the presence of a large volume of well mixed crystal rich homogeneous magma residing in the shallow plumbing system of the volcano two possible trigger mechanism of the effusive event are here proposed i a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation degassing and mixing with the crystal rich shallow magma which re homogenised the system these processes eventually led to the rise of the magma at a higher level and failure of the conduit walls ii the onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades the process of progressive refilling initiated after the 1985 effusive eruption ultimately culminated on 28 december 2002 with the failure of the conduit wall and the opening of vents 100 150 m below the summit craters

bronze age upland settlement decline in southwest england testing the climate change hypothesis abstract the division of land on dartmoor during the bronze age by the construction of moor wide boundaries known as reaves represents a significant development in agricultural practice and land tenure previous research relating to the dartmoor reaves suggests this way of life may have continued for no longer than 200 400 years it has been suggested that their abandonment occurred as the result of a deteriorating climate although there are no published palaeoclimatic reconstructions from the area we therefore test the hypothesis that on dartmoor a marked climatic deterioration occurred in the late bronze age that can be linked to the abandonment of the reaves a palaeoclimatic reconstruction derived from testate amoebae and peat humification analyses is presented from tor royal bog central dartmoor the first such record from southwest england a major shift to a cooler and or wetter climate is inferred from ca 1395 to 1155 cal bc that is coincident with the period hypothesised as encompassing the abandonment this climatic deterioration is replicated in sites in northern britain suggesting it was a widespread event it is concluded that while the evidence supports a climatically forced retreat there are a range of other socio economic factors that must also be taken into consideration

seismic tomographic imaging of the eastern mediterranean mantle implications for terminal stage subduction the uplift of anatolia and the development of the north anatolian fault

volcaniclastic dykes tell on fracturing explosive eruption and lateral collapse at stromboli volcano italy abstract in the upper part of the stromboli volcano in the le croci and bastimento areas two dyke like bodies of volcanic breccia up to two metre thick crosscut and intrude the products of vancori and neostromboli volcanoes we describe the lithofacies association of these unusual volcaniclastic dykes interpret the setting of dyke forming fractures and the emplacement mechanism of internal deposits and discuss their probable relationships with the explosive eruption and major lateral collapse events that occurred at the end of the neostromboli period the dyke volcaniclastic deposits contain juvenile magmatic fragments pyroclasts suggesting a primary volcanic origin their petrographic characteristics are coincident with the neostromboli products the architecture of the infilling deposits comprises symmetrically nested volcaniclastic units separated by sub vertical boundaries which are parallel to the dyke margins the volcanic units are composed of distinctive lithofacies the more external facies is composed of fine and coarse ash showing sub vertical laminations parallel to the contact wall the central facies comprises stratified lithic rich breccia and lapilli tuff whose stratification is sub horizontal and convolute discordant to the dyke margins only at le croci dyke the final unit shows a massive tuff breccia facies the volcaniclastic dykes experienced a polyphasic geological evolution comprising three stages the first phase consisted in fracturing explosive intrusion related to magma rising and upward injection of magmatic fluids and pyroclasts the second phase recorded the dilation of fractures and their role as pyroclastic conduits in an explosive eruption possibly coeval with the lateral collapse of the neostromboli lava cone finally in the third phase the immediately post eruption mass flow remobilization of pyroclastic deposits took place on the volcano slopes

the selection of sites for paleovegetational studies the judicious selection of sites for paleovegetational and paleoclimatic studies permits paleoecologists to answer specific research questions that go beyond primary descriptions of past vegetation we present a model that describes the relationship between basin size and pollen source area and predicts the proportions of local extralocal and regional pollen sampled by lake basins of different size the distinctive sampling properties of lakes peats and small hollows can be exploited to provide details of pattern in paleovegetation so long as attention is given to the limitations and problems of these types of sites combinations of site types in a single study most fully exploit the information contained in sediments

seismic gravity and magnetic surveys in the central part of the red sea their interpretation and implications for the structure and evolution of the red sea abstract while there is unanimous agreement that the axial part of the red sea has witnessed seafloor spreading since the early pliocene opinions diverge considerably with regard to the situation in the main trough and shelves new high precision data comprising palaeomagnetic seismic gravity magnetic and bathymetric measurements from the central and northern parts of the red sea have been examined to discriminate between the earlier proposed hypotheses and to formulate an evolutionary model for the red sea the results show that oceanic crust extends for about 80 km at 19 n on each side of the spreading axis symmetrical seafloor spreading magnetic anomalies are recognized out to anomaly 3a 6 m y b p between 18 30 and 19 45 n anomaly 2a between 19 45 and 20 n and near 21 n anomaly 2 near 22 n and only anomaly 1 near 23 30 n although anomaly 3a is the oldest recognizable magnetic anomaly the extent and configuration of the oceanic basement as determined from seismic measurements indicate that spreading has started and continued without a hiatus since 10 12 m y b p prior to the initiation of oceanic accretion an extension of 40 55 km i e 50 70 has taken place in the proterozoic continental lithosphere whereas a separation of 70 160 km has occurred during the seafloor spreading phase several lines of evidence indicate that the shelves and the marginal parts of the main trough are of continental nature

source mechanisms of explosions at stromboli volcano italy determined from moment tensor inversions of very long period data 1 seismic data recorded in the 2 30 s band at stromboli volcano italy are analyzed to quantify the source mechanisms of strombolian explosions during september 1997 to determine the source centroid location and source mechanism we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous elastic medium that takes topography into account two source centroids are identified each representative of the distinct event types associated with explosive eruptions from two different vents the observed waveforms are well reproduced by our inversion and the two source centroids that best fit the data are offset 220 and 260 m beneath and 160 m northwest of the active vents the source mechanisms include both moment tensor and single force components the principal axes of the moment tensor have amplitude ratios 1 1 2 which can be interpreted as representative of a crack if one assumes the rock matrix at the source to have a poisson ratio n 1 3 a value appropriate for hot rock both imaged cracks dip 60 to the northwest and strike northeast southwest along a direction parallel to the elongation of the volcanic edifice and a prominent zone of structural weakness as expressed by lineaments dikes and brittle structures for our data set the volume changes estimated from the moments are 200 m 3 for the largest explosion from each vent together with the volumetric source is a dominantly vertical force with a magnitude of 10 8 n consistent with the inferred movement of the magma column perched above the source centroid in response to the piston like rise of a slug of gas in the conduit index terms 7215 seismology earthquake parameters 7280 seismology volcano seismology 8419 8414 volcanology eruption mechanisms keywords very long period seismicity moment tensor inversions eruption mehanics

global shear speed structure of the upper mantle and transition zone s u m m a r y the rapid expansion of broad band seismic networks over the last decade has paved the way for a new generation of global tomographic models significantly improved resolution of global upper mantle and crustal structure can now be achieved provided that structural information is extracted effectively from both surface and body waves and that the effects of errors in the data are controlled and minimized here we present a new global vertically polarized shear speed model that yields considerable improvements in resolution compared to previous ones for a variety of features in the upper mantle and crust the model sl2013sv is constrained by an unprecedentedly large set of waveform fits 3 4 of a million broad band seismograms computed in seismogram dependent frequency bands up to a maximum period range of 11 450 s automated multimode inversion of surface and s wave forms was used to extract a set of linear equations with uncorrelated uncertainties from each seismogram the equations described perturbations in elastic structure within approximate sensitivity volumes between sources and receivers going beyond ray theory we calculated the phase of every mode at every frequency and its derivative with respect to sand p velocity perturbations by integration over a sensitivity area in a 3 d reference model the normally small perturbations of the 3 d model required to fit the waveforms were then linearized using these accurate derivatives the equations yielded by the waveform inversion of all the seismograms were simultaneously inverted for a 3 d model of shear and compressional speeds and azimuthal anisotropy within the crust and upper mantle elaborate outlier analysis was used to control the propagation of errors in the data source parameters timing at the stations etc the selection of only the most mutually consistent equations exploited the data redundancy provided by our data set and strongly reduced the effect of the errors increasing the resolution of the imaging our new shear speed model is parametrized on a triangular grid with a 280 km spacing in well sampled continental domains lateral resolution approaches or exceeds that of regionalscale studies the close match of known surface expressions of deep structure with the distribution of anomalies in the model provides a useful benchmark in oceanic regions spreading ridges are very well resolved with narrow anomalies in the shallow mantle closely confined near the ridge axis and those deeper down to 100 120 km showing variability in their width and location with respect to the ridge major subduction zones worldwide are well captured extending from shallow depths down to the transition zone the large size of our waveform fit data set also provides a strong statistical foundation to re examine the validity field of the jwkb approximation and surface wave ray theory our analysis shows that the approximations are likely to be valid within certain time frequency portions of most seismograms with high signal to noise ratios and these portions can be identified using a set of consistent criteria that we apply in the course of waveform fitting

analogue modeling of flank instability at mount etna understanding the driving factors 1 mount etna is characterized by significant flank instability whose triggering factors are still a matter of debate we use analog models to investigate the role of different factors in the models a cone and base of granular material simulate the volcanic edifice and its basement the asymmetric geometry of the basement simulates the topographic gradient around the volcano injections of silicone sets a and b and low viscosity vegetable oil set c simulate the pressurization of plutonic complex deep reservoirs and the emplacement of dikes respectively other experiments set d reproduce regional extensional tectonics in the last 105 years within layers with different cohesion simulating strength differences in the basement laser scanner and control points allow the tracking of surface deformation with submillimeter precision the asymmetric topography enhances flank instability on the side with the weakest confinement i e seaside providing the preparing factor for instability in sets a and b any type of pressurized reservoir enhances up to 10 times the amount of flank instability toward the seaside with respect to the other flanks of the volcano in set c dike emplacement enhances seaside flank instability up to 8 times regional tectonics and crustal layering in set d enhance flank instability up to 2 and 1 3 times respectively considering the duration and frequency of the simulated processes in nature we propose a semiquantitative evaluation and hierarchy of the factors controlling flank instability at etna magmatic activity point like source inflation and dike emplacement provides the most important triggering factor extensional tectonics in the last 105 years and crustal layering are more than 10 times less effective this study shows the importance of differential buttressing at the volcano base for flank instability this condition is an important indication to expect asymmetric activity in any volcano flank eruptions and deformation

the structure of the dead sea basin abstract the dead sea basin is located along the left lateral transform boundary between the arabian and sinai plates its structure and history are known from surface geology drilling seismic reflection and other geophysical data the basin comprises a large pull apart almost 150 km long and mostly 8 10 km wide which is flanked by a few kilometres wide zones of normal faulting the basin formed at about 15 ma or earlier close to the beginning of the transform motion and it reached about half its present length before the end of the miocene a strong negative gravity anomaly records a thick sediment basin fill 5 km under half its length reaching a maximum of 10 km the fill includes a few km of salt ca 6 4 ma which forms several diapirs at any one time large parts of the basin subsided simultaneously but the site of fastest subsidence seems to have shifted northward sedimentation rates reached at least hundreds of metres per million years or more in the miocene and 1 km myr in later periods the basin structure is dominated by longitudinal faults intrabasinal faults which delimit the pull apart and which are the extensions of the major strike slip faults north and south of the basin and normal faults which extend along the basin margins the latter faults express a small component of extension across the basin whereas the pull apart resulted from the much larger lateral motion along the basin in addition transverse faults divide the pull apart into several segments with somewhat different histories the pull apart grew by becoming longer parallel to the transform motion at shallow levels this was probably achieved by normal slip on transverse listric faults while the fill between them was little deformed the crust under the basin was stretched and thinned during basin lengthening which caused its subsidence basin formation was accompanied by uplifting of its flanks by 1 km sparse igneous activity occurred along the basin and its flanks its presence suggests a thermal anomaly in the lower lithosphere beneath the basin and adjacent parts of the transform

subaerial submarine evidence of structures feeding magma to stromboli volcano italy and relations with edifice flank failure and creep abstract structural field data including parameters of 109 sheets strike mostly n10 55 e average dip angle mostly 70 90 average thickness two peaks at 1 2 m and 4 2 m and of 14 eruptive fissures and vents as well as bathymetric and numerical data suggest that stromboli experienced the development of a volcanic rift zone across the cone summit with a tendency to widen towards the lower submarine flanks during the last 100 ka inside this rift zone intrusive sheets mostly strike ne and become more abundant more steeply dipping and thicker on approaching the rift axis this rift persistence reflects the edifice s state of stress with a nw se horizontal least principal stress on the magma intrusion paths after 13 ka ago sheets mainly intruded with a horseshoe shaped geometry in plan view along the boundaries of the northwestern unstable volcano flank where four main lateral collapses occurred during the last 13 ka they also intruded with a ne strike across the volcano summit and the northeastern volcano flank the horseshoe shaped geometry is influenced by the lateral creep of the volcano flank which provides space for intrusion along the transtensional boundaries of the unstable sector where thinner sheets were emplaced when the collapse depression was filled up by new deposits ne striking thicker dykes emplaced across the northwestern volcano flank indicating a rapid re establishment of regional tectonic forces across the cone unbuttressing due to the present sciara del fuoco depression and ongoing flank creeping can account for intrusions also inside the sciara del fuoco the latter in 2007

major eruptive style changes induced by structural modifications of a shallow conduit system the 2007 2012 stromboli case stromboli is known for its mild persistent explosive activity from the vents located within the summit crater depression at the uppermost part of the sciara del fuoco sdf depression effusive activity lava flows at this volcano normally occurs every 5 15 years involving often the opening of eruptive fissures along the sdf and more rarely overflows from the summit crater between the end of the 2007 effusive eruption and december 2012 the number of lava flows inside and outside the crater depression has increased significantly reaching a total of 28 with an average of 4 8 episodes per year an open question is why this activity has become so frequent during the last 6 years and was quite rare before in this paper we describe this exceptional activity and propose an interpretation based on the structural state of the volcano changed after the 2002 2003 and even more after the 2007 flank effusive eruption we use images from the stromboli fixed cameras network as well as ground photos plume so2 and co2 fluxes released by the summit crater and continuous fumarole temperature recording to unravel the interplay between magma supply structural and morphology changes and lava flow output our results might help forecast the future behaviour and hazard at stromboli and might be applicable to other open conduit volcanoes

growth after collapse the volcanic and magmatic history of the neostromboli lava cone island of stromboli italy this study focuses on the holocene neostromboli lava cone which is part of the stromboli volcano aeolian islands italy it represents an important example of the structure and behaviour of lava cone re growth shortly after a large scale volcano sector collapse neostromboli s eruptive style is dominated by extrusion of sheet like a a lava flows and associated autoclastic breccias the lava cone developed during five phases of activity phases a to e representing discrete episodes of lava effusion characterised by rapid changes in magma composition spatial development of the feeder system and physical properties of erupted lavas through time although they all belong to the potassic series ks with sio2 49 55 wt and mgo 2 50 6 25 wt the neostromboli lavas have distinct petrogenetic characteristics ranging from leucite free and low sr shoshonitic basalts phases a and b to leucite bearing shoshonitic basalts with high phase c and intermediate phase d sr contents and to leucite free biotite bearing shoshonites phase e three different batches of mantle derived relatively primitive basic magmas fed the activity of phases a c and d the evolution phases a to b is inferred to have occurred in a continuously replenished tapped and crystallizing rtf magma chamber whereas phase e products were dominantly generated by fractional crystallization from phase d magmas the neostromboli cone shows summit flank and satellite vents and sheet intrusions with different geometry and location through time reflecting the interplay of regional tectonics precursory instability processes and volcano load

an automatic phase picker for local and teleseismic events an automatic detection algorithm has been developed which is capable of time p phase arrivals of both local and teleseismic earthquakes but rejects noise bursts and transient events for each signal trace the envelope function is calculated and passed through a nonlinear amplifier the resulting signal is then subjected to a statistical analysis to yield arrival time first motion and a measure of reliability to be placed on the p arrival pick an incorporated dynamic threshold lets the algorithm become very sensitive thus even weak signals are timed precisely during an extended performance evaluation on a data set comprising 789 p phases of local events and 1857 p phases of teleseismic events picked by an analyst the automatic picker selected 66 per cent of the local phases and 90 per cent of the teleseismic phases the accuracy of the automatic picks was ideal i e could not be improved by the analyst for 60 per cent of the local events and 63 per cent of the teleseismic events

dynamics of the december 2002 flank failure and tsunami at stromboli volcano inferred by volcanological and geophysical observations 1 the 2002 effusive flank eruption at stromboli volcano started on december 28 after several months of strong explosive activity at the summit craters on december 30 the seismic network recorded two large flank failures and associated tsunami waves this is the first time that a flank collapse and tsunami and their associated phenomena have been recorded by a multi disciplinary monitoring system volcanological and geophysical monitoring as well as thermal surveys performed immediately before and after the failure allowed us to define and interpret the sequence of events the still on going eruption has provided for the first time the opportunity to look into the dynamics of stromboli s effusive eruptions flank failure and landslide formation and their potential hazard

the rapid drift of the indian tectonic plate the breakup of the supercontinent gondwanaland into africa antarctica australia and india about 140 million years ago and consequently the opening of the indian ocean is thought to have been caused by heating of the lithosphere from below by a large plume whose relicts are now the marion kerguelen and reunion plumes plate reconstructions based on palaeomagnetic data suggest that the indian plate attained a very high speed 18 20 cm yr 1 during the late cretaceous period subsequent to its breakup from gondwanaland and then slowed to approximately 5 cm yr 1 after the continental collision with asia approximately 50 myr ago the australian and african plates moved comparatively less distance and at much lower speeds of 2 4 cm yr 1 refs 3 5 antarctica remained almost stationary this mobility makes india unique among the fragments of gondwanaland here we propose that when the fragments of gondwanaland were separated by the plume the penetration of their lithospheric roots into the asthenosphere were important in determining their speed we estimated the thickness of the lithospheric plates of the different fragments of gondwanaland around the indian ocean by using the shear wave receiver function technique we found that the fragment of gondwanaland with clearly the thinnest lithosphere is india the lithospheric roots in south africa australia and antarctica are between 180 and 300 km deep whereas the indian lithosphere extends only about 100 km deep we infer that the plume that partitioned gondwanaland may have also melted the lower half of the indian lithosphere thus permitting faster motion due to ridge push or slab pull

shear velocity structure of jordan from explosion seismic data summary combined analysis of p and s wave data from seismic refraction lines in jordan has led to the derivation of a poisson s ratio model for the crust this model shows that the upper crust including the sediments has an average poisson s ratio of around 0 25 except beneath nw jordan where the sediments have a high ratio of around 0 32 however the lower crust below about 20 km depth has high poisson s ratios ranging from 0 29 to 0 32 these high poisson s ratios may be interpreted mineralogically in terms of high feldspar and low quartz content in the rocks e g gneiss amphibolite of the lower crust or fluid phases in the form of separated penny shaped inclusions

thickness of the lithosphere east of the dead sea transform summary we use the s receiver function method to study the lithosphere at the dead sea transform dst a temporary network of 22 seismic broad band stations was operated on both sides of the dst from 2000 to 2001 as part of the desert project we also used data from six additional permanent broad band seismic stations at the dst and in the surrounding area that is in turkey saudi arabia egypt and cyprus clear s to p converted phases from the crust mantle boundary moho and a deeper discontinuity which we interpret as lithosphere asthenosphere boundary lab have been observed the moho depth 30 38 km obtained from s receiver functions agrees well with the results from p receiver functions and other geophysical data we observe thinning of the lithosphere on the eastern side of the dst from 80 km in the north of the dead sea to about 65 km at the gulf of aqaba on the western side of the dst the few data indicate a thin lab of about 65 km for comparison we found a 90 km thick lithosphere in eastern turkey and a 160 km thick lithosphere under the arabian shield respectively these observations support previous suggestions based on xenolith data heat flow observations regional uplift history and geodynamic modelling that the lithosphere around dst has been significantly thinned in the late cenozoic likely following rifting and spreading of the red sea

how to cope with volcano flank dynamics a conceptual model behind possible scenarios for mt etna abstract volcano flank dynamics poses a serious hazard also involving the inhabited lower slopes mt etna is a well studied unstable volcano and a significant amount of data has been collected on the dynamics of its eastern and southern flanks we first propose a conceptual model to describe and explain flank dynamics at etna we identify the preconditions as due to the differential unbuttressing conditions at the volcano base and the triggering factors as shallow magmatic sources dikes reservoirs evidence and parameters and or observations for flank dynamics are listed summarizing the 1994 2010 period of activity based on this we then propose a set of scenarios possibly occurring in case of unrest of the unstable flanks of mt etna flank unrest is a variation in the steady state condition of the volcano flanks possibly accompanied by significant ground deformation seismicity and eruptions the scenarios may provide a general reference and recommendation in case of five types of multi hazard processes related either as a cause or effect to flank dynamics 1 edifice inflation 2 emplacement of dikes along the ne and or s rifts 3 seismicity along pernicana fault system 4 seismicity on the s sector 5 seismicity along timpe fault system each scenario is analyzed and recommendations are given the scenarios may or may not be related to each other in the sense that the probability of occurrence of one scenario may or may not be contingent or dependent upon the prior occurrence of another these scenarios provide a qualitative analysis of the multi hazard processes related to flank dynamics a more quantitative i e probabilistic characterization is under consideration

palynological evidence for the age and rate of sedimentation along the dead sea rift and structural implications abstract pollen diagrams obtained for eight deep boreholes penetrating the thick sequences of the dead sea rift fill correlated with dated marine sequences of the coastal plain in israel enable stratigraphie assignment of the continental deposits to be made the sedimentary units of the rift valley are of two main provenances those deposited in troughs within the rift limits of predominantly lacustrine environment attaining thicknesses in the order of 1 2 km for which the trough is the final erosion base level and those not limited to the rift boundaries but known from wide areas in israel mostly laid down in river systems that crossed the rift region on their way to the sea these fluviatile formations are in the order of hundreds of meters thick in the rift valley region which acted as an intermediate basin the first group of rock units of late miocene through early middle pliocene to glacial pleistocene ages indicate phases of considerable subsidence the earlier termed the erythrean and the later the levantine phase these are predated in the late oligocene through middle miocene by gentle subsidence and separated during the late pliocene preglacial pleistocene by another period of relative quietness in tectonic activity

the dyke swarm of mount calanna etna italy an example of the uppermost portion of a volcanic plumbing system a new multidisciplinary study combining geology petrography and geochemistry on the rocks of the isolated hill of mount calanna mount etna italy has provided evidence for the existence of a dyke swarm formed by more than 200 dykes distributed over an area of 0 7 km2 with an intensity of intrusion up to 40 all bodies are deeply altered and the geological and mesostructural surveying of 132 dykes revealed that they intruded in e w direction with an average dip of 60 the faults affecting the outcrop have in general an e w strike and dip of 55 these have all normal motion and have been interpreted as coeval with the dykes this interpretation contrasts with the previous hypothesis that considered mount calanna as a thrust resulting from compressive deformation resulting from the gravitational spreading of the volcanic edifice mount calanna is here interpreted as the uppermost portion of a vertically extensive magmatic plexus that fed the eruptive activity of one or more eruptive center s sited in the valle del bove area measurements of the apparent densities on 23 dykes and host rock samples give an average value of 2 420 kg m3 for the entire complex 15 lower than the density expected for hawaiitic magma placing an important constraint on the geophysical identification of similar structures considering that mount etna is not an old eroded edifice but an active and growing volcano the exposure of this subvolcanic structure can be regarded as exceptional its geometry and physical characteristics can be thus regarded as an interesting example of the present day shallow plumbing system of mount etna as well as of other basaltic volcanoes

multiple sector collapses at stromboli volcano italy how they work this paper demonstrates that four large sector collapses have affected the nw flank of the stromboli volcano in the past 13 ka alternating with growth phases in order to contribute to the evaluation of the critical conditions which trigger lateral collapses a reconstruction of the geometry of each collapse of the volcano edifice in the four stages that preceded the relative collapse events is also presented and a computation of the landslide volume this reconstruction is based on new field data plotted in three dimensions prior to the initial 13 ka collapse the volcano was 1125 100 m high above sea level the collapse had a volume of 2 23 0 87 km3 whereas the pre collapse volcano volume was 218 8 7 7 km3 the next edifice that failed was 900 70 m high a s l the collapse volume was 1 0 54 km3 with a precollapse volcano volume of 201 4 5 4 km3 the edifice then grew to 1000 60 m a s l the third collapse had a volume of 1 08 0 39 km3 and occurred within a volcano with a volume of 209 1 4 6 km3 this was followed by a new growth phase followed by the last collapse with a volume of 0 73 0 22 km3 the volcano volume was about the same as the present one the present active crater zone is at 780 m a s l in the first three collapses sliding surfaces cut the main magma conduit in the last collapse the upper scarp coincided with the conduit location dyking along a main ne trending weakness zone across the volcano summit exerted a lateral force for collapse inception the decrease of the landslide volumes with the age and the concentric scarps of the four collapses suggest that the younger sliding planes tended to become more superficial and to decrease the areal extent this is interpreted as due to a successively weaker eruptive products from dominantly lavas to dominantly pyroclastics and b the feedback effects between collapses and dykes that injected along the lateral segments of the first collapse slide plane

a pollen based pseudobiomisation approach to anthropogenic land cover change the degree of anthropogenic modification of land cover through the mid to late holocene is of significant interest for archaeologists climate modellers and conservation ecologists amongst others spatially extensive pollen data provide an appropriate resource for the reconstruction of land cover change however traditional simple methods e g the ap nap ratio do not provide the degree of detail required for these user groups a range of more sophisticated methods have been developed e g mechanistic model based methods but they require a high degree of understanding of the pollen vegetation relationship which is resource and time consuming this paper proposes a method of intermediate complexity by which major land cover changes can be assessed for individual sites and regions a pseudobiomisation approach is used in which pollen taxa are assigned to different land cover classes lcc and the sum of adjusted pollen proportions for each class used to determine an lcc affinity score for individu

new integrated geodetic monitoring system at stromboli volcano italy stromboli is a composite volcano forming the northernmost island of the aeolian archipelago volcanic arc tyrrhenian sea on december 28th 2002 lava flows outpoured from the northern wall of the ne crater and descended into the sciara del fuoco sdf a deep depression marking the nw flank of the volcano edifice on december 30th 2002 two landslides occurred on the northern part of the sdf they moved a mass in the order of tens of millions of cubic meters both above and below sea level the landslide produced a tsunami causing significant damage to the eastern coast of the island reaching the other aeolian islands and the sicilian and southern italian coasts this event led to the upgrading of the ground deformation monitoring system already existing on the island the new requirement was the real time detection of the deformations related to potential slope failures of the sdf to this end a remotely controlled monitoring system based both on gps and geodetic techniques was planned and set up in a few months the new monitoring system allowed to continuously measure the ground deformations occurring on the sdf by integrating both terrestrial and satellite geodetic techniques although this system was severely damaged during the 7 month long eruption it allowed to monitor important eruptive phases for the first time an accurate data set on the actual mass movements of the sdf and the crater area was available it provided data that significantly supported the civil protection authorities in making decisions and constrains theories related to landslide movements and volcanic activity after the end of the eruption the system was overhauled in order to optimize the instruments and set up a monitoring system aimed at measuring deformations forecasting other flank collapses

dike propagation driven by volcano collapse a general model tested at stromboli italy 1 analogue experiments investigate how flank collapse affects dike propagation within volcanoes water magma analogue is injected within a gelatin cone volcano analogue with a lateral collapse the injections form dikes that away from the collapse become radial the dikes propagating nearby the collapse focus towards the collapse sides becoming subparallel to them because of the stress reorientation due to the unbuttressing only dikes formed along the collapse axis passing through the mean points of the collapse map view propagate radially within the collapse this general model is applied at stromboli the stromboli dikes cluster along and parallel to the collapse sides similar to the experiments nevertheless the current location of the conduit along the collapse axis leads to dike propagation within the collapse infill rather than at its sides this may have occurred during the 2002 03 eruption when diking in the collapse triggered a landslide and tsunami within the collapse

dyke emplacement and related hazard in volcanoes with sector collapse the 2007 stromboli italy eruption in february 2007 two effusive vents opened along the flank of sciara del fuoco depression at stromboli the summit craters collapsed obstructing the central conduit choking the vents and increasing the deformation within sciara del fuoco here a new vent opened releasing the excess magmatic pressure the eruption continued after a summit explosion until april the vents were fed by laterally propagating dykes vent location is similar to that of the 2002 2003 eruption that eruption was fed by dykes triggering landslides which in turn produced a tsunami however the 2007 eruption did not develop landslides suggesting that their triggering also depends on other factors i e magmatic pressure

slip rate on the dead sea transform fault in northern araba valley jordan the araba valley lies between the southern tip of the dead sea and the gulf of aqaba this depression blanketed with alluvial and lacustrine deposits is cut along its entire length by the dead sea fault in many places the fault is well defined by scarps and evidence for left lateral strike slip faulting is abundant the slip rate on the fault can be constrained from dated geomorphic features displaced by the fault a large fan at the mouth of wadi dahal has been displaced by about 500 m since the bulk of the fanglomerates were deposited 77 140 kyr ago as dated from cosmogenic isotope analysis 10 be in chert of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan holocene alluvial surfaces are also clearly offset by correlation with similar surfaces along the dead sea lake margin we propose a chronology for their emplacement taken together our observations suggest an average slip rate over the late pleistocene of between 2 and 6 mm yr 1 with a preferred value of 4 mm yr 1 this slip rate is shown to be consistent with other constraints on the kinematics of the arabian plate assuming a rotation rate of about 0 396 myr 1 around a pole at 31 1 n 26 7 e relative to africa

moho depth and three dimensional p and s structure of the crust and uppermost mantle in the eastern mediterranean and middle east derived from tomographic inversion of local isc data summary 82 000 p and s arrival times from 3000 sources recorded by 250 seismic stations from the revised isc catalogue are employed to study a circular area of 6 radius centred on the dead sea we use the linearized tomographic approach based on the rays constructed in a 1 d spherical velocity model and corrected for the moho depth variation and relief all the sources were relocated as the result of simultaneous iterative inversion we get 3 d p and s velocity anomalies in the crust and uppermost mantle moho depth and corrected source parameters the resulting images fit well with the existing tectonic elements in the study area in the crust a narrow p and s low velocity anomaly marks the position of the dead sea transform dst that is interpreted as sediments in the shallower layer and a zone of fractured and deformed rocks in the middle and lower crust there is a narrow 50 km wide band of thickening of the crust along the dst in the arava valley between the red sea and dead sea and some 100 km north of the dead sea this zone may be associated with the minimum of the lithospheric strength and therefore explain the location of the dst in the arava valley the velocity anomalies under the crust and the map of the moho depth clearly distinguish the oceanic levant basin and continental types of crust asia minor zagros cyprus and eratosthenes mount verification of the results takes an important part in this study inversions of different starting models and independent processing of data subsets show high robustness of the results synthetic tests clearly show the limits of the resolving power of the inversion with the existing data set

lake sediments erosion and landscape change during the holocene in britain and ireland abstract lakes are excellent repositories of air borne and especially stream borne materials it has long been recognised that lake sediments contain a strong record of catchment soils via the inputs of minerogenic and chemical erosional products to these may be added a variety of palaeoecological indicators including pollen fungi sphagnum leaves and faunal remains pollen analysis in particular enables land use change to be assessed over many millennia and demonstrates the landscape impacts of woodland clearance grazing and crop cultivation radiocarbon dating provides a chronology for environmental and agricultural change and acts as an indicator of erosion in its own right the use of such indicators to reconstruct past instances and patterns of erosion is demonstrated with reference mainly to 50 british and irish lake sites and especially those which have produced signals of erosion in the form of accelerated sediment accumulation and inversed or reversed sequences of radiocarbon dates during the mid and late holocene sites displaying even or decreased sedimentation through time are concentrated in northern and northwestern scotland and have either no clear signs of human impact or only so towards the latter part of the holocene this pattern probably reflects a combination of factors including low population densities thin soils and the sealing effect of blanket peat in contrast all sites with accelerated erosion have indications of anthropogenic impact this is often prior to levels of increased sedimentation showing a delay in system response while the spread of dates for the start of the rise in sediment accumulation spans 6200 940 bp three clusters are evident at 5295 4970 4530 4235 and 2980 2810 bp radiocarbon inversions mostly reversals are evident for 18 sites no obvious causal patterning is indicated and they probably demonstrate no more than the fact that catchment soils including peats around a particular site were pushed beyond an erosional threshold sufficient to age the sediments deposited within the lakes it is hoped that improvements in data quality will allow the refinement of such exercises in the future and that lakes will be valued as repositories of long term landscape sensitivity

spatio temporal evolution of rockfall activity from 2007 to 2011 at the piton de la fournaise volcano inferred from seismic data abstract seismic data have been used to catalog the location and volume of most of the rockfalls that occurred at the piton de la fournaise volcano from may 2007 just after the major collapse of the dolomieu summit crater floor to may 2011 this catalog made it possible to compare the evolution of the number and volume of rockfalls at a high temporal resolution and to investigate their links with eruptions seismicity deformations and rainfalls affecting the piton de la fournaise volcano results show that the purge of unstable areas created by the dolomieu crater floor collapse occurred in two phases a first phase lasting three months during which the intense rockfall activity immediately following the collapse decreased abruptly and a second phase lasting more than two years during which the daily volume of the rockfalls slowly decreased before reaching a steady state a detailed study of 4 time periods including 3 eruptive cycles indicates that strong seismicity can increase the number of rockfalls furthermore when a dike reaches the surface at the summit of the central cone giving birth to an eruption the associated local forcing can in some cases increase the volume of rockfalls possibly by creating or expanding weak zones in most cases this is not observed for dike intrusions that do not reach the surface the newly created weak zones are most often far from the eruptive fissures of the ongoing eruption but close to the location of the next eruption this suggests that these distant zones are also weakened at depth thus creating preferred paths for future dikes propagating toward the surface the impact of rainfall on rockfall activity was also studied given that la reunion island is subject to very intense rainfall events our results show that rainfall can in some cases trigger rockfalls rapidly with response times of less than a day but not systematically and no triggering rainfall threshold was found

the stromboli volcano landslides of december 2002 a seismological description 1 we analyse seismograms of the slump episodes at stromboli on december 30 2002 using a simple single force model we estimate the volume involved in the individual subevents and attempt a chronological reconstruction of the whole process our results indicate the occurrence of two main events that could be interpreted as a submarine slump which caused the observed tsunami and a subaerial slump which did not produce destructive sea waves a total volume of about 20 106 m3 results for the submarine event which developed over about 2 minutes with several distinct detachments the first and largest displacing a volume of 10 8 106 m3 the second subaerial slump involved at least 2 5 106 m3 in about 90 s a large long period pulse is also recognizable in the seismograms of the stromboli station we tentatively interpret this feature as tilt caused by the water load associated with the inundation in the ficogrande area on the northeastern side of the island

a receiver function study across the dead sea transform summary we report on a receiver function study of the crust and upper mantle within desert a multidisciplinary geophysical project to study the lithosphere across the dead sea transform dst a temporary seismic network was operated on both sides of the dst between 2000 april and 2001 june the depth of the moho increases smoothly from about 30 to 34 38 km towards the east across the dst with significant north south variations east of the dst these moho depth estimates from receiver functions are consistent with results from steep and wide angle controlled source techniques steep angle reflections and receiver functions reveal an additional discontinuity in the lower crust but only east of the dst this leads to the conclusion that the internal crustal structure east and west of the dst is different the p to s converted phases from both discontinuities at 410 and 660 km are delayed by 2 s with respect to the iasp91 global reference model this would indicate that the transition zone is consistent with the global average but the upper mantle above 410 km is 3 4 per cent slower than the standard earth model

crustal shear velocity structure across the dead sea transform from two dimensional modelling of desert project explosion seismic data an analysis of the shear s waves recorded during the wide angle reflection refraction wrr experiment as part of the desert project crossing the dead sea transform dst reveals average crustal s wave velocities of 3 3 3 5 km s 1 beneath the wrr profile together with average crustal p wave velocities of 5 8 6 1 km s 1 from an already published study this provides average crustal poisson s ratios of 0 26 0 27 v p v s 1 76 1 78 below the profile the top two layers consisting predominantly of sedimentary rocks have s wave velocities of 1 8 2 7kms 1 and poisson s ratios of 0 25 0 31 v p v s 1 73 1 91 beneath these two layers the seismic basement has average s wave velocities of around 3 6 km s 1 east of the dst and about 3 7 km s 1 west of the dst and poisson s ratios of 0 24 0 25 v p v s 1 71 1 73 the lower crust has an average s wave velocity of about 3 75 km s 1 and an average poisson s ratio of around 0 27 v p v s 1 78 no sn phase refracted through the uppermost mantle was observed the results provide for the first time information from controlled source data on the crustal s wave velocity structure for the region west of the dst in israel and palestine and agree with earlier results for the region east of the dst in the jordanian highlands a shear wave splitting study using sks waves has found evidence for crustal anisotropy beneath the wrr profile while a receiver function study has found evidence for a lower crustal high s wave velocity layer east of the dst below the profile although no evidence was found in the s wave data for either feature the s wave data are not incompatible with crustal anisotropy being present as the wrr profile only lies 30 degrees off the proposed symmetry axis of the anisotropy where the difference in the two s wave velocities is still very small in the case of the lower crustal high s wave velocity layer if the velocity change at the top of this layer comprises a small first order discontinuity underlain by a 2 km thick transition zone instead of just a large first order discontinuity then both the receiver function data and the wrr data presented here can be satisfied finally the s wave velocities and poisson s ratios which have been derived in this study are typical of continental crust and do not require extensional processes to explain them

vertical and lateral propagation of radial dikes inferred from the flow direction analysis of the radial dike swarm in komochi volcano central japan dikes with lateral and outward intrusion directions named l type dike and dikes with vertical and upward intrusion directions v type dike are recognized in a radial dike swarm of komochi volcano japan by the combined analysis of the preferred orientations of deformed vesicles and anisotropy of magnetic susceptibility ams intrusion directions of magmas were examined for 41 dike outcrops among them 19 dikes were classified as l type dike and 15 dikes were as v type the l type dikes distribute over the area of the dike swarm radiating from the central conduit which is named daikokuiwa stock and the v type dikes occur mainly in the peripheral portion of the volcano the l type dikes are characterized with evolved whole rock compositions similar to those of rocks consisting of the central conduit whereas the v type dikes have less fractionated composition and are enrich in mafic phenocryst as compared to the l type dikes the outward intrusion directions of the l type dikes and their petrological similarity to the rock of the central conduit indicate that these dikes intruded from the shallow part of the central conduit where the magmas underwent fractional crystallization and degassing the petrological characteristics of the v type dikes suggest that the less fractionated magma intruded directly from a magma chamber in which mafic phenocryst crystals accumulated the larger dike thickness and higher magnetic foliation of the v type dike as compared to the l type dike indicate higher magmatic overpressure which was possibly result of the direct connection to the pressurized magma chamber and vertical growth of the dikes with buoyant magma solidification of the central conduit is favorable for the accumulation of internal excess pressure in the magma chamber to break the wall rock fissure eruptions independent of the central conduit have occurred in many volcanoes and these fissure eruptions might be fed by the dikes directly propagated from the deeper magma chamber

structure of the earth s crust in jordan from potential field data abstract gravity and magnetic data were collected and used to study the crustal structure of jordan three new geophysical maps of jordan were created a moho discontinuity map a crystalline basement surface map and a map showing the lowest limit of magnetic blocks depths of the curie isotherm were also calculated results indicate that the depth to the moho discontinuity in jordan varies from 32 to 33 km in the northwest to 38 km in the southeast the basement complex rocks outcrop on the surface in the southwest but lie at about 8 km in the northeast the curie isotherm 585 c lies at a depth of about 10 km in the area east of the dead sea and dips southeastward towards the al sirhan wadi sirhan southeast jordan where it is located at 35 km depth local isostasy of rock masses blocks in jordan does not occur nevertheless this does not rule out the possible existence of isostasy in a regional scale at greater depths within the mantle

seismic refraction profiles between cyprus and israel and their interpretation summary a long seismic refraction profile was carried out between southern israel and cyprus the seismic energy was generated by 33 sea shots each of 0 8 t explosives and was recorded by land stations in israel and cyprus and by ocean bottom seismographs deployed along the profile the results showed that the continental crust of southern israel thins towards the mediterranean underneath a northward thickening sedimentary cover cyprus is underlain by a 35 km thick continental crust thinning south wards and extending to mt eratosthenes between mt eratosthenes and the israel continental shelf the crystalline crust is composed of high velocity 6 5 km s 1 material and is about 8 km thick it is covered by 12 14 km of sediments and may represent a fossil oceanic crust

lithosphere structure across the dead sea transform as constrained by rayleigh waves observed during the desert experiment summary the interdisciplinary dead sea rift transect desert project that was conducted in israel the palestine territories and jordan has provided a rich palette of data sets to examine the crust and uppermost mantle beneath one of earth s most prominent fault systems the dead sea transform dst as part of the passive seismic component thirty broad band sensors were deployed in 2000 across the dst for roughly one year during this deployment we recorded 115 teleseismic earthquakes that are suitable for a fundamental mode rayleigh wave analysis at intermediate periods 35 150 s our initial analysis reveals overall shear velocities that are reduced by up to 4 per cent with respect to reference earth model prem to the west of the dst we find a seismically relatively fast but thin lid that is about 80 km thick towards the east shallow seismic velocities are low while a deeper low velocity zone is not detected this contradicts the currently favoured thermomechanical model for the dst that predicts lithospheric thinning through mechanical erosion by an intruding plume from the red sea on the other hand our current results are somewhat inconclusive regarding asthenosphere velocities east of the dst due to the band limitation of the recording equipment in jordan

the rotation of arabia and the levant fault system abstract we establish the kinematics of the rotation of arabia with respect to africa and show that the rotation rate of africa increased by a factor of about four in late serravallian time about 12 13 ma ago we discuss evidence that oceanic accretion started simultaneously in the gulf of aden and in the red sea at this time it is also at this time that the levant and anatolian fault systems were initiated our initial reconstruction of the red sea rift in late oligocene early miocene time approximately superposes the present shore lines which coincide with the mid point of the zones of rapid crustal thinning the future continental slopes the amount of extension during the early phase of continental rifting is obtained by assuming that the total volume of continental crust is conserved during extension and by checking these estimates through closure around the sinai triple junction in the late miocene the southern evant fault zone was a zone of distributed shear deformation through counterclockwise block rotation extending soul h ward within the northernmost red sea since the early pliocene the shear motion has been localized within the gulf of aqaba changing the tectonic pattern in the northern red sea

infrasonic monitoring at stromboli volcano during the 2003 effusive eruption insights on the explosive and degassing process of an open conduit system 1 stromboli is an open conduit volcano characterized by persistent conduit degassing and explosive dynamics during the 2003 effusive eruption we monitored this activity with a five element array deployed at 450 m from the active craters the array allows us to track in real time changes of explosive activity in terms of source position and excess pressure release infrasonic monitoring located the new active vents in the same preeruptive position revealing that the collapse of the crater terrace has not changed the geometry of the shallow feeding system elevation of the infrasonic source is stable at 750 m above sea level coincident with the elevation of the crater terrace this suggests a shallow position of the magma column or if the source is embedded in the conduit diffraction at the crater rim at the end of the eruption back azimuth analysis indicates that explosive activity was progressively reestablished at all of the craters following a ne toward sw direction along the collapsed trench the array detected significant small amplitude 1 pa infrasonic activity occurring at a rate of approximately one pulse every 2 s and generally located in only one vent at a time this persistent activity is not related to strombolian explosion but we infer it is reflecting the overpressurized degassing of the magma column amplitude distribution of 7 million infrasonic signals shows that this degassing is 1 order of magnitude more energetic than the explosions besides infrasonic amplitude distribution presents a decay with a double slope indicating that explosions and degassing are driven by conduit dynamics acting at two different rates

discerning magmatic flow patterns in shallow level basaltic dykes from the ne rift zone of tenerife spain using the anisotropy of magnetic susceptibility ams technique discerning magmatic flow patterns in shallow level basaltic dykes from the north east rift zone of tenerife spain using the anisotropy of magnetic susceptibility ams technique

scale dependent location of hydrothermal vents stress field models and infrared field observations on the fossa cone vulcano island italy article i nfo hydrothermal venting occurs on numerous volcanoes of various age setting topographic and structural expression vent locations are commonly found not within volcanic craters only but predominantly at the crater margins and topographic highs a case example is vulcano island italy where the control on such vent locations along crater margins remained poorly understood however this paper describes numerical models combined with field observations and infrared imaging to explore the mechanisms that control the ascent paths of fluids in the fossa cone on vulcano using finite element modelling we calculate the gravitational stress in the volcanic edifice imposed by the topography results predict hydrofractures to be arranged in radial patterns at depth and in concentric patterns close to the surface furthermore low compressive stress values are found at the rims of the nested craters we compare the stress models to fumarole field data using a forward looking infrared camera we recorded images of the entire cone images were assembled to a mosaic and geocoded providing the first map of a remotely sensed temperature field in high resolution at la fossa the degassing and high temperature anomalies are found to be located mainly at the crests of the craters predominately in the northern and southern sector of the main crater therefore the stress distribution favours and indeed corresponds to the occurrence of fumaroles at la fossa the stress models also yield compression at the bottom of the crater where temperatures are cool thus we consider that the overall distribution of the fumaroles at the fossa cone is controlled by topography additional mechanisms contribute to the exact position of the degassing sites the influence of the lithological control seems to be strong in the southwestern part of the crater where the fumaroles are located 10 20 m below the inner crater rim in bedded strata in the northern part of the crater the exhalation sites can mainly be found at surface fractures and cracks emphasizing the structural control on the location of the fumaroles at this sector of the fossa cone using combined theoretical modelling and field observations this study helps to shed light into the processes directing fluids in volcanic edifices elsewhere and might contribute to the evaluation of upcoming hazard scenarios

surficial structures of the northern red sea axial valley from 23 n to 28 n time and space evolution of neo oceanic structures abstract during recent french cruises in the northern red sea the surficial structures of the axial valley were studied by means of bathymetry magnetics and single channel reflection seismics new compilation maps have been established and comparison of the various data allow different segments of the northern red sea axial valley to the distinguished where only intra evaporitic deformations 24 25 n large volcanic outcrops mabahiss deep 25 30 26 n or several recent isolated volcanic intrusions 26 27 n characterize different stages of evolution this new information allows reconstruction of the evolution of oceanization cells from a simple intra evaporitic deep to a limited oceanic rift zone such as those observed in the central red sea a major characteristic of this evolution also depicted in other young oceanic rifts is a succession of volcanic and tectonic phases the major event in the northern red sea axial valley is a recent episode of voluminous but well localized magmatism it would represent a new stage in the red sea evolution and thus may have some implications on earlier phases

evidence from the northern red sea on the transition from continental to oceanic rifting abstract the northern red sea is an active rift in the last stages of continental rifting which is beginning to undergo the transition to oceanic seafloor spreading the rift can be divided into two distinct regions the marginal areas consist of a series of bathymetric terraces and as indicated by geophysical data are underlain by a series of rotated fault blocks the axial depression which forms the axis of deep water is a continuous region 10 to 25 km wide near the center of the sea which is characterized by high heat flow a large gravity minimum and very deformed sediments both regions are divided along strike into segments roughly 60 km long by cross trending transfer zones the presently active tectonics are characterized by the concentration of extension and deformation in the axial depression and by the emplacement of a number of large intrusions the intrusions occur at distinct sites located at the intersection of transfer zones with the faults bounding the rotated blocks in the marginal areas and at deeps located in the axial depression halfway between transfer zones although extension is becoming concentrated in the axial depression geophysical data imply that at least the upper few kilometers of the crust in that region consists of non magnetic continental type material and that this ca apace has been ruptured by large intrusions only at the deeps a wide range of crustal seismic velocities has been observed in the northern red sea including velocities normally associated with oceanic crust the velocity variations appear spatially related to corresponding large variations in basement rock type observed on shore in the eastern desert of egypt the northern red sea is in an intermediate stage between a continental rift valley and a young ocean basin and delineation of its structure and tectonics allows a model to be developed for the evolution of a rifted continental margin rifting starts in a series of linked half grabens 50 60 km long and formed over detachment surfaces which probably penetrate no deeper than the mid or lower crust this style of rifting can accommodate at least the amcunt of extension represented by the gulf of suez 35 km at some greater amount of extension the rift acquires a more symmetric shape probably through the development of antithetically faulted blocks in the hanging wall extension in this stage is still distributed throughout the rift and is accommodated in the upper crust by rotation of fault blocks at the stage represented by the northern red sea extension becomes concentrated in an axial depression and begins to be partially accommodated by large intrusions which form deeps the position of the deeps is controlled by the transfer zones established in the earliest stages of rifting with further extension the deeps serve as nucleation points that develop into small discrete cells of seafloor spreading these cells grow and coalesce to form a continuous mid ocean ridge spreading center such as is found in the southern red sea

imaging ruptured lithosphere beneath the red sea and arabian peninsula abstract the red sea rift an archetype of a newly formed ocean basin is an ideal environment in which to study the controversial processes associated with continental rifting different models have been proposed to explain how rifting in the red sea evolved however accurate constraints on lithospheric structure have not been available to discriminate rifting models we use the s wave receiver function technique to produce the first images of the lithosphere asthenosphere boundary lab structure along the red sea and throughout the arabian peninsula lithospheric thickness varies considerably with thin lithosphere centered on the rift axis thickening toward the arabian interior gravity data are well fit by our structural model and indicate that high surface topography along the rift flank is not in isostatic equilibrium requiring dynamic compensation for its support while our derived structure is consistent with active rifting processes previous studies demonstrated that the red sea initiated as a passive rift therefore our results suggest a two stage rifting history where extension and erosion by flow in the underlying asthenosphere are responsible for variations in lab depth lab topography guides asthenospheric flow beneath western arabia and the red sea demonstrating the important role lithospheric variations play in the thermal modification of tectonic environments

mechanisms for ground surface fracturing and incipient slope failure associated with the 2001 eruption of mt etna italy analysis of ephemeral field data abstract during the july august 2001 eruption of mt etna development of extensional fractures faults and grabens accompanied magma intrusion and subsequent volcanic activity during the first days of the eruption we performed an analysis of attitude displacement and propagation of fractures and faults exposed on the ground surface in two sites torre del filosofo and valle del leone located along the same fracture system in the region surrounding the valle del bove depression on the eastern flank of mt etna fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system the investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes in particular the fracture system propagated parallel to the gentle slope

structural features of the 2007 stromboli eruption abstract on 27 february 2007 two ne sw and nnw sse dike fed effusive vents opened to the north at 650 and 400 m above sea level asl of the summit craters at stromboli forming a fissure parallel to the inner walls of the sciara del fuoco sdf sector collapse depression the formation of these vents was soon followed by rapid subsidence of the summit crater area this partly obstructed the central conduit temporarily choking the fissure and increasing the deformation of the upper part of sdf the reactivation of the nnw sse vent and the opening of a new vent located at 500 m asl fed by a second dike released the internal pressure and surface deformation ceased the eruption then continued again from the 400 m vent after a summit explosion on 15 march until ending in early april after a progressive decrease of magma output repeated ne sw dike intrusions have occurred in recent years close to the upper se limit of the sdf in that zone named bastimento the eruptive fractures traced the discontinuities that borders the sdf increasing the risk of triggering new sector collapse whereas the ne sw trending structures lie along the regional volcano structural trend of the aeolian arc through stromboli the nnw sse vents are oblique to this trend and may be controlled by the anomalous stress field within the unstable flank of the sdf another fundamental aspect of the 2007 eruption is the collapse of the central conduit due to the rapid and deep magma drainage linked to the opening of the 400 m vent the intrusion of dikes and development of flank vents during the 2007 eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms but the opening of new effusive vents released the internal pressures diminishing the hazard

palaeoecological evidence for the prehistoric settlement of bodmin moor cornwall southwest england part ii land use changes from the neolithic to the present abstract radiocarbon dated pollen sequences from two areas of bodmin moor rough tor in the north west and the east moor are presented and the evidence for settlement in the prehistoric period on the moor considered the nature and extent of human impact in the two areas are compared and the evidence for anthropogenic activity in the environmental record is related to that deduced from the archaeology a tentative model of settlement and land use from the neolithic to the iron age is proposed with early activity in the neolithic leading to a peak of settlement in the bronze age and continuing activity on the moor during the iron age and into the romano british period human activity may have begun in the earliest neolithic and was possibly associated with construction of the hill top enclosure at rough tor the bronze age peak of activity that is apparent in the archaeology is also represented in the palynological record activity in the iron age and later shows that the moorland was intensively used for grazing and probably hay production until settlement expanded back onto the uplands in the medieval period this last phase resulted in the impoverishment of the soils and development of the current acid grassland and heath dominated vegetation of the moor finally various suggestions are made for future research into the palaeoecology of bodmin moor

sliding episodes during the 2002 2003 stromboli lava effusion insights from seismic volcanic and statistical data analysis 1 repeated phenomena of flank instability accompanied the 28 december 2002 to 21 july 2003 eruption of stromboli volcano the major episodes were two tsunamigenic landslides on 30 december 2002 2 d after the volcano unrest after 30 december sliding processes remodeled the area affected by slope instability we propose analyses of 565 sliding episodes taking place from december 2002 to february 2003 we try to shed light on their main seismic features and links with the ongoing seismic and volcanic activity using variogram analysis as well a characterization of the seismic signals in the time and frequency domains is presented for 185 sliding episodes their frequency content is between 1 hz and 7 hz on the basis of the dominant peaks and shape of the spectrum we identify three subclasses of signals one of which has significant energy below 2 hz low frequency signatures were also found in the seismic records of the landslides of 30 december which affected the aerial and submarine northwestern flank of the volcano accordingly we surmise that spectral analysis might provide evidence of sliding phenomena with submarine runouts we find no evidence of sliding processes induced by earthquakes additionally a negative statistical correlation between sliding episodes and explosion quakes is highlighted by variogram analysis variograms indicate a persistent behavior memory of the flank instability from 5 to 10 d we interpret the climax in the occurrence rate of the sliding processes between 24 and 29 january 2003 as the result of favorable conditions to slope instability due to the emplacement of nw se aligned dike fed vents located near the scarp of the landslide area afterward the stabilizing effect of the lava flows over the northwestern flank of the volcano limited erosive phenomena to the unstable loose slope not covered by lava

historical context and chronology of bronze age land enclosure on dartmoor uk the upland of dartmoor southwest england is one of the flagship prehistoric landscapes within britain owing to the excellent survival of extensive prehistoric coaxial field systems archaeological surveys and rescue excavations during the 1970s and 1980s did much to further the understanding of this landscape however much remains to be explored in particular the chronology of enclosure the nature of the pre enclosure landscape and the relationship between bronze age communities and their environment reconsideration of this landscape is important given the place it holds in our understanding of subdivision of the landscape across northwest europe during prehistory this paper presents new palaeoecological data recovered as part of an integrated archaeological and palaeoecological project on northeast dartmoor the sequences detailed here include the first dated neolithic period palaeoenvironmental data from within the prehistoric enclosed land on the moor providing a longer term context for enclosure neolithic groups are implicated in the first establishment of heathland in the study area at around 3630 3370 cal bc during the early bronze age reestablishment of hazel scrub in the study area implies reduced use of the upland although it is not clear whether this is local or indicative of the wider landscape a combination of pollen and fungal spore data indicates a substantial shift to species rich grassland with grazing animals at c 1480 cal bc in a phase that lasted 400 years the later bronze age and early iron age are characterised by low intensity use of the upland these data provide new chronological data for land cover change on dartmoor and whilst they broadly confirm existing models of upland land use in later prehistory their proximity to the standing archaeology affords a more nuanced interpretation of local change

multidisciplinary study of flank instability phenomena at stromboli volcano italy 1 this study concerns the unstable scarp named sciara del fuoco sdf at stromboli volcano merging geo structural observations live cam records in the visible and ir bands analysis of vertical aerial photographs and seismic records these are used to assess morpho structural changes between 2002 and 2004 the onset of the lava effusion on 28 december 2002 preceded a gravitational collapse by two days affecting a wide area of the sdf above and below sea level we surmise that the collapse enhanced latent instability of the scarp the 2002 2003 lava flows had a remarkable stabilizing effect on wide portions 50 of the sdf whilst erosive phenomena continued in the zone not covered by lava this caused unrelenting regression of the upper landslide scarp toward the summit craters in the form of rockfalls and debris flows if the crater conduit were involved in the sliding then a change in eruptive behavior cannot be excluded

later holocene vegetation history of the isles of scilly uk coastal influence and human land use in a small island context small islands tend to experience exacerbated environmental social vulnerabilities due to isolation size and a small resource base the response of social communities to environmental stress can be addressed by compiling palaeoecological proxies for land management alongside archaeological records this paper presents pollen data from four new late holocene sequences that lie around sea level on the isles of scilly south west england to understand the impact of coastal change on island communities interpretation of sequences near the coastal zone can be confounded by problems in disentangling human impact from maritime and wetland influence multivariate analysis is used to separate samples influenced by maritime conditions and wetland development from inland human land management practices during the bronze age clearance of woodland resulted in an intensively managed pastoral system and archaeological datasets indicate that maritime resources formed an important part of the subsistence economy despite coastal change that resulted in loss of land area and reduced the extent of the intertidal zone the pollen data and evidence from existing archaeological data show continuity through later prehistory and into the medieval period the archaeological data and pollen evidence point towards a highly resilient community that employed a mixed and varied subsistence base copyright c 2015 john wiley sons ltd

piping and pipeflow in a deep peat catchment abstract natural pipes are common in many upland blanket peats yet little is known about pipe network morphology or pipeflow processes most information on soil piping comes from the shallow peaty podzols of the welsh uplands where monitoring suggests that pipes may be important contributors to streamflow this paper presents information on piping and pipeflow from a deep upland blanket peat catchment in the pennine hills of northern england pipe outlets are found throughout the soil profile ranging from the underlying substrate at 3 m depth to pipes which are within a few centimetres of the surface mean pipe diameters range from 3 to 70 cm some pipes are over 150 m long slopes in the catchment are less steep than those usually associated with soil piping continuous flow records were obtained from 15 gauging sites on 8 separate pipes the pipeflow response from deep blanket peat was found to be different to that reported in the shallow peaty podzols of the welsh uplands the distinction between ephemeral and perennial pipe types does not appear to be useful within the deep pennine blanket peat response times from all of the pipes are short even from pipes deep within the peat at the same time pipes have a prolonged recession limb such that they maintain low flow for longer periods than most other runoff production processes within the catchment pipeflow contributes around 10 of the streamflow volume but can at times contribute up to 30 soil pipes may therefore be far more important in some upland peat catchments than previous work has hitherto suggested

crustal structure of the dead sea basin dsb from a receiver function analysis summary the dead sea transform dst is a major left lateral strike slip fault that accommodates the relative motion between the african and arabian plates connecting a region of extension in the red sea to the taurus collision zone in turkey over a length of about 1100 km the dead sea basin dsb is one of the largest basins along the dst the dsb is a morphotectonic depression along the dst divided into a northern and a southern sub basin separated by the lisan salt diapir we report on a receiver function study of the crust within the multidisciplinary geophysical project dead sea integrated research desire to study the crustal structure of the dsb a temporary seismic network was operated on both sides of the dsb between 2006 october and 2008 april the aperture of the network is approximately 60 km in the e w direction crossing the dsb on the lisan peninsula and about 100 km in the n s direction analysis of receiver functions from the desire temporary network indicates that moho depths vary between 30 and 38 km beneath the area these moho depth estimates are consistent with results of near vertical incidence and wide angle controlled source techniques receiver functions reveal an additional discontinuity in the lower crust but only in the dsb and west of it this leads to the conclusion that the internal crustal structure east and west of the dsb is different at the present day however if the 107 km left lateral movement along the dst is taken into account then the region beneath the desire array where no lower crustal discontinuity is observed would have lain about 18 ma ago immediately adjacent to the region under the previous desert array west of the dst where no lower crustal discontinuity is recognized

a crustal structure study of jordan derived from seismic refraction data abstract the interpretation of a deep seismic refraction study in jordan performed in may 1984 shows that much of the country is underlain by continental crust 32 35 km thick and normal mantle with a velocity of 8 0 8 2 km s in the aqaba region southwest and central jordan east of wadi araba the crustal thickness is of the order of 32 35 km while in the amman region it is not less than 35 km in southeast jordan the crust thickens to at least 37 km in what is probably the transition to the arabian shield type of crust the boundaries between the upper and lower crust at about 20 km depth and the lower crust and uppermost mantle are probably transition zones the upper crystalline crust has velocities of 5 8 6 5 km s while the lower crust has velocities greater than or around 6 65 km s while the crystalline basement is exposed in southwest jordan and is at a depth of 2 2 5 km north of amman it is at a depth of not less than 5 km in central jordan a comparison of the crustal type and structure of jordan and the adjacent dead sea rift with that of the black forest and the rhine valley yields a striking resemblance the situation of the jordan dead sea rift is explained in terms of the continental crust of arabia rifting in preference to the thin oceanic crust of the mediterranean sea

interpretation of a seismic refraction survey across the arabian shield in western saudi arabia abstract in february 1978 seismic refraction profiles were recorded by the u s geological survey along a 1000 km line across the arabian shield in western saudi arabia this report presents a traveltime and relative amplitude study in the form of velocity depth functions for each individual profile assuming horizontally flat layering the corresponding cross section of the lithosphere showing lines of equal velocity reaches to a depth of 60 80 km the crust thickens abruptly from 15 km beneath the red sea rift to about 40 km beneath the arabian shield the upper crust of the western arabian shield yields relatively high velocity material at about 10 km depth underlain by velocity inversions while the upper crust of the eastern shield is relatively uniform the lower crust with a velocity of about 7 km s is underlain by a transitional crust mantle boundary for the lower lithosphere beneath 40 km depth the data indicate the existence of a laterally discontinuous lamellar structure where high velocity zones are intermixed with zones of lower velocities beneath the crust mantle boundary of the red sea rift most probably strong velocity inversions exist here the data do not allow a detailed modelling velocities as low as 6 0 km s seem to be encountered between 25 and 44 km depth

interpretation of data from the monitoring thermal camera of stromboli volcano aeolian islands italy twenty eruptive events from the northeast crater of stromboli volcano recorded by a thermal monitoring camera in early 2004 were analysed in order to understand the eruptive dynamics selected events were chosen to be typical of explosions that characterize the steady activity of stromboli in terms of jet height and duration most of the explosions consisted of clast rich single bursts originating from the same vent inside the northeast crater conspicuous ash emission was scarce eruptions were preceded by the flashing of a perturbation wave characterized by low temperatures and an average propagation velocity of about 35 100 m s 1 this perturbation was thought to be caused by the bursting of the gas slug at the bottom of the crater and is interpreted as an air wave this was immediately followed by the expansion of a jet of hot gas and particles at a velocity of 35 75 m s 1 ejecta coarser than 138 cm appeared 1 6 2 s after the onset of the explosion moving at a variable velocity 30 60 m s 1 eruptive events were either vertical or inclined 7 13 towards the nnw this inclination is thought to be a consequence either of the morphology of the conduit following modest rock falls that partially obstructed the uppermost part of the crater or of the displacement of the internal conduit due to the explosive activity of the volcano the instability of the summit area is a further possible cause of the deformation of the conduit

anatomy of an unstable volcano from insar multiple processes affecting flank instability at mt etna 1994 2008 1 volcano deformation may occur under different conditions to understand how a volcano deforms as well as relations with magmatic activity we studied mt etna in detail using interferometric synthetic aperture radar insar data from 1994 to 2008 from 1994 to 2000 the volcano inflated with a linear behavior the inflation was accompanied by eastward and westward slip on the eastern and western flanks respectively the portions proximal to the summit showed higher inflation rates whereas the distal portions showed several sectors bounded by faults in some cases behaving as rigid blocks from 2000 to 2003 the deformation became nonlinear especially on the proximal eastern and western flanks showing marked eastward and westward displacements respectively this behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002 2003 eruptions from 2003 to 2008 the deformation approached linearity again even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002 the eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those largely inactive to the south in addition from 1994 to 2008 part of the volcano base south west and north lower slopes experienced a consistent trend of uplift on the order of 0 5 cm yr this study reveals that the flanks of etna have undergone a complex instability resulting from three main processes in the long term 103 104 years the load of the volcano is responsible for the development of a peripheral bulge in the intermediate term 101 years observed from 1994 to 2000 inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks in the short term 1 year observed from 2001 to 2002 the emplacement of feeder dikes along the ne and south rifts results in a nonlinear focused and asymmetric deformation on the eastern and western flanks deformation due to flank instability is widespread at mt etna regardless of volcanic activity and remains by far the predominant type of deformation on the volcano

structural geometry and evolution of the dead sea jordan rift system as deduced from new subsurface data abstract analysis of deep drilling data and seismic reflection surveys obtained in recent years permit establishment of a tectonic model of the dead sea jordan rift system that is in part conformable with some of the many often controversial theories on this subject but which also introduces new information negating some concepts that are widely accepted in the literature the dead sea jordan rift system is not a tensional graben between two parallel sets of faults but instead can be best defined as a sinistral transform connecting an incipient oceanic ridge the red sea with an upthrusted collision zone the taurus range the shear is caused by the opening of the red sea and the motion of the arabian sub plate away from the african plate the shearing occurs along a largely south north trending slightly arcuate une consisting of a series of en echelon left stepping left lateral strike slip master faults of varying lengths these faults characteristically die out to the north by bending outward northeast and the movement is taken up by the strike slip faults to the left i e to the west where overlap of the two faults occurs very narrow and very deep grabens have evolved in places the width being equal to the depth the narrowness of these grabens is dictated by the closeness of the overlapping segments of the successive strike slip faults this feature points to the probability that the en echelon strike slip faults have a common root zone at great depth these grabens are not typical leaky pull aparts in that they have no gravimetric magnetic or heat flow anomalies nor are they closed on all four sides by large faults their northern ends are characterized by gradually rising graben floors without major diagonal cross faults the dead sea jordan rift system sensu stricto extends over a distance of 420 km from the northern shore of the gulf of elat to the northern margin of the hula valley southward it is connected with the red sea along the gulf of elat transition zone which has elements of strike slip as well as tensional opening a northern transition zone exists between the hula valley and the taurus arc where diminishing strike slip movement is compensated by several underthrust belts the time of the beginning of the movement along the rift can be established as pre middle miocene because mid miocene sediments overlie an upper cretaceous graben floor rifting has continued intermittently to the present volcanism in the northern fifth of the rift is genetically associated with the seismically active tensional golan hauran jebel drouz wadi sirhan tectonic trend which has a north west southeast orientation and not with the north south trending dead sea jordan rift

radon mapping automatic measurements and extremely high 222rn emissions during the 2002 2007 eruptive scenarios at stromboli volcano abstract we report additional radon data collected at stromboli during 2002 2007 the whole data set of periodic measurements has been systematically analyzed to retrieve the values of background threshold and anomaly for all the stations of the network maps of radon concentrations in space and time correlate with changes in volcanic activity higher radon emissions are essentially concentrated at summit stations and may also affect some stations located onto the summit eastern sector of the cone along the n60 e fracture zone as well as two stations placed at the ne edge of sciara del fuoco most of these stations are well above their threshold values during effusive eruptions namely 2002 2003 and 2007 due to the progressive structural adjustment of the volcano edifice coupled with the opening and resetting of the fracture network a two year long timeseries of automatic 222 rn measurements 2005 2007 was analyzed together with local environmental parameters and selected geophysical data on seismic tremor and infrasonic puffing the data show good correlation between radon and the latter parameters particularly during periods of high strombolian activity march april 2006 and before the onset of the february 27 2007 lava effusion with radon emissions being well above 20 000 bq m 3 extremely high radon emissions up to 1 7 10 6 bq m 3 were recorded along the fractures of the sw crater during the first two months of the 2002 2003 effusive eruption very high radon emissions up to 470 000 bq m 3 for 222 rn and 780 000 bq m 3 for 220 rn respectively were also detected by the automatic measurements at the summit station during june 20 early july 2007 i e just prior to the resuming of the strombolian activity at summit craters these data give us the opportunity to estimate the relative depths of the summit fractures during fracturing being constrained between 200 and 310 m this is in good agreement with the hypocentral depths of the so called hybrid events and the source of the very long period seismic signals vlp localized at a depth of about 500 m a s l below the upper central part of the sciara del fuoco

effusive to explosive transition during the 2003 eruption of stromboli volcano the persistent explosive activity of stromboli volcano italy ceased in december 2002 and correlated with the onset of a seven month long effusive eruption on the volcano flank from new vents that opened just below the summit craters we intensively monitored this effusive event collecting and interpreting in real time an extensive multiparametric geophysical data set the resulting data synergy allowed detailed insights into the conduit dynamics that drove the eruption and the transition back to the typical strombolian activity we present a direct link between gas flux magma volume flux and seismicity supporting a gas driven model whereby the balance between gas flux and gas overpressure determines whether the system will support effusive or explosive activity this insight enabled us to monitor the migration of the magma column up the conduit and to explain the onset of explosive activity

neogene tectonic and stratigraphic events in the gulf of suez rift area egypt abstract the gulf of suez neogene syn rift section contains at least five datable intra basinal unconformities or stratigraphie hiatuses these events and associated changes in sedimentary sequences seen in the basin can be related to changes in suez rift subsidence miocene eustasy and the tectonic effects of adjacent red sea and dead sea rifting the first hiatus spans oligocene to earliest miocene time and separates syn rift from pre rift strata throughout the region this erosional event resulted from regional emergence during the oligocene and the initiation of suez rifting a second hiatus from 21 19 ma separates the poorly dated shallow marine nukhul formation of aquitanian to early burdigalian age from the overlying upper bathyal shales of the middle burdigalian to langhian nn3 5 rudeis formation this hiatus resulted from both a brief lowstand in early burdigalian sea level and increased suez rift related tectonism this event climaxed with the rapid tectonic subsidence that established deep marine conditions by 19 ma a third major event occurs within the rudeis at 17 ma nn4 n7 and marks the initiation of uplift of i he rift shoulders and margins and decelerated subsidence or even minor uplift in the axial trough hiatuses are seen over paleohighs e g tilted fault blocks whereas coarse elastics are deposited in more basinal areas in submarine fans and as turbidites a fourth unconformity at 14 ma separates the middle miocene kareem formation from overlying anhydrites and open marine shales of the belayim formation minor tectonic uplift throughout the suez region resulted from this event and a sill was established between the mediterranean and suez basins allowing cyclic anhydrite marl deposition from 14 to 11 ma this post kareem event may be the sedimentary response to initiation of movement along the dead sea aqaba transform a sharp drop in sea level at 11 ma restricted the suez basin even more and marked the initiation of massive halite precipitation in the central and southern suez well south of the sill area a final major neogene event occurs at the miocene pliocene boundary and is marked by a major unconformity caused by tectonic uplift this tectonic pulse is related to initiation of red sea sea floor spreading and acceleration of sinistral motion along the dead sea aqaba transform at 5 ma this event establishes the marine connection with the red sea and the sedimentary environments seen in the gulf of suez today

extension and rifting the zeit region gulf of suez abstract a field analysis of faults and fractures in the ras gharib ras gemsa region of the gulf of suez shows that the main late cenozoic extension occurred perpendicular to the rift axis three main types of dip slip normal faults successively developed as the tilt of blocks bounded by antithetic normal faults increased determinations of the amount of extension from structural data are compatible with estimates made using subsidence data through a simplified model of lithospheric stretching the uplift of rift shoulders is related in chronology and volume to the subsidence of the rift the geometry of fault patterns and directions of extension suggests that the late cenozoic total movement corresponds to a counterclockwise rotation of 4 5 of sinai relative to africa with a pole close to cairo

understanding shallow magma emplacement at volcanoes orthogonal feeder dikes during the 2002 2003 stromboli italy eruption 1 understanding how shallow magma is emplaced within volcanoes is crucial for hazard assessment the 2002 2003 stromboli eruption provides the opportunity to investigate shallow magma emplacement resulting from orthogonal feeder dikes and its possible effects stromboli erupted in 2002 2003 when effusive activity replaced strombolian activity on december 28 a ne sw fissure propagated from the lava filled northernmost summit crater on december 29 a nw se fissure propagated north of the craters feeding nw se aligned vents on december 30 this area collapsed reaching the sea and generating a tsunami in mid february 2003 the nw se fissure became inactive while the ne sw effusive fissure continued until july a model for shallow magma emplacement is proposed the lateral propagation of a ne sw dike from the northernmost crater was triggered below a nw se dike propagating from the magma filled ne tip of the ne sw elongated conduit fed the nw se aligned vents in february the conduit periphery became solidified freezing the nw se dike and the transport of magma was limited to the central part focusing its rise below the craters this fed the ne sw fissure until the supply decreased further july returning to the ordinary level sustaining strombolian activity orthogonal dike emplacement followed the trajectories of the maximum gravitational stress 1 partly controlled by the irregular topography of the uppermost edifice the emplacement of orthogonal dikes in a limited area is feasible at non perfectly conical active volcanoes where the maximum gravitational stress may show variations from a purely radial path

lithospheric structure of the jordan dead sea transform from earthquake data abstract p wave travel times from 89 shallow earthquakes m 6 recorded at the jordan university seismological station unj from epicentral distances in the range 140 km x 1308 km are utilized in the derivation of a lithospheric model for the jordan dead sea transform region the selected events are of high signal noise ratio for most events the standard deviation of the origin time is in the range 0 1 1 2 s one dimensional ray tracing is used to model the p wave travel times results indicate that an average crustal thickness of about 35 km beneath the station as derived from explosion data is confirmed by the earthquake data the pn velocity for the uppermost mantle is 8 07 0 02 km s the first upper mantle refractor below the moho occurs at a depth of about 54 km with an apparent velocity at this discontinuity of 8 4 0 06 km s being measured the thickness of the layer below this discontinuity appears to be of the order of only 2 3 km below this the data are interpreted to represent a low velocity zone where the velocity gradually decreases to a minimum of about 8 1 km s at a depth of 80 km and increases thereafter at a constant rate of 0 02 s 1 down to a depth of 105 km at this depth the next refractor occurs producing a constant velocity of 8 6 0 04 km s the layer below this refractor seems to extend to a depth of not less than 150 km

two stage red sea rifting inferred from mantle earthquakes in neoproterozoic lithosphere abstract we use earthquake geothermometry measured heat flow and structural constraints from p wave receiver functions to model the thermal evolution of the lithosphere beneath harrat lunayyir we suggest that the lithosphere thinned to its present 60 km thickness in a second stage of lithospheric thinning at 15 12 ma following initial red sea extension at 27 ma harrat lunayyir is an active volcanic field located in the arabian shield 150 km east of the red sea rift axis in the lithospheric mantle beneath harrat lunayyir we locate 64 high frequency earthquakes at depths of 42 48 km all with m l 2 5 these brittle failure earthquakes must have nucleated at relatively low temperatures based upon global maximum nucleation depths and temperature dependent deformation experimental results therefore the mantle earthquakes show that the upper mantle lithosphere is not in thermal equilibrium with the shallow 60 km underlying asthenosphere our thermal modeling indicates that the lithosphere beneath harrat lunayyir thinned to its current 60 km thickness at 12 2 ma as constrained by thermal modeling of 1 surface heat flow 2 the depth to the mid crustal brittle ductile transition and 3 the depth to the upper mantle brittle ductile transition