fragmentation of the adriatic promontory new chronological constraints from neogene shortening rates across the southern alps ne italy key points folded alluvial surfaces and balanced cross section constrain post lgm and neogene shortening rates decrease in shortening rate and change in compression direction are inferred at 1 2 ma kinematic reorganization is best explained by a shift from nubia driven to adria driven convergence abstract the eastern southern alps are located at the northern tip of the adria microplate which imposes 2 0 2 5 mm yr of n s convergence relative to stable eurasia we map surface evidence of recent folding faulting in this area from a 5 m dem in the eastern part of the belt observations reveal a 30 km wide zone of active folding composed of at least five growing anticlines the most recent ones warped the post glacial alluvial surface by 10m combining these findings with published geological and geophysical data allows us to infer that active thrusting occurs along a single deeply rooted thrust which accommodates the indentation of the adriatic crust resolving the observed pattern of uplift on the inferred fault geometry indicates that nne ssw shortening across the eastern southern alps has occurred at a rate of about 1 5 mm yr over the post glacial period on the other hand a balanced cross section for the eastern southern alps at the scale of the upper crust constrains a minimum of 43 km of finite shortening over the last 14ma yielding a shortening rate of about 3 mm yr which is two times higher than the post glacial shortening rate this decrease in the shortening rate is associated to the pleistocene activation of new thrusts that is compatible with a change in the direction of compression the inferred local change in the kinematics of thrusting during the pleistocene is consistent with a change from nubia imposed to adria imposed convergence indicating that the fragmentation of the adriatic promontory could have occurred 1 2 ma ago

broadband waveform inversion of moderate earthquakes in the messina straits southern italy abstract we report the first application of the cut and paste cap method to compute earthquake focal mechanisms in the messina straits area by waveform inversion of pnl and surface wave segments this application of cap has furnished new knowledge about low magnitude earthquake mechanics that will be useful for improved understanding of the local geodynamics this is possible because the cap inversion technique can be applied to small earthquakes for which traditional moment tensor inversion methods are not appropriate and p onset focal mechanisms in the study area fail because of a lack of sufficient observations we estimate the focal mechanisms of 23 earthquakes with local magnitudes in the range of 3 4 occurring in the 2004 2008 time period and recorded by the broadband stations of the italian national seismic network and the mediterranean very broadband seismographic network mednet run by the istituto nazionale di geofisica e vulcanologia ingv the solutions show that normal faulting is the prevailing style of seismic deformation in the northern part of the study area while co existence of normal faulting and strike slip has been detected in the southern part in the whole area of investigation the t axes of focal mechanisms display a preferential northwest southeast direction of extension combined with the findings of previous investigations this improved database of focal mechanisms allows us to better detail the transitional area between the extensional domain related to subduction trench retreat southern calabria and the compressional one associated with continental collision western central sicily the observed spatial change of seismic deformation regime offers new data to current seismotectonic and seismic hazard investigations in the area of messina straits where a magnitude 7 2 earthquake caused more than 60 000 casualties on 28 december 1908

a no net rotation model of present day surface motions a significant portion of the earth s surface consists of zones of diffuse deformation the interior regions of these diffuse zones of deformation move at distinctly different velocities from that of adjacent plates and because of their complexities have been ignored in previous no net rotation nnr models we have calculated a new nnr model from a continuous velocity field that incorporates both rigid plate motion and velocity gradients within plate boundary zones when compared with earlier nnr models we find significantly different angular velocities for many plates differences between the nnr model presented here and earlier nnr models can be attributed to the effect of including velocity gradients in diffuse plate boundary zones as well as to the actual differences between geodetically derived surface motions and geologic estimates

extension controls quaternary tectonics geomorphology and sedimentation of the n appennies foothills and adjacent po plain italy abstract in the middle pleistocene thrusting in the n apennine fold and thrust belt came to an end and foredeep sedimentation in the adjacent po plain basin ceased a new tectono sedimentary regime was installed extensional faults were activated in the foothills and are limited to the northeast by a major sw dipping normal fault the bologna fault for which a vertical displacement of 1000 m is estimated the region northeast of the fault i e its footwall was progressively tilted towards the po plain the sw sectors of the tilting region were progressively uplifted above sea level subjected to erosion thereby feeding a deltaic system which prograded towards the northeast in the subsiding regions compressional structures without major deformation are recorded in the zone of maximum curvature all these features are explained by the onset of extensional deformation along the bologna fault and consequent flexural unloading of its footwall the evidence therefore shows that the transition region between the n apennine foothills and po plain has been under a tensional stress regime since the middle pleistocene

kinematics of the western africa eurasia plate boundary from focal mechanisms and gps data summary the western mediterranean displays a complex pattern of crustal deformation distributed along tectonically active belts developed in the framework of slow oblique plate convergence we used earthquake and global positioning system gps data to study the present day kinematics and tectonics of the africa eurasia plate boundary in this region crustal seismicity and focal mechanisms analysed in terms of seismic moment release and seismic deformation outline the geometry of major seismic belts and characterize their tectonics and kinematics continuous gps data have been analysed to determine euler vectors for the nubian and eurasian plates and to provide the global frame for a new mediterranean gps velocity field obtained by merging continuous and campaign observations collected in the 1991 2005 time span gps velocities and displacements predicted by the nubia eurasia rotation pole provide estimates of the deformation accommodated across the tectonically active belts the rather simple deformation occurring in the atlantic region characterized by extension about perpendicular to the middle atlantic and terceira ridges and right lateral motion along the gloria transform fault turns into a complex pattern of deformation occurring along broader seismic belts where continental lithosphere is involved our analysis reveals a more complex fragmentation of the plate boundary than previously proposed the roughly e w trending mainly compressive segments i e southwestern iberia northern algeria and southern tyrrhenian where plate convergence is largely accomodated across rather localized deformation zones and partially transferred northward to the adjacent domains i e the algero balearic and tyrrhenian basins are interrupted by regions of more distributed deformation i e the rif alboran betics tunisia libya and eastern sicily or limited seismicity i e the strait of sicily which are characterized by less homogeneous tectonics regimes mainly transcurrent to extensional in correspondence of the observed breaks tectonic structures with different orientation interfere and we find belts with only limited deformation i e the high and middle atlas the tunisian atlas and the offshore tunisia libya belt that extends from the plate boundary into the nubian plate along pre existing tectonic lineaments our analysis suggest that the sicilian pelagian domain is moving independently from nubia according to the presence of a right lateral and extensional decoupling zone corresponding to the tunisia libya and strait of sicily deformation zone despite the space variability of active tectonic regimes plate convergence still governs most of the seismotectonic and kinematic setting up to the central aeolian region in general local complexities derive from pre existing structural features inherited from the tectonic evolution of the mediterranean region on the contrary along calabria and the apennines the contribution of the subducted ionian oceanic lithosphere and the occurrence of microplates i e adria appear to substantially modify both tectonics and kinematics finally gps data across the gibraltar arc and the tyrrhenian calabria domain support the hypothesis that slab rollback in these regions is mostly slowed down or stopped

glacial isostatic adjustment observed using very long baseline interferometry and satellite laser ranging geodesy in global space geodetic solutions radial site motions are usually estimated relative to the geocenter the center of figure of the solid earth most geodesists estimate the motion of the geocenter assuming both that sites do not move radially and that sites move laterally as predicted by plate motion model nuvel 1a demets et al 1990 1994 here we estimate the motion of the geocenter assuming that the plate interiors deform radially and laterally as predicted by the postglacial rebound model of peltier 1994 or that of peltier 1996 without assuming a priori knowledge about relative plate motion radial site motions estimated relative to this rebound adjusted geocenter are in the same reference frame as the rebound model predictions whereas site motions estimated without adjusting for rebound are not we further constrain the motion of the rebound adjusted geocenter using satellite laser ranging s sensitivity to the center of mass of the solid earth the oceans and the atmosphere by assuming that the mean velocity between the rebound adjusted geocenter and the center of mass is negligible over the time period of geodetic measurement twenty years of observation with satellite laser ranging and very long baseline interferometry record the isostatic response of the solid earth to the unloading of the late pleistocene ice sheets the misfits of the postglacial rebound model of peltier 1994 and that of peltier 1996 are 34 and 16 less respectively than the misfit of the rigid plate model sites at onsala sweden and algonquin park ontario are observed to be rising at 3 mm yr and 2 mm yr respectively reflecting unloading of the fennoscandian and laurentide ice sheets sites along the east coast of the united states are subsiding at 2 mm yr indicating that the forebulge produced by the laurentide ice sheet is currently collapsing very slowly sites beneath the margins of the ice sheets during the last glacial maximum are currently moving laterally away from the ice sheet centers at 1 5 mm yr in disagreement with the moderately fast outward motion predicted by the model of peltier 1996

itrf2000 a new release of the international terrestrial reference frame for earth science applications 1 for the first time in the history of the international terrestrial reference frame the itrf2000 combines unconstrained space geodesy solutions that are free from any tectonic plate motion model minimum constraints are applied to these solutions solely in order to define the underlying terrestrial reference frame trf the itrf2000 origin is defined by the earth center of mass sensed by satellite laser ranging slr and its scale by slr and very long baseline interferometry its orientation is aligned to the itrf97 at epoch 1997 0 and its orientation time evolution follows conventionally that of the no net rotation nnr nuvel 1a model the itrf2000 orientation and its rate are implemented using a consistent geodetic method anchored over a selection of itrf sites of high geodetic quality ensuring a datum definition at the 1 mm level this new frame is the most extensive and accurate one ever developed containing about 800 stations located at about 500 sites with better distribution over the globe compared to past itrf versions but still with more site concentration in western europe and north america about 50 of station positions are determined to better than 1 cm and about 100 sites have their velocity estimated to at or better than 1 mm yr level the itrf2000 velocity field was used to estimate relative rotation poles for six major tectonic plates that are independent of the trf orientation rate a comparison to relative rotation poles of the nuvel 1a plate motion model shows vector differences ranging between 0 03 and 0 08 m y equivalent to approximately 1 7 mm yr over the earth s surface itrf2000 angular velocities for four plates relative to the pacific plate appear to be faster than those predicted by the nuvel 1a model the two most populated plates in terms of space geodetic sites north america and eurasia exhibit a relative euler rotation pole of about 0 056 0 005 m y faster than the pole predicted by nuvel 1a and located about 10 n 7 e more to the northwest compared to that model

coupled mantle dripping and lateral dragging controlling the lithosphere structure of the nw moroccan margin and the atlas mountains a numerical experiment abstract recent studies integrating gravity geoid surface heat flow elevation and seismic data indicate a prominent lithospheric mantle thickening beneath the nw moroccan margin lab 200 km depth followed by thinning beneath the atlas domain lab about 80 km depth such unusual configuration has been explained by the combination of mantle underthrusting due to oblique africa eurasia convergence together with viscous dripping fed by asymmetric lateral mantle dragging requiring a strong crust mantle decoupling in the present work we examine the physical conditions under which the proposed asymmetric mantle drip and drag mechanism can reproduce this lithospheric configuration we also analyse the influence of varying the kinematic boundary conditions as well as the mantle viscosity and the initial lithosphere geometry results indicate that the proposed drip drag mechanism is dynamically feasible and only requires a lateral variation of the lithospheric strength the further evolution of the gravitational instability can become either in convective removal of the lithospheric mantle mantle delamination or subduction initiation the model reproduces the main trends of the present day lithospheric geometry across the nw moroccan margin and the atlas mountains the characteristic time of the observed vertical movements the amplitude and rates of uplift in the atlas mountains and offers an explanation to the miocene to pliocene volcanism an abnormal constant tectonic subsidence rate in the margin is predicted

the seismic velocity structure of northern appalachian crust around western newfoundland the crustal velocity structure beneath western newfoundland is constrained by a reanalysis of older regional refraction profiles together with an analysis of one new profile initial interpretation of the older data gave inconsistent and discontinuous structures that are difficult to reconcile with more recent deep reflection profiles we also show that traveltimes predicted by the earlier models often do not yield acceptable fits to the original observations our reinterpretation reveals a simpler pattern in which the crust is characterized by a persistent high velocity lower crustal hvlc layer this layer has velocities of 7 0 7 9 kmls and thicknesses of 5 23 km it is thickest beneath the grenville crustal block east of the appalachian structural front and thins or is possibly absent within the central block analysis of the new much higher resolution profile off western newfoundland confirms the existence of the hvlc layer with a velocity of 7 2 kmls and thicknesses of 11 19 km increasing to

moment tensor inversion for iberia maghreb earthquakes 2005 2008 abstract we present and discuss a set of 77 moment tensor solutions for earthquakes in the iberia maghreb region from mid 2005 to the end of 2008 with moment magnitudes ranging from 3 2 to 6 0 inversion is based upon full three component intermediate period waveforms recorded at regional seismic broadband stations following the recent densification of permanent broadband networks and large scale temporary deployments at present more than 150 stations are recording in spain portugal and morocco this unprecedented station density allows analysis of small events from available short distance recordings and in general leads to more reliable source estimates due to data redundancies that permit elimination of waveforms affected by noise or complicated propagation effects the solutions for 2005 2008 constitute an important upgrade of the iberia maghreb moment tensor inventory to 225 solutions to date enhancing the image of seismotectonics at the compressive n algerian margin in the betic alboran shear zone and at the transpressive sw iberian margin as well as providing valuable constraints on seismic deformation in the western betics and the iberian foreland where little information has been previously available new solutions for the foreland and three recent seismic series in the western betics show strike slip and reverse faulting style contrasting with the dominance of normal faulting in the adjacent areas towards east in these areas as well as at the sw iberian margin faulting orientations are heterogeneous including solutions with opposite kinematics this indicates control by local stress conditions and points to fault interaction along the n algerian margin a counterclockwise rotation of slip vectors of thrust events from east to west becomes apparent several solutions for the area offshore cape st vincent are located at sub moho depths between 40 and 60 km supporting a large brittle layer thickness in the oceanic lithosphere

episodic tectonic plate reorganizations driven by mantle convection abstract periods of relatively uniform plate motion were interrupted several times throughout the cenozoic and mesozoic by rapid plate reorganization events r hey geol soc am bull 88 1977 1404 1420 p a rona e s richardson earth planet sci lett 40 1978 1 11 d c engebretson a cox r g gordon geol soc am spec pap 206 1985 r g gordon d m jurdy j geophys res 91 1986 12389 12406 d a clague g b dalrymple us geol surv prof pap 1350 1987 5 54 j m stock p molnar nature 325 1987 495 499 c lithgow bertelloni m a richards geophys res lett 22 1995 1317 1320 m a richards c lithgow bertelloni earth planet sci lett 137 1996 19 27 c lithgow bertelloni m a richards rev geophys 36 1998 27 78 it has been proposed that changes in plate boundary forces are responsible for these events m a richards c lithgow bertelloni earth planet sci lett 137 1996 19 27 c lithgow bertelloni m a richards rev geophys 36 1998 27 78 we present an alternative hypothesis convection driven plate motions are intrinsically unstable due to a buoyant instability that develops as a result of the influence of plates on an internally heated mantle this instability which has not been described before is responsible for episodic reorganizations of plate motion numerical mantle convection experiments demonstrate that high rayleigh number convection with internal heating and surface plates is sufficient to induce plate reorganization events changes in plate boundary forces or plate geometry are not required

intraplate deformation in western europe deduced from an analysis of the international terrestrial reference frame 1997 itrf97 velocity field although tectonic deformation in western europe is essentially concentrated in the appenines and alpine alps pyrenees mountain ranges several large historical and instrumentally recorded earthquakes m 6 are known in the supposedly stable part of europe because of its accuracy and internal consistency at a global scale the international terrestrial reference frame 1997 itrf97 velocity field allows testing of intraplate rigidity in western europe at a millimeter per year level using the full statistical information available on the itrf97 velocities we identify a subset of sites located in central europe that satisfies a rigid cap rotation with residual velocities 1 mm yr and therefore provide a stable europe reference frame serf in this reference frame we find residual velocities at european itrf sites that are consistent with known active tectonic features we identify a northward motion at sites located in italy with internal deformation of the adriatic block rather than rigid plate motion and a westward motion of the westernmost part of europe of the order of 1 2 mm yr relative to central europe the relative motion of the adriatic block and western europe agrees with the current extension known in the tyrrhenian sea and the apennines in central europe we find active deformation 1 mm yr in the eastern alps and western carpathians in the alpine range our results indicate e w extension across the western alps and n s compression across the central and eastern alps in agreement with the strain regime deduced from seismotectonic observations in belgium and the netherlands we find residual velocities of 1 1 5 mm yr to the northwest at all the sites most likely accommodated along the upper and lower rhine graben structures an important outcome of this study is the identification of internal deformation of the order of 1 2 mm yr in an area usually interpreted as stable europe this result should be further checked as new denser and more accurate space geodetic data sets with longer observation time spans become available for europe

contrasts between debris flows hyperconcentrated flows and stream flows at a channel of mount semeru east java indonesia abstract in order to differentiate between different types of sediment laden flows in volcanic channels we carried out observation of debris flows hyperconcentrated flows and stream flows in the curah lengkong river on the southeast slope of mount semeru in east java indonesia the aims of this study are 1 to provide quantitative data for these flows in motion 2 to compare the data for different types of flow that occur in the same river 3 to assess the influence of rainfall on debris flows hyperconcentrated flows and streamflow generation the curah lengkong river transports large volumes of sediment in the range of 1 10 5 to 5 10 5 m 3 per debris flow and 10 3 to 10 5 m 3 per hyperconcentrated flow and stream flow large sediment discharges result from the following factors continuous and voluminous sediment supply of fine juvenile material by daily explosions of the semeru volcano pyroclastic source material emplaced on steep slopes strong erosion of weathered river banks and strong rainfall intensities the occurrence of the flows focuses in the period from november through april and the daily timing of it is the mid to late afternoon nearly all debris flows are triggered by stationary rainfall confined to the upper slopes of mount semeru whereas hyperconcentrated flows and stream flows are mainly generated by migratory or regional rains driven upwards on the eastern slope this slope receives its maximum of annual rainfall 3800 mm at 800 m asl the peak surface velocity of debris flows is always greater than the peak frontal velocity the peak discharge of debris flows occurs several minutes after the passage of the flow front volumetric concentrations of sediment are high 48 to 69 between the debris flow front and the point of peak discharge after the peak discharge it usually decreases gradually contrary to the case of debris flows high concentration of sediment appears in various portion of hyperconcentrated flows and stream flows near the front in the mid point or at the back of flows although the concentration of sediments in them is much less than in of debris flows relationships between sediment discharge total volume and peak discharge show a very strong positive correlation for debris flows and hyperconcentrated flows therefore sediment discharge can be roughly estimated from direct visual observation

localized and distributed erosion triggered by the 2015 hurricane patricia investigated by repeated drone surveys and time lapse cameras at volcan de colima mexico abstract in october 2015 patricia a major category 5 hurricane made landfall in western mexico resulting in 500 mm cumulated rainfall and lahar generation along the southerly directed montegrande valley of volcan de colima we monitored lahar deposition and erosion using time lapse trail cameras and conducted repeated camera drone overflights two days before and after the hurricane using photogrammetric processing we derive a unique dataset of high resolution digital terrain models and study the geomorphologic impacts of a single lahar event results reveal different types of erosion at 8 km distance from the volcano with overland flow and rill networks developing into major erosion gullies exceeding a depth of 4 m as well as bank collapse oversteepening and marginal erosion we find alternating deposition and erosion zones that depend on general slope and valley width and find that the overland flow related erosion is an important contributor to the bulking process of lahars moreover this study shows that camera monitoring is very useful for studying the relationship between volcano landscape evolution and hydrometeorological extremes and for rapid assessment associated with single lahar events

evidence for motion between nubia and somalia along the southwest indian ridge the east african rift marks the northern boundary of the nubian west african and somalian east african plates and has formed by horizontal stretching due to the separation of these plates1 south of 20 s any expression of deformation or seismicity due to the relative motion of these two distinct plates vanishes although the boundary must continue until it intersects another plate boundary the nearest such boundary is that of the antarctic plate marked by the southwest indian ridge but previous analyses of plate motion data have indicated no significant difference between nubia antarctica and somalia antarctica motion2 3 here we show using a large compilation of plate motion data that nubia antarctica motion does differ from somalia antarctica motion and we determine a relative angular velocity of the two plates that has compact confidence limits our analysis places the pole of rotation near to the southern limit of african seismicity implying that the southern part of the nubian somalian plate boundary is a diffuse zone of convergence up to 2 mm yr 1 whereas up to 6 mm yr 1 of separation is accommodated across the east african rift about half the separation rate of the slowest mid ocean ridge

sediment transportation and deposition by rain triggered lahars at merapi volcano central java indonesia abstract a lahar is a general term for a rapidly flowing mixture of rock debris and water other than normal streamflow from a volcano and refers to the moving flow located in the populated area of central java the stratovolcano merapi 2965 m is prone to lahar generation due to three main factors 1 millions of cubic meters of pyroclastic deposits are the product of frequent pyroclastic flows which have occurred on 2 to 4 year intervals 2 rainfall intensity is high often 40 mm in 2 h on average during the rainy season from november to april and 3 drainage pattern is very dense following the 22 november 1994 eruption of merapi 31 rain triggered lahar events were recorded in the boyong river between december 1994 and may 1996 on merapi s slopes instantaneous sediment concentration at any given time of the lahars varies widely over time and space lahars are transient sediment water flows whose properties are unsteady so that the sediment load fluctuates during the flow the boundary between the flow types debris flow with sediment concentration 60 volume or hyperconcentrated flow with sediment concentration ranges from 20 to 60 volume may fluctuate within the flow itself grain size distribution physical composition of sediments shear stress yield stress and water temperature play each a role on this boundary natural self damming and rapid breakout are partly responsible for the sediment variations of the flows debris flow phases at merapi typically last a few minutes to 10 min and are often restricted to the lahar front debris flow surges are sometimes preceded and always followed by longer hyperconcentrated flow phases as a result mean sediment concentration of the lahars is low commonly from 20 to 50 volume besides transient normal streamflow phases sediment concentration low sediment load and frequent transient flows in the merapi channels may result from at least three factors 1 several breaks in slope along the channel increase the deposition rate of sediment and hinder the bulking capacity of the lahars 2 source material is mainly coarse debris of merapi type block and ash flows consequently the remobilization of coarse debris is more difficult and the clast deposition is accelerated 3 variations of rainfall intensity over time and space common in tropical monsoon rainfall also influence the sediment load variations of the lahars sedimentologic analyses of the lahar deposits in the boyong river at merapi encompass clast supported and matrix supported debris flow deposits hyperconcentrated flow deposits and streamflow deposits the stratigraphic succession of massive and stratified beds observed immediately after any given lahar event in the boyong river indicates that the sediment concentration varies widely over time and space during a single lahar event sedimentation rate varies from 3 to 4 5 cm min during relatively long lived surges to as much as 20 cm min during short lived surges these results indicate that the sediment load fluctuates during lahar flow further demonstrating that lahars are transient sediment water flows with unsteady flow properties

in flow evolution of lahar deposits from video imagery with implications for post event deposit interpretation mount semeru indonesia abstract the hazardous and unpredictable nature of lahars makes them challenging to study yet the in flow processes characterizing these events are important to understand as a result much of the previous research on lahar sedimentation and flow processes has been derived from experimental flows or stratigraphic surveys of post event deposits by comparison little is known on the time dependent sediment and flow dynamics of lahars in natural environments using video footage of seven lahars on the flanks of semeru volcano east java indonesia the present study offers new insights on the in flow evolution of sediment in natural lahars video analysis revealed several distinctive patterns of sediment entrainment and deposition that varied with time related fluctuations in flow these patterns were used to generate a conceptual framework describing possible processes of formation for subsurface architectural features identified in an earlier lateral survey of lahar deposits on semeru volcano gomez and lavigne 2010a the formation of lateral discontinuities was related to the partial erosion of transitional bank deposits followed by fresh deposition along the erosional contact this pattern was observed over the course of several lahar events and within individual flows observations similarly offer potential explanations for the formation of lenticular features depending on flow characteristics these features appeared to form by preferential erosion or deposition around large stationary blocks and by deposition along channel banks during episodes of channel migration or channel constriction finally conditions conducive to the deposition of fine laminated beds were observed during periods of attenuating and surging flow these results emphasize the difficulties associated with identifying process structure relationships solely from post event deposit interpretation and illustrate that an improved understanding of the time dependent sediment dynamics in lahars may be advantageous when interpreting post event structural features

how rigid is the stable interior of the north american plate we analyze data from eight permanent gps stations broadly distributed through the interior of the north american plate and use the resulting velocities to estimate an euler vector describing motion of stable north america as a single rigid plate the site velocities fit the single plate model with a mean residual of 1 3 mm yr the residuals do not appear to reflect post glacial rebound and tests for differential motion between eastern and western north america at the new madrid seismic zone show no resolvable motion within uncertainties the residuals likely reflect observational error and thus our estimate of the stability of the plate interior is likely an upper bound

geodetic constraints on the rigidity and relative motion of eurasia and north america gps observations in northeastern asia when combined with observations from the global network for the period 1992 1999 yield an angular rotation vector between eurasia and north america consistent with and a factor of two more precise than estimates derived using gps or vlbi data previously available from only western eurasia the new vector implies a pole of relative rotation 1200 km more to the northwest than predicted by the nuvel 1a global plate model suggesting a significant change in the relative motion of eurasia and north america over the past 3 myr the standard deviations of horizontal velocities from rigid plate motion for nineteen stations in eurasia and ten in north america are less than 1 mm yr the observations place an upper bound of 2 mm yr at 95 confidence for relative motion between western and eastern eurasia

downstream dilution of a lahar transition from debris flow to hyperconcentrated streamflow nearly instantaneous melting of snow and ice by the march 19 1982 eruption of mount st helens released a 4 106 m3 flood of water from the crater that was converted to a lahar volcanic debris flow through erosion and incorporation of sediment by the time it reached the base of the volcano over the next 81 km that it traveled down the toutle river the flood wave was progressively diluted through several mechanisms a transformation from debris flow to hyperconcentrated streamflow began to occur about 27 km downstream from the crater when the total sediment concentration had decreased to about 78 by weight 57 by volume the hyperconcentrated lahar runout flood wave transporting immense quantities of sand in suspension continued to experience progressive downstream dilution although turbulence was significantly dampened by the extremely high suspended load very large standing waves and antidune waves were observed the hyperconcentrated lahar runout flow deposited an unusual faintly stratified coarse sand which locally contained small isolated gravel lenses very similar deposits in the quaternary stratigraphy of mount st helens and other cascades volcanoes suggest that lahars may be more frequent than previously recognized

revised history of early tertiary plate motion in the south west pacific reanalysis of early tertiary magnetic anomalies on the pacific plate south of the campbell plateau indicates that in early tertiary time there was a previously unrecognized triple junction of the pacific the antarctic and a third plate now beneath the bellingshausen sea corresponding revised parameters for pacific antarctica motion do not require early tertiary displacements within antarctica or new zealand but suggest a change in direction of the pacific plate over the hotspots of approximately the same sense and timing as the hawaiian emperor bend

geology tectonics and the 2002 2003 eruption of the semeru volcano indonesia interpreted from high spatial resolution satellite imagery abstract the paper illustrates the application of high spatial resolution satellite images in interpreting volcanic structures and eruption impacts in the tengger semeru massif in east java indonesia we use high spatial resolution images ikonos and spot 5 and aerial photos in order to analyze the structures of semeru volcano and map the deposits geological and tectonic mapping is based on two dems and on the interpretation of aerial photos and four spot and ikonos optical satellite images acquired between 1996 and 2002 we also compared two thermal surface kinetic temperature aster images before and after the 2002 2003 eruption in order to delineate and evaluate the impacts of the pyroclastic density currents semeru s principal structural features are probably due to the tectonic setting of the volcano a structural map of the tengger semeru massif shows four groups of faults orientated n40 n160 n75 and n105 to n140 conspicuous structures such as the se trending horseshoe shaped scar on semeru s summit cone coincide with the n160 trending faults the direction of minor scars on the east flank parallels the first and second groups of faults the semeru composite cone hosts the currently active jonggring seloko vent this is located on and buttressed against the mahameru edifice at the head of a large scar that may reflect a failure plane at shallow depth dipping 35 towards the se this failure plane may correspond to a weak basal layer of weathered volcaniclastic rocks of tertiary age we suggest that the deformation pattern of semeru and its large scar may be induced by flank spreading over the weak basal layer of the volcano it is therefore necessary to consider the potential for flank and summit collapse in the future the last major eruption took place in december 2002 january 2003 and involved emplacement of block and ash flows we have used the 2003 aster surface kinetic temperature image to map the 2002 2003 pyroclastic density current deposits we have also compared two 10 m pixel images acquired before and after the event to describe the extent and impact of an estimated volume of 5 45 106 m3 of block and ash flow deposits an ash rich pyroclastic surge escaped from one of the valley confined block and ash flows at 5 to 8 km distance from the crater and swept across the forest and tilled land on the sw side of the bang river valley downvalley the temperature of the pyroclastic surge decreased and a mud rich deposit coated the banks of the bang river valley thus hazard mitigation at semeru should combine 1 continuous monitoring of the eruptive activity through an early warning system and 2 continuous remote sensing of the morphological changes in the drainage system due to the impact of frequent pyroclastic density currents and lahars

fast kinematic waveform inversion and robustness analysis application to the 2007 mw 5 9 horseshoe abyssal plain earthquake offshore southwest iberia an m w 5 9 earthquake occurred beneath the horseshoe abyssal plain hap offshore southwest iberia on 12 february 2007 the region where the earthquake occurred has a high seismogenic and tsunamigenic potential the purpose of this paper is twofold 1 to extract information about the source of the earthquake that contributes to the understanding of regional tectonics and 2 to evaluate the applicability of a fast algorithm to study a moderate earthquake offshore mainland portugal we employed the kiwi tools which implement a multistep inversion algorithm to infer both the point and finite source properties of the earthquake in order to assess the robustness of our solutions we performed independent sets of inversions that take different datasets and assumptions e g green s functions passbands wave types as inputs we also performed bootstrap analyses in order to appraise the robustness of the source parameters we concluded that the 2007 hap earthquake centroid is located at 35 841 n 10 611 w at a depth of 39 km scalar moment m is consistently retrieved with an average value of graphic 1 moment magnitude m w 5 9 the finite fault parameters are difficult to resolve given the existing data approximately 70 of our bootstrap solutions indicate a true rupture plane that trends west northwest east southeast strike 128 dip 46 and rake 138 the location and strike of this fault plane coincide with the southwest iberian margin swim faults however the 46 dip is difficult to reconcile with the subvertical nature of the swim faults online material inversion results using teleseismic data prem and body waves only 1 embed inline graphic 1 gif

east west extension and holocene normal fault scarps in the hellenic arc examination of surface fault traces with spot images and in the field corroborates the inference that the active tectonics of southern peloponnesus and crete are dominated by approximately north south normal faulting and approximately east west extension the heights of holocene normal fault scarps yield first order regional estimates of fault slip rates between 0 1 and 2 3 mm yr most of the surface scarps probably ruptured during past earthquakes such as that which destroyed sparta in 464 b c on the sparta fault the holocene average slip rate and the recurrence time of large earthquakes may be 1 mm yr and 3000 yr respectively the regional pattern of quaternary faulting suggests that the east west extension near the hellenic subduction zone is fast about 5 10 m y the change from north south to east west extension in the late pliocene 2 4 ma implies that the aegean is starting to collide with the northern margin of africa

seismic imaging of the eastern algerian margin off jijel integrating wide angle seismic modelling and multichannel seismic pre stack depth migration this study presents the results of a deep seismic survey across the north algerian margin based on the combination of 2 d multichannel and wide angle seismic data simultaneously recorded by 41 ocean bottom seismometers deployed along a north south line extending 180 km off jijel into the algerian offshore basin and 25 land stations deployed along a 100 km long line cutting through the lesser kabylia and the tellian thrust belt the final model obtained using forward modelling of the wide angle data and pre stack depth migration of the seismic reflection data provides an unprecedented view of the sedimentary and crustal structure of the margin the sedimentary layers in the algerian basin are 3 75 km thick to the north and up to 4 5 5 km thick at the foot of the margin they are characterized by seismic velocities from 1 9 to 3 8 km s 1 messinian salt formations are about 1 km thick in the study area and are modelled and imaged using a velocity between 3 7 and 3 8 km s 1 the crust in the deep sea basin is about 4 5 km thick and of oceanic origin presenting two distinct layers with a high gradient upper crust 4 7 6 1 km s 1 and a low gradient lower crust 6 2 7 1 km s 1 the upper mantle velocity is constrained to 7 9 km s 1 the ocean continent transition zone is very narrow between 15 and 20 km wide the continental crust reaches 25 km thickness as imaged from the most landward station and thins to 5 km over a less than 70 km distance the continental crust presents steep and asymmetric upper and lower crustal geometry possibly due to either asymmetric rifting of the margin an underplated body or flow of lower crustal material towards the ocean basin present time deformation as imaged from three additional seismic profiles is characterized by an interplay of gravity driven mobile salt creep and active thrusting at the foot of the tectonically inverted algerian margin

longitudinal structure of pyroclastic flow deposits revealed by gpr survey at merapi volcano java indonesia abstract in 2006 merapi volcano indonesia erupted for a few months producing several block and ash flows reaching a maximum distance of 7 5 km from the main vent during the eruption we conducted a survey on those flow deposits in the gendol valley at kaliadem village about 4 5 km from the merapi submit using a ground penetrating radar gpr the upper deposit was studied in its distal reaches whereas the one below was studied in its medial reaches the field study was carried out with a commercial ramac gpr coupled with 100 mhz antennas and the data treatment conducted with reflex software from this survey we determined both deposits local 1 thickness reaching a maximum of 15 m and 2 internal architecture this last one is governed by long reflecting horizons extending over 20 to 30 m that delimit layers showing progradation patterns in their distal reaches within these layers we could also observe an internal architecture of still unknown origin the layers are interpreted as the result of the flow pulses that progressively deposited downstream ward by progradation however the interpretation of those gpr profiles is a bit hazardous because of the absence of outcrops and we can only proceed by analogy with other studies nevertheless despite numerous limitations gpr is a helpful tool to understand pyroclastic deposits structure when no visual observations are available

a high resolution model for eurasia north america plate kinematics since 20 ma summary we derive the first chronologically detailed model of eurasia north america plate motion since 20 ma from ship and airplane surveys of the well expressed magnetic lineations along this slowly spreading plate boundary including previously unavailable dense russian magnetic data from the southern reykjanes ridge and northern mid atlantic ridge near the charlie gibbs fracture zone from more than 7000 crossings of 21 magnetic anomalies from anomaly 1n 0 78 ma to anomaly 6n 19 7 ma we estimate best fitting finite rotations and realistic uncertainties linear regressions of total opening distances versus their reversal ages at different locations along the plate boundary show that reversal boundaries are shifted systematically outwards from the spreading axis with respect to their idealized locations with the outward shift ranging from more than 5 km between iceland and the charlie gibbs fracture zone to 2 km elsewhere this outward displacement which is a consequence of the finite zone of seafloor accretion degrades estimates of the underlying plate motion and is thus removed for the ensuing kinematic analysis the corrected plate motion rotations reveal surprising previously unrecognized features in the relative motions of these two plates within the uncertainties motion was steady from 20 to 8 ma around a pole that was located 600 km north of the present pole with seafloor spreading rates that changed by no more than 5 per cent 1 mm yr 1 along the reykjanes ridge during this period seafloor spreading rates decreased abruptly by 20 2 per cent at 7 5 6 5 ma coinciding with rapid southward migration of the pole of rotation and a5 10 counter clockwise change in the plate slip direction eurasia north america plate motion since 6 7 ma has remained remarkably steady with an apparently stationary axis of rotation and upper limit of 2 per cent on any variations in the rate of angular rotation during this period based on the good agreement between seismotectonic constraints on present deformation in northeast asia and directions of motion that are predicted by our 6 7 ma to present pole we hypothesize that motion has remained steady to the present and attempt to test this hypothesis with published gps estimates for eurasia north america motion we find however that gps estimates that are tied to recent versions of the international geodetic reference frame and rely principally on station velocities from europe give implausible estimates of recent motion with the most recently published gps model predicting convergence along the southern gakkel ridge and in the laptev sea where seafloor spreading occurs an alternative gps estimate that is not tied to the international terrestrial reference frame and employs gps station velocities from northeastern asia is marginally consistent with our 6 7 0 ma motion estimate

volcaniclastic sequences at the foot of tacana volcano southern mexico implications for hazard assessment extensive volcaniclastic deposits have originated from the tacana volcanic complex tvc throughout its evolution the valleys of the coatan and cahuacan rivers have been the main routes for descending flows which have occasionally reached the pacific ocean as a result three fans have been deposited or increased their volume the most recent tapachula is 13 km long and covers an area of 48 km2 that has been largely urbanized by the city of tapachula which is located 30 km sw of the tvc the 0 7 km3 fan is bounded by the coatan river to the west and the cahuacan river to the east and is composed of a complex succession of volcaniclastic deposits accumulated between 23 000 and 1 300 years ago in response to remobilization of debris along the coatan river basin collectively the three fans consist of 34 stacked units grouped into five stratigraphic sequences from the oldest to the youngest these sequences are as follows 1 pre tacana chanjale fan comprising five units associated with the remobilization of material produced during the formation of the chanjale caldera 1 myr ago 2 mal paso mal paso fan comprising four units emplaced between 100 000 and 23 000 years ago 3 lower tapachula tapachula fan consisting of two units deposited around 23 000 years ago 4 upper tapachula tapachula fan consisting of 14 units emplaced between 14 300 and 1 300 years ago and 5 the topmost sequence coatan is made up of 11 units deposited during the past 1 300 years inside the valley of the coatan river today 200 000 people live on top of the tapachula fan which makes the city vulnerable to future lahars from the tvc

sea level change and vertical land movements since the last two millennia along the coasts of southwestern turkey and israel abstract this paper provides new relative sea level data inferred from coastal archaeological sites located along the turkish coasts of the gulf of fethye 8 sites and israel between akziv and caesarea 5 sites the structures selected are those that for effective functioning can be accurately related to sea level at the time of their construction thus their positions with respect to present sea level provide a measure of the relative sea level change since their time of construction useful information was obtained from the investigated sites spanning an age range of 2 3 1 6 ka bp the inferred changes in relative sea level for the two areas are distinctly different from a rise of 2 41 to 4 50 m in turkey and from 0 to 0 18 m in israel sea level change is the combination of several processes including vertical tectonics glacio hydro isostatic signals associated with the last glacial cycle and changes in ocean volume for the israel section the present elevations of the mis 5 5 tyrrhenian terraces occur at a few meters above present sea level and vertical tectonic displacements are small data from gps and tide gauge measurements also indicate that any recent vertical movements are small the mis 5 5 shorelines are absent from the investigated section of the turkish coast consistent with crustal subsidence associated with the hellenic arc the isostatic signals for the israel section of the coast are also small ranging from 0 11 mm yr to 0 14 mm yr depending on site and earth model and the observed eustatic average sea level change corrected for this contribution is a rise of 13 5 2 6 cm during the past 2 ka this is attributed to the time integrated contribution to sea level from a combination of thermal expansion and other increases in ocean volume the observed sea levels from the turkish sites in contrast indicate a much greater rise of up to 2 2 mm yr since 2 3 ka bp occurring in a wide area between knidos and kekova the isostatic signal here is also one of a rising sea level of up to 1 mm yr and site and earth model dependent and the corrected tectonic rate of land subsidence is 1 48 mm yr this is the primary cause of dramatic relative sea level rise for this part of the coast

tests of the rigid plate hypothesis and bounds on intraplate deformation using geodetic data from very long baseline interferometry the geodetic results of ma et al 1994 from very long baseline interferometry are used to assess rates of intraplate deformation we analyze the resulting set of velocities of 18 plate interior sites nine on the north american plate four western european sites on the eurasian plate three on the pacific plate and two on the australian plate we formulate three alternative error budgets based partly on the work of ryan et al 1993a an optimistic error budget a conservative error budget and an upper bound error budget all three budgets assume the existence of a previously unmodeled error that is inversely proportional to the time span of observations at a site use of the conservative error budget indicates no significant motion between sites on any one of the four plates use of the upper bound error budget designed to be precisely large enough to be consistent with rigid plates places a usefully small upper bound on how fast any site might be moving relative to the rest of its plate speeds faster than 2 mm yr are excluded at the 95 confidence level for seven of the 18 plate interior sites adjustments of the site velocities for motion due to postglacial rebound as predicted from the model of tushingham and peltier 1991 give an insignificant improvement to the fit of the horizontal velocities to the rigid plate model the velocities of six sites near the western margin of the interior of the north american plate were also analyzed use of the conservative error budget indicates that a site near fairbanks alaska has an upper bound of 3 mm yr on its speed a site in nome alaska has an upper bound on its speed of 8 mm yr and a site in penticton british columbia has an upper bound on its speed of 4 mm yr of three sites on the colorado plateau two move marginally significantly and one moves insignificantly relative to stable north america upper limits on their speeds relative to stable north america range from 4 to 5 mm yr we conclude that the data do not yet demonstrate significant velocities between sites in the stable interior of any one plate but do provide useful and small upper bounds of 2 mm yr or less on the speeds of the best observed intraplate sites six sites near the western margin of the north american interior have upper bound speeds of 3 to 8 mm yr

origin characteristics and behaviour of lahars following the 1990 eruption of kelud volcano eastern java indonesia in contrast to most twentieth century eruptions of kelud volcano eastern java the 10 february 1990 plinian eruption was not accompanied by lake outburst lahars however at least 33 post eruption lahars occurred between 15 february and 28 march 1990 they swept down 11 drainage systems and travelled as far as 24 km at an estimated mean peak velocity in the range of 4 11 m s 1 the deposits volume 30 000 000 m3 were approximately 7 m thick 2 km from vent and 3 m thick 10 km from vent on the volcaniclastic apron surrounding the volcano subtle but significant sedimentological differences in the deposits relate to four flow types a early massive deposits are coarse poorly sorted slightly cohesive and commonly inversely graded they are inferred to record hot lahars that incorporated pumice and scoria from pyroclastic flow deposits probably by rapid remobilization of hot proximal pyroclastic flow deposits by rainfall runoff sedimentary features such as clasts subparallel to bedding and thick reversely to ungraded beds suggest that these flows were laminar b abundant very poorly sorted deposits include non cohesive clast supported inversely graded beds and ungraded finer grained and cohesive matrix supported beds these beds display layering and vertical segregation density stratification suggesting unsteady properties of pulsing debris flows they are interpreted as deposited from segments of flow waves at a middle distance downstream that incorporated pre eruption sediments sedimentological evidence suggests unsteady flow properties during progressive aggradation c fine grained poorly sorted and ungraded deposits are interpreted as recording late hyperconcentrated streamflows that formed in the waning stage of an overflow and transformed downcurrent into streamflows d ungraded crudely stratified deposits were emplaced by flows transitional between hyperconcentrated flows and streamflows that traveled farther downvalley as far as 27 km from the vent at kelud the transformation of flow and behavior occurs within only 10 km of the source at the apex of the alluvial fans the rapid change of flow behavior is attributed to the low fines content and to the unsteady flow regime which may be due to a the rapid deposition of bedload owing to the break in channel gradient close to the vent and to changes in channel cross section and roughness and b the very low silt clay content in the non cohesive deposits these deposits mix with water to produce streamflows

coupled fluid dynamics sediment transport modelling of a crater lake break out lahar mt ruapehu new zealand summary lahars and other sudden onset floods are highly dynamic with temporally and spatially evolving sediment loads numerical models of sudden onset flood behaviour particularly those applied to real world events have tended to neglect sediment transport processes this is a serious though perhaps understandable shortcoming given a lack of field measurements on flow bed interactions the extra computational complexity required and the problem of iteratively updating plastic channel boundaries this paper applies a fluid dynamics model with suspended sediment and bedload transport to calculate flow conditions and rapid landscape change due to an initially dilute lahar from mt ruapehu new zealand we take advantage of an unprecedented dataset of net topographic changes determined from pre and post lahar airborne lidar surveys and time series of hydrological measurements to run and validate the model a sensitivity analysis of key controls on water surface elevation and final sediment thickness illustrates how the flow was supply limited in the upper reaches it was capable of transporting a greater volume and calibre of material than that available modelled patterns of net erosion and deposition can replicate those observed r 2 0 79 and are dominantly controlled by channel gradient and topographic

seismotectonics of the lower cheliff basin structural background of the el asnam algeria earthquake the 1980 el asnam earthquake should be understood within its tectonic environment a seismotectonic map of the lower cheliff basin scale 1 500 000 has been synthesized from known geologic tectonic and seismological work on the region and from satellite photos the data set was integrated by a computer in order to handle different scales and projections several important tectonic features divide the region into 5 domains active faults and recent folds are consistent with a nnw sse direction of compression the cheliff basin is limited to the south by the relizane fault the basin is also crossed by three broken folds the eastern one being the one associated with the el asnam fault historical and instrumental seisinicity seems to be located at both ends of relizane fault it is suggested that the sites corresponding to folds and reverse faulting crossing the basin are relevant to seismic risk a simple tectonic model is proposed

global plate velocities from the global positioning system we have analyzed 204 days of global positioning system gps data from the global gps network spanning january 1991 through march 1996 on the basis of these gps coordinate solutions we have estimated velocities for 38 sites mostly located on the interiors of the africa antarctica australia eurasia nazca north america pacific and south america plates the uncertainties of the horizontal velocity components range from 1 2 to 5 0 mm yr with the exception of sites on the pacific and nazca plates the gps velocities agree with absolute plate model predictions within 95 confidence for most of the sites in north america antarctica and eurasia the agreement is better than 2 mm yr we find no persuasive evidence for significant vertical motions 3 standard deviations except at four sites three of these four were sites constrained to geodetic reference frame velocities the gps velocities were then used to estimate angular velocities for eight tectonic plates absolute angular velocities derived from the gps data agree with the no net rotation nnr nuvel 1a model within 95 confidence except for the pacific plate our pole of rotation for the pacific plate lies 11 5 west of the nnr nuvel 1a pole with an angular speed 10 faster our relative angular velocities agree with nuvel 1a except for some involving the pacific plate while our pacific north america angular velocity differs significantly from nuvel 1a our model and nuvel 1a predict very small differences in relative motion along the pacific north america plate boundary itself our pacific australia and pacific eurasia angular velocities are significantly faster than nuvel 1a predicting more rapid convergence at these two plate boundaries along the east pacific rise our pacific nazca angular velocity agrees in both rate and azimuth with nuvel 1a

active deformation at the southwestern alps ligurian basin junction france italy boundary evidence for recent change from compression to extension in the argentera massif abstract several hundred earthquakes of small and moderate magnitude occur each year at the southwestern alps ligurian basin junction in addition the historical seismicity data attests for earthquakes of magnitude close to 6 5 despite the seismic hazard and the vulnerability of this region the present day driving mechanism of deformation and the major structures accommodating these deformations remain unclear this littoral area presents a strong topographic gradient from 3000 masl on the argentera alpine massif to 2500 m u s l in the ligurian basin and a strong structural inheritage resulting from 50 my geological evolution combining different processes such as continental collision and ocean basin opening we present new results about the kinematics of the corsica sardinia continental block with respect to the western alpine belt from 7 years of continuous gps measurements we show that a small part of the nubia eurasia convergence is certainly transferred northward of the maghrebides deformation belts to the corsica sardinia block in the southwesternmost alps from torino to the mediterranean coast the baselines reveal differential motions of lengthening between the po plain and the argentera and shortening between the argentera and the ligurian domain in a region where few focal solutions are available we determine seven new focal mechanisms located in the argentera massif these new data underline a quaternary change from compression to extension in that part of the western alpine belt the focal mechanisms calculated attest for extensional faulting at shallow level between 1 and 11 km depth we add 7 focal mechanisms from the literature to calculate the stress tensor a homogeneous solution indicates a direction of extension broadly perpendicular to the topographic axis culmination of the argentera in contrast the earthquakes recorded below 15 km at the northwestern margin of the po plain testify reverse faulting and a compressional state of stress in the deep crust thus we point out that the stress field is vertically heterogeneous in the crust of the argentera area the ligurian domain is mainly characterized by reverse and strike slip faulting the major earthquakes are located in the northern margin and at the ocean continent transition these earthquakes are assumed to result from the reactivation in a compressional state of stress of the structures formed during the oligo miocene opening of the ligurian basin finally we propose three hypotheses to explain the current deformation at the alps ligurian basin junction taking into account the far field kinematics between the nubia and the eurasia plates the topographic gradient between the argentera massif and the ligurian oceanic floor and the distribution of the deformations

crustal velocity field of western europe from permanent gps array solutions 1996 2001 we derive a new geodetic velocity field for western europe and the western mediterranean by rigorously combining 1 a selection of 36 itrf2000 sites 2 a solution from a subset of sites of the european permanent gps network euref epn 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy of the order of i mm yr 1 or better its analysis shows that central europe defined as east of the rhine graben and north of the alps and the carpathians behaves rigidly at a 0 4 mm yr 1 level and defines a stable europe reference frame in that reference frame we find no significant motion at sites located west of the rhine graben and on the iberian peninsula which sets an upper bound of 0 6 mm yr 1 on horizontal motion across the rhine graben and the pyrenees we find that the current strain pattern in the western alps combines e w extension and right lateral shear we confirm a counterclockwise rotation of the adriatic microplate which appears to control the strain pattern along its boundaries in the friuli area the alps and the apennines our results also suggest that the africa eurasia plate motion in the western mediterranean may be 40 50 per cent slower that the nuvel1a plate motion model and rotated 20 30 counterclockwise

lahars at merapi volcano central java an overview abstract merapi volcano in central java is one of the most active volcanoes in the world at least 23 of the 61 reported eruptions since the mid 1500s have produced source deposits for lahars the combined lahar deposits cover about 286 km 2 on the flanks and the surrounding piedmonts of the volcano at merapi lahars are commonly rain triggered by rainfalls having an average intensity of about 40 mm in 2 h most occur during the rainy season from november to april and have average velocities of 5 7 m s at 1000 m in elevation a wide range of facies may be generated from a single flow which may transform downvalley from debris flow to hyperconcentrated streamflow because of the high frequency and magnitude of the lahar events lahar related hazards are high below about 450 600 m elevation in each of the 13 rivers which drain the volcano hazard zone maps for lahar were produced by pardyanto et al volcanic hazard map merapi volcano central java 1 100 000 geol surv of indonesia bandung ii 4 1978 and the japanese indonesian cooperation agency master plan for land conservation and volcanic debris control in the area of mt merapi jakarta 1980 but these maps are of a very small scale to meet modern zoning requirements more recently a few large scale maps 1 10 000 and 1 2000 scale and risk assessments have been completed for a few critical river systems

people s behaviour in the face of volcanic hazards perspectives from javanese communities indonesia abstract this paper is concerned with the way in which the indonesian people living on the slopes or near active volcanoes behave in the face of volcanic threats it explores the role of three factors in the shaping of this behaviour e g risk perception cultural beliefs and socio economic constraints the paper is mainly based on field data collected during the last 5 years on four volcanoes in central java namely sumbing sindoro dieng and merapi the common assumption that hazard knowledge risk perception and people s behaviour are closely related and conditional on volcanic activity is debatable in the indonesian context factors that play a role in hazard knowledge e g basic knowledge of volcanic processes personal experience of volcanic crisis time lapsed since the last volcanic eruption etc differ from those that influence risk perception indeed local people often underestimate the scientifically or statistically estimated risk this poor risk perception is characterized by an approximate personal representation of the volcanic processes an excess of trust in concrete countermeasures the presence of a physical visual obstructions or cultural beliefs related to former eruptions in addition the commonly acknowledged factors that influence hazard knowledge and or risk perception may be at odds with the non hazard related factors that prompt or force people to live in or to exploit areas at risk these factors may be either socio cultural e g attachment to place cultural beliefs etc or social and socio economical e g standard of living strength of people s livelihoods well being these factors are fundamental in explaining the short term behaviour in the face of a developing threat during a volcanic crisis

volcanic hazards at mount semeru east java indonesia with emphasis on lahars mt semeru the highest mountain in java 3 676 m is one of the few persistently active composite volcanoes on earth with a plain supporting about 1 million people we present the geology of the edifice review its historical eruptive activity and assess hazards posed by the current activity highlighting the lahar threat the composite andesite cone of semeru results from the growth of two edifices the mahameru old semeru and the seloko young semeru on the se flank of the summit cone a n130 trending scar branched on the active jonggring seloko vent is the current pathway for rockslides and pyroclastic flows produced by dome growth the eruptive activity recorded since 1818 shows three styles 1 the persistent vulcanian and phreatomagmatic regime consists of short lived eruption columns several times a day 2 increase in activity every 5 to 7 years produces several kilometer high eruption columns ballistic bombs and thick tephra fall around the vent and ash fall 40 km downwind dome extrusion in the vent and subsequent collapses produce block and ash flows that travel toward the se as far as 11 km from the summit and 3 flank lava flows erupted on the lower se and e flanks in 1895 and in 1941 1942 pyroclastic flows recur every 5 years on average while large scale lahars exceeding 5 million m3 each have occurred at least five times since 1884 lumajang a city home to 85 000 people located 35 km e of the summit was devastated by lahars in 1909 in 2000 the catchment of the curah lengkong river on the ese flank shows an annual sediment yield of 2 7 105 m3 km 2 and a denudation rate of 4 105 t km 2 yr 1 comparable with values reported at other active composite cones in wet environment unlike catchments affected by high magnitude eruptions sediment yield at mt semeru however does not decline drastically within the first post eruption years this is due to the daily supply of pyroclastic debris shed over the summit cone which is remobilised by runoff during the rainy season three hazard prone areas are delineated at mt semeru 1 a triangle shaped area open toward the se has been frequently swept by dome collapse avalanches and pyroclastic flows 2 the s and se valleys convey tens of rain triggered lahars each year within a distance of 20 km toward the ring plain 3 valleys 25 km s se and the ring plain 35 km e toward lumajang can be affected by debris avalanches and debris flows if the steep sided summit cone fails

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

large scale internal structure of the sanbongi fan towada volcano japan putting the theory to the test using gpr on volcaniclastic deposits abstract the towada caldera volcano is located between the prefectures of aomori and akita northeast honshu island japan the caldera today filled by a lake has produced 15 000 years ago a complex eruption emplacing an ignimbrite topped by the lake outburst flood deposit through which the present oirase river erodes this flood deposit has shaped the geomorphologic feature named sanbongi fan on which towada city extends this flood event hypothesis is mainly based on sedimentological and geomorphological evidences of floods mainly from outcrops retrieved from the sanbongi fan area because of the lack of extended outcrops typical of the japanese environment the present paper has therefore put the theory to the test using gpr ground penetrating radar radargram extending along a 640 m length the gpr used for the survey was a pulse ekko pro with 50 mhz antennas and the software reflex was used to process the data the radargrams have displayed a sole unit which the gpr could not penetrate it can be interpreted as the ignimbrite on top of this deposit a series of subhorizontal layers with the alternation between a backset and a foreset extends between 5 m and 3 m depth above 3 m the units are regular and subhorizontal the deposit is also characterized by the extensive presence of boulders which are located along three bands 1 on top of the ignimbrite 2 in the units deposited by the outburst flood between 3 and 5 m depths 3 and in the units close to the surface although part of these punctual elements are most certainly anthropogenic compared with the outcrops the present research confirms that the material located above the ignimbrite material have been deposited by the outburst flood creating large sheet patterns which have transported boulders these sheets display backset and foreset patterns depending on the position of the deposit indicating flow pulsation or surges under a high energy flow condition

the 1985 nevado del ruiz volcano catastrophe anatomy and retrospection abstract this paper seeks to analyze in an objective way the circumstances and events that contributed to the 1985 nevado del ruiz catastrophe in order to provide useful guidelines for future emergencies the paper is organized into two principal parts in the first part an anatomy of the catastrophe is developed as a step by step chronicle of events and actions taken by individuals and organizations during the period november 1984 through november 1985 this chronicle provides the essential background for the crucial events of november 13 this year long period is broken down further to emphasize important chapters the gradual awareness of the awakening of the volcano a long period of institutional skepticism reflecting an absence of credibility the closure of the credibility gap with the september 11 phreatic eruption followed by an intensive effort to gird for the worst and a detailed account of the day of reckoning the second part of the paper retrospection examines the numerous complicated factors that influenced the catastrophic outcome and attempts to cull a few lessons from armero in order to avoid similar occurrences in the future in a nutshell the government on the whole acted responsibly but was not willing to bear the economic or political costs of early evacuation or a false alarm science accurately foresaw the hazards but was insufficiently precise to render reliable warning of the crucial event at the last possible minute catastrophe was therefore a calculated risk and this combination the limitations of prediction detection the refusal to bear a false alarm and the lack of will to act on the uncertain information available provided its immediate and most obvious causes but because the crucial event occurred just two days before the armero emergency management plan was to be critically examined and improved the numerous circumstances which delayed progress of emergency management over the previous year also may be said to have contributed to the outcome thus the catastrophe was not caused by technological ineffectiveness or defectiveness nor by an overwhelming eruption or by an improbable run of bad luck but rather by cumulative human error by misjudgment indecision and bureaucratic shortsightedness armero could have produced no victims and therein dwells its immense tragedy

recognition classification and mechanical description of debris flows abstract various types of flow or mass movement involving water and sediments occur on steep slopes in mountainous areas among them debris flows are peculiar events during which a large volume of a highly concentrated viscous water debris mixture flows through a stream channel throughout the world these phenomena cause considerable damage but remain poorly understood although a basic knowledge is already available concerning their recognition and propagation firstly a synthesis of the useful practical criteria of recognition is proposed debris flows must be seen as intermediate phenomena between hyperconcentrated flows intense bed load transport and landslides separated from them by sharp transitions of some characteristics celerity deposit nature and flow type two parameters solid fraction and material type thought to be appropriate for a sound and practical classification are brought out and the corresponding complete classification of flow and mass movements in mountain areas is presented two extreme debris flow types are thus distinguished muddy debris flows and granular debris flows a critical review of recent advances in debris flow dynamic is then proposed it is pointed out that adequate work must be carried out in the field of non newtonian fluid mechanics in particular one fundamental rheological property of debris flow materials is the yield stress which explains thick deposits on steep slopes and can be inferred from field measurements furthermore it can be used to estimate viscous dissipation within the bulk during flow relevant models predicting muddy debris flow dynamics are already available whereas further progress is needed concerning granular flows

coseismic deformation of the may 21st 2003 mw 6 8 boumerdes earthquake algeria from gps measurements 1 on may 21st 2003 a mw 6 8 earthquake struck the central part of northern algeria causing extensive damage in the boumerdes area 40 km east of algiers it is among the largest events to occur in the western mediterranean over the past 25 years we present gps measurements of horizontal coseismic displacements that provide new constraints on the rupture geometry modeling the data with a uniform dislocation on a rectangular fault in an elastic half space we find that the rupture occurred on a reverse fault dipping 42 s with its upper edge 6 km offshore and lower edge 4 km inland the amplitude distribution of the coseismic displacements indicates that the rupture did not reach the surface at least in its western part and ended to the west around 3 4 e offshore faults like that of the boumerdes earthquake could account for part of the africa eurasia relative plate motion in the western mediterranean and represent a significant seismic threat for algeria

gpr derived architecture of a lahar generated fan at cotopaxi volcano ecuador the internal geometry of volcaniclastic fans produced by aggradation during lahar events is difficult to examine in modern settings because of the frequent lack of three dimensional exposures this makes it challenging to i reconstruct the spatial and temporal evolution of such fans and ii interpret observed facies stratigraphy in the context of lahar flow dynamics from proximal to distal fan reaches this research therefore presents the results of a ground penetrating radar gpr survey of the rumipamba fan at the mouth of the burrohuaycu quebrada on the southwestern flank of cotopaxi volcano a survey grid consisting of 50 individual gpr profiles representing a total length of 19 4 km was constructed covering most of the 4 km2 large fan surface all gpr profiles were collected using a pulseekko 100 with a 400 v transmitter fan sediments consist of sandy and gravelly lahar deposits alternating with volcanic fallout including ash and pumice lapilli at times reworked by fluvial processes deposits could be ground truthed to a depth of 3 m whereas gpr penetration depth reaches 15 m data interpretation was based on classification into 15 distinct radar facies characterized by the nature of their bounding surfaces and or internal features cross referenced where possible with shallow exposures three main facies were identified parallel irregular and clinoform erosional contacts were distinguished from aggradational ones vertical channel fill and lateral accretion flow parallel versus flow transverse and proximal distal variations in deposit architecture were featured the results of this study confirm the existence of two major channel systems in the northern and southern extremities of the fan and the more recent formation of a smaller central fan channel system deposit architecture is complex and facies chronologies illustrate that lahars have affected the entire survey area

volcanic tectonic and mass wasting processes offshore terceira island azores revealed by high resolution seafloor mapping terceira island in the azores archipelago lies at the intersection of four submarine volcanic ridges new high resolution bathymetric and seismic reflection data have been used to analyze the main volcanic tectonic and mass wasting features of the island offshore volcanic features such as linear volcanic centers and pointy and flat topped cones are mainly concentrated on the narrow western and north western ridges characterized by an overall rugged morphology fault scarps dominate mainly the broad eastern and south eastern ridges which are characterized by an overall smooth and terrace like morphology on the eastern ridge faults form a series of horsts and grabens related to the onshore lajes graben the strikes of the fault scarps linear volcanic centers and alignment of volcanic cones on the ridges reveal two main structural trends wnw ese and nnw sse consistent with the main tectonic structures observed on the azores plateau in contrast a large variability of strike was observed in inter ridge areas reflecting the relative importance of regional and local stresses in producing these structures mass wasting features are subordinate and mostly represented by hundred meter wide scars that indent the edge of the insular shelf surrounding the island apart from two large deeper scars identified on the southern steep flank of the western ridge finally the remarkable morpho structural differences between the western and eastern ridges are discussed in the framework of the evolution of the terceira volcanic edifice and hypothesized to reflect successive stages of ridge evolution

gps and tectonic evidence for a diffuse plate boundary at the azores triple junction abstract we use gps bathymetric structural and seismic data to define the pattern of present deformation along the northern half of the azores plateau where the nubia eurasia plate boundary terminates at the axis of the mid atlantic ridge mar new and existing campaign gps velocities from the azores islands reveal extension oblique to a series of en echelon volcanic ridges occupied by terceira s jorge pico and faial islands in a frame of reference defined by 69 continuous gps stations on the eurasia plate terceira island moves 2 1 mm yr away from eurasia consistent with the island s location within the terceira rift and plate boundary structure the volcanic ridges south of the terceira rift move toward wsw at progressively faster rates reaching a maximum of 3 5 0 5 mm yr 2 for the pico faial volcanic ridge the hypothesis that the terceira rift accommodates all nubia eurasia plate motion is rejected at high confidence level based on the motions of sites on s jorge island just west of terceira rift all of the islands move relative to the nubia plate with pico island exhibiting the slowest motion only 1 0 5 mm yr 2 detailed bathymetry from the interior of the hypothesized azores microplate reveals faults that crosscut young mar seafloor fabric these observations and the gps evidence for distributed deformation described above argue against the existence of a rigid or semi rigid azores microplate and instead suggest that nubia eurasia plate motion is accommodated by extension across a 140 km wide zone east of the mar axis most likely bounded to the north by the northern shoulder of the terceira rift the mar spreading rate along the western end of the azores deformation zone 38 5 n 39 5 n is intermediate between the eurasia north america rate measured at 39 5 n and the nubia north america rate measured at 38 5 n consistent with the joint conclusions that the nubia eurasia boundary is broad where it intersects the mar and the azores triple junction is diffuse rather than discrete

cenozoic global plate motions cenozoic global plate motions relative to the hot spots are investigated and compared to plate motions in a mean lithosphere reference frame plate motions were analyzed over six time intervals divided by ages 10 25 43 48 and 56 ma chosen as much as possible to coincide with key plate reorganizations alternative motion circuits and rotational parameters were considered and evaluated with paleomagnetic data from the pacific and north american plates the circuit found to be in best agreement with the paleomagnetic data is one in which the hot spots in the atlantic region are assumed to be fixed relative to the hot spots in the pacific region throughout the cenozoic the hot spot and mean lithosphere reference frames have been in continual slow relative motion the rate of motion is nonuniform however most of the motion having occurred during the middle cenozoic the net cenozoic rotation of the lithosphere relative to the hot spots is described by a right handed rotation of 7 about a euler pole at 46 s 87 e which yields a 5 displacement of the north poles of the two reference frames this motion is small enough that inferences drawn about plate speeds in one reference frame should be valid in the other analysis of the global motions resulting from our preferred model showed that many characteristics of current plate motions have persisted throughout the cenozoic plate speeds correlate with latitude plates moving faster near the equator than near the poles throughout the cenozoic as at present continental plates except for the indian plate moved slower than oceanic plates throughout the cenozoic even the structure of the velocity fields as revealed in a contour of root mean square velocities in equatorial bands persists throughout the cenozoic the migration of the paleomagnetic axis over time is also compared to the hot spot and mean lithosphere reference frames the paleomagnetic axis has shifted 5 10 relative to the hot spot frame and a lesser amount relative to the mean lithosphere frame

kinematics of the iberia maghreb plate contact from seismic moment tensors and gps observations the iberian peninsula and the maghreb experience moderate earthquake activity and oblique nw se convergence between africa and eurasia at a rate of 5 mm yr coeval extension in the alboran basin and a n35 e trending band of active left lateral shear deformation in the alboran betic region are not straightforward to understand in the context of regional shortening and evidence complexity of deformation at the plate contact we estimate 86 seismic moment tensors mw 3 3 to 6 9 from time domain inversion of near regional waveforms in an intermediate period band those and previous moment tensors are used to describe regional faulting style and calculate average stress tensors the solutions associated to the trans alboran shear zone show predominantly strike slip faulting and indicate a clockwise rotation of the largest principal stress orientation compared to the regional convergence direction 1 at n350 e at the n algerian and sw iberian margins reverse faulting solutions dominate corresponding to n350 e and n310 e compression respectively over most of the betic range and intraplate iberia we observe predominately normal faulting and wsw ene extension 3 at n240 e from gps observations we estimate that more than 3 mm yr of african nubian eurasian plate convergence are currently accommodated at the n algerian margin 2 mm yr in the moroccan atlas and 2 mm yr at the sw iberian margin 2 mm yr is a reasonable estimate for convergence within the alboran region while alboran extension can be quantified as 2 5 mm yr along the stretching direction n240 e superposition of both motions explains the observed left lateral transtensional regime in the trans alboran shear zone two potential driving mechanisms of differential motion of the alboran betic gibraltar domain may coexist in the region a secondary stress source other than plate convergence related to regional scale dynamic processes in the upper mantle of the alboran region as well as drag from the continental scale motion of the nubian plate along the southern limit of the region in the atlantic ocean the 3 5 mm yr westward motion of the gibraltar arc relative to intraplate iberia can be accommodated at the transpressive sw iberian margin while available gps observations do not support an active subduction process in this area

evidence for a post 3 16 ma change in nubia eurasia north america plate motions we combine updated gps velocities from the nubian nu eurasian eu and north american na plates with 500 new 3 16 myr average seafloor spreading rates and nine transform fault azimuths from the northern atlantic and arctic basin seafloor spreading centers to estimate and test for changes in the relative motion between these plates the numerous new seafloor spreading rates and gps velocities improve our ability to detect recent changes in the relative motions of these plates the angular velocity vector that best fits the eu na gps velocities lies significantly north of the 3 ma average pole in accord with previously published geologic evidence that the eu na pole has migrated northward since v3 ma although we also find evidence for a significant post 3 ma change in nu na motion it is less compelling because the nubian plate gps velocity field is sparse and nu na seafloor spreading rates appear to have remained steady within the 1 mm yr 31 uncertainties if we systematically decrease the seafloor spreading rates to correct for outward displacement of seafloor spreading magnetic lineations the nu eu pole derived from gps site velocities lies more than 30 angular degrees south of the tightly constrained 3 ma average estimate and predicts significantly slower and more oblique present day nu eu convergence in the mediterranean both models for nu eu motion pass a key test for their accuracy namely they correctly predict strike slip motion along the well mapped gloria fault east of the azores the change to more oblique nu eu motion may reflect increasing difficulty in maintaining margin normal convergence within this continent continent collision zone 8 2003 published by elsevier b v

transverse architecture of lahar terraces inferred from radargrams preliminary results from semeru volcano indonesia semeru volcano is the highest mountain of java indonesia and a vulcanian explosion occurs every 15 minutes on average since 1967 thus a constantly renewed stock of material and the heavy monsoon rainfall 3700 mm yr 1 at 1500 m above sea level a s l provide a perfect setting for the study of lahars and their deposits hence we examined the architecture of lahars terraces 9 5 km from the summit in the curah lengkong valley we first used ground penetrating radar gpr over vertical exposures of the lahars cut bank terraces this allowed us to better understand transversal radargrams across terraces which are not visually accessible in the field preliminary results from a single radargram are very instructive since 1 they prove that the lateral architecture does not correspond to that observed from banks only 2 we could observe the presence of lenses and stratigraphic discontinuities 3 the setting of the various units can also help reconstruct deposition processes and the chronology of different units in order to finalize these preliminary results we however need to perform multiple gpr radargrams and provide a complete set of results copyright 2010 john wiley sons ltd

crustal motion along the eurasia nubia plate boundary in the calabrian arc and sicily and active extension in the messina straits from gps measurements 1 we investigate crustal deformation along the eurasia nubia plate boundary in calabria and sicily revealed by the gps velocity field obtained by the combination of continuous site velocities with previous results from episodic campaigns we recognize two distinct crustal domains characterized by different motions and styles of deformation convergence in sicily is taken up by crustal shortening along the former tyrrhenian back arc passive margin in agreement with seismological data and geological evidence of recent cessation of deformation along the plio pleistocene subduction front the analysis of the gps data and the consistency between earthquake slip vectors and convergence direction suggest that eu nu convergence in sicily does not require intermediate crustal blocks significant eurasia 3 mm yr to nne and nubia fixed 5 mm yr to ese residual velocities in calabria suggest instead the presence of an intermediate crustal block which can be interpreted as a forearc sliver or as an independent ionian block according to the first hypothesis subduction is still active in the ionian wedge although we find no evidence for active back arc spreading in the tyrrhenian sea the n115 e oriented sicily calabria gps relative motion is consistent with the extension observed during the 1908 mw 7 1 messina earthquake we suggest that up to 3 mm yr 80 of this estimated relative motion between sicily and the calabrian arc may be taken up in the messina straits

block and ash flow deposition a conceptual model from a gpr survey on pyroclastic flow deposits at merapi volcano indonesia in 2006 a series of block and ash flows swept the southwestern and southern flanks of merapi volcano java indonesia in the k gendol valley near the village of kaliadem we conducted a gpr survey on the most distal lobe of the june 14th second block and ash flow deposit for this 100 m long transect we used a commercial gpr ramac mounted with 100 mhz antennas we measured the topography with a synchronized gps and a laser rangefinder back at the laboratory we processed the dataset with the software reflex data of the subsurface reveals a series of layers separated by strong reflective horizons these horizons are the manifestation of intercalations of fine materials in between more coarse layers the architecture of these layers presents progradation retrogradation and aggradation patterns that we relate to the block and ash flow deposition process based on these observations we proposed a relative chronology of the deposition and a simple conceptual model of the deposition the model show that the block and ash flow can deposit either long close to horizontal single layers or shorter layers that imbricate themselves following different patterns progradation retrogradation or aggradation nevertheless we remained cautious since we only studied a very short portion of the deposit and similar experiences need to be repeated moreover there are reflections in the radargram that we could not identify and further studies need to be conducted

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

insights into lahar deposition processes in the curah lengkong semeru volcano indonesia using photogrammetry based geospatial analysis near surface geophysics and cfd modelling abstract semeru volcano is an active stratovolcano located in east java indonesia where historic lava flows occasional pyroclastic flows and vulcanian explosions on average every 5 min to 15 min generate a stock of material that is remobilized by lahars mostly occurring during the rainy season between october and march every year several lahars flow down the curah lengkong valley on the south east flank of the volcano where numerous lahar studies have been conducted in the present contribution the objective was to study the spatial distribution of boulder size clasts and try to understand how this distribution relates to the valley morphology and to the dynamic and deposition dynamic of lahars to achieve this objective the method relies on a combination of 1 aerial photogrammetry derived geospatial data on boulders distribution 2 ground penetrating radar data collected along a 2 km series of transects and 3 a cfd model of flow to analyse the results from the deposits results show that

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

cenozoic plate driving forces past studies of plate driving forces have concluded that the forces due to subducted slabs in the upper mantle and those due to the thickening of the oceanic lithosphere are the principal driving forces we reexamine the balance of driving forces for the present day and extend our analysis through the cenozoic using an analytical torque balance method which accounts for interactions between plates via viscous coupling to the induced mantle flow we use an evolving mantle density heterogeneity field based on the last 200 myr of subduction to drive plate motions an approach which has proven successful in predicting the present day mantle heterogeneity field we find that for plausible upper mantle viscosities the forces due to subducted slabs in the cenozoic and mesozoic account for in excess of 90 of plate driving forces and those due to lithospheric thickening for less than 10

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

confirmation of the astronomical calibration of the magnetic polarity timescale from sea floor spreading rates the dating of the history of reversals of the earth s magnetic field since the jurassic period has been based primarily on radiometric dating of a small number of reversals with most ages of individual reversals interpolated or extrapolated on the basis of the widths of marine magnetic anomalies recently however pliocene and pleistocene reversals have been dated by an entirely independent method which relies on correlating climate proxies such as oxygen isotope ratios in sediments with calculated variations of the earth s orbit and inclination1 4 the dates obtained from this astronomical calibration are 3 8 older than radiometrically calibrated ages published between 1979 and 1989 see for example refs 5 and 6 although recent dating by the 40ar 39ar method tends to confirm the astronomical calibration7 10 at least for the past 3 3 myr here i use sea floor spreading rates determined from high precision plate rotation solutions for five plate pairs to test the astronomically calibrated timescale over the past 5 32 myr the results suggest that the errors in the astronomical calibration are no greater than 0 02 myr and also show that spreading rate can remain constant for several million years even for fast moving plates

moment tensor solutions for the iberian maghreb region during the iberarray deployment 2009 2013 abstract we perform regional moment tensor inversion for 84 earthquakes that occurred in the iberian maghreb region during the second and third leg of iberarray deployment 2009 2013 during this period around 300 seismic broadband stations were operating in the area reducing the interstation spacing to 50 km over extended areas we use the established processing sequence of the iag moment tensor catalogue increasing to 309 solutions with this update new moment tensor solutions present magnitudes ranging from mw 3 2 to 6 3 and source depths from 2 to 620 km most solutions correspond to northern algeria where a compressive deformation pattern is consolidated the betic rif sector shows a progression of faulting styles from mainly shear faulting in the east via predominantly extension in the central sector to reverse and strike slip faulting in the west at the sw iberia margin the predominance of strike slip and reverse faulting agrees with the expected transpressive character of the eurasian nubia plate boundary new strike slip and oblique reverse solutions in the trans alboran shear zone reflect its left lateral regime the most significant improvement corresponds to the atlas mountains and the surroundings of the gibraltar arc with scarce previous solutions reverse and strike slip faulting solutions in the atlas system display the accommodation of plate convergence by shortening in the belt at the gibraltar arc several new solutions were obtained at lower crustal and subcrustal depths these mechanisms show substantial heterogeneity covering the full range of faulting styles with highly variable orientations of principal stress axes including opposite strike slip faulting solutions at short distance the observations are not straightforward to explain by a simple geodynamic scenario and suggest the interplay of different processes among them plate convergence in old oceanic lithospheric with large brittle thickness at the sw iberia margin as well as delamination of thickened continental lithosphere beneath the betic rif arc

seismic anisotropy of northeastern algeria from shear wave splitting analysis abstract there are few studies of internal deformation under northern africa here we present such a study we analyze teleseismic shear wave splitting for northeast algeria to improve our knowledge of lithospheric and asthenospheric deformation mechanisms in this region we study waveform data generated by tens of teleseismic events recorded at five recently installed broadband bb stations in algeria these stations cover an area 2 across extending from the tellian geological units in the north to the saharan atlas units in the south analysis of sks wave splitting results insignificant spatial variations in fast polarization orientation over a scale length of at most 100 km the seismic anisotropy shows three clear spatial patterns a general ene wsw orientation is observed under the stations in the north this polarization orientation follows the direction of the tell atlas mountain chain which is perpendicular to the convergence direction between africa and eurasia delay times vary significantly across the region between 0 6 and 2 0 s at several stations there is an indication of a wnw ese polarization orientation which is apparently related to a later geodynamic evolutionary phase in this region a third pattern of seismic anisotropy emerges in the south with an orientation of roughly n s we discuss these observations in light of geodynamic models and present day geodetic motion

multi scale topographic analysis of merbabu and merapi volcanoes using wavelet decomposition with the increasing availability of data geo sciences have experienced deep changes in handling and processing it one of the presently explored research directions concerns the systematic decomposition and understanding of topographical features without the subjective interactions of humans this can eventually lead to fully automated algorithms for topographic analysis and understanding this paper aims at being a contribution to this broad research area for the specific cases of stratovolcanoes whose general geometry are very similar to a perfect cone more specifically this paper addresses two issues 1 is it possible to separate erosion features local variations from structural features large variations on stratovolcanoes through mathematical expression 2 can information on volcanic activity intensity age etc be retrieved from a topographic analysis the study has been conducted from two volcanoes in central java indonesia the merapi and the merbabu the dem of these volcanoes has been sampled using concentric circles with a radius ranging from 500 to 5 000 m horizontal distance to the summit the data conversion and sampling was performed in arcmap while the data analysis was carried out with matlab using discrete meyer wavelet decomposition results provide an insight on large scale topographic variations long wave wavelet that have been separated from rapidly varying topographic features such as lahar channels short wave wavelets observations proved that flanks where the most recent volcanic activity occur like at merapi volcano on the s se flank present a very low variability of long wave variations whereas short wave variations are important the author argues that this feature is due to highly erosive lahars that dig the valleys combined with a recent production of material and volcanic growth keeping the overall structure regular flanks with lesser activity are characterized at the two volcanoes by important long wave variations most certainly due to long term differential erosion and different level of short waves variations comparing the two volcanoes results show that the valleys of merapi and merbabu volcanoes are deeply incised indicating recent periods of high activity with reworkable material eroded by lahars and other channels deepening processes the topography of the summit area of merapi volcano is smoother than at merbabu volcano where deep erosion features extend up to the summit area this difference is most certainly due by the material production at the summit of merapi volcano developing such classification is important for automated mapping and computer recognition of volcanic past activities and their impacts on landscapes it is the based for the development of decision trees that assist computer assisted and automated computer vision

the enormous chillos valley lahar an ash flow generated debris flow from cotopaxi volcano ecuador the chillos valley lahar cvl the largest holocene debris flow in area and volume as yet recognized in the northern andes formed on cotopaxi volcano s north and northeast slopes and descended river systems that took it 326 km north northwest to the pacific ocean and 130 km east into the amazon basin in the chillos valley 40 km downstream from the volcano depths of 80 160 m and valley cross sections up to 337 000 m2 are observed implying peak flow discharges of 2 6 6 0 million m3 s the overall volume of the cvl is estimated to be 3 8 km3 the cvl was generated approximately 4500 years bp by a rhyolitic ash flow that followed a small sector collapse on the north and northeast sides of cotopaxi which melted part of the volcano s icecap and transformed rapidly into the debris flow the ash flow and resulting cvl have identical components except for foreign fragments picked up along the flow path juvenile materials including vitric ash crystals and pumice comprise 80 90 of the lahar s deposit whereas rhyolitic dacitic and andesitic lithics make up the remainder the sand size fraction and the 2 to 10 mm fraction together dominate the deposit constituting 63 and 15 wt of the matrix respectively whereas the silt size fraction averages less than 10 wt and the clay size fraction less than 0 5 wt along the 326 km runout these particle size fractions vary little as does the sorting coefficient average 2 6 there is no tendency toward grading or improved sorting limited bulking is recognized the cvl was an enormous non cohesive debris flow notable for its ash flow origin and immense volume and peak discharge which gave it characteristics and a behavior akin to large cohesive mudflows significantly then ash flow generated debris flows can also achieve large volumes and cover great areas thus they can conceivably affect large populated regions far from their source especially dangerous therefore are snow clad volcanoes with recent silicic ash flow histories such as those found in the andes and alaska

waveform inversion of small to moderate earthquakes located offshore southwest iberia summary in this paper we apply the kinematic waveform inversion kiwi tools to the study of smallto moderate earthquakes in southwest sw iberia the earthquakes have magnitudes in the range ml 3 5 4 9 with the exception of one earthquake with magnitude ml 6 0 most events are located offshore are recorded with a large azimuthal gap and generate waves that travel throughastronglyheterogeneous crustalstructure weobtainnewestimatesofcentroid depth seismic moment strike dip and rake for 12 of the 29 studied events the earthquakes whose waveforms we cannot successfully model are 1 located too far from the stations 2 have small magnitude hence low signal to noise ratio or 3 are located within the cadiz basin which is a major sedimentary basin that affects wave propagation notably our results indicate that onshore earthquakes occur at shallow depths 15 km whereas offshore earthquakes occur deeper down to 46 km focal mechanisms indicate transpressive faulting

developing building damage scales for lahars application to merapi volcano indonesia lahar damage to buildings can include burial by sediment and or failure of walls infiltration into the building and subsequent damage to contents the extent to which a building is damaged will be dictated by the dynamic characteristics of the lahar i e the velocity depth sediment concentration and grain size as well as the structural characteristics and setting of the building in question the focus of this paper is on quantifying how buildings may respond to impact by lahar we consider the potential for lahar damage to buildings on merapi volcano indonesia as a result of the voluminous deposits produced during the large vei 4 eruption in 2010 a building damage scale has been developed that categorises likely lahar damage levels and through theoretical calculations of expected building resistance to impact approximate ranges of impact pressures we found that most weak masonry buildings on merapi would be destroyed by dilute lahars with relatively low velocities ca 3 m s and pressures ca 5 kpa however the majority of stronger rubble stone buildings may be expected to withstand higher velocities to 6 m s and pressures to 20 kpa we applied this preliminary damage scale to a large lahar in the putih river on 9 january 2011 which inundated and caused extensive building damage in the village of gempol 16 km southwest of merapi the scale was applied remotely through the use of public satellite images and through field studies to categorise damage and estimate impact pressures and velocities within the village results were compared with those calculated independently from manning s calculations for flow velocity and depth within gempol village using an estimate of flow velocity at one upstream site as input the results of this calculation showed reasonable agreement with an average channel velocity derived from travel time observations the calculated distribution of flow velocities across the area of damaged buildings was consistent with building damage as classified by the new damage scale the complementary results even given the basic nature of the tools and data suggest that the damage scale provides a valid representation of the failure mode that is consistent with estimates of the flow conditions the use of open source simplified tools and data in producing these consistent findings is very promising

the miocene to present kinematic evolution of the eastern mediterranean and middle east and its implications for dynamics the present kinematics in the eastern mediterranean and middle east is now well constrained by gps measurements and dominated by a circular counterclockwise motion while arabia rotates rigidly the rotational velocities increase from the levant to aegea causing extension in western anatolia we place the present pattern in light of the post middle miocene geological history and propose that in addition to the effects of the hellenic subduction and zagros collision subduction zones on driving the surface motion an underlying asthenospheric flow is also required this counterclockwise toroidal flow is expected to exist around the eastern edge of the african slab owing to subduction rollback and it helps explain the initiation of the north anatolia fault the extrusion and uplift of anatolia and the mid miocene to recent volcanism in eastern anatolia the afar plume had a similar effect on the acceleration of arabia at 40 mya