imaging and modeling the ionospheric airglow response over hawaii to the tsunami generated by the tohoku earthquake of 11 march 2011 1 although only centimeters in amplitude over the open ocean tsunamis can generate appreciable wave amplitudes in the upper atmosphere including the naturally occurring chemiluminescent airglow layers due to the exponential decrease in density with altitude here we present the first observation of the airglow tsunami signature resulting from the 11 march 2011 tohoku earthquake off the eastern coast of japan these images are taken using a wide angle camera system located at the top of the haleakala volcano on maui hawaii they are correlated with gps measurements of the total electron content from hawaii gps stations and the jason 1 satellite we find waves propagating in the airglow layer from the direction of the earthquake epicenter with a velocity that matches that of the ocean tsunami the first ionospheric signature precedes the modeled ocean tsunami generated by the main shock by approximately one hour these results demonstrate the utility of monitoring the earth s airglow layers for tsunami detection and early warning

metamorphic evolution partial melting and miocene exhumation of lower crust in the edough metamorphic core complex west mediterranean orogen eastern algeria abstract the edough massif is the easternmost crystalline massif of the maghrebides which represent the southeastern part of the west mediterranean orogen it emerges from below the greenschist facies tellian units that represent the thrusted mesozoic to eocene passive paleomargin of northern africa deposited on the thinned continental crust the top of the crystalline pile of the edough massif is characterised by metasedimentary rocks affected by medium to high pressure 12 14 kbar and medium temperature metamorphic conditions of ca 600 c the northern part of the massif as well as the overlying allochthonous amphibole peridotite unit in the north is characterised by high pressure granulite facies t 800 c and p 12 kbar nearly isothermal decompression is documented in metapelites by late to post kinematic crystallisation of sillimanite and andalusite overprinting kyanite the core of the dome comprises essentially diatexite and granite gneisses a late low pressure evolution and overprinting 2 3 kbar took place in paleozoic rocks in proximity to granite gneisses the predominant igneous mineralogy of granite gneisses suggests that they represent synmetamorphic and syn kinematic sheeted intrusions generated through a high degree melting of metasediments geochronology of the metamorphic rocks u pb on monazite sm nd on garnet wr pairs 40 ar 39 ar on amphiboles and micas yields ages bracketed between 24 and 16 ma suggesting that regional metamorphism of the edough massif took place during the late tertiary synchronous with the greenschist facies metamorphism recorded in the overlying mesozoic tellian units the edough massif represents a metamorphic core complex exhumed through tectonic denudation assisted by syn to late metamorphic low angle n dipping normal ductile shear zones an exhumation rate of 6 8 km ma and associated cooling rate of 200 300 c ma is implied we conclude that the edough massif represents part of the former thinned continental crust of africa involved in a late eocene northward subduction beneath the suboceanic domain that separated paleo europe and africa in mesozoic time the upward syn metamorphic tectonic emplacement at 40 45 km depth of slices of spinel peridotites detached from the lower mantle may be responsible for the local granulite facies occurrences their emplacement is a consequence of the long lived transtensional sinistral then dextral kinematics having taken place between the african and european plates

high resolution altimetry reveals new characteristics of the december 2004 indian ocean tsunami 1 the indian ocean tsunami which occurred on december 26 2004 was the first to be clearly observed using satellite altimeters the wave amplitude observed in deep ocean by topex and jason 1 was close to 60 cm about 2 hours after the earthquake envisat crossed the tsunami wave 3h15 after the earthquake and measured a 35 cm wave even though it flew over the tsunami 7h20 after the earthquake gfo still observed a wave close to 20 cm to better extract the tsunami signal from altimeter measurements a specific ocean variability mapping technique is used this technique proves to be mandatory for discriminating tsunami waves from other ocean signals altimeter signals are then compared with those derived from the cea commissariat a l energie atomique model outputs for the first time with altimeter data peculiar short wavelengths signals along jason 1 and envisat profiles have been detected from the analysis of 20 hz altimeter measurements such high wavenumber signals can be explained by the dispersive propagation of tsunami waves these observations highlight the essential role of satellite altimeter measurements to better understand and to improve models of tsunami wave propagation and dissipation

submergence and uplift associated with the giant 1833 sumatran subduction earthquake evidence from coral microatolls the giant sumatran subduction earthquake of 1833 appears as a large emergence event in fossil coral microatolls on the reefs of sumatra s outer arc ridge stratigraphic analysis of these and living microatolls nearby allow us to estimate that 1833 emergence increased trenchward from about 1 to 2 m this pattern and magnitude of uplift are consistent with about 13 m of slip on the subduction interface and suggest a magnitude mw of 8 8 9 2 for the earthquake the fossil microatolls also record rapid submergence in the decades prior to the earthquake with rates increasing trenchward from 5 to 11 mm yr living microatolls show similar rates and a similar pattern the fossil microatolls also record at least two less extensive emergence events in the decades prior to 1833 these observations show that coral microatolls can be useful paleoseismic and paleogeodetic instruments in convergent tectonic environments

impact of hellenic arc tsunamis on corsica france in the historical period the eastern mediterranean has been devastated by several tsunamis the two most damaging were those of ad 365 and ad 1303 generated by great earthquakes of magnitude 8 at the hellenic plate boundary recently events of 6 7 magnitude have occurred in this region as the french tsunami warning center has to ensure the warning for the french coastlines the question has raised the possibility for a major tsunami triggered along the hellenic arc to impact the french coasts the focus is on the corsica coasts especially to estimate what would be the expected wave heights and from which threshold of magnitude it would be necessary to put the population under cover this study shows that a magnitude 8 0 earthquake nucleated along the hellenic arc could induce in some cases a tsunami that would be observed along the corsica coasts and for events of 8 5 magnitude amplitudes exceeding 50 cm can be expected which would be dangerous in harbors and beach areas especially the main contribution of these results is the establishment of specific thresholds of magnitude for the tsunami warning along the french coasts 7 8 for the advisory level coastal marine threat with harbors and beaches evacuation and 8 3 for the watch level inland inundation threat for tsunamis generated along the hellenic arc

reconstruction of ionospheric perturbation induced by 2004 sumatra tsunami using a computerized tomography technique a computerized tomography technique is used to reconstruct a 3 d profile of electron density perturbation in the ionosphere based on the total electron content data recorded at a planned gps receiver network simulations are conducted using the data of the 2004 sumatra event an effective early warning system may become feasible based on this work

tide gauge observations of the indian ocean tsunami december 26 2004 the magnitude 9 0 earthquake centered off the west coast of northern sumatra 3 307 n 95 947 e on december 26 2004 at 00 59 utc united states geological survey usgs 2005 usgs earthquake hazards program latest earthquakes earthquake hazards program http earthquake usgs gov eqinthenews 2004 usslav 2005 generated a series of tsunami waves that devastated coastal areas throughout the indian ocean tide gauges operated on behalf of national and international organizations recorded the wave form at a number of island and continental locations this report summarizes the tide gauge observations of the tsunami in the indian ocean available as of january 2005 and provides a recommendation for the use of the basin wide tide gauge network for future warnings

the mw 8 0 antofagasta northern chile earthquake of 30 july 1995 a precursor to the end of the large 1877 gap abstract an m w 8 0 earthquake occurred on 30 july 1995 in the antofagasta region northern chile the main rupture corresponding to thrust faulting developed from 10 to 50 km in depth along the subduction interface between the nazca and the south american plates the 1995 earthquake took place just south of the large seismic gap where a great earthquake m 9 had occurred in 1877 most of the 1995 rupture was located within a local network consisting of nine short period stations that had been previously installed at the southern end of the 1877 gap and the aftershock sequence could be accurately monitored little destruction resulted from the 1995 earthquake in spite of its large size ground acceleration in antofagasta reached 29 of gravity a tsunami wave 2 to 2 5 m high was observed along the coast from mejillones to taltal one strong foreshock m w 6 2 occurred in the 1995 hypocentral region 6 months before the main event body wave modeling of broadband seismograms from the global network along with the analysis of the aftershock distribution allows us to propose a well constrained model for the whole rupture process some additional details of the rupture were obtained from an accelerometer record at antofagasta the main rupture started as a double even with thrust mechanism below the southern part of the mejillones peninsula and it propagated southward in a n200 e direction with an average velocity of 2 8 km sec it ended near the trench in normal faulting the total rupture area and seismic moment are 185 90 km 2 and 1 2 10 28 dyne cm respectively the aftershock distribution delineates a well defined rupture surface along the subduction interface the distribution of epicenters during the first 20 h of aftershock activity shows a sharp northern boundary beneath the mejillones peninsula hence the 1995 main rupture did not propagate north of the mejillones peninsula into the 1877 gap aftershocks during the following 2 weeks indicate a growth of the initial rupture zone toward the north the mechanisms of the strongest aftershocks are similar to that of the mainshock the down dip termination of the main rupture corresponds to the maximum depth 50 km of the region that had been identified as the locked part of the subduction interface from the analysis of the microseismicity recorded by the local network prior to the 1995 event a well constrained dislocation model is proposed for the 1995 main rupture which produces surface displacements in good agreement with available observations of coastal uplift and gps measurements the dislocation model as well as global positioning system gps measurements indicate that the 1995 earthquake generated e w extension in the coastal region of antofagasta the atacama fault located 40 to 50 km above the 1995 main rupture showed small fresh surface ruptures near sierra remiendos 70 km to the sse of antofagasta with a maximum vertical offset of 20 cm this offset corresponds to normal faulting which is in agreement with the e w co seismic extension the mejillones peninsula appears to be the surface expression of a barrier that interrupted the propagation of the 1995 rupture to the north into the region of the 1877 gap modeling of static stress changes induced by the antofagasta earthquake indicates an increase in compressive stresses along a direction transverse to the trench immediately to the north of the 1995 rupture surface thus the chances for the reactivation of the 1877 gap after this event are greater now

mesozoic tertiary structural evolution of an extensional gneiss dome the kesebir kardamos dome eastern rhodope bulgaria greece the tectonic evolution of the rhodope massif involves mid cretaceous contractional deformation and protracted oligocene and miocene extension we present structural kinematic and strain data on the kesebir kardamos dome in eastern rhodope which document early tertiary extension the dome consists of three superposed crustal units bounded by a low angle nne dipping detachment on its northern flank in bulgaria the detachment separates footwall gneiss and migmatite in a lower unit from intermediate metamorphic and overlying upper sedimentary units in the hanging wall the high grade metamorphic rocks of the footwall have recorded isothermal decompression direct juxtaposition of the sedimentary unit onto footwall rocks is due to local extensional omission of the intermediate unit structural analysis and deformational metamorphic relationships give evidence for several events the earliest event corresponds to top to the sse ductile shearing within the intermediate unit interpreted as reflecting mid late cretaceous crustal thickening and nappe stacking late cretaceous palaeocene eocene late tectonic to post tectonic granitoids that intruded into the intermediate unit between 70 and 53 ma constrain at least pre latest late cretaceous age for the crustal stacking event subsequent extension related deformation caused pervasive mylonitisation of the footwall with top to the nne ductile then brittle shear ductile flow was dominated by non coaxial deformation indicated by quartz c axis fabrics but was nearly coaxial in the dome core latest events relate to brittle faulting that accommodated extension at shallow crustal levels on high angle normal faults and additional movement along strike slip faults radiometric and stratigraphic constraints bracket the ductile then brittle extensional events at the kesebir kardamos dome between 55 and 35 ma extension began in paleocene early eocene time and displacement on the detachment led to unroofing of the intermediate unit which supplied material for the syn detachment deposits in supra detachment basin subsequent cooling and exhumation of the footwall unit from beneath the detachment occurred between 42 and 37 ma as indicated by mica cooling ages in footwall rocks and extension proceeded at brittle levels with high angle faulting constrained at 35 ma by the age of hydrothermal adularia crystallized in open spaces created along the faults this was followed by late eocene oligocene post detachment overlap successions and volcanic activity crustal extension described herein is contemporaneous with the closure of the vardar ocean to the southwest it has accommodated an earlier hinterland directed unroofing of the rhodope nappe complex and may be pre cursor of and or make a transition to the aegean back arc extension that further contributed to its exhumation during the late miocene this study underlines the importance of crustal extension at the scale of the rhodope massif in particular in the eastern rhodope region as it recognizes an early tertiary extension that should be considered in future tectonic models of the rhodope and north aegean regions

low temperature thermochronologic record of eocene migmatite dome emplacement and late cenozoic landscape development shuswap core complex british columbia exhumed mid to lower crustal rocks offer an opportunity to determine the mechanisms conditions timing and consequences of the ascent of hot rocks from deep to shallow crustal levels we used results of low t thermochronology zircon and apatite u th he apatite fission track to document the very shallow emplacement 1800 m have preserved eocene fission track ages and evidence of rapid cooling 60 c myr this eocene cooling event corresponds to rapid exhumation by upward flow of partially molten crust and final exhumation by detachment faulting samples collected below 1800 m in elevation display a wide range of apatite fission track ages 43 15 ma and track length distributions that reflect prolonged residence in the apatite partial annealing zone these age elevation relations imply that the dome rocks reached the near surface 2 km during initial upward flow and tectonic exhumation in the eocene and that little erosion of the eocene surface has occurred since that time thermal modeling of the lowest elevation samples 600 m and intrasample apatite u th he age variations reveal enhanced erosion and relief production at the onset of continental glaciations at 3 ma our work illustrates the dynamic links between deep and shallow crustal processes and the evolution of topography in a deeply incised hot orogen

vertical extrusion and horizontal channel flow of orogenic lower crust key exhumation mechanisms in large hot orogens a large database of structural geochronological and petrological data combined with a bouguer anomaly map is used to develop a two stage exhumation model of deep seated rocks in the eastern sector of the variscan belt an early sub vertical fabric developed in the orogenic lower and middle crust during intracrustal folding followed by the vertical extrusion of the lower crustal rocks these events were responsible for exhumation of the orogenic lower crust from depths equivalent to 18 20 kbar to depths equivalent to 8 10 kbar and for coeval burial of upper crustal rocks to depths equivalent to 8 9 kbar following the folding and vertical extrusion event sub horizontal fabrics developed at medium to low pressure in the orogenic lower and middle crust during vertical shortening fabrics that record the early vertical extrusion originated between 350 and 340 ma during building of an orogenic root in response to se directed saxothuringian continental subduction fabrics that record the later sub horizontal exhumation event relate to an eastern promontory of the brunia continent indenting into the rheologically weaker rocks of the orogenic root indentation initiated thrusting or flow of the orogenic crust over the brunia continent in a north directed sub horizontal channel this sub horizontal flow operated between 330 and 325 ma and was responsible for a heterogeneous mixing of blocks and boudins of lower and middle crustal rocks and for their progressive thermal re equilibration the erosion depth as well as the degree of reworking decreases from south to north pointing to an outflow of lower crustal material to the surface which was subsequently eroded and deposited in a foreland basin indentation by the brunia continental promontory was highly noncoaxial with respect to the se oriented saxothuringian continental subduction in the early visean suggesting a major switch of plate configuration during the middle to late visean

far field simulation of tsunami propagation in the pacific ocean impact on the marquesas islands french polynesia the islands in the marquesas archipelago are most exposed to far field tsunamis in french polynesia four recent earthquakes located at the pacific rim kurile 1994 chile 1995 mexico 1995 and peru 1996 earthquakes generated trans pacific tsunamis and caused contrasting inundations in several inhabited marquesian bays the aim of this study is to better understand the amplification phenomena observed in the marquesas islands and to improve the risk assessment we present here numerical simulations of these four tsunamis by means of a finite difference model solving the equations of tsunami propagation at different scales the water heights computed in the bays are in excellent agreement with the available observations and thus validate our numerical method these numerical results allow us to determine 1 which propagation azimuths are dangerous for the whole marquesas archipelago and 2 the behavior of each studied bay amplitude frequency in response to tsunami waves we observe that the seismogenic subduction zone along south america is likely to define one of the most dangerous tsunami generation areas for the marquesas archipelago owing to the source geometries and to the trapping of the tsunami energy by bathymetric features in the southern pacific ocean fracture zones seamount chains

high frequency tsunami signals of the great indonesian earthquakes of 26 december 2004 and 28 march 2005 tsunamis generated by the great indonesian earthquakes of 26 december 2004 m w 9 3 and 28 march 2005 m w 8 6 produced high frequency 5 mhz dispersed signals recorded by hydrophone stations offshore from diego garcia and cape leeuwin australia and by many seismic stations in the indian ocean and on the coast of antarctica for the first and greater earthquake the dispersed energy is commonly observed to 30 mhz and in one case to 60 mhz the high frequency signals are consistent with being generated at pointlike sources the earliest arriving tsunami signals originate from a point near 4 3 n 93 8 e determined using event to station distances estimated by matching predicted dispersion to observations the location is further constrained with azimuth estimates from an array of hydrophones fine structure in the tsunami signal indicates a second high frequency source just south of great nicobar island near 6 5 n 93 6 e the point sources are located close to the maximum slip area determined in several other seismic and tsunami studies the dispersion of much later arriving energy is consistent with travel over longer paths and matches predictions for reflections of the tsunami from bathymetric features in the indian ocean basin for the 28 march 2005 tsunami the high frequency dispersion is observed at the diego garcia hydrophone station and the ais seismic station and tsunami signals without apparent dispersion are seen at four other seismic stations phase velocities estimated at hydroacoustic stations agree with linear dispersion theory at frequencies above 12 mhz

mechanisms of continental subduction and exhumation of hp and uhp rocks abstract we discuss possible scenarios of continental collision and their relation to mechanisms of exhumation of hp and uhp rocks inferred from thermo mechanical numerical models accounting for thermo rheological complexity of the continental lithosphere due to this complexity mechanisms of continental convergence are versatile and different in many aspects from those that control oceanic subduction elucidating these mechanisms from conventional observations is difficult and requires additional constraints such as those derived from petrological data indeed exhumation of hp uhp rocks is an integral part of convergent processes and burial exhumation dynamics inferred from metamorphic p t t paths provides strong constraints on the collision scenarios metamorphic rocks also play an active role due to their contrasting physical properties rheology density fluid transport capacity numerical thermo mechanical experiments suggest that hp uhp exhumation can only be produced in subduction contexts as well as that long lasting 10 myr continental subduction can only occur in case of cold strong lithospheres t moho t e 50 km and of relatively high convergence rates 3 5 cm yr 1 in this case high density uhp material in the crustal part of subduction interface provides additional pull on the slab and is not always exhumed to the surface in case of slower convergence and or weaker lithosphere t e 1 is generally sufficient to drive continental subduction during the first several myr of convergence but pertinent subduction requires faster convergence rates 3 5 cm yr 1 we suggest that most continental orogenic belts could have started their formation from continental subduction but this process has been generally limited in time

the 2004 december 26 indian ocean tsunami impact on sri lanka cascade modelling from ocean to city scales summary the 2004 december 26 indian ocean tsunami severely hit sri lanka although it was not in the direct path of the initial tsunami waves the western coast was struck by diffracted waves that caused much damage the numerical model geowave is used to compute tsunami generation propagation and inundation from the earthquake source to the sri lankan coast a nested grid system is constructed to increase the resolution until galle bay on the southwestern coast where a 20 m grid is used the six nested topobathymetric grids are interpolated from etopo2 and high resolution data at sea as onshore simulation results are compared with tsunami height data from national oceanic and atmospheric administration noaa us and geological survey mines bureau gsmb sri lanka when the grid resolution increases the discrepancy between the model and the data remains on average good whereas its spread increases we then conclude that the order of magnitude of the tsunami height is consistent from the 180 m resolution grid but the spatial imprecision is too high to locally predict reliable water heights nevertheless the comparison between computed time series of sea surface elevation at the colombo tide station and tide gauge data shows a very good agreement as both amplitude and arrival time of the first wave are well reproduced when focusing onshore the modelled inundation limit is compared with the limit measured in the field with its a priori setup computed inundation spreads much farther behind the field limit we then integrate more accurate nearshore conditions into the model non linear shallow water equations are chosen instead of fully non linear boussinesq equations the bottom friction on land is increased to a much higher value than at sea the buildings cover and the low tide conditions are taken into account in the dem the resulting high resolution simulation agrees better with field data even if discrepancies are still locally observed in places of dem imprecision and in a river valley this simulation however demonstrates that taking into account nearshore and onshore features may significantly improve tsunami impact assessment

dispersive and reflected tsunami signals from the 2004 indian ocean tsunami observed on hydrophones and seismic stations 1 the tsunami caused by the great sumatra earthquake on 26 december 2004 generated dispersive signals recorded on hydrophones near diego garcia and cape leeuwin australia and on seismographs in coastal locations around the indian ocean the onset of these signals was coincident with predicted tsunami arrival times signal durations were from 12 to more than 36 hours and signal frequencies ranged from less than 1 mhz at onset to 25 mhz signal onset times and dispersion are consistent with propagation from the earthquake rupture zone to the receivers as tsunami waves signal arrival azimuths were estimated from coherent processing of groups of sensors the azimuth and dispersion of the signal are consistent with the direct tsunami wave and secondary signals are consistent with reflections of the tsunami from the mascarene plateau and other bathymetric features in the indian ocean

rupture process of the 2004 sumatra andaman earthquake from tsunami waveform inversion the aim of this work is to infer the slip distribution and rupture velocity along the rupture zone of the 26 december 2004 sumatra andaman earthquake from available tide gage records of the tsunami we selected waveforms from 14 stations distributed along the coast of the indian ocean then we subdivided the fault plane into 16 subfaults both along strike and downdip following the geometry and mech anism proposed by banerjee et al 2005 and computed the corresponding green s functions by numerical solution of the shallow water equations through a finite difference method the slip distribution and rupture velocity were determined simul taneously by means of a simulated annealing technique we compared the recorded and synthetic waveforms in the time domain using a cost function that is a trade off between the l1 and l2 norms preliminary tests on a synthetic dataset together with a posteriori statistical analysis of the model ensemble enabled us to assess the ef fectiveness of the method and to quantify the model uncertainty the main finding is that the best source model features a nonuniform distribution of coseismic slip with high slip values concentrated into three main patches the first is located in the southern part of the fault off the coast of the aceh province the second between 6 5 n and 11 n and the third at depth between 11 n and 14 n furthermore we estimated that the rupture propagated at an average speed of 2 0 km sec

seismology speed and size of the sumatra earthquake we now have a clearer picture of the seismic features of last year s gigantic event our seismological results reveal that indonesia s devastating sumatra andaman earthquake on 26 december 2004 was 2 5 times larger than initial reports suggested second only to the 1960 chilean earthquake in recorded magnitude they indicate that it slowly released its energy by slip along a 1 200 km fault generating a long rupture that contributed to the subsequent tsunami now that the entire rupture zone has slipped the strain accumulated from the subduction of the indian plate beneath the burma microplate has been released and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary although large earthquakes on segments to the south still present a threat

kinematic interpretation of the 3d shapes of metamorphic core complexes 1 metamorphic core complexes form dome shaped structures in which the ductile crust is exhumed beneath a detachment fault the 3d dome geometry inferred by mapping the schistosity in the exhumed crust can be either elongated normal to the stretching direction or along it in the first case the domes are interpreted as having formed during extension however in the second case they are interpreted either as strike slip transpressive or constrictive extensional structures depending on the geodynamic context numerical models of metamorphic core complexes published to date are all two dimensional and therefore theoretically only apply to domes which are elongated normal to the stretching direction here we explore by means of 3d thermomechanical modeling the impact of 3d kinematic extensional boundary conditions on the shape of metamorphic core complexes we examine the impact of a transtensional step over and of horsetail splay fault kinematics on the dynamics of exhumation finite strain and p t paths and compare them to cylindrical 3d models we show for the first time that domes formed in transtensional step over or at the tip of propagating strike slip faults display a finite strain field which can be interpreted as characteristic of a transpressive domes although no shortening was applied in the far field applying our models to the cyclades we propose that the coeval formation of domes elongated normal and parallel to the stretching during the miocene can be the result of horsetail splay fault kinematics which could correspond to the formation of a tear in the aegean slab

pedestal craters on ganymede abstract the high resolution voyager images of ganymede show a class of fresh craters 6 89 km in diameter which is distinguished by an ejecta blanket similar to those seen for some types of martian craters one hundred and eighty five were identified and studied for trends with respect to latitude longitude and terrain type no correlation of the ratio of ejecta diameter to crater diameter was found as a function of latitude or longitude and there is only a suggestion of a trend in this ratio with respect to major terrain types central peak frequency is greatest for the smaller crater diameters central pit occurrence dominates central peak occurrence at crater diameters 35 km we conclude that the ejecta morphology probably results from impact into an icy target the question of whether atmospheric ejecta particle drag contributes to ejecta blanket morphologies on planets with an atmospheric cannot be resolved entirely from the voyager images the image resolution is insufficient to show diagnostic flow features on the ejecta if they exist or to detect evidence of any other ejecta deposits which would lie beyond the pedestal predicted by some researchers to exist only on bodies with an atmosphere

modelling of the total electronic content and magnetic field anomalies generated by the 2011 tohoku oki tsunami and associated acoustic gravity waves summary in this work numerical simulations of the atmospheric and ionospheric anomalies are performed for the tohoku oki tsunami 2011 march 11 the tsunami atmosphere ionosphere tai coupling mechanism via acoustic gravity waves agws is explored theoretically using the tai coupled model for the modelled tsunami wave as an input the coupled model simulates the wind density and temperature disturbances or anomalies in the atmosphere and electron density magnetic anomalies in the f region of the ionosphere also presented are the gps total electron content tec and ground based magnetometer measurements during the first hour of tsunami and good agreements are found between modelled and observed anomalies at first within 6 min from the tsunami origin the simulated wind anomaly at 250 km altitude and tec anomaly appear as the dipole shaped disturbances around the epicentre then as the concentric circular wave fronts radially moving away from the epicentre with the horizontal velocity 800 m s 1 after 12 min followed by the slow moving horizontal velocity 250 m s 1 wave disturbance after 30 min the detailed vertical horizontal propagation characteristics suggest that the anomalies appear before and after 30 min are associated with the acoustic and gravity waves respectively similar propagation characteristics are found from the gps tec and magnetic measurements presented here and also reported from recent studies the modelled magnetic anomaly in the f region ionosphere is found to have similar temporal variations with respect to the epicentre distance as that of the magnetic anomaly registered from the ground based magnetometers the high frequency component 10 min of the simulated wind tec and magnetic anomalies in the f region develops within 6 7 min after the initiation of the tsunami suggesting the importance of monitoring the high frequency atmospheric ionospheric anomalies for the early warning these anomalies are found to maximize across the epicentre in the direction opposite to the tsunami propagation suggesting that the large atmospheric ionospheric disturbances are excited in the region where tsunami does not travel

deep crustal source of gneiss dome revealed by eclogite in migmatite montagne noire french massif central in orogens worldwide and throughout geologic time large volumes of deep continental crust have been exhumed in domal structures extension driven ascent of bodies of deep hot crust is a very efficient mechanism for rapid heat and mass transfer from deep to shallow crustal levels and is therefore an important mechanism in the evolution of continents the dominant rock type in exhumed domes is quartzofeldspathic gneiss typically migmatitic that does not record its former high pressure hp conditions in its equilibrium mineral assemblage rather it records the conditions of emplacement and cooling in the mid shallow crust mafic rocks included in gneiss may however contain a fragmentary record of a hp history and are evidence that their host rocks were also deeply sourced an excellent example of exhumed deep crust that retains a partial hp record is in the montagne noire dome french massif central which contains well preserved eclogite garnet omphacite rutile quartz in migmatite in two locations one in the dome core and the other at the dome margin both eclogites record p 1 5 0 2 gpa at t 700 20 c but differ from each other in whole rock and mineral composition deformation features shape and crystallographic preferred orientation cpo extent of record of prograde metamorphism in garnet and zircon and degree of preservation of inherited zircon rim ages of zircon in both eclogites overlap with the oldest crystallization ages of host gneiss at c 310 ma interpreted based on zircon rare earth element abundance in eclogite zircon as the age of hp metamorphism dome margin eclogite zircon retains a widespread record of protolith age c 470 450 ma the same as host gneiss protolith age whereas dome core eclogite zircon has more scarce preservation of inherited zircon possible explanations for differences in the two eclogites relate to differences in the protolith mafic magma composition and history and or the duration of metamorphic heating and extent of interaction with aqueous fluid affecting zircon crystallization differences in hp deformation fabrics may relate to the position of the eclogite facies rocks relative to zones of transpression and transtension at an early stage of dome development regardless of differences both eclogites experienced hp metamorphism and deformation in the deep crust at c 310 ma and were exhumed by lithospheric extension with their host migmatite near the end of the variscan orogeny the deep crust in this region was rapidly exhumed from 50 to 10 km where it equilibrated under low p high t conditions leaving a sparse but compelling record of the deep origin of most of the crust now exposed in the dome

numerical modeling of the great 2004 indian ocean tsunami focus on the mascarene islands on 26 december 2004 the m w 9 2 sumatra earthquake triggered the greatest tsunami ever observed in recent times the unprecedented quality and variety of observations on modern instruments provide opportunities to refine modeling techniques as well as our perception of tsunami hazard in oceanic regions where historical events are not as frequent as in the pacific ocean we present a numerical modeling of the 2004 tsunami on the mascarene islands with refined computations on la reunion island where postevent survey observations and one tide gauge record are available we use two different source models models a and b to account for the observations and we also test an additional source model model c to study the effect of a tsunami originating in the 1833 epicentral area southern sumatra a wave trapped on the edge of la reunion may explain the greatest water heights reached in the western coastline of the island the observed tide gauge data are reasonably well fit models a and b the run up data can also be explained with our models late disturbances observed in la pointe des galets may be explained by a late tsunami reflection from madagascar or by harbor resonances finally we also show that model c 1833 like strikes la reunion more heavily than models a and b

coseismic slip and afterslip of the great mw 9 15 sumatra andaman earthquake of 2004 we determine coseismic and the first month postseismic deformation associated with the sumatra andaman earthquake of 26 december 2004 from near field global positioning system gps surveys in northwestern sumatra and along the nicobar andaman islands continuous and campaign gps measurements from thailand and malaysia and in situ and remotely sensed observations of the vertical motion of coral reefs the coseismic model shows that the sunda subduction mega thrust ruptured over a distance of about 1500 km and a width of less than 150 km releasing a total moment of 6 7 7 0 10 22 n m equivalent to a magnitude m w 9 15 the latitudinal distribution of released moment in our model has three distinct peaks at about 4 n 7 n and 9 n which compares well to the latitudinal variations seen in the seismic inversion and of the analysis of radiated t waves our coseismic model is also consistent with interpretation of normal modes and with the amplitude of very long period surface waves the tsunami predicted from this model fits rela tively well the altimetric measurements made by the jason and topex satellites neither slow nor delayed slip is needed to explain the normal modes and the tsunami wave the near field geodetic data that encompass both coseismic deformation and up to 40 days of postseismic deformation require that slip must have continued on the plate interface after the 500 sec long seismic rupture the postseismic geodetic moment of about 2 4 10 22 nm mw 8 8 is equal to about 30 5 of the coseismic moment release evolution of postseismic deformation is consistent with rate strengthening frictional afterslip online material summary of geodetic data used in this study

rupture process of the 2004 sumatra andaman earthquake the 26 december 2004 sumatra andaman earthquake initiated slowly with small slip and a slow rupture speed for the first 40 to 60 seconds then the rupture expanded at a speed of about 2 5 kilometers per second toward the north northwest extending 1200 to 1300 kilometers along the andaman trough peak displacements reached 15 meters along a 600 kilometer segment of the plate boundary offshore of northwestern sumatra and the southern nicobar islands slip was less in the northern 400 to 500 kilometers of the aftershock zone and at least some slip in that region may have occurred on a time scale beyond the seismic band

infrasound associated with 2004 2005 large sumatra earthquakes and tsunami 1 large earthquakes that occurred in the sumatra region in 2004 and 2005 generated acoustic waves recorded by the diego garcia infrasound array the progressive multi channel correlation pmcc analysis is performed to detect the seismic and infrasound signals associated with these events the study is completed by an inverse location procedure that permitted reconstruction of the source location of the infrasonic waves the results show that ground motion near the epicenter and vibrations of nearby land masses efficiently produced infrasound the analysis also reveals unique evidence of long period pressure waves from the tsunami earthquake m9 0 of december 26 2004

the giant shakhdara migmatitic gneiss dome pamir india asia collision zone 2 timing of dome formation 1 cenozoic gneiss domes exposing middle lower crustal rocks cover 30 of the surface exposure of the pamir western india asia collision zone they allow an unparalleled view into the deep crust of the asian plate we use titanite monazite and zircon u th pb mica rb sr and 40ar 39ar zircon and apatite fission track and zircon u th he ages to constrain the exhumation history of the 350 90 km shakhdara alichur dome southwestern pamir doming started at 21 20 ma along the gunt top to n normal shear zone of the northern shakhdara dome the bulk of the exhumation occurred by nnw ward extrusion of the footwall of the crustal scale south pamir normal shear zone along the southern shakhdara dome boundary footwall extrusion was active from 18 15 ma to 2 ma at 10 mm yr slip and with vertical exhumation rates of 1 3 mm yr it resulted in up to 90 km n s extension coeval with n s convergence between india and asia erosion rates were 0 3 0 5 mm yr within the domes and 0 1 0 3 mm yr in the horst separating the shakhdara and alichur domes and in the southeastern pamir plateau rates were highest along the dome axis in the southern part of the shakhdara dome incision along the major drainages was up to 1 0 mm yr thermal modeling suggests geothermal gradients as high as 60 c km along the trace of the south pamir shear zone and their strong n s variation across the dome the gradients relaxed to 40 45 c km since the end of doming

the great sumatra andaman earthquake of 26 december 2004 the two largest earthquakes of the past 40 years ruptured a 1600 kilometer long portion of the fault boundary between the indo australian and southeastern eurasian plates on 26 december 2004 seismic moment magnitude mw 9 1 to 9 3 and 28 march 2005 mw 8 6 the first event generated a tsunami that caused more than 283 000 deaths fault slip of up to 15 meters occurred near banda aceh sumatra but to the north along the nicobar and andaman islands rapid slip was much smaller tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer

age of metamorphism and deformation in the montagne noire dome french massif central tapping into the memory of fine grained gneisses using monazite u th pb geochronology recent work has revealed that the montagne noire dome located in the foreland of the variscan belt french massif central contains a record of nearly coeval late variscan eclogitization and migmatization given these new results it is important to understand the chronology of events that produced high grade metamorphism and exhumation using u th pb dating of monazite this study confirms ages of 315 300 ma for high t metamorphism in the augen gneiss that makes up a large fraction of the montagne noire dome and documents for the first time 295 ma monazite ages in compositionally varied fine grained gneisses that form folded continuous layers within the core of the dome the fine grained gneiss layers are intensely sheared and are interpreted to have localized late high t deformation in the core of the dome these sheared fine grained gneisses form a network of shear zones that were kinematically linked to the extensional and strike slip deformation zones that exhumed the montagne noire dome in a pull apart s l domain continued deformation recrystallization and fluid flow within these shear zones likely drove rejuvenation of monazite for 5 million years after much of the melt had crystallized in the montagne noire dome

computational approaches to studying non linear dynamics of the crust and mantle we outline a mathematical formulation for mantle convection which can deal with the viscoelastic plastic rheology of the cool parts of the lithosphere this formulation is then analyzed to expose the numerical challenges inherent in the equations and a suitable solution strategy is outlined with this strategy in place we discuss a parallel implementation explaining how we maintain computational efficiency in a tiered and modular software environment we show two examples from geodynamics which demonstrate the capability of the numerical method and its implementation c 2007 elsevier b v all rights reserved

tsunami source of the 2004 sumatra andaman earthquake inferred from tide gauge and satellite data tsunami source of the 2004 sumatra andaman earthquake was esti mated from a joint inversion of tsunami waveforms recorded on tide gauges and sea surface heights captured by satellite altimetry measurements the earthquake the largest in the past 40 years caused devastating tsunami damage to countries around the indian ocean but the tsunami source in particular its northern end was not well resolved although aftershocks and crustal deformation extended from off north western sumatra island through the nicobar islands to the andaman islands some seismic wave analyses indicated a shorter source length several hundred kilometers we used tsunami waveforms recorded at 12 tide gauge stations around the source and the sea surface heights measured by three satellites jason1 topex poseidon and envisat we numerically computed tsunami propagation using realistic bathym etry more than 66 000 depth points were digitized from nautical charts and combined with the etopo2 data inversion of satellite data indicates that the tsunami source extended to the andaman islands with a total length of 1 400 km but such a model produces much larger tsunami waveforms than observed at indian tide gauge stations inversion of tide gauge records and the joint inversion indicate that the tsunami source was about 900 km long the largest slip about 13 to 25 m was located off sumatra island and the second largest slip up to 7 m near the nicobar islands the slip distribution is similar for different rupture velocities and rise times with a slow velocity of 1 km sec and a rise time of 3 min yielding the largest variance reduction

mode of crustal extension determined by rheological layering the results of numerical modelling show that the mechanical stratification of the crust provides the fundamental control on fault spacing and ultimately the mode of extension macroscopic pre existing structures and weaknesses are often thought to govern the behaviour of continental crust under extension and many prior studies have focussed on the effect of heterogeneities in triggering faulting and exhumation of lower crustal material the role played by such features is in fact subordinate to that exerted by the rheological contrast from upper to lower crust in our numerical model the temperature gradient dictates the transition from a strong brittle upper crust to a weaker ductile lower crust we see two distinct extension modes that depend on this vertical rheological contrast the distributed faulting mode and the metamorphic core complex mode the ratio of the integrated strength of the upper to lower crust is an indicator of the resulting mode of extension when this strength ratio is small i e the lower crust is relatively strong the result is distributed densely spaced faulting with limited slip on each fault and no exposure of lower crustal rocks an example could be faulting in the north sea a large strength ratio hence a weak lower crust that flows easily leads to stretching being strongly localised onto relatively few normal fault zones each fault accommodates large displacements eventually dissecting the upper crust and resulting in exhumation of the lower crust this is representative of the metamorphic core complexes of the western u s a and the aegean the actual critical strength ratio for the transition between modes will depend upon secondary factors such as the relative thickness of the lower crust with respect to the upper crust and the degree of fault weakening d 2005 elsevier b v all rights reserved

fluids p t paths and the fates of anatectic melts in the earth s crust this paper presents a model for the longevity and physical behaviour of anatectic melts in the earth s crust it is assumed that a thermal anomaly has caused partial fusion of biotite plagioclase quartz rocks to produce a granitic melt and restitic solids the focus is on the potential chemical and physical outcomes as a function of the various p t fluid conditions rocks undergoing fluid present melting will sustain an increase in bulk density and will become more gravitationally stable diapiric up welling of such material should not occur in fluid absent melting the bulk density will decrease and foster gravitational instability stresses in the surrounding rocks could however lead to fracture and rapid evacuation of the melt with excess fluid and without melt segregation isobaric cooling will cause immediate freezing if t rises above the biotite quartz melting reaction freezing will still occur at the original reaction t diapiric up welling should not occur biotite bearing diatexites might be formed by large degrees of fusion but magma ascent is unlikely in isothermal decompression immediate freezing will ensue and the migmatite should contain orthopyroxene rather than biotite with excess fluid and melt segregation cooling will induce freezing at the fluid saturated granite solidus magma ascent could however occur even for xflh2o 1 in isothermal decompression melt will persist to the granite solidus for the imposed xflh2o limited magma ascent could occur all granites should contain primary igneous biotite for fluid deficient rocks without melt segregation freezing will occur at the t of the original melting if the reaction is overstepped solidification will occur at the original xflh2o magma formation is unlikely migmatites should contain either pyroxene retrogressed to biotite or biotite alone on decompression immediate freezing is likely if t remains at the biotite quartz reaction for higher t melt will survive decompression and freeze at the fluid saturated solidus for some increased xflh2o magma ascent is possible and the melt will freeze very close to the wet granite solidus in fluid deficient rocks with melt segregation cooling and crystallization will cause fluid saturation in situ segregated melt will freeze at the original xflh2o melt ascent will however cause exsolution of a co2 rich fluid with fluid escape melt will freeze close to the wet granite solidus an increase in melt proportion may accompany magma ascent or source up welling any low p granite intrusion should be charnockitic for fluid absent rocks without melt segregation freezing will occur on cooling to the t of the original reaction only transitory migmatites could be formed but melt will survive decompression almost to the h2o saturated granite solidus the rocks will reveal former melt presence only in the existence of veins of coarse retrograde biotite with isothermal decompression further melting may occur forming an orthopyroxene bearing granulite facies migmatite in fluid absent situations with melt segregation magma could be efficiently transported to higher crustal levels if the melt proportion were insufficient for magma formation granulite facies migmatites would result ascending melt would progressively dissolve any entrained restite the granites produced should be charnockitic to aid in interpretation of the modelling results we suggest that it may be slightly more common for the highest grade metamorphic terranes to exhibit isobaric cooling paths that fluid present anatexis is normally limited to the shallower parts of the crust and that fluid absent reactions are more likely at greater depths we conclude that the best models for natural fluid present anatexis are those dealing with essentially pure h2o fluid and that fluid deficient conditions will dominate over fluid excess we also believe that it is common for melts to be physically segregated on scales larger than the diffusion paths of many elements

hotspots in the southern oceans an absolute frame of reference for motion of the gondwana continents abstract the geometry and geochronology of aseismic ridges and oceanic islands in the southern oceans provide a good test of the proposition that hotspots remain fixed over long periods of time that is motion of an order of magnitude less than the relative motion between plate pairs in most cases it is concluded that inter hotspot movement cannot be discerned for the period 100 m y to present and that widely distributed hotspots in the atlantic and indian oceans provide a frame of reference for plate motions following the disintegration of gondwanaland which is independent of paleomagnetism this frame of reference is absolute in that it gives the motion of the lithosphere with respect to the mantle hotspots the absolute motion model indicates that africa and antarctica are now moving only very slowly that there has been significant relative movement between east and west antarctica since the cretaceous and prescribes the relative motion between the somali and african plates

strain and retrogression partitioning explain long term stability of crustal roots in stable continents away from tectonically active regions the continental crust has an average thickness of 40 1 km yet it shows a remarkable variability from 25 to 65 km comparable to that of the most tectonically active regions here we consider the problem of the formation and preservation of anomalous deep crustal roots in stable intracontinental regions using two dimensional thermomechanical experiments we show that the interplay between partial melting the formation of garnet pyroxene bearing rocks and their strain rate dependent retrogression result in the preservation of thick and strong crustal roots we argue that it is the partitioning into narrow regions of strain retrogression and weakening coupled into a positive feedback loop that explains why strong high grade crustal roots remain largely immune to gravitational stresses and are able to persist over hundreds of millions of years

the tsunami induced by the 2003 zemmouri earthquake mw 6 9 algeria modelling and results summary a strong tsunami with sea disturbances observed along the algerian coast but with significant damage mainly in the balearic islands spain harbours affected the western mediterranean following the 2003 zemmouri earthquake m w 6 9 algeria an average regional uplift of 0 55 m was measured along the shoreline in the epicentral area field observations main shock and aftershocks characteristics are consistent with thrust along a 55 km long rupture trending ne sw dipping se the seismotectonic parameters indicate a hypocentre 7 8 km deep and a possible fault break between 5 and 15 km offshore several tide gauges located in the western mediterranean coast indicated an average of 0 4 m of sea level change with a maximum of 2 m in the balearic islands we generated high resolution bathymetry grids from the algerian coasts to the balearic islands coasts in order to test different seismic sources with different fault rupture location strike and dip and model the tsunami initiation and propagation for the modelling we employed the crank nicolson numerical schema with a finite difference method and the okada elastic dislocation theory for the fault rupture we also highlight the different factors responsible for waves amplification around the balearic coast the best fit between synthetic and real data tide gauges gps levelling and coastal uplift as compared to run up values are obtained for a thrust rupture comparable with the earthquake fault inferred from seismotectonic studies and located within 15 km offshore an analysis of t waves reinforces the earthquake rupture origin for the tsunami this study presents the results and modelling of a major tsunami recorded in the western mediterranean sea

finite element numerical simulation of tsunamis generated by earthquakes near a circular island a numerical model for the propagation of tsunamis generated by earthquakes is applied to study the impact of the water waves against the coast of a circular island the hydraulic source is modeled by means of the static deformation of the seafloor produced by an offshore seismic fault the initial sea surface disturbance is assumed to equal the seabed displacement that is computed analytically through the classical dislocation theory of plane faults with uniform slip the wave propagation is described by means of the shallow water approximation of the navier stokes equations and is computed in a radially symmetric domain for which a quasi analytical solution is available the governing equations are solved numerically by means of a finite element fe method making use of the galerkin procedure the mesh consisting of triangular elements of variable size after a preliminary test of the numerical model against the analytical results several simulations are performed by varying the fault location dimension and dip as well as by varying the radial profiles of the basin bathymetry most attention is devoted to studying the amplification of tsunami waves impacting the island coast what is seen is that depending on the source characteristics namely fault length dip strike and distance from the island and on the basin bathymetry high amplifications in the range 1 to 5 are normally obtained not only in the front of the island as is expected but also on the lee side of the island because of positive interference of waves traveling around the island in both directions under particular conditions downwardly concave bathymetry the largest amplifications are found neither on the front side nor on the lee side but at intermediate places along the island coast

use of hydroacoustic and seismic arrays to observe rupture propagation and source extent of the mw 9 0 sumatra earthquake 1 the rupture of the sumatra earthquake mw 9 0 is complex and quite difficult to estimate using classical source inversion methods due to the exceptional rupture duration to fix the problem of geographical extent and rupture duration we use array processing of hydroacoustic and regional seismic data the cmar seismic array and the diego garcia hydroacoustic station h08s installed by the international monitoring system are respectively 15 2 and 25 7 far from the hypocenter the estimation of azimuth and velocity variations of homogeneous wave fronts across the arrays gives us the opportunity to understand how the rupture propagates the smooth and regular variations of azimuth fit a rupture extension of 1235 km and a duration of 515 s this study proves that the combination of array analysis using the different technologies installed for the ctbt is an interesting way of research for a rapid estimation of tsunamigenic earthquakes

the 15 august 2007 peru earthquake and tsunami influence of the source characteristics on the tsunami heights the tsunami caused by the 2007 peru earthquake mw 8 0 provoked less damage than by the seismic shaking itself numerous casualties due to the earthquake in the vicinity of pisco however it propagated across the pacific ocean and small waves were observed on one tide gauge in taiohae bay nuku hiva marquesas french polynesia we invert seismological data to recover the rupture pattern in two steps the first step uses surface waves to find a solution for the moment tensor and the second step uses body waves to compute the slip distribution in the source area we find the slip distribution to consist of two main slip patches in the source area the inversion of surface waves yields a scalar moment of 8 9 1020 nm and body wave inversion gives 1 4 1021 nm the inversion of tsunami data recorded on a single deep ocean sensor also can be used to compute a fault slip pattern yielding a scalar moment of 1 1 1021 nm we then use these different sources to model the tsunami propagation across the pacific ocean especially towards nuku hiva while the source model taken from the body wave inversion yields computed tsunami waves systematically too low with respect to observations on the central pacific ocean dart buoy as on the polynesian tide gauge the source model established from the surface wave inversion is more efficient to fit the observations confirming that the tsunami is sensitive to the low frequency component of the source finally we also discuss the modeling of the late tsunami arrivals in taiohae bay using several friction coefficients for the sea bottom

the origin of contractional structures in extensional gneiss domes the juxtaposition of domains of shortening and extension at different scales in orogens has fueled many debates about driving forces and tectonic interpretations including timing of deformation at the orogen scale gravitational collapse and mass transfer from orogenic plateaux to forelands explain some of these juxtapositions at a regional scale structures in gneiss domes are commonly contractional yet are coeval with regional extension and denudation here we use three dimensional numerical experiments to show that crustal flow in orogenic domains does not necessarily conform to plate motion we document contractional crustal flow associated with the formation of a gneiss dome in an orogenic pull apart setting where localized extension and crustal thinning focus the exhumation of deep crust we show that the flow field results in a complex strain pattern in which an extensional strain regime that is collinear with the direction of plate motion is partitioned into the shallow crust whereas contractional structures and fabrics at a high angle to the direction of imposed transport develop in the deep crust advective mass transfer across regions of contrasting yet coeval strain regimes leads to a polyphase tectonic history we observe structural features remarkably similar to those documented in some natural gneiss domes such as the montagne noire which developed in a dextral pull apart domain at the southern margin of the french massif central

propagation and amplification of tsunamis at coastal boundaries when tsunamis hit a coastal area they often cause substantial damage and loss of life at locations otherwise well protected from normal even severe wind generated waves an example of such a catastrophe took place on 12 december 1992 when an earthquake of magnitude ms 7 5 occurred in the eastern region of flores island indonesia1 2 one of the areas hardest hit by the resulting tsunamis was babi a small coastal island two villages on the island were completely destroyed even though both were located in sheltered areas where wave conditions are normally calm here we describe the results of numerical and laboratory experiments that show how unlike wind generated waves tsunamis are capable of penetrating into sheltered coastal areas without significantly losing their energy for the case of babi island the original tsunami wave was split into two with one wave propagating around each side of the island the two waves met in the sheltered region and the subsequent amplification of wave amplitude resulted in the destructive flow onto the beach

post orogenic extension and metamorphic core complexes in a heterogeneous crust the role of crustal layering inherited from collision application to the cyclades aegean domain summary the development of metamorphic core complexes mcc corresponds to a mode of lithospheric continental stretching that follows collision in most of the models that explain the formation of the mcc high thermal gradients are necessary to weaken the lower crust and to induce its ascent such models fail to explain the exhumation of high pressure low temperature metamorphic rocks in metamorphic core complex structures as observed in the cycladic blueschists in the aegean domain besides account for the lithological crustal stratification induced from collision has never been tested in this paper we use fully coupled thermomechanical modelling to investigate the impact of structural heritage and initial thermal gradient on the behaviour of the post orogenic continental lithosphere the models are designed and validated by petrological structural and time data from the cyclades as a result high thermal gradients moho temperature higher than 800 c are neither necessary nor always sufficient to induce the development of a metamorphic core complex at the contrary the rheological layering of the crust inherited from collision is a first order parameter controlling the development of extensional structures in post orogenic settings cold mcc can develop if the crust is made of a strong nappe thrust on top of weaker metamorphic cover and basement units as observed in the cyclades

crustal deformation and fault slip during the seismic cycle in the north chile subduction zone from gps and insar observations summary the different phases of the earthquake cycle can produce measurable deformation of the earth s surface this work is aimed at describing the evolution of that deformation in space and time as well as the distribution of causal slip on the fault at depth we have applied gps and synthetic aperture radar sar interferometry insar techniques to northern chile where fast plate convergence rates are associated with large subduction earthquakes and extensive crustal deformation the region of northern chile between 18 s and 23 s is one of the most important seismic gaps in the world with no rupture having occurred since 1877 in 1995 the mw 8 1 antofagasta earthquake ruptured the subduction interface over a length of 180 km in the region immediately to the south of this 450 km long gap the coseismic deformation associated with this event has been documented previously here we use gps position time series for 40 benchmarks measured between 1996 and 2000 and ers sar interferograms for the interval between 1995 and 1999 to map both the post seismic deformation following the 1995 event and the ongoing interseismic deformation in the adjacent gap region in the seismic gap the interseismic velocities of 20 30 mm yr 1 to the east with respect to south america are mapped both the gps and the insar measurements can be modelled with 100 per cent coupling of the thrust interface of the subduction to a depth of 35 km with a transition zone extending down to 55 km depth the slip rate in that zone increases linearly from zero to the plate convergence rate south of the gap the interferometric map shows interseismic deformation superimposed with deformation following the 1995 earthquake and covering the same area as the coseismic deformation some 40 per cent of this deformation is related to seismic activity in the 3 3 yr following the 1995 event in particular slip during a mw 7 1 earthquake in 1998 however most of the signal 60 per cent corresponds to post seismic deformation resulting from widespread aseismic slip in the subduction interface the afterslip appears to have occurred down dip in the transition zone at 35 55 km depth and to have propagated laterally northwards at 25 45 km depth under the mejillones peninsula which is a prominent geomorphological feature at the boundary between the 1877 and 1995 rupture zones we propose a simple slip model for the seismic cycle associated with the antofagasta earthquake where the transition zone alternates between aseismic shear and seismic slip

dynamics and structural development of metamorphic core complexes the development of metamorphic core complexes mccs in a thickened continental lithosphere is studied using fully coupled thermomechanical numerical code accounting for elastic brittle ductile properties of constituent rocks for mccs to develop the middle lower crust and the sub moho mantle are required to be weak enough to flow laterally so as to simultaneously feed the exhuming dome and enable the moho to keep a flat geometry the conditions are satisfied with initial moho temperatures of 800 c or higher with crustal thicknesses of 45 km or greater and with initial effective viscosities lower than 1020 pa s and 1022 pa s in the lower crust and the underlying mantle respectively a compositional mainly density anomaly with the properties of granite is placed centrally in the crust to localize strain at the onset of deformation during a first stage of upper crust necking the deformation pattern is relatively symmetrical and dominated by graben formation in the upper crust when the first ductile layers reach the surface a second stage of dome amplification and widening occurs dome amplification is accommodated by horizontal flow in the ductile crust giving an early symmetrical pattern of conjugate shear zones with no obvious detachment zone the system then rapidly becomes asymmetric with the localization of a detachment zone along one dome limb further accommodating dome widening thus the exhumation process of a metamorphic dome results in the progressive development of a detachment zone depending on initial moho temperature the detachment zone can migrate in space or die out and be replaced by a new one with an opposite dip

exhumation of the ultrahigh pressure tso morari unit in eastern ladakh nw himalaya a case study exhumation processes of the ultra high pressure uhp tso morari dome nw himalaya are investigated using structural petrological and geochronological data the uhp tso morari unit is bounded by the low grade metamorphic indus suture zone to the ne and mata unit to the sw three deformation phases d1 d2 and d3 are observed only d3 is common to the uhp unit and the surrounding units in the uhp unit the first deformation phase d1 produced upright folds under eclogitic conditions 20 kbar 580 60 c d1 is overprinted by d2 structures related to a nw se trending open anticline this phase is characterized by blueschist mineral associations and corresponds to the quasi isothermal decompression from a depth of 90 km eclogitic conditions up to 30 40 km the final exhumation phase of the tso morari unit is dominated by tectonic denudation and erosion d3 associated with a slight temperature increase radiochronological analyses indicate that the uhp exhumation process began during the eocene exhumation was fast during d1 d2 and slowed down through d3 in oligocene time the change in the deformation style from d1 d2 to d3 in the tso morari unit coincides with changes in the exhumation rates and in the metamorphic conditions these changes may reflect the transition from an exhumation along the subduction plane in a serpentinized wedge to the vertical uplift of the tso morari unit across the upper crust

plate boundary deformation associated with the great sumatra andaman earthquake the sumatra andaman earthquake of 26 december 2004 is the first giant earthquake moment magnitude m w 9 0 to have occurred since the advent of modern space based geodesy and broadband seismology it therefore provides an unprecedented opportunity to investigate the characteristics of one of these enormous and rare events here we report estimates of the ground displacement associated with this event using near field global positioning system gps surveys in northwestern sumatra combined with in situ and remote observations of the vertical motion of coral reefs these data show that the earthquake was generated by rupture of the sunda subduction megathrust over a distance of 1 500 kilometres and a width of 150 kilometres megathrust slip exceeded 20 metres offshore northern sumatra mostly at depths shallower than 30 kilometres comparison of the geodetically and seismically inferred slip distribution indicates that 30 per cent additional fault slip accrued in the 1 5 months following the 500 second long seismic rupture both seismic and aseismic slip before our re occupation of gps sites occurred on the shallow portion of the megathrust where the large aceh tsunami originated slip tapers off abruptly along strike beneath simeulue island at the southeastern edge of the rupture where the earthquake nucleated and where an m w 7 2 earthquake occurred in late 2002 this edge also abuts the northern limit of slip in the 28 march 2005 m w 8 7 nias simeulue earthquake

thermal rheological and kinematic conditions for channelized lower crustal flow in a threshold example abstract lower crustal flow zones occur in large and hot orogens and rifts where they occur in association with large areas possessing high gravitational potential energy gpe and low lower crust viscosity lower crustal flow zones are also known from regions where neither the rheological nor gpe conditions are sufficiently well developed for widespread flow to occur for these examples the conditions required to form crustal flow zones are less well defined one such case occurs within the ca 600 530 ma petermann orogeny in central australia this work investigates the conditions under which this flow zone developed considering differences with the adjacent regions where flow is not observed a transect of crustal structure in the central petermann orogen is developed that takes into account geological and geophysical data including time constrained pressure and temperature estimates for the petermann orogeny the deformation of this region is reconstructed showing that lower crustal flow was driven by high amplitude crustal scale folding the folding extruded the lower crust towards the foreland causing crustal thickening and buoyant uplift of the orogenic core channelized lower crustal flow is not known from either the eastern or western parts of the orogen and a comparison with these regions suggests three main conditions are required firstly the lower crust must be sufficiently hot and volatile rich to allow melt weakening secondly crustal rheology must allow ductile deformation of the mid to lower crust without high strength layers finally a high degree of lateral confinement is required to form pressure gradients capable of driving flow these three conditions were met only in the central petermann orogen and not in the east or the west this example of a lower crustal flow zone illustrates the combined influence of thermal rheological and kinematic threshold conditions on the initiation and development of channelized lower crustal flow in orogens

tsunami detection by satellite altimetry we present what is to our knowledge the first direct observation of the deformation of the surface of the ocean upon passage of a tsunami wave on the high seas far from the influence of shorelines and continental shelves we use satellite altimetry data from the ers 1 and topex poseidon programs complemented by spectrogram techniques and synthetic maregrams to examine the case of seven recent tsunamigenic earthquakes we make a positive identification of the tsunami wave field in the case of the 1992 nicaraguan tsunami which we detect at 15 s 106 w five hours after origin time we model the observed spectrogram by injecting a synthetic of variable amplitude into the signal of a repetitive cycle of the satellite along the same track concluding that the nicaraguan tsunami had a zero to peak amplitude of 8 cm in that region in the case of the 1995 chilean tsunami a large scatter in the spectral properties of the reference tracks renders the detection tentative we fail to detect the tsunamis of five other large events including the 1996 biak and 1996 peru earthquakes primarily on account of unfavorable source directivity in the geometry of existing satellite tracks and of the strong and incoherent noise produced by large current systems such as the kuroshio in the northwest pacific

coastal amplification laws for the french tsunami warning center numerical modeling and fast estimate of tsunami wave heights along the french riviera tsunami modeling tools in the french tsunami warning center operational context provide rapidly derived warning levels with a dimensionless variable at basin scale a new forecast method based on coastal amplification laws has been tested to estimate the tsunami onshore height with a focus on the french riviera test site nice area this fast prediction tool provides a coastal tsunami height distribution calculated from the numerical simulation of the deep ocean tsunami amplitude and using a transfer function derived from the green s law due to a lack of tsunami observations in the western mediterranean basin coastal amplification parameters are here defined regarding high resolution nested grids simulations the preliminary results for the nice test site on the basis of nine historical and synthetic sources show a good agreement with the time consuming high resolution modeling the linear approximation is obtained within 1 min in general and provides estimates within a factor of two in amplitude although the resonance effects in harbors and bays are not reproduced in nice harbor especially variation in tsunami amplitude is something that cannot be really assessed because of the magnitude range and maximum energy azimuth of possible events to account for however this method is well suited for a fast first estimate of the coastal tsunami threat forecast

bimodal behavior of extended continental lithosphere modeling insight and application to thermal history of migmatitic core complexes abstract extensional migmatitic core complexes micc expose partially molten crustal rocks exhumed during post thickening extension low heat flow in active collisional mountains suggests that there is i either input from extra crustal heat sources or ii under assessment of the pre extensional collisional heat content to form high grade metamorphic core complexes we evaluate these two hypotheses by varying thermal gradients and crustal thicknesses of two dimensional thermo mechanical numerical models simulating the extension of a stratified lithosphere for moho temperatures 35 and 50 km extension leads to a rifting mode dictated by the upwelling of the asthenosphere in that case no micc is formed for moho temperatures 700 c and or crustal thicknesses 60 km extension develops micc while maintaining a flat moho similar to wide extensional systems such as the aegean and the basin and range however when crustal strain softening is switched on it produces for both mentioned conditions miccs with similar crustal geometries testifying that partial melting in miccs can result from both extra crustal syn extensive heat asthenospheric advection and collisional heat typically miccs induced by asthenospheric heat show the sequence lower crustal migmatization doming and crustal ultra high temperature uht conditions and mantle melting in a short temporal range from 5 to 10 model ma after asthenospheric upwelling the convective migmatitic dome is shifted horizontally with respect to the asthenospheric culmination and dome migmatites experience isobaric heating to peak conditions in contrast collisional heat induced miccs exhibit pre extensional migmatization and subsequent doming at 3 4 model ma in this case the asthenosphere generating lower crustal uht conditions and mantle melts upwells lately and is not symptomatic for micc formed in short extensional pulses

tsunami hazard in la reunion island sw indian ocean scenario based numerical modelling on vulnerable coastal sites several major tsunamis have affected the southwest indian ocean area since the 2004 sumatra event and some of them 2005 2006 2007 and 2010 have hit la reunion island in the southwest indian ocean however tsunami hazard is not well defined for la reunion island where vulnerable coastlines can be exposed this study offers a first tsunami hazard assesment for la reunion island we first review the historical tsunami observations made on the coastlines where high tsunami waves 2 3 m have been reported on the western coast especially during the 2004 indian ocean tsunami numerical models of historical scenarios yield results consistent with available observations on the coastal sites the harbours of la pointe des galets and saint paul the 1833 pagai earthquake and tsunami can be considered as the worst case historical scenario for this area in a second step we assess the tsunami exposure by covering the major subduction zones with syntethic events of constant magnitude 8 7 9 0 and 9 3 the aggregation of magnitude 8 7 scenarios all generate strong currents in the harbours 3 7 m s 1 and about 2 m of tsunami maximum height without significant inundation the analysis of the magnitude 9 0 events confirms that the main commercial harbour port est is more vulnerable than port ouest and that flooding in saint paul is limited to the beach area and the river mouth finally the magnitude 9 3 scenarios show limited inundations close to the beach and in the riverbed in saint paul more generally the results confirm that for la runion the sumatra subduction zone is the most threatening non local source area for tsunami generation this study also shows that far field coastal sites should be prepared for tsunami hazard and that further work is needed to improve operational warning procedures forecast methods should be developed to provide tools to enable the authorities to anticipate the local effects of tsunamis and to evacuate the harbours in sufficient time when such an earthquake occurs

mafic granulite rheology implications for a weak continental lower crust abstract the jelly sandwich model of continental rheology long the consensus model has recently been challenged the controversy is based on the rheology of mafic granulite that is thought to make up most of the lower continental crust however because of technical issues in experimental rock deformation there are very few data on this problem here we report the rheology and fabrics of a reconstituted fine grained nominally dry i e no hydrous mineral mafic granulite 57 plagioclase 24 clinopyroxene 14 orthopyroxene 5 opaque minerals 0 16 0 28 wt h 2 o deformed at 1 1 1 2 gpa pressure in a modified griggs type deformation apparatus the rheology of this mafic granulite can be described by the constitutive equation of e a 3 2 0 4 exp 244 35 kj mol r t where e is in s 1 in mpa t in kelvin and a 10 2 0 1 6 mpa 3 2 s 1 our results provide new experimental evidence in support of the jelly sandwich lithosphere strength model and imply that mafic granulite with a moderate amount of water 0 05 0 08 wt h 2 o is likely to be a weak layer in the lithosphere both pyroxenes and plagioclase develop pronounced fabrics in responding to axial deformation the deformation mechanism is dislocation creep with 100 001 and 001 100 010 100 being the dominant slip systems for pyroxenes and plagioclase respectively the low strength of mafic granulite is ascribed largely to the significant weakening effect of dissolved water in pyroxenes and plagioclase a weak continental lower crust has many important implications for geodynamics of crust mantle interactions such as lower crust channel flow and delamination

the giant shakhdara migmatitic gneiss dome pamir india asia collision zone 1 geometry and kinematics 1 cenozoic gneiss domes comprise one third of the surface exposure of the pamir and provide a window into the deep crustal processes of the india asia collision the largest of these are the doubly vergent composite shakhdara alichur domes of the southwestern pamir tajikistan and afghanistan they are separated by a low strain horst top to sse noncoaxial pervasive flow over the up to 4 km thick south pamir shear zone exhumed crust from 30 40 km depth in the 250 80 km shakhdara dome the top to nne alichur shear zone exposed upper crustal rocks in the 125 25 km alichur dome the gunt shear zone bounds the shakhdara dome in the north and records alternations of normal shear and dextral transpression it contributed little to bulk exhumation footwall exhumation along two low angle normal sense detachments resulted in up to 90 km syn orogenic n s extension extension in the southwestern pamir opposes shortening in a fold thrust belt north of the domes and in particular in the tajik depression where an evaporitic decollement facilitated upper crustal shortening gravitational collapse of the pamir plateau margin drove core complex formation in the southwestern pamir and shortening of the weak foreland adjacent to the plateau overall this geometry defines a vertical extrusion scenario comprising frontal and basal underthrusting and thickening and hanging gravitationally driven normal shear in contrast to the himalayan vertical extrusion scenario erosion in the pamir was minor preserving most of the extruded deep crust including the top of the south pamir shear zone at peak elevations throughout the dome

gneiss domes and orogeny many gneiss domes record positive feedback between decompression and partial melting of orogenic middle crust exhumed orogens are riddled with gneiss domes cored by migmatites that underwent dehydration melting during decompression the decreasing buoyancy associated with increasing melt fraction drives further decompression at near isothermal conditions as the partially molten crust rises diapirically this combination of processes may explain the generation and retention of large volumes of crustally derived melt recorded in many deep seated migmatite terranes and inferred for active orogens in exhumed orogens the signature of the rapid ascent of partially molten crust is a gneiss dome cored by migmatite granite the large volume of material involved in the vertical transfer of partially molten crust indicates that the formation of gneiss domes is an efficient mechanism for heat advection during orogenesis

three dimensional waveform modeling of ionospheric signature induced by the 2004 sumatra tsunami 1 the sumatra december 26th 2004 tsunami produced internal gravity waves in the neutral atmosphere and large disturbances in the overlying ionospheric plasma to corroborate the tsunamigenic hypothesis of these perturbations we reproduce with a 3d numerical modeling of the ocean atmosphere ionosphere coupling the tsunami signature in the total electron content tec data measured by the jason 1 and topex poseidon satellite altimeters the agreement between the observed and synthetic tec shows that ionospheric remote sensing can provide new tools for offshore tsunami detection and monitoring

the 26 december 2004 sumatra tsunami analysis of tide gauge data from the world ocean part 1 indian ocean and south africa the m w 9 3 megathrust earthquake of december 26 2004 off the northwest coast of sumatra in the indian ocean generated a catastrophic tsunami that was recorded by a large number of tide gauges throughout the world ocean part 1 of our study of this event examines tide gauge measurements from the indian ocean region at sites located from a few hundred to several thousand kilometers from the source area statistical characteristics of the tsunami waves including wave height duration and arrival time are determined along with spectral properties of the tsunami records

the global reach of the 26 december 2004 sumatra tsunami numerical model simulations combined with tide gauge and satellite altimetry data reveal that wave amplitudes directionality and global propagation patterns of the 26 december 2004 sumatra tsunami were primarily determined by the orientation and intensity of the offshore seismic line source and subsequently by the trapping effect of mid ocean ridge topographic waveguides

insight into the 2004 sumatra andaman earthquake from gps measurements in southeast asia data collected at 60 global positioning system gps sites in southeast asia show the crustal deformation caused by the 26 december 2004 sumatra andaman earthquake at an unprecedented large scale small but significant co seismic jumps are clearly detected more than 3 000 km from the earthquake epicentre the nearest sites still more than 400 km away show displacements of 10 cm or more here we show that the rupture plane for this earthquake must have been at least 1 000 km long and that non homogeneous slip is required to fit the large displacement gradients revealed by the gps measurements our kinematic analysis of the gps recordings indicates that the centroid of released deformation is located at least 200 km north of the seismological epicentre it also provides evidence that the rupture propagated northward sufficiently fast for stations in northern thailand to have reached their final positions less than 10 min after the earthquake hence ruling out the hypothesis of a silent slow aseismic rupture data culled from gps stations in indonesia malaysia singapore thailand india and china have answered more questions relating to the 26 december sumatra andaman megathrust earthquake permanent displacements were seen 3 000 km away final displacements occurred within 10 minutes of the earthquake ruling out slow aseismic slip on the fault

the 2006 july 17 java indonesia tsunami from satellite imagery and numerical modelling a single or complex source summary the mw 7 8 2006 july 17 earthquake off the southern coast of java indonesia has been responsible for a very large tsunami causing more than 700 casualties the tsunami has been observed on at least 200 km of coastline in the region of pangandaran west java with run up heights from 5 to more than 20 m such a large tsunami with respect to the source magnitude has been attributed to the slow character of the seismic rupture defining the event as a so called tsunami earthquake but it has also been suggested that the largest run up heights are actually the result of a second local landslide source here we test whether a single slow earthquake source can explain the tsunami run up using a combination of new detailed data in the region of the largest run ups and comparison with modelled run ups for a range of plausible earthquake source models using high resolution satellite imagery spot 5 and quickbird the coastal impact of the tsunami is refined in the surroundings of the high security permisan prison on nusa kambangan island where 20 m run up had been recorded directly after the event these data confirm the extreme inundation lengths close to the prison and extend the area of maximum impact further along the nusa kambangan island about 20 km of shoreline where inundation lengths reach several hundreds of metres suggesting run up as high as 10 15 m tsunami modelling has been conducted in detail for the high run up permisan area nusa kambangan and the pltu power plant about 25 km eastwards where run up reached only 4 6 m and a video recording of the tsunami arrival is available for the permisan prison a high resolution dem was built from stereoscopic satellite imagery the regular basin of the pltu plant was designed using photographs and direct observations for the earthquake s mechanism both static infinite and finite kinematic ruptures are investigated using two published source models the models account rather well for the sea level variation at pltu showing a better agreement in arrival times with the finite rupture and predict the permisan area to be one of the regions where tsunami waves would have focussed however the earthquake models that match the data at ptlu do not predict that the wave heights at permisan are an overall maximum and do not predict there more than 10 m of the 21 observed hence our results confirm that an additional localized tsunami source off nusa kambangan island such as a submarine landslide may have increased the tsunami impact for the permisan site this reinforces the importance for hazard assessment of further mapping and understanding local potential for submarine sliding as a tsunami source added to usual earthquake sources

seismic history and seismotectonics of the sunda arc historic records of the last 300 years reveal two great interplate earthquakes 1833 mw 8 1861 mw 8 8 which ruptured major segments of the sumatra fore arc in western indonesia a significant percentage of interplate slip along this portion of the plate boundary appears to occur seismically the ends of these rupture zones are coincident with clusters of large ms 7 and moderate 6 ms 7 shocks and with heterogeneities in the plate interface as inferred from geologic and geophysical data the northern extent of the 1833 rupture zone is coincident with a group of moderate and large earthquakes a structural arch in the fore arc and a fracture zone on the subducted plate the southern portion is coincident with a very prominent cluster and the along strike extension of a sediment filled trough on the subducted plate prior to this study sumatra was characterized as relatively aseismic as inferred from the lack of great earthquakes in the instrumental record of this century java and the lesser sunda islands had major ms 6 earthquakes in the historic record but none are of the same magnitude as the great events near sumatra there is no clear evidence that shocks in the java fore arc were interplate events yet geophysical data indicate recent uplift of the trench slope break and a change in strike of the trench axis where the northernmost flank of the roo rise a prominent bathymetrie high appears to be interacting with the fore arc this feature was formed at a ridge crest and is more buoyant and thus more difficult to subduct than the surrounding seafloor there is no increase in seismicity associated with this tectonism however that may indicate a lack of contact between the crystalline portions of the plates at this time we infer that a majority of slip on the plate interface near java occurs aseismically the variation in occurrence of great interplate earthquakes along the sunda arc may be interpreted in terms of a model that attributes variation in interplate coupling to the age of the subducted lithosphere great interplate earthquakes occur near sumatra where the age of the youngest crust is 46 ma the characteristics of the sunda arc and analogies with pacific arcs imply that the entire length of sumatra has the potential to produce great thrust earthquakes its seismic potential should be considered high as there has been no recurrence of the great events of 1833 and 1861 in contrast no such events have been reported off java and the lesser sunda islands where the oldest crust is 152 ma the plate interface near java and the lesser sunda islands should be considered to have low seismic potential

kinematics and source zone properties of the 2004 sumatra andaman earthquake and tsunami nonlinear joint inversion of tide gauge satellite altimetry and gps data 1 we re analyzed the source of the 26 december 2004 sumatra andaman earthquake and tsunami through a nonlinear joint inversion of an inhomogeneous data set made up of tide gauges satellite altimetry and far field gps recordings the purpose is twofold 1 the retrieval of the main kinematics rupture parameters slip rake and rupture velocity and 2 the inference of the rigidity of the source zone we independently estimate the slip from tsunami data and the seismic moment from geodetic data to derive the rigidity our results confirm that the source of the 2004 sumatra andaman earthquake has a complex geometry constituted by three main slip patches with slip peaking at 30 m in the southern part of the source the rake direction rotates counterclockwise at the northern part of the source according to the direction of convergence along the trench the rupture velocity is higher in the deeper than in the shallower part of the source consistent with the expected increase of rigidity with depth it is also lower in the northern part consistent with known variations of the incoming plate properties and shear velocity our model features a rigidity 20 30 gpa that is lower than the preliminary reference earth model prem average for the seismogenic volume the source rigidity is one of the factors controlling the tsunami genesis for a given seismic moment the lower the rigidity the higher the induced seafloor displacement the general consistence between our source model and previous studies supports the effectiveness of our approach to the joint inversion of geodetic and tsunami data for the rigidity estimation

a bayesian source model for the 2004 great sumatra andaman earthquake the 2004 m w 9 1 9 3 sumatra andaman earthquake is one of the largest earthquakes of the modern instrumental era despite considerable efforts to analyze this event the different available observations have proven difficult to reconcile in a single finite fault slip model in particular the critical near field geodetic records contain variable and significant postseismic signal between 2 weeks and 2 months worth while the satellite altimetry records of the associated tsunami are affected by various sources of uncertainties e g source rupture velocity and mesoscale oceanic currents in this study we investigate the quasi static slip distribution of the sumatra andaman earthquake by carefully accounting for the different sources of uncertainties in the joint inversion of available geodetic and tsunami data to this end we use nondiagonal covariance matrices reflecting both observational and modeling uncertainties in a fully bayesian inversion framework modeling errors can be particularly large for great earthquakes here we consider a layered spherical earth for the static displacement field nonhydrostatic equations for the tsunami and a 3 d megathrust interface geometry to alleviate some of the potential epistemic uncertainties the bayesian framework then enables us to derive families of possible models compatible with the unevenly distributed and sometimes ambiguous measurements we infer two regions of high fault slip at 3 n 4 n and 7 n 8 n with amplitudes that likely reach values as large as 40 m and possibly larger these values are a factor of 2 larger than typically found in previous studies potentially an outcome of commonly assumed forms of regularization finally we find that fault rupture very likely involved shallow slip within the resolution provided by the existing data we cannot rule out the possibility that fault rupture reached the trench

modeling of the february 1996 peruvian tsunami the february 1996 peruvian earthquake generated a larger tsunami than expected from its surface magnitude this discrepancy as well as the long rupture duration indicate that this event is a tsunami earthquake the associated tsunami was strong locally with runup heights of 1 to 5 meters along a coastline of 400 km it is shown that this tsunami can be modeled for a seismic moment of 2 1020 nm using a rigidity of 2 1010 n m the tsunami propagation is modeled solving long wave equations by a finite difference method the maximum run up heights in the region of chimbote can be simulated using a grid increment of 10 meters the propagation of this small tsunami across the pacific ocean is modeled taking into account frequency dispersion the only notable amplification occurred in the marquesas islands where wave heights of 2 meters were observed and are simulated

numerical investigation of deep crust behavior under lithospheric extension abstract what are the conditions under which lithospheric extension drives exhumation of the deep orogenic crust during the formation of gneiss domes the mechanical link between extension of shallow crust and flow of deep crust is investigated using two dimensional numerical experiments of lithospheric extension in which the crust is 60 km thick and the deep crust viscosity and density parameter space is explored results indicate that the style of extension of the shallow crust and the path magnitude and rate of flow of deep crust are dynamically linked through the deep crust viscosity with density playing an important role in experiments with a high viscosity deep crust three main groups of domes are defined based on their mechanisms of exhumation across the viscosity density parameter space in the first group low viscosity low density deep crust domes develop by lateral and upward flow of the deep crust at km m y 1 velocity rates i e rate of experiment boundary extension in this case extension in the shallow crust is localized on a single interface and the deep crust traverses the entire thickness of the crust to the earth s near surface in 5 m y this high exhuming power relies on the dynamic feedback between the flow of deep crust and the localization of extension in the shallow crust the second group intermediate viscosity low density deep crust has less exhuming power because the stronger deep crust flows less readily and instead accommodates more uniform extension which imparts distributed extension to the shallow crust the third group represents the upper limits of viscosity and density for the deep crust in this case the low buoyancy of the deep crust results in localized thinning of the crust with large upward motion of the moho and lithosphere asthenosphere boundary these numerical experiments test the exhuming power of the deep crust in the formation of extensional gneiss domes

reconstruction of tsunami inland propagation on december 26 2004 in banda aceh indonesia through field investigations this paper presents the results from an extensive field data collection effort following the december 26 2004 earthquake and tsunami in banda aceh sumatra the data were collected under the auspices of tsunarisque a joint french indonesian program dedicated to tsunami research and hazard mitigation which has been active since before the 2004 event in total data from three months of field investigations are presented which detail important aspects of the tsunami inundation dynamics in banda aceh these include measurements of runup tsunami wave heights flow depths flow directions event chronology and building damage patterns the result is a series of detailed inundation maps of the northern and western coasts of sumatra including banda aceh and lhok nga

tsunami hazard in the marmara sea turkey a numerical approach to discuss active faulting and impact on the istanbul coastal areas abstract the westward propagation of the seismic ruptures along the north anatolian fault naf during the 20th century has increased the probability that the next rupture will be located offshore in the marmara sea in the prolongation of the 1999 izmit earthquake faulting historical tsunamis have been evidenced in the marmara sea e g those associated with the 1509 may 1766 strong earthquakes that broke submarine parts of the naf in the vicinity of istanbul and future submarine events are expected to produce tsunamis as well that could be triggered either by submarine coseismic displacements or by landsliding the assessment of their amplitude and extent of their effects is discussed in this paper through numerical modeling based on both earthquake and landsliding sources we use a finite difference method that yields the maximum water levels reached in the marmara sea and the effects run up values around the coasts of istanbul using a set of three nested bathymetric grids with a decreasing cell size to focus on istanbul first we consider probable earthquake sources along the northern branch of the emerged naf namely in the eastern cinarcik basin magnitude mw 7 2 in the western tekirdag and central basins magnitude mw 7 5 and along the whole branch magnitude mw 7 6 the impact obtained in istanbul is all the more important as a normal component in the eastern basin is present and maximum water levels can reach 2 m along the shoreline provoking locally significant inundations these results show that the historical tsunami observations around istanbul 1509 may 1766 provided they are directly due to earthquake sources imply a significant normal component in the eastern basin whatever the extent of the rupture westward conversely a source located in the western and or central basin does not provoke large waves in istanbul e g august 1766 most probably finally we test three landslide sources in the southern vicinity of istanbul and show that the damage is expected to be larger than in the case of earthquake sources for moderate to large volumes involved this kind of source in addition to the coseismic deformation could therefore be a good candidate to explain the historical waves in istanbul especially in 1509 where run up values as high as 6 m have been reported provided we are confident in the historical documents available

use of anisotropy of magnetic susceptibility ams in the study of tsunami deposits application to the 2004 deposits on the eastern coast of banda aceh north sumatra indonesia abstract we studied emplacement dynamics of the december 26 2004 tsunami deposits in artificial shallow ponds and in shallow lagoons along the northern coast of sumatra in banda aceh area successive tsunami waves inundated topographic lows which acted as sediment traps and favored preservation of deposits individual waves led to the deposition of fining upwards sedimentary sequences this multiple normal grading deposit with a thickness ranging from 2 to 80 cm constitutes a site of major interest for the study of the deposits emplaced by a tsunami wave train the main interest lies in the characteristics of the deposits that can be correlated to the behavior of the waves attested by numerous testimonies in this setting we aimed at testing the applicability of the ams anisotropy of magnetic susceptibility technique as a proxy of unconsolidated sediment fabric the combination of this proxy and traditional sedimentary analysis helped reconstructing the hydrodynamic conditions particularly the flow direction prevailing during sedimentation we applied the ams technique on eight sections stretching inland from 1 5 km to 2 2 km from the pre tsunami coastline grain size and ams data from these deposits provide similar and partially complementary information traction dominates in the basal parts of the deposits and occurs mainly for the basal layers of the sequences whereas settling dominates for the upper layers of these sequences the vertical evolution of the ams parameters within the deposits is related to the arrival of the successive waves with variations in the traction and decantation processes during deposition variations of current strength during sedimentation are related to the wave s momentum and to the progressive infill of topographic depressions the vertical change of the fifth coarsest percentile vs the median grain sizes of the deposits suggests strong variations of the energy of the currents and confirms the evolution of the ams parameters in the present study the fabric of the deposits which developed exclusively during the uprush phase of the cycle also allows the reconstruction of flood directions that are both normal and parallel to the shoreline with variations related to flow dynamics mean grain size and local topographic control due to the absence of backwash in between the waves and low velocity of the final backwash information about the sedimentation conditions of the tsunami deposits appears to be better preserved in topographic depressions in areas located remote from the seashore the ams proxy appears to be a promising tool for further studies of recent and paleo tsunami deposits

source area and rupture parameters of the 31 december 1881 mw 7 9 car nicobar earthquake estimated from tsunamis recorded in the bay of bengal 1 on the morning of 31 december 1881 a submarine earthquake beneath the andaman islands generated a tsunami with a maximum crest height of 0 8 m that was recorded by eight tide gauges surrounding the bay of bengal since the earthquake occurred 8 years before the construction of the world s first teleseismic recording seismometer little has been known about its rupture parameters or location waveform and amplitude modeling of the tsunami indicate that it was generated by a mw 7 9 0 1 rupture on the india andaman plate boundary resulting in 10 60 cm of uplift of the island of car nicobar the rupture consisted of two segments the northern 40 km long segment is separated from the southern 150 km long segment by a 100 km region corresponding to the westward projection of the west andaman spreading center the main rupture occurred between 8 5 n and 10 n with a total area of 150 km 60 km dipping 20 e with a mean slip of 2 7 m the recurrence time for 1881 type events is estimated to be 114 200 years on the basis of inferred gps convergence rates and inferred plate closure vectors although slip partitioning in the region may extend this estimate by as much as 30

could a 1755 like tsunami reach the french atlantic coastline constraints from twentieth century observations and numerical modeling the tsunami generated by the 1 november 1755 earthquake off the coast of portugal affected mainly the coastlines of the iberian peninsula and northwest morocco but was also observed in some places along the north atlantic coasts to determine whether the event could have effected the french coastline we conducted a study to search for signs of the tsunami in historical records from all tide gauge stations off the french atlantic coast during the twentieth century specifically for the 28 february 1969 and the 26 may 1975 tsunamis that were recorded by the portuguese tide gauge network because many recordings are available in la rochelle located on the southwest coast of france we focused our study on this harbor the analysis of the tide gauge data shows no evidence for tsunamis in la rochelle neither in 1969 nor in 1975 to confirm this lack of tsunami signals we used nonlinear shallow water equations to compute the tsunami propagation to the french atlantic coastline for both 1969 and 1975 events results obtained from these simulations confirm otherwise unnoticeable wave amplitudes at la rochelle harbor in a second step tsunamis from three different scenarios for the 1755 earthquake were modeled to estimate the impact of such a tsunami on the french atlantic coast with a focus on la rochelle harbor a comparison of the functions of tide configuration was made in order to analyse the difference in impact the results show that while the harbor is poorly impacted several areas western part of the island of re and northern coast of the island of oleron may have experienced a moderate impact from 0 5 to 1 m especially since the tide was high at the time of arrival possibly causing local inundations in lowland areas

tsunami impact computed from offshore modeling and coastal amplification laws insights from the 2004 indian ocean tsunami the 2004 indian ocean tsunami gave the opportunity to gather unprecedented tsunami observation databases for various coastlines we present here an analysis of such databases gathered for 3 coastlines among the most impacted in 2004 in the intermediate and far field thailand myanmar se india sri lanka and se madagascar non linear shallow water tsunami modeling performed on a single 4 coarse bathymetric grid is compared to these observations in order to check to which extent a simple approach based on the usual energy conservation laws either green s or synolakis laws can explain the data the idea is to fit tsunami data with numerical modeling carried out without any refined coastal bathymetry topography to this end several parameters are discussed namely the bathymetric depth to which model results must be extrapolated using the green s law or the mean bathymetric slope to consider near the studied coast when using the synolakis law using extrapolation depths from 1 to 10 m generally allows a good fit however a 0 1 m is required for some others especially in the far field madagascar possibly due to enhanced numerical dispersion such a method also allows describing the tsunami impact variability along a given coastline then using a series of scenarios we propose a preliminary statistical assessment of tsunami impact for a given earthquake magnitude along the indonesian subduction conversely the sources mostly contributing to a specific hazard can also be mapped onto the sources providing a first order definition of which sources are threatening the 3 studied coastlines

controls on the thermomechanical evolution of hyperextended lithosphere at magma poor rifted margins the example of espirito santo and the kwanza basins high quality long offset seismic data from many distal rifted margins show evidence for hyper extended 10 km thick crust direct observation of such domains is challenging as they lie at great water depth buried beneath thick sedimentary sequences and formed by rock assemblages that are hydrated and geophysically indistinguishable only a few drill holes have penetrated basement at ultradistal rifted margins these observations together with outcrops of preserved analogs exposed in collisional orogens suggest that the complex interaction of detachment faults rooted in a subhorizontal shear zone in the hyperextended crust or in the serpentinized mantle controls the formation of the ocean continent transition while depth dependent thinning controls the early phases of rifting conforming to classical rift models we still have a superficial understanding of how normal faults and subhorizontal shear zones form and evolve during rifting and lithospheric breakup here we develop a rheological parameterization to simulate the formation of and slip on large offset normal faults rooted in growing brittle to ductile shear zones the evolution of these structures leads to the creation of a hyperextended crust and eventually exhumed serpentinized mantle we also propose a simplified formulation to simulate magmatic underplating and seafloor spreading the resulting numerical models provide a self consistent picture for the evolution of magma poor rifted margins from initiation of rifting to seafloor spreading the model results are compared with first order observations of the kwanza and espirito santo conjugate margins in the south atlantic as well as of magma poor margins globally

detailed coseismic slip distribution of the 1944 tonankai earthquake estimated from tsunami waveforms coseismic slip distribution on the fault plane of the 1944 tonankai earthquake is estimated from inversion of tsunami waveforms three improvements from a previous study satake 1993 are made these are 1 smaller subfaults are used to resolve detailed slip distribution 2 the sub faults fit better to the plate interface geometry and 3 finer and more accurate bathymetry data is used the inversion result shows that a maximum slip of about 3 m occurred on the plate interface off shima peninsula the total seismic moment is estimated to be 2 0 1021 nm mw 8 2 the result confirms that the 1944 tonankai earthquake did not rupture the plate interface beneath the tokai region and supports the existence of the seismic gap in the tokai region suggested by ishibashi 1981 the slip of about 1 5 m on the plate interface beneath atsumi peninsula northeast of the large slip area is necessary to explain the observed tsunami waveforms although no seismic moment release was estimated from strong motion data by kikuchi et al 1999 this may suggest that the rupture beneath atsumi peninsula was slow

on the use of satellite altimetry to infer the earthquake rupture characteristics application to the 2004 sumatra event summary standard data and methods such as the inversion of seismic and gps data have been used extensively to infer the details of the 2004 december 26 earthquake the unprecedented large size of this event gave the opportunity to modern altimeters to provide the first clear records of a tsunami in deep ocean therefore allowing us to study the rupture history from an independent perspective we invert the jason 1 and topex poseidon altimetry records considering the new constraints available on the geometry of the fault plane and taking them into account in a 3 d rupture model the data are corrected for the non negligible effect of satellite motion during measurements our results show that the rupture propagated over the 1500 km of subduction zone initially identified by the aftershock distribution with a magnitude of mw 9 1 our solution compares well with the latitudinal distribution of slip inferred from other data sets with a maximum of energy release north of sumatra and two other slip patches near the nicobar and andaman islands based on waveform comparison we assert that the shallow portion of the megathrust offshore banda aceh had slip amplitudes of more than 20 m also we find that significant amounts of slip about 10 m concentrated below the andaman islands and did not propagate on the shallow portion of the interface although synthetic tests tend to show less resolution in the northern part of the rupture this solution is compatible with the near field data gps coral heads and imagery and would allow one to explain the apparent paradox between the large local displacements and the moderate tsunami observed locally finally we demonstrate the rapidly dominating effect of propagation and slip distribution over the rupture velocity and how it precludes the direct estimate of this latter parameter

viscous collision in channel explains double domes in metamorphic core complexes in hot orogens gneiss domes are a response to upper crustal stretching and lower crustal flow two dimensional thermal mechanical modeling shows that localization of extension in the upper crust triggers in the deep crust oppositely verging horizontal flows that converge beneath the extended region upon viscous collision both flowing regions rotate upward to form two upright domes of foliation double domes separated by a steep median high strain zone in such systems horizontal shortening in the infrastructure develops in an overall extensional setting dome material follows a complex depth dependent strain history from shearing in the deep crustal channel to contraction upon viscous collision in the median high strain zone to extension upon advection into the shallow crust this depth dependent strain history is likely a general feature of dome evolution and is arguably well preserved in double domes such as the montagne noire france and naxos greece gneiss domes

geomagnetic dependence of ionospheric disturbances induced by tsunamigenic internal gravity waves summary a series of ionospheric anomalies following the sumatra tsunami has been recently reported in the literature these anomalies show the signature in the ionosphere of tsunami generated internal gravity waves igw propagating in the neutral atmosphere over the ocean all these anomalies observed in the total electron content tec measured by gps or altimeters show geographical heterogeneity in the perturbed tec amplitude and suggest a dependence on geomagnetic latitude this latitudinal dependence has been taken into account in the previous 3 d modelling used for the interpretation of the tec topex and jason data here we present an accurate description of the ocean atmosphere ionosphere coupling method and focus on the properties of the propagation of tsunamigenic igw in the neutral atmosphere and their interaction with the ionospheric plasma the analytical dependence on the geomagnetic field in the neutral plasma coupling discussed in detail and quantitative modelling is used to describe the propagation of a simple tsunami wave at the global scale what emphasize the role of geomagnetic field within the neutral plasma coupling at the equatorial and mid latitude regions the results presented here in terms of electron density and tec variations show a strong geometric dependance involving the magnetic field inclination and the propagative direction of the tsunami if the strongest electron density and tec perturbations are located around 15 0 and 15 north the structure and amplitude of the modelled perturbation changes in the two