slip distribution from the 1 april 2007 solomon islands earthquake a unique image of near trench rupture 1 we estimate the slip distribution from the mw 8 1 solomon islands earthquake in 2007 from two post seismic surveys measuring uplifted coral and submerged coastal features the occurrence of islands extremely proximal to the trench and nucleation of rupture allowed for the collection of unprecedented coseismic deformation dataset along a large megathrust earthquake using data from the two surveys along the southeastern half of the slip zone within five weeks of the event we model the elastic dislocation to identify the optimal 29 and alternate 20 dip and distribution of thrust along the southern rupture the vertical deformation which includes both coseismic and early postseismic deformation has highly variable and large slip within 25 km of the trench and straddling ranongga island the shallow focus of slip in the near trench area may explain the locally high tsunami run up on portions of simbo island however the aseismic contribution of afterslip remains unknown

crustal deformation associated with an m8 1 earthquake in the solomon islands detected by alos palsar abstract on april 1 2007 utc a large mw 8 1 interplate earthquake struck the solomon islands subduction zone where complicated tectonics result from the subduction of four plates extensive ground movements and a large tsunami occurred in the epicentral area causing severe damage over a wide area using alos palsar data and the dinsar technique we detected crustal deformation exceeding 2 m in islands close to the epicenter a slip distribution of the inferred seismic fault was estimated using geodetic information derived from dinsar processing and field investigations the result indicates large slip areas around the hypocenter and the centroid it is possible that the largest slip area is related to subduction of the plate boundary between the woodlark and australian plates a small slip area between those large slip areas may indicate weak coupling due to thermal activity related to volcanic activity on simbo island the 2007 earthquake struck an area where large earthquake has not occurred since 1970 most of this seismic gap was filled by the 2007 events however a small seismic gap still remains in the southeastern region of the 2007 earthquake

characteristics on fault coupling along the solomon megathrust based on gps observations from 2011 to 2014 the solomon megathrust along the western solomon arc generated two megathrust earthquakes in the past decade mw 8 1 in 2007 and mw 7 1 in 2010 to investigate the interseismic deformation and inferred coupling on the megathrust we deployed the first continuous gps network in the western solomon islands our 2011 2014 gps data and the back slip inversion model show coupling ratio as high as 73 along the southeastern 2007 rupture segment but only 10 on average along the segment of 2010 event based on the spatial distribution of coseismic slip aftershock clusters derived coupling pattern and paleo geodetic records we discovered the former as a semi permanent asperity and the latter as a potential megathrust barrier we propose that a characteristic earthquake of magnitude not less than mw 8 will recur in an interval of 100 or more years by either single or doublet earthquake

configuration of the indian moho beneath the nw himalaya and ladakh 1 teleseismic receiver function analysis of seismograms recorded on a 700 km long profile of 17 broadband seismographs traversing the nw himalaya shows a progressive northward deepening of the indian moho from 40 km beneath delhi south of the himalayan foredeep to 75 km beneath taksha at the karakoram fault similar studies by wittlinger et al 2004 to the north of the karakoram fault show that the moho continues to deepen to 90 km beneath western tibet before shallowing substantially to 50 60 km at the altyn tagh fault the continuity of the indian moho imaged in the receiver functions reported here along with those of wittlinger et al 2004 suggest that in this part of the himalayan orogen the indian plate may penetrate as far as the bangong suture and possibly as far north as the altyn tagh

rupture across arc segment and plate boundaries in the 1 april 2007 solomons earthquake the largest earthquakes are generated in subduction zones and the earthquake rupture typically extends for hundreds of kilometres along a single subducting plate these ruptures often begin or end at structural boundaries on the overriding plate that are associated with the subduction of prominent bathymetric features of the downgoing plate here we determine uplift and subsidence along shorelines for the 1 april 2007 moment magnitude m w 8 1 earthquake in the western solomon islands using coral microatolls which provide precise measurements of vertical motions in locations where instrumental data are unavailable we demonstrate that the 2007 earthquake ruptured across the subducting simbo ridge transform and thus broke through a triple junction where the australian and woodlark plates subduct beneath the overriding pacific plate previously no known major megathrust rupture has involved two subducting plates we conclude that this event illustrates the uncertainties of predicting the segmentation of subduction zone rupture on the basis of structural discontinuities

organic petrology and rockeval analysis of the lower carboniferous emma fiord formation in sverdrup basin canadian arctic archipelago abstract samples of the lower carboniferous emma fiord formation from two localities in the sverdrup basin of arctic canada were examined using reflected white and fluorescent light the samples from kleybolte peninsula on ellesmere island show a relatively high level of thermal maturity in contrast those from grinnell peninsula on devon island are immature to marginally mature and include subbituminous coals and oil shales two types of oil shales are distinguished on the basis of liptinite content mineral matrix rockeval pyrolysis analysis and concentration of boron one is characterized by a liptinite rich clay carbonate matrix with a relatively high hydrogen index and boron content and the other by a liptinite poor carbonate matrix with a relatively low hydrogen index and boron content hydrogen rich components of these shales consist of alginite matrix bituminite and minor amounts of exsudatinite and sporinite kerogen types iii and iv comprise only minor components of the organic matter thermal maturity of the grinnell peninsula oil shales increases with depth matrix bituminite in these oil shales has seeped into cavities and microfractures in the kerogen types iii and iv forming exsudatinite the distribution and character of the organic constituents and also the concentration of boron in these samples indicate a fresh to brackish water environment

seismic velocity structure beneath the western solomon islands from the joint inversion of receiver functions and surface wave dispersion curves abstract an mw 8 1 earthquake occurred in 2007 and induced a tsunami that hit the western solomon islands and caused casualties this motivated us to deploy a seismic network around the rupture zone of the 2007 event to investigate the seismic velocity structure of the western solomon islands we select seismograms of teleseismic events recorded by our seismic network joint inversion of p wave receiver functions and surface wave group velocity dispersion curves is used to estimate station based 1 d velocity models the resulting velocity models show a highly variable crustal structure across the region the moho depths beneath the stations range from 25 to 40 km a low velocity zone lvz is observed at most seismic stations in this work our study provides preliminary station based seismic velocity models for the study region and more stations will be deployed in the continuing project an integrated 3 d velocity model will be determined in the future

multistep modelling of teleseismic receiver functions combined with constraints from seismic tomography crustal structure beneath southeast china summary with a growing number of modern broad band seismographic stations in asia the conditions have improved to allow higher resolution structural studies on regional scales here we perform a receiver based study of the lithosphere of southeast china using waveform records ofexcellentqualityfrom14chinesenationaldigitalseismicnetworkandfourglobalseismic network stations calculating the theoretical receiver functions rfs that match the observed rfs from teleseismic waveforms is an established technique for retrieving information about crustalanduppermantlestructurebeneathaseismicreceiver rfs however arepredominantly sensitivetothegradientsinthelithosphericelasticparameters anditisimpossibletodetermine a non unique distribution of seismic parameters such as absolute shear wave speeds as a function of depth unless other geophysical data are combined with rfs thus we combine rfswithindependentinformationfromshearandcompressionalwavespeedsaboveandbelow the mohoroviy discontinuity available from the existing tomographic studies we introduce a statistical approach for automatically selecting only mutually coherent rfs from a large set of observed waveforms furthermore an interactive forward modelling software is introduced and applied to observed rfs to define a prior physically acceptable range of elastic parameters in the lithosphere this is followed by a grid search for a simple crustal structure an initial model for a linearized iterative inversion is constructed from multiple constraints including results from the grid search for shear wave speed the moho depth versus vp vs ratio domain search and tomography the thickness of the crust constrained by our multistep approach appears to be more variable in comparison with tomographic studies with the crust thinning significantly towards the east we observe low values of vp vs ratios across the entire region which indicates the presence of a very silicic crust we do not observe any correlation between the crustal thickness or age of the crust with vp vs ratios which argues against a notion that there is a simple relationship between mineralogical composition and crustal thickness and age on a global scale

crustal structure of the darjeeling sikkim himalaya and southern tibet analysis of data from nine temporary broadband seismic stations operated across west bengal and sikkim along with publicly available data from seismographs in the surrounding region provides the first image of the descending indian plate beneath the darjeeling sikkim himalaya the down going indian crust is imaged by receiver function common conversion point stacking using data from 32 sites in combination with more detailed analyses from simultaneous modelling of receiver function data and rayleigh wave group velocity dispersion at 13 stations compared to locations farther south on the indian shield our southernmost station shows evidence for thickened crust beneath the mahanadi rift basin with a possible mafic basal layer north of the mahanadi rift the indian moho is 38 km deep below the archean terranes of the northeast part of the indian shield the moho then dips gently northward beneath the himalayan foreland basin reaching a depth of 44 48 km below the himalayan foothills below sikkim the moho continues to deepen but there are indications of secondary structures in the receiver function image and modelling results suggesting some imbrication of the crust as it flexes downward the crust thickens further beneath the greater himalaya and southern tibet reaching depths of 65 70 km below the southern tibet detachment std below the lhasa terrane north of the std a double discontinuity exists with interfaces at 55 60 km and 80 km depth there is a significant reduction in the average shear wave velocity of the crystalline crust between sites to the south of and on the himalayan foreland basin and sites in the himalaya and to the north below the himalaya and southern tibet the p to s conversion ps has a lower amplitude compared to that observed at sites on the undeformed indian shield this decrease in amplitude of the moho ps phase could arise from a lower impedance contrast across the crust mantle boundary or from scattering due to deformation of the crust and moho a coherent negative arrival beneath the darjeeling sikkim himalaya indicate the presence of a low velocity zone lvz possibly associated with the main himalayan thrust this lvz can be traced beneath the darjeeling sikkim himalaya but disappears beneath the greater himalaya

ancestral heritage saves tribes during 1 april 2007 solomon islands tsunami 1 the 1 april 2007 magnitude ms 8 1 earthquake off the new georgia group in the solomon islands generated a tsunami that killed 52 with locally focused run up heights of 12 m local flow depths of 5 m as well as tectonic uplift up to 3 6 m and subsidence down to 1 5 m a reconnaissance team deployed within one week investigated 65 coastal settlements on 13 remote islands the ancestral heritage run to high ground after an earthquake passed on to younger generations by survivors of smaller historic tsunamis triggered an immediate spontaneous self evacuation containing the death toll

the use of discrete fracture network simulations in the design of horizontal hillslope drainage networks in fractured rock abstract characteristics of fracture networks are explored in a discrete fracture network framework to provide design guidelines for horizontal drainage networks in fractured rock central to the study is defining how fracture attributes relate to fracture network structure and network scale fluid flow and in turn how flow characteristics of fracture networks influence horizontal drain length and orientation multiple realizations of stochastic fracture networks generated from both synthetic and field specific data sets serve as a basis for understanding physical fracture network structure and resultant global flow and for performing intersection analyses of hillslope drains with flowing fractures study results indicate that the logarithm of the standard deviation of fracture transmissivity log t is the single most important attribute for drainage network design as higher values of log t describe heterogeneous flow patterns where only a small portion of the network conducts a significant quantity of fluid thus recommended drain lengths for intersecting significantly conductive fractures increase with increases in log t fracture trace length orientation and density also play a role albeit secondary to the distribution of transmissivity in defining drain length as a function of drain orientation relative to the mean fracture set orientation the spatially discontinuous nature of fracture networks and the wide range in transmissivity values found in natural fracture networks tend to produce high degrees of variability in computed intersection distances between drains and fractures conducting significant quantities of fluid to account for this variability a conservative approach is recommended where horizontal drain lengths along a pre defined orientation are scaled by discrete fracture network computed intersection distances equal to the upper 95th confidence interval

compound specific isotopic variability in uinta basin native bitumens paleoenvironmental implications abstract we have analyzed the solvent extracts from three different types of native bitumens from the uinta basin in northeastern utah by a variety of analytical techniques including gc irms to evaluate variations in the paleodepositional environment during two periods of lake uinta deposition the gilsonite and tabbyite bitumens are associated with parachute creek member sediments deposited during a major expansion of ancient lake uinta compound specific isotopic analyses of s carotane and phytane 13 c 32 6 to 32 1 0 from these bitumens reflect input from primary photosynthetic producers such as cyanobacteria sterane 13c values 34 5 to 29 2 0 refflect contributions from lacustrine algae while extremely depleted 13c values for methylhopanes 58 1 to 61 5 0 suggest input from methanotrophic bacteria variations in the 13c values of the hopanes 51 4 to 37 7 0 imply additional input from other bacterial sources the wurtzilite bitumen was generated from the saline facies of the green river formation deposited during a later regression of lake uinta compound specific isotopic analyses of phytane 13 c 30 1 0 and steranes 13 c 29 6 to 26 7 0 from this bitumen indicate continued input from primary producers and eukaryotes the higher relative concentrations of gammacerane 13 c 26 9 0 indicate increasing input from aerobic protozoa we observed a slight enrichment in 13c in the wurtzilite extract and several biomarkers and suggest that this is a result of sulfate reducing bacteria outcompeting methanogens thereby eliminating the influence of methanotrophs in this later saline stage of deposition

the energetic 2010 mw 7 1 solomon islands tsunami earthquake summary on 2010 january 3 a moment magnitude mw 7 1 earthquake struck the solomon islands very near the san cristobal trench causing extensive landslides and surprisingly large tsunami waves because of the unique proximity of islands to the trench 20 km and earthquake a post seismic survey successfully identified unexpected widespread coseismic subsidence towards the trench up to 80 cm with no discernable post seismic deformation approximately 1000 km from the earthquake ocean bottom pressure sensors measured 1 2 cm open ocean tsunami waves though spatially limited the local tsunami wave heights up to 7 m were comparable to the much larger adjacent 2007 mw 8 1 earthquake the seismically determined focal mechanism broad scale subsidence tsunami amplitude and open ocean wave heights are all explained by an extremely shallow low angle thrust adjacent to the impinging subduction of the two seamounts near the trench this event belongs to a potentially new class of shallow tsunami earthquakes that is not identified as deficient in radiated seismic energy

joint inversion of receiver functions and surface waves with enhanced preconditioning on densely distributed cndsn stations crustal and upper mantle structure beneath china we present shear wave velocity structure beneath china by joint modeling of teleseismic receiver function and rayleigh wave group velocity dispersion data observed at 1000 permanent broadband seismic stations in the chinese national digital seismic network cndsn a ray parameter based stacking method is employed to minimize artifacts in stacking receiver functions from different sources the rayleigh wave dispersion curve is extracted from group velocity tomographic models at all applicable periods enhanced preconditions are applied on the linearized iterative inversion to regularize and balance multiple types of data the velocity profile inversion at each station starts from an initial model derived from sediments crustal thickness vp vs ratio and pn sn models this multistep approach not only reduces uncertainty and nonuniqueness of the velocity inversion but also efficiently fills information gap in each data set we then generate a 3 d s velocity model by combining and smoothing all the 1 d models the obtained 3 d model reveals crustal and upper mantle velocity structures that are well correlated with tectonic features of china for example our model shows a clear east west bimodal distribution at 35 km deep low velocity in the crust beneath central and eastern tibetan plateau and sedimentary structure in major cratons and basins our model is consistent with existing tomographic models in large scale but provides more structural details in regional and local scales

the crustal structure of the western himalayas and tibet we present new high resolution shear velocity models for the western himalayas and west tibet from the joint inversion of p receiver functions recorded using seismic stations from four arrays in this region and fundamental mode rayleigh wave group velocity maps from 5 70 s covering central and southern asia the tibetan plateau is a key locality in understanding large scale continental dynamics a large number of investigations has examined the structure and processes in eastern tibet however western tibet remains relatively understudied previous studies in this region indicate that the western part of the tibetan plateau is not a simple extension of the eastern part the areas covered by these arrays include the karakoram and altan tagh faults and major terrane boundaries in west tibet and the himalayas the arrays used include broadband data collected by the west tibet array a u s china deployment on the western side of the tibetan plateau between 2007 and 2011 we use the shear wave velocity models to obtain estimates of moho depth the moho is deep 68 84 km throughout west tibet we do not observe significant steps within the moho beneath west tibet a large step in moho depth is observed at the altyn tagh fault where moho depths are 20 30 km shallower to the north of the fault compared to those to the south beneath the lhasa terrane and tethyan himalayas we observe a low velocity zone in the midcrust this feature is not interrupted by the karakoram fault suggesting that the karakoram fault does not cut through the entire crust

crustal structure along the aleutian island arc new insights from receiver functions constrained by active source data 1 moho depth and vp vs estimates from stacking phases of receiver functions along the aleutian island arc give new constraints on its composition and structure they expand on the current understanding of island arcs and their relationship to continental crust production we also present an approach for including constraints from active source data in receiver function analysis in a region with sparse data coverage to complement this analysis moho depth averages 37 5 km with an average uncertainty of 2 5 km along the entire arc excluding the westernmost island of attu yields an average crustal thickness of 38 5 2 9 km the vp vs ratio decreases moving eastward along the arc with an average value of 1 80 in the western and central portion of the arc built on oceanic crust but 1 63 in the eastern section built on continental crust this may reflect tectonic and compositional changes along the arc however overall the arc appears more mafic than continental crust near constant crustal thickness despite significant compositional changes may indicate that nonmagmatic processes such as erosion and isostasy act to regulate arc thickness additionally strong conversions from an upper crustal magma chamber are observed beneath akutan island confirming and clarifying the geometry of the magma body inferred from other techniques they indicate a volcanic body much larger than the eruptive edifice a feature that must persist between eruptive cycles

slab1 0 a three dimensional model of global subduction zone geometries 1 we describe and present a new model of global subduction zone geometries called slab1 0 an extension of previous efforts to constrain the two dimensional non planar geometry of subduction zones around the focus of large earthquakes slab1 0 describes the detailed non planar three dimensional geometry of approximately 85 of subduction zones worldwide while the model focuses on the detailed form of each slab from their trenches through the seismogenic zone where it combines data sets from active source and passive seismology it also continues to the limits of their seismic extent in the upper mid mantle providing a uniform approach to the definition of the entire seismically active slab geometry examples are shown for two well constrained global locations models for many other regions are available and can be freely downloaded in several formats from our new slab1 0 website http on doi gov d9arbs we describe improvements in our two dimensional geometry constraint inversion including the use of average active source seismic data profiles in the shallow trench regions where data are otherwise lacking derived from the interpolation between other active source seismic data along strike in the same subduction zone we include several analyses of the uncertainty and robustness of our three dimensional interpolation methods in addition we use the filtered subduction related earthquake data sets compiled to build slab1 0 in a reassessment of previous analyses of the deep limit of the thrust interface seismogenic zone for all subduction zones included in our global model thus far concluding that the width of these seismogenic zones is on average 30 larger than previous studies have suggested

free hydrocarbons in uinta basin utah data indicate that wurtzilite is mainly alicyclic whereas gilsonite and albertite contain more aromatic structures however the presence of a substantial amount of condensed aromatic systems in general structure of the bitumens is not confirmed generation of the gilsonite from source oil shales has resulted in significant reduction of oxygen the changes in the character of the gilsonite and wurtzilite appear to be facies dependent but the difference between gilsonite and albertite is not only due to organic facies variation but also to significant diagenetic changes all evidence suggests that expulsion of the uinta basin bitumens except ozocerite has not been associated with any catagenetic changes the strong graphitizing potential of the uinta basin gilsonite w rtzilite and albertite suggests the absence or lack of thermally stable oxygen in the molecular structure of the bitumens and their source oil shales

an inverted continental moho and serpentinization of the forearc mantle volatiles that are transported by subducting lithospheric plates to depths greater than 100 km are thought to induce partial melting in the overlying mantle wedge resulting in arc magmatism and the addition of significant quantities of material to the overlying lithosphere asthenospheric flow and upwelling within the wedge produce increased lithospheric temperatures in this back arc region but the forearc mantle in the corner of the wedge is thought to be significantly cooler here we explore the structure of the mantle wedge in the southern cascadia subduction zone using scattered teleseismic waves recorded on a dense portable array of broadband seismometers we find very low shear wave velocities in the cold forearc mantle indicated by the exceptional occurrence of an inverted continental moho which reverts to normal polarity seaward of the cascade arc this observation provides compelling evidence for a highly hydrated and serpentinized forearc region consistent with thermal and petrological models of the forearc mantle wedge this serpentinized material is thought to have low strength and may therefore control the down dip rupture limit of great thrust earthquakes as well as the nature of large scale flow in the mantle wedge

lithospheric structure of the arabian shield from the joint inversion of receiver functions and surface wave group velocities abstract we estimate lithospheric velocity structure for the arabian shield by jointly modeling receiver functions and fundamental mode group velocities from events recorded by the 1995 1997 saudi arabian portable broadband deployment receiver functions are primarily sensitive to shear wave velocity contrasts and vertical travel times and surface wave dispersion measurements are sensitive to vertical shear wave velocity averages so that their combination bridge resolution gaps associated with each individual data set our resulting models correlate well with the observed surface geology the asir terrane to the west consists of a 10 km thick upper crust of 3 3 km s overlying a lower crust of 3 7 3 8 km s in the afif terrane to the east the upper crust is 20 km thick and has an average velocity of 3 6 km s and the lower crust is about 3 8 km s separating the terranes the nabitah mobile belt is made of a gradational upper crust up to 3 6 km s at 15 km overlying an also gradational lower crust up to 4 0 km s the crust mantle transition is found to be sharp in terranes of continental affinity east and gradual in terranes of oceanic affinity west the upper mantle shear velocities range from 4 3 to 4 6 km s temperatures around 1000 c are obtained from our velocity models for a thin upper mantle lid observed beneath station taif and suggest that the lithosphere could be as thin as 50 60 km under this station