reservoir sedimentation i delta and density current deposits in china where rivers draining loess soils have some of the highest sediment concentrations in the world reservoir sedimentation is a serious problem that has been the subject of intensive investigation since 1957 this paper describes patterns of sediment deposition and erosion drawing on field measurements in china at the sanmenxia guanting shanyiujiang and liujiaxia reservoirs as well as the shanshenggorig barrage and xijin hydropower station the longitudinal and lateral geometry of reservoir deltas is described it is shown that a marked change in grain size can occur at the downstream limit of the delta even when this limit is not apparent from geometry density current data for guanting reservoir are presented problems caused by reservoir sedimentation in china are described including aggredation in the backwater region causing increased flood levels elevated ground water levels and navigation impairment deposition from or into a tributary entry of sediments into hydropower turbines a

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

loess and floods high resolution multi proxy data of last glacial maximum lgm slackwater deposition in the flinders ranges semi arid south australia abstract terrace remnants of late pleistocene fine grained valley fill deposits silts deeply entrenched by ephemeral traction load streams in arid areas remain a puzzle they have been attributed to a variety of origins ranging from lacustrine to alluvial floodplains we here report a centimetre scale multi proxy study of a 7 m section of silts in the semi arid flinders ranges of south australia which span the lead up to and peak of the last glacial maximum lgm the results of detailed lithostratigraphic mapping high resolution parametric particle size analysis automated mineralogy induced magnetic susceptibility carbon stable isotope geochemistry and a chronostratigraphy based on 27 ams radiocarbon and 6 luminescence ages are discussed in terms of sediment provenance depositional environment and weathering history with the aim of reconstructing the regional palaeo environment the data are consistent with a fluctuating aeolian fluvial interplay dominating the extended lgm environment with a greater impact on the landscape than all combined geomorphic processes since then accordingly weathered slope mantles and loess accessions were eroded and entrained by numerous small and at least a dozen large scale flood events and trapped in an intra montane floodplain extending into brachina gorge upstream of this narrow constriction recurrent backflooding is discussed resulting in a thick sequence of layered to laminated slackwater couplets aggradation and degradation of valley fills appear to be largely controlled by fine sediment supply from the valley slopes replenished by wind blown dust from upwind playa lakes and source bordering dunefields in conclusion this study demonstrates how dust storms and flooding rains can account for pluvial features previously explained by the opposing effects of reduced precipitation and evaporation in the colder more arid glacial landscape of southern australia

finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

rupture kinematics of the 2005 mw 8 6 nias simeulue earthquake from the joint inversion of seismic and geodetic data the 2005 mw 8 6 nias simeulue earthquake was caused by rupture of a portion of the sunda megathrust offshore northern sumatra this event occurred within an array of continuous global positioning system gps stations and produced measurable vertical displacement of the fringing coral reefs above the fault rupture thus this earthquake provides a unique opportunity to assess the source character istics of a megathrust event from the joint analysis of seismic data and near field static co seismic displacements based on the excitation of the normal mode data and geodetic data we put relatively tight constraints on the seismic moment and the fault dip where the dip is determined to be 8 to 10 with corresponding moments of 1 24 10 22 to 1 00 10 22 n m respectively the geodetic constraints on slip distribution help to eliminate the trade off between rupture velocity and slip kine matics source models obtained from the inversion of various combinations of the teleseismic body waves and geodetic data are evaluated by comparing predicted and observed long period seismic waveforms 100 500 sec our results indicate a rela tively slow average rupture velocity of 1 5 to 2 5 km sec and long average rise time of up to 20 sec the earthquake nucleated between two separate slip patches one beneath nias and the other beneath simeulue island the gap between the two patches and the hypocentral location appears to be coincident with a local geological disrup tion of the forearc coseismic slip clearly tapers to zero before it reaches the trench probably because the rupture propagation was inhibited when it reached the accre tionary prism using the models from joint inversions we estimate the peak ground velocity on nias island to be about 30 cm sec an order of magnitude slower than for thrust events in continental areas this study emphasizes the importance of util izing multiple datasets in imaging seismic ruptures

joint earthquake source inversions using seismo geodesy and 3 d earth models a joint earthquake source inversion technique is presented that uses insar and long period teleseismic data and for the first time takes 3 d earth structure into account when modelling seismic surface and body waves ten average source parameters moment latitude longitude depth strike dip rake length width and slip are estimated hence the technique is potentially useful for rapid source inversions of moderate magnitude earthquakes using multiple data sets unwrapped interferograms and long period seismic data are jointly inverted for the location fault geometry and seismic moment using a hybrid downhill powell monte carlo algorithm while the insar data are modelled assuming a rectangular dislocation in a homogeneous halfspace seismic data are modelled using the spectral element method for a 3 d earth model the effect of noise and lateral heterogeneity on the inversions is investigated by carrying out realistic synthetic tests for various earthquakes with different faulting mechanisms and magnitude mw 6 0 6 6 synthetic tests highlight the improvement in the constraint of fault geometry strike dip and rake and moment when insar and seismic data are combined tests comparing the effect of using a 1 d or 3 d earth model show that long period surface waves are more sensitive than long period body waves to the change in earth model incorrect source parameters particularly incorrect fault dip angles can compensate for systematic errors in the assumed earth structure leading to an acceptable data fit despite large discrepancies in source parameters three real earthquakes are also investigated eureka valley california 1993 may 17 mw 6 0 aiquile bolivia 1998 february 22 mw 6 6 and zarand iran 2005 may 22 mw 6 5 these events are located in different tectonic environments and show large discrepancies between insar and seismically determined source models despite the 40 50 km discrepancies in location between previous geodetic and seismic estimates for the eureka valley and aiquile earthquakes the seismic data are found to be compatible with the insar location a 30 difference in strike between insar and seismic derived source models is also resolved when taking 3 d earth structure into account in the analysis of the eureka valley earthquake the combination of both insar and seismic data further constrains the dip for the zarand earthquake and in all cases the seismic moment is more robustly constrained in the joint inversions than in the individual data set inversions unmodelled lateral heterogeneities in earth and the models could partly explain some of the observed source parameter discrepancies related to the seismic data the authors 2014 published by oxford university press on behalf of the royal astronomical society

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

bayesian rupture imaging in a complex medium the 29 may 2012 emilia northern italy earthquake we develop a new approach to image earthquake rupture from strong motion data we use a large data set of aftershock waveforms interpolated over the seismic fault to obtain green s function approximations next we deploy a bayesian inversion method to characterize the slip distribution the rupture velocity the slip duration and their uncertainties induced by errors in the green s functions the method is applied to the 29 may 2012 mw 6 emilia earthquake which ruptured a fault buried below the po plain sediments northern italy despite the particularly complex wave propagation the near field strong motion observations are well reproduced with 15 rupture parameters the rupture and slip velocities were notably slow 0 5 vs and 0 5 m s respectively implying that the fault was difficult to break this method opens some perspectives for earthquake rupture studies in areas where numerical simulations suffer from imprecise knowledge of the velocity structure

aftershocks of the andreanof islands earthquake of june 10 1996 and local seismotectonics three questions have been addressed in connection with an mw 7 7 earthquake that occurred in the andreanof islands alaska on june 10 1996 first was there any variation in seismic activity rate during the previous five years that might have been diagnostic of the imminent occurrence of this event the answer based on the usgs pde catalog is no second though there were abundant pre event earthquakes and aftershocks on both sides of adak canyon why was there very little activity under the canyon itself a property that has been observed previously it is not possible to resolve the cause of the behavior with existing seismological data finally how does one explain the eastern group of aftershocks which fell within the zone of abundant aftershocks of the 1986 mw 8 andreanof islands earthquake when very little of the 1996 mainshock moment was released under or to the east of adak canyon one explanation of these aftershocks is that the recent aftershocks are late aftershocks of 1986 whose occurrence within a short time was induced by the stress pulse but not seismic slip from the 1996 earthquake though large earthquakes in the aleutians occur in distinct tectonic blocks the boundaries of these blocks may not always be defined reliably by aftershock zones

the enigma of a late pleistocene wetland in the flinders ranges south australia abstract lying in a semi arid region the flinders ranges have rocky weathering limited hillslopes and streams within the ranges are active only during rare downpours when they transport boulders gravel and coarse sand however silt and clay rich valley fill deposits incised by present streams occur as terraces and terrace remnants such deposits are not accumulating today in and upstream of brachina gorge in the central ranges these remnant valley fills are exposed in bank sections up to 18 m high at some localities exposures show horizontal centimetre scale beds of fine sand and clayey silt that can be traced for several hundred metres and contain gastropods diatoms and phytoliths consistent with sluggish shallow water flow under fresh to brackish conditions ams 14 c and osl dating shows that these valley fill deposits accumulated between 33 and 17 ka an interval that embraces the last glacial maximum lgm formerly thought to be lake beds aust j earth sci 46 1999 61 the valley fills are shown here to have accumulated in a fluvial wetland that extended westward from the middle reaches of brachina creek through brachina gorge and joined with aggraded fan deposits beyond the ranges aggradation of this wetland requires a substantial reduction of both rainfall variability and evaporation which would be favoured by the low temperatures and reduced incursions of summer rainfall this is consistent with climatic reconstructions by miller et al nature 385 1997 241 and johnson et al science 284 1999 1150 for lake eyre north of the flinders ranges at the lgm demise of the wetland was heralded by a major influx of coarse alluvium followed by channelling and dissection erosion was interrupted by an episode of aggradation and floodplain widening represented by remnants of a wide terrace inset below the primary wetland surface this episode which is interpreted as a return to lower climatic variability ceased with establishment of the present climatic regime which has resulted in stripping of the late pleistocene deposits from much of the brachina valley

an energy duration procedure for rapid determination of earthquake magnitude and tsunamigenic potential summary we introduce a rapid and robust energy duration procedure based on the haskell extended source model to obtain an earthquake moment and a moment magnitude med using seismograms at teleseismic distances 30 90 this procedure combines radiated seismic energy measures on the p to s interval of broadband signals and source duration measures on high frequency p wave signals the med energy duration magnitude is scaled to correspond to the global centroid moment tensor cmt moment magnitude mcmtw and can be calculated within about 20 min or less after origin time ot the measured energy and duration values also provide the energy to moment ratio used for identification of tsunami earthquakes the med magnitudes for a set of recent large earthquakes match closely mcmtw even for the largest great earthquakes these results imply that the med measure is accurate and does not saturate after the 2004 december 26 sumatra andaman mega thrust earthquake magnitude estimates available within 1 hr of ot ranged from m 8 0 to 8 5 the cmt magnitude available about 3 hr after ot was mcmtw 9 0 and several months after the event mw 9 1 9 3 was obtained from analysis of the earth normal modes the energy duration magnitude for this event is med 9 2 a measure that is potentially available within 20 min after ot after the 2006 july 17 java earthquake the magnitude was evaluated at m 7 2 at 17 min after ot the cmt magnitude available about 1 hr after ot was mcmtw 7 7 the energy duration results for this event give med 7 8 with a very long source duration of about 160 s and a very low value indicating a possible tsunami earthquake

sea level and climatic controls on turbidite occurrence for the past 26 kyr on the flank of the gaoping canyon off sw taiwan submarine canyons are major conduits for delivery of sediments originating from the continental margin into the deep sea here we analyze the effects of changing sea levels and climate e g sediment supply on the frequency of turbidites over the last 26 kyr our study is based on high resolution age controls for turbidites in core md178 10 3291 from a water depth of 2070 m on the flank of the gaoping canyon offshore in sw taiwan unlike most other submarine canyons worldwide the head of the gaoping canyon has remained connected to the river mouth during the recent flooding of the continental shelf our results reveal that turbidity currents are less frequent during periods of sea level lowstand in contrast turbidity currents have been more frequent since 12 kyr bp during the final stage of rising sea level and sea level highstands this may be the result of increased terrestrial sediment delivery due to enhanced rainfall intensity moreover comparing to other source to sink systems the turbidite occurrence in the flank of gaoping canyon through the last glacial cycle might have been more strongly influenced by climatic changes due to short sediment storage response time

the 1996 earthquakes in sulawesi indonesia we study the rupture process of the 1 january mw 7 9 16 july mw 6 6 and 22 mw 7 july 1996 earthquakes in sulawesi indonesia a teleseismic body waveform inversion of very broadband records shows that these events occurred beneath the accretionary prism the main shock was due to a well determined fault with a strike of 53 n and a very shallow dip of 7 from its source time function duration 30 sec and the aftershock distribution we estimate a rupture area of 90 60 km2 and an average slip of 1 80 m the surface displacement computed with our best model fits well the displacement vector at the only available gps station at tomini the tsunami generated by the mainshock had an approximate source radius of 45 km which roughly agrees with the rupture size estimated above the earthquakes took place in a relay zone between the trench and the palu koro transcurrent fault they ruptured a shallow dipping thrust fault which corresponds to the subduction interface under the north sulawesi arm the slip vectors of all the events have a nnw orientation parallel to the direction of convergence between the north sulawesi arm and the celebes sea among the peculiarities of the rupture process we found that the july 22 aftershock was the only event to have a well defined precursor 1 8 sec before the main p wave onset

effects of three dimensional earth structure on cmt earthquake parameters abstract we investigate errors in centroid earthquake parameters due to unmodeled structural heterogeneity we generate a simulated dataset consisting of synthetic seismograms for 50 earthquakes and 150 stations distributed globally to generate the synthetic seismograms we use a spectral element wave propagation package specfem3d globe that accounts for the earth s three dimensional structure an established centroid moment tensor inversion algorithm from the global cmt project is used to invert the synthetic dataset with and without added noise for earthquake source parameters this algorithm uses a one dimensional earth structure together with approximate corrections for three dimensional structure to model the seismograms we interpret the differences between the estimated source parameters and the parameters used to compute the synthetic dataset as errors due to unmodeled structural heterogeneity and the presence of noise we expect that the errors obtained in this study are representative of the errors in the global cmt catalogue we find that the errors in scalar moment moment tensor elements and location are small on average the depth and centroid time are however biased by a small amount we find that the error in depth can be reduced significantly by applying corrections for the difference in the velocity structure at the source and receiver locations from the earth s average structure in the cmt inversions this modification has a minimal effect on the errors in centroid time we do not find large errors in scalar moments even where the crustal thickness at the source is very different from the earth s average crustal thickness

supercycle at the ecuadorian subduction zone revealed after the 2016 pedernales earthquake large earthquakes are usually assumed to release all of the strain accumulated since the previous event implying a reduced seismic hazard after them however long records of seismic history at several subduction zones suggest supercycle behaviour where centuries long accumulated strain is released through clustered large earthquakes resulting in an extended period of enhanced seismic hazard here we combine historical seismology results present day geodesy data and dense local observations of the recent mw 7 8 2016 pedernales earthquake to reconstruct the strain budget at the ecuador subduction zone since the great 1906 earthquake we show that the pedernales earthquake involved the successive rupture of two patches on the plate interface that were locked prior to the earthquake and most probably overlaps the area already ruptured in 1942 by a similar earthquake however we find that coseismic slip in 2016 exceeds the deficit accumulated since 1942 the seismic moment of every large earthquake during the twentieth century further exceeds the moment deficit accumulated since 1906 these results together with the seismic quiescence before 1906 highlighted by historical records and marine palaeoseismology argue for an earthquake supercycle at the ecuador colombia margin this behaviour which has led to an enhanced seismic hazard for 110 years is possibly still going on and may apply to other subduction zones that recently experienced a great earthquake large earthquakes are often assumed to reset the seismic hazard of a region analysis of recent and historical seismicity in ecuador suggests that this region may experience clusters of large earthquakes and extended periods of high seismic hazard

experimental study of reservoir turbidity current a series of experiments were conducted in a flume to study the hydraulic characteristics of the turbidity current in a reservoir kaolin was used as the suspended material the plunge points were found to be unstable initially as the experiment went on it moved downstream from the incipient plunge location and finally reached a stable location the densimetric froude number of the incipient and the stable plunge points are approximately equal to 1 0 and 0 6 respectively it is found that the length of the plunge region is 15 times the water depth at the stable plunge point the volumetric flow rates in the plunge region increase 17 during the plunging process about 70 of the water discharge and 80 of the sediment discharge are confined to the denser layer a layer close to the channel bed with approximately constant concentration the thickness of the turbidity current increases while the layer averaged velocity and concentration decrease in the longitudinal direction the layer averaged velocity has the smallest variation rates equations for the dimensionless velocity and concentration profiles are obtained

back propagating super shear rupture in the 2016 mw7 1 romanche transform fault earthquake how an earthquake rupture propagates strongly influences the potentially destructive ground shaking complex ruptures often involve slip along multiple faults which masks information on the frictional behaviour of fault zones geometrically smooth ocean transform fault plate boundaries offer a favourable environment to study fault dynamics because strain is accommodated along a single wide fault zone that offsets the homogeneous geology here we present an analysis of the 2016 mw 7 1 earthquake on the romanche fracture zone in the equatorial atlantic using data from both nearby seafloor seismometers and global seismic networks we show that this rupture had two phases 1 upward and eastward propagation towards a weaker region where the transform fault intersects the mid ocean ridge and then 2 an unusual back propagation westwards at a supershear speed towards the centre of the fault we suggest that deep rupture into weak fault segments facilitated greater seismic slip on shallow locked zones this highlights that even earthquakes along a single distinct fault zone can be highly dynamic observations of back propagating ruptures are sparse and the possibility of reverse propagation is largely absent in rupture simulations and unaccounted for in hazard assessments in one earthquake an oceanic transform fault ruptured in one direction and then backwards at a speed exceeding that of shear wave propagation according to an analysis of data recorded by nearby seafloor and global seismometers

fault process and broadband ground motion simulations of the 23 october 2011 van eastern turkey earthquake abstract on 23 october 2011 an m w 7 1 earthquake occurred in eastern turkey close to the towns of van and ercis causing more than 600 casualties and widespread structural damage the earthquake ruptured a 60 70 km long northeast southwest fault with a thrust mechanism in agreement with regional tectonic stress regime we studied the fault process of the event and the recorded ground motions using different sets of data regional records 0 005 0 010 hz are used to constrain the centroid moment tensor solution near regional data 100 200 km from the fault are used for relocation of the hypocenter and in the frequency range 0 05 0 15 hz for inversion of the rupture propagation by two methods multiple point source model isola and multiple finite extent mufex source model mufex also provides an estimate of the model uncertainty which is quite large due to unfavorable station distribution we arrive at several plausible scenarios equally well fitting the observed data including global positioning system coseismic displacements with different styles of the rupture propagation a few alternative source models are used for broadband 0 1 10 hz ground motion simulations by means of the hybrid integral composite source model only models comprising source complexities such as a delayed rupture of shallow asperities enable explanation of the acceleration record at the only available near fault station which exhibits a long duration and two prominent wave groups these complex rupture models are used to simulate the ground motion in the near fault area specifically at van and ercis where records of the mainshock were missing providing reasonable agreement with the observed spatial distribution of damage

co and postseismic deformation of the 28 march 2005 nias mw 8 7 earthquake from continuous gps data 1 global positioning system gps measurements registered up to 5m of coseismic displacements during the 28 march 2005 mw 8 7 nias earthquake indonesia the vertical offsets put tight constraints on the northern and southern limit of the rupture the inferred coseismic slip distribution indicates high slip patches near the epicenter and near the southern extent of the 26 december 2004 aceh andaman rupture where aftershocks have been abundant six months of postseismic time series are better fit with a logarithmic instead of exponential function suggesting that the postseismic deformation is likely controlled by afterslip our inversion model predicts afterslip to be concentrated both up and down dip from patches of maximum coseismic slip where aftershocks are sparse the shallow afterslip adds further evidence that the earthquake probably did not break the surface with implications for tsunami generation and instead caused aseismic deformation in shallow parts of the subduction zone after the event

compatibility of reservoir sediment flushing and river protection in this paper we propose a system of numerical models for the compatibility assessment of reservoir sediment flushing and protection of downstream river environments the model system is made up of two simulation models the first model simulates soil erosion in watershed slopes and sediment transport in the tributary of the reservoir by means of a weighted essentially nonoscillatory weno method which is conservative and fourth order accurate in space and time the second model simulates velocity and suspended solid concentration fields in the reservoirs this model is based on the three dimensional 3d numerical integration of motion and concentration equations expressed in contravariant form on a generalized boundary conforming curvilinear coordinate system by using a conservative and higher order accurate numerical scheme the proposed system of models is applied to the pieve di cadore veneto italy reservoir and to its catchment area by comparing suspended solid concentrations that are discha

source inversion of w phase speeding up seismic tsunami warning w phase is a long period phase arriving before s wave it can be interpreted as superposition of the fundamental first second and third overtones of spheroidal modes or rayleigh waves and has a group velocity from 4 5 to 9 km s 1 over a period range of 100 1000 s the amplitude of long period waves better represents the tsunami potential of an earthquake because of the fast group velocity of w phase most of w phase energy is contained within a short time window after the arrival of the p wave at a distance of 50 w phase energy is contained within 23 min after the origin time which is the distinct advantage of using w phase for rapid tsunami warning purposes we use a time domain deconvolution method to extract w phases from the broad band records of global seismic networks the bandwidth of w phase is approximately from 0 001 to 0 01 hz and we bandpass filter the data from 0 001 to 0 005 hz in most cases having extracted w phase from the vertical component records we perform a linear inversion using a point source to determine mw and the source mechanism for several large earthquakes including the 2004 sumatra andaman earthquake the 2005 nias earthquake the 2006 kuril is earthquake and the 2007 sumatra earthquake w phase inversion yields reliable solutions and holds promise of the use of w phase for rapid assessment of tsunami potential

seismology energy radiation from the sumatra earthquake we determined the duration of high frequency energy radiation from indonesia s great sumatra andaman earthquake 26 december 2004 to be about 500 seconds this duration can be translated into a rupture length of about 1 200 km which is more than twice as long as that inferred from body wave analyses performed soon after the event our analysis was able rapidly to define the extent of rupture thereby aiding the assessment of seismic hazard in the immediate future

the timing of linear dune activity in the strzelecki and tirari deserts australia abstract linear dunes occupy more than one third of the australian continent but the timing of their formation is poorly understood in this study we collected 82 samples from 26 sites across the strzelecki and tirari deserts in the driest part of central australia to provide an optically stimulated luminescence chronology for these dunefields the dunes preserve up to four stratigraphic horizons bounded by palaeosols which represent evidence for multiple periods of reactivation punctuated by episodes of increased environmental stability dune activity took place in episodes around 73 66 35 32 22 18 and 14 10 ka intermittent partial mobilisation persisted at other times throughout the last 75 ka and dune activity appears to have intensified during the late holocene dune construction occurred when sediment was available for aeolian transport in the strzelecki and tirari deserts this coincided with cold arid conditions during marine isotope stage mis 4 late mis 3 and mis 2 and the warm dry climates of the late pleistocene holocene transition period and late holocene localised influxes of sediment on active floodplains and lake floors during the relatively more humid periods of mis 5 also resulted in dune formation the timing of widespread dune reactivation coincided with glaciation in southeastern australia along with cooler temperatures in the adjacent oceans and antarctica

rapid estimation of rupture extent for large earthquakes application to the 2004 m9 sumatra andaman mega thrust 1 rapid estimation of the rupture extent of large earthquakes is critical for tsunami warning and emergency response the hypocenter of a distant earthquake is determined from the first seismic p waves within about 15 minutes after the event however methods for determining the size and rupture extent of very large earthquakes rely on long period recordings and aftershock locations which are not available until several hours or more after the event here we introduce a method for rapid estimation of the rupture termination location for large earthquakes based on short period p wave recordings available about 30 minutes after an event the hypocenter and the rupture termination location provide estimates of the extent of rupture and the event size application to the 2004 m9 sumatra andaman earthquake gives a rupture termination location near the andaman islands about 1100 km north of the hypocenter and a rupture duration of about 8 minutes

fault slip distribution of the 1995 colima jalisco mexico earthquake abstract broadband teleseismic p waves have been analyzed to recover the rupture history of the large m s 7 4 colima jalisco mexico shallow interplate thrust earthquake of 9 october 1995 ground displacement records in the period range of 1 60 sec are inverted using a linear finite fault waveform inversion procedure that allows a variable dislocation duration on a prescribed fault the method is applied using both a narrow fault that simulates a line source with a dislocation window of 50 sec and a wide fault with a possible rise time of up to 20 sec that additionally allows slip updip and downdip from the hypocenter the line source analysis provides a spatio temporal image of the slip distribution consisting of several large sources located northwest of the hypocenter and spanning a range of rupture velocities the two dimensional finite fault inversion allows slip over this rupture velocity range and indicates that the greatest coseismic displacement 3 4 m is located between 70 and 130 km from the hypocenter at depths shallower than about 15 km slip in this shallow region consists of two major sources one of which is delayed by about 10 sec relative to a coherent propagation of rupture along the plate interface these two slip sources account for about one third of the total p wave seismic moment of 8 3 10 27 dyne cm m w 7 9 and may have been responsible for the local tsunami observed along the coast following the earthquake

tufas and travertines of the mediterranean region a testing ground for freshwater carbonate concepts and developments actively forming travertine and tufa sites are widespread in temperate and warm climates such as the mediterranean region but also develop in other climatic regimes from the arctic to equatorial latitudes the terms travertine and tufa are sometimes applied indiscriminately today however each has a specific definition most studied deposits are active or of quaternary especially holocene age there are fewer tertiary and even less late mesozoic examples on record in part this is because of a recognition problem as these deposits commonly preserve as fragmentary erosional remnants physico chemical precipitation of calcium carbonate is commonly considered to be the main mechanism contributing to tufa and travertine deposition rapid cooling of waters further aids the process in thermal travertine sites however biomediation of calcium carbonate associated with prokaryote microphyte biofilms is now recognized to be equally important in slow flowing and near static sites much of this precipitation occurs in close association with cyanobacterial heterotrophic bacterial and diatoms the mediterranean region figures significantly in the development of travertine and tufa research consequently this article employs key literature on mediterranean examples to illustrate developments and concepts in freshwater carbonate research modern work started in the 1950s and defined many previously unknown outcrops many such sites became the targets for early radiocarbon dating studies since the late 1970s a number of laboratory based and field based classification schemes have been proposed some schemes were based on associated macrovegetation types others were based on petrological characteristics or on geometry and sedimentary facies characteristics of late the sedimentological modelling has benefited greatly from the use of shallow geophysical techniques in order to better define the internal geometries of the deposits two distinct research strands were developed during the 1990s both aimed at a better understanding of environmental change the first considered biocomponents the research was multifaceted and ranged from exploring the role of micro organisms in cement and lime mud precipitation to biostratigraphic analysis of contained pollen and invertebrate remains these provided proxy environmental information which has helped to define past climate variability in the region the second research strand focussed on geochemical signatures as a proxy tool for defining environmental change this definition was made possible by new petrological studies which have greatly aided the recognition of primary depositional fabrics this improved knowledge has reduced the sampling dangers of diagenetic contamination inherent in earlier geochemical studies lithofacies modelling has also brought to light important early post depositional neomorphic changes which obscure primary fabrics and complex diagenetic histories have been revealed stable isotope signatures of carbon and oxygen have also been used to define palaeo water temperature fine tuning of depositional time frames has also been achieved from absolute dating techniques employing radiocarbon and uranium thorium

the june 23 2001 peru earthquake and the southern peru subduction zone 1 the plate boundary between the south american and nazca plate along the south central peru coast has been the site of large destructive earthquakes for many centuries including the june 23 2001 mw 8 4 event this underthrusting event has a fault area of 320 km by 100 km based on relocated aftershocks during the first three weeks following the mainshock modeling of the teleseismic broadband p waves of the 2001 peru earthquake indicates two pulses of moment release with the larger second pulse located 130 km southeast of the mainshock initiation indicating a unilateral rupture to the southeast based on intensity and tsunami reports previous earthquakes in 1868 and 1604 were larger than the 2001 earthquake while an event in 1784 was smaller this provides further evidence that the size of earthquakes along the peru coast has changed between successive earthquake cycles

refined rupture velocity estimation of the 2009 l aquila earthquake mw 6 3 central italy derived from apparent source time functions in this paper we obtain an accurate estimation of the rupture velocity of the 6 april 2009 mw 6 3 l aquila earthquake central apennines by analyzing its apparent source time functions astfs these astfs have been extracted by deconvolv ing an empirical green s function egf at seismic stations located 200 800 km from the earthquake from the study of duration shape and directivity of astfs at numerous and well distributed stations we show that the area between the two main slip patches of the earthquake ruptured at a relatively slow velocity 1 6 km s we next validate simulta neously the astfs and the slip model independently obtained through the joint inversion of strong motion broadband teleseismic global positioning system and interferometric synthetic aperture radar data the good agreement in shape and duration between the observed and theoretical astfs is an indication for the reliability of the inferred source model and for the robustness of the rupture velocity estimations of this study

a great earthquake rupture across a rapidly evolving three plate boundary on 1 april 2007 a great tsunamigenic earthquake moment magnitude 8 1 ruptured the solomon islands subduction zone at the triple junction where the australia and solomon sea woodlark basin plates simultaneously underthrust the pacific plate with different slip directions the associated abrupt change in slip direction during the great earthquake drove convergent anelastic deformation of the upper pacific plate which generated localized uplift in the forearc above the subducting simbo fault potentially amplifying local tsunami amplitude elastic deformation during the seismic cycle appears to be primarily accommodated by the overriding pacific forearc this earthquake demonstrates the seismogenic potential of extremely young subducting oceanic lithosphere the ability of ruptures to traverse substantial geologic boundaries and the consequences of complex coseismic slip for uplift and tsunamigenesis

modeling the rupture process of the 2003 september 25 tokachi oki hokkaido earthquake using 1 hz gps data received 10 september 2004 accepted 3 october 2004 published 3 november 2004 1 high rategpshasthepotentialtorecoverbothdynamic and static displacements accurately we analyze 1 hz gps data recorded during the 2003 tokachi oki earthquake the 1 hz gps displacement waveforms show good agreement with integrated accelerometer records except for low frequency noise that are inherently present in integrated seismic records the gps waveforms were inverted to model the spatio temporal evolution of the fault slip during the rupture the slip is found to propagate downdip in the subduction zone with largest moment release 50 km northwest of the hypocenter the region of largest slip agrees in general with traditional seismic studies indicating that 1 hz gps can be used for finite fault studies the 1 hz gps slip model shows clearer contrast with afterslip distributions than those inferred from strong motion data possibly because 1 hz gps is more sensitive to cumulative slip distribution index terms 1294 geodesy and gravity instruments and techniques 7209 seismology earthquake dynamics and mechanics 7212 seismology earthquake ground motions and engineering citation miyazaki s k m larson k choi k hikima k koketsu p bodin j haase g emore and a yamagiwa 2004 modeling the rupture process of the 2003 september 25 tokachi oki hokkaido earthquake using 1 hz gps data geophys res lett 31 l21603 doi 10 1029 2004gl021457

sediment transport dynamics near a river inflow in a large alpine lake sediment dynamics were investigated in lake maggiore italy with field observations from october to mid december 2012 three moorings were deployed in pallanza bay a small embayment on the western side of the lake near the toce river inflow to measure temperature and currents throughout the water column and suspended sediment concentration ssc was estimated with acoustic instrumentation river intrusions are shown to dominate observed ssc although a small amount of sediment resuspension was observed at the site of the shallowest mooring during a large wind event that produced strong upwelling of the thermocline followed by downwelling although vertical turbulent sediment flux is typically assumed to indicate resuspension and the upward transport of sediment w c 0 downward turbulent sediment flux was observed w c 0 near the bed during the largest observed intrusion event the downward turbulent sediment flux significantly contributes to net deposition rates which are one order of magnitude larger than rates of erosion measured during the two major events observed horizontal transport of sediment occurs in vertically confined layers due to buoyancy driven intrusions beneath the intrusions sediment settles out of the water column at settling rates that appear to be constant with depth based on acoustic doppler current profiler backscatter measurements the effective settling velocities needed to produce the observed vertical transport of ssc during an inflow intrusion are one order of magnitude larger than those due to the stokes settling velocity ws alone particle flocculation and possible convective instabilities may play a role in generating the large observed effective settling rates

observation and simulation of floodwater intrusion and sedimentation in the shichikashuku reservoir wash load sedimentation during flood events is studied through comprehensive field measurements at the shichikashuku reservoir japan and numerical simulation field data during a flooding event caused by a typhoon in 1996 are used to set the boundary conditions for the model and to verify the simulation in the field experiments continuous monitoring of inflow turbidity is shown to be an effective and reliable means of estimating sediment influx in the simulations the proposed model is shown to provide an accurate reproduction of floodwater currents and sedimentation in the reservoir the model achieves good accuracy and resolution by adopting an orthogonal curvilinear grid to discretize the reservoir and by solving the flow field using a three dimensional standard k e turbulence model the simulation reproduces the observed velocity turbidity and distribution of sedimentation well demonstrating the potential utility of such models in the management of reservoir water quality and sedimentation

global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity abstract application of the scardec method provides the apparent source time functions together with seismic moment depth and focal mechanism for most of the recent earthquakes with magnitude larger than 5 6 6 using this large dataset we have developed a method to systematically invert for the rupture direction and average rupture velocity v r when unilateral rupture propagation dominates the approach is applied to all the shallow z

redshift of earthquakes via focused blind deconvolution of teleseisms we thank the editor prof huajian yao and reviewers jiuxun yin and anonymous for providing their valuable feedback we thank our colleagues nafi toks oz matt li aurelien mordret tom herring hongjian fang and michael floyd for providing insight and expertise that greatly assisted this research we thank martin mai from king abdullah university of science and technology for his informative commentary of a draft version the material is based upon work assisted by a grant from equinor any opinions findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of equinor ld is also supported by afosr grant fa9550 17 1 0316

the 2015 mw 7 1 earthquake on the charlie gibbs transform fault repeating earthquakes and multimodal slip on a slow oceanic transform the 2015 mw 7 1 earthquake on the charlie gibbs transform fault along the mid atlantic ridge is the latest in a series of seven large earthquakes since 1923 we propose that these earthquakes form a pair of quasi repeating sequences with the largest magnitudes and longest repeat times for such sequences observed to date we model teleseismic body waves and find that the 2015 earthquake ruptured a distinct segment of the transform from the previous 1998 earthquake the two events display similarities to earthquakes in 1974 and 1967 respectively we observe large oceanic transform earthquakes to exhibit characteristic slip behavior initiating with small slip near the ridge and propagating unilaterally to significant slip asperities nearer the center of the transform these slip distributions combined with apparent segmentation support multimode slip behavior with fault slip accommodated both seismically during large earthquakes and aseismically in between

rupture process of large earthquakes in the northern mexico subduction zone the cocos plate subducts beneath north america at the mexico trench the northernmost segment of this trench between the orozco and rivera fracture zones has ruptured in a sequence of five large earthquakes from 1973 to 1985 the jan 30 1973 colima event m s 7 5 at the northern end of the segment near rivera fracture zone the mar 14 1979 petatlan event m s 7 6 at the southern end of the segment on the orozco fracture zone the oct 25 1981 playa azul event m s 7 3 in the middle of the michoacan gap the sept 19 1985 michoacan mainshock m s 8 1 and the sept 21 1985 michoacan aftershock m s 7 6 that reruptured part of the petatlan zone body wave inversion for the rupture process of these earthquakes finds the best earthquake depth focal mechanism overall source time function and seismic moment for each earthquake in addition we have determined spatial concentrations of seismic moment release for the colima earthquake and the michoacan mainshock and aftershock these spatial concentrations of slip are interpreted as asperities and the resultant asperity distribution for mexico is compared to other subduction zones the body wave inversion technique also determines the moment tensor rate functions but there is no evidence for statistically significant changes in the moment tensor during rupture for any of the five earthquakes an appendix describes the moment tensor rate functions methodology in detail

rapid determination of mw from broadband p waveforms we analyze broadband seismograms for magnitude 5 to 7 earthquakes which occurred in and around japan to develop a technique to determine moment magnitude from first arrival p waveforms we theoretically consider displacements of the p wave portion on broadband seismograph record as an approximate source time function and integrate them to obtain scalar moments at each station we show that a combination of multiple records will give a good estimation of moment magnitude without correcting for the source mechanism this technique is quite simple and robust so it will be effective for a rapid evaluation of the tsunami potential of a large earthquake

a new procedure for gridding elevation and stream line data with automatic removal of spurious pits abstract a morphological approach to the interpolation of regular grid digital elevation models dems from surface specific elevation data points and selected stream lines is described the approach has given rise to a computationally efficient interpolation procedure which couples the minimization of a terrain specific roughness penalty with an automatic drainage enforcement algorithm the drainage enforcement algorithm removes spurious sinks or pits yielding dems which may be used to advantage in hydrological process studies the drainage enforcement algorithm has also been found to significantly increase the accuracy of dems interpolated from sparse but well chosen surface specific elevation data moreover it facilitates the detection of errors in elevation data that would not be detected by more conventional statistical means and forms a sound physical basis for cartographic generalization

near synchronous interhemispheric termination of the last glacial maximum in mid latitudes isotopic records from polar ice cores imply globally asynchronous warming at the end of the last glaciation however 10be exposure dates show that large scale retreat of mid latitude last glacial maximum glaciers commenced at about the same time in both hemispheres the timing of retreat is consistent with the onset of temperature and atmospheric co2 increases in antarctic ice cores we suggest that a global trend of rising summer temperatures at the end of the last glacial maximum was obscured in north atlantic regions by hypercold winters associated with unusually extensive winter sea ice

three dimensional modeling of turbid density currents in imha reservoir south korea abstractthe propagation dynamics of the turbid density currents of the imha reservoir is investigated using the flow 3d computational fluid dynamics code the renormalization group rng e turbulence scheme in a reynolds averaged navier stokes rans framework was applied for the field investigation a new particle dynamics algorithm was developed and coupled with the flow 3d model to simulate the settling of sediment particles and the model was tested with field measurements during typhoon ewiniar the coupled model correctly predicted the spatial and temporal evolution of intrusive density currents with plunging flows at a depth of 20 m and interflows propagating downstream at about 0 2 m s the simulation results with sediment settling demonstrated that the ratio of transported to initial sediment concentration c0 ci varies as a function of particle size ds and sediment concentration density currents can be classified into three regimes 1 a suspended regime ds 10 m where interflows will

a mixed seismic aseismic stress release episode in the andean subduction zone in subduction zones stress is released by earthquakes and transient aseismic slip the latter falls into two categories slow slip and afterslip slow slip events emerge spontaneously during the interseismic phase and show a progressive acceleration of slip with a negligible contribution of synchronous tremors or microseismicity to the energy or moment release1 2 3 4 5 6 7 8 9 10 11 12 in contrast afterslip occurs immediately after large and moderate earthquakes decelerates over time and releases between 20 and 400 of the moment released by the preceding earthquake13 14 15 16 17 18 here we use seismic and gps data to identify transient aseismic slip that does not fit into either of these categories we document a seismic aseismic slip sequence which occurred at shallow depths along a weakly coupled part of the andean subduction zone19 in northern peru and lasted seven months the sequence generated several moderate earthquakes that together account for about 25 of the total moment released during the full sequence equivalent to magnitude 6 7 transient slip immediately followed two of the earthquakes with slip slowing at a logarithmic rate considered separately the moment released by transient slip following the second earthquake was more than 1 000 of the moment released during the earthquake itself a value incompatible with classical models of afterslip synchronous seismic swarms and aseismic slip may therefore define a stress release process that is distinct from slow slip events and afterslip

geomorphic changes leading to natural desertification versus anthropogenic land conservation in an arid environment the negev highlands israel the negev highlands in southern israel are currently under an erosive regime causing degradation of soil and vegetation a process which has often been attributed to land mismanagement and overgrazing caused by the local bedouin population to estimate the anthropogenic role in the erosional processes in the negev highlands two similar drainage basins were selected and studied one undisturbed with almost no human impact and the other with intensive human modification including the establishment of roman to early islamic agriculture field observations and luminescence dating indicate that during the late pleistocene glacial period ois 4 and 3 deposition of fluvio loess sediments with minor erosion cycles occurred in the negev highlands severe erosion started during ois 2 and continued into the holocene as the climate shifted during the termination of the pleistocene to the present interglacial phase higher rain intensity generated the incision of gullies and channels into the fine grained alluvial sediments of the previous phase causing extended soil erosion and reducing the natural biomass and the agricultural potential establishment of runoff harvesting farms in the 3rd century interrupted the holocene natural erosion and gully incision and led to the redeposition of up to 3 5 m of fine alluvial loess sediments originating from late pleistocene loess sections this accumulation is not related to any late holocene pluvial climatic phase and is solely the result of farming we conclude that since the end of the pleistocene a dynamic change in the soil rock ratio related to the long term process of adjustment of the geomorphologic system to the holocene climate has been taking place within the drainage basins in the negev highlands the fluvio loess sediments deposited in the region during ois 4 and 3 have been eroding since the latest pleistocene throughout the holocene this process causes degradation of the biomass and agricultural potential and leads onto natural desertification of the region the historical intervention by establishment of runoff harvesting agriculture which as a by product resulted in the accumulation of redeposited loess sediments counteracted the natural trend of soil erosion this was in fact a land conservation act applied by the ancient farmers in the semi arid regions of the middle east deserts this activity and its geomorphic consequences are in contrast to the well documented land degradation trend generated by recent anthropogenic impact on marginal lands elsewhere in any case the human impact either contributing to land degradation or to soil conservation is super imposed on the natural long term trend leading toward desertification

the 13 january 2001 el salvador earthquake a multidata analysis 1 on 13 january 2001 a large normal faulting intermediate depth event mw 7 7 occurred 40 km off the el salvadorian coast central america we analyze this earthquake using teleseismic regional and local data we first build a kinematic source model by simultaneously inverting p and sh displacement waveforms and source time functions derived from surface waves using an empirical green s function analysis in an attempt to discriminate between the two nodal planes 30 trenchward dipping and 60 landward dipping we perform identical inversions using both possible fault planes after relocating the hypocentral depth at 54 km we retrieve the kinematic features of the rupture using a combination of the neighborhood algorithm of sambridge 1999 and the simplex method allowing for variable rupture velocity and slip we find updip rupture propagation yielding a centroid depth around 47 km for both assumed fault planes with a larger variance reduction obtained using the 60 landward dipping nodal plane we test the two possible fault models using regional broadband data and near field accelerograms provided by universidad centro americana 2001 near field data confirm that the steeper landward dipping nodal plane is preferred rupture propagated mostly updip and to the northwest resulting in a main moment release zone of approximately 25 km 50 km with an average slip of 3 5 m the large slip occurs near the interplate interface at a location where the slab steepens dip significantly the occurrence of this event is well explained by bending of the subducting plate

interactions between fluvial and eolian geomorphic systems and processes examples from the sahara and australia abstract the remains of once integrated drainage systems are still discernible in many of the hot deserts of the world some of these date back to the mesozoic as in arid western australia where they now form chains of salt lakes others were active in miocene times such as the sahabi rivers that once flowed from chad to the mediterranean a few remained active during quaternary interglacials as in the sahara all contributed sediments that were reworked by wind during drier phases to form desert dunes the desert dunes of australia and of the 9500 km long chain of deserts extending from the sahara through arabia to the thar desert of india originated from sediments eroded from the uplands and deposited in closed interior basins formed during the course of late mesozoic and cenozoic faulting rifting and epeirogenic movements it was the unconsolidated neogene sediments laid down in large subsiding sedimentary basins such as the kufra sirte basin in libya and the chad basin which provided the source material for the late pliocene and quaternary desert dunes of the sahara one effect of the progressive build up of high latitude ice sheets during the neogene was to steepen the temperature and pressure gradients between the equator and the poles resulting in increased trade wind velocities stronger winds were better able to mobilize the alluvial sands of the increasingly dry sahara and adjacent deserts and to fashion them into desert dunes a more subtle form of interaction between eolian and fluvial processes concerns the interplay between desert dust loess accumulation on hill slopes in arid regions and the onset of fine grained valley fill accumulation by sluggish low energy streams in mountain valleys some of these late pleistocene wetlands served as refuge areas for plants reptiles and invertebrates at a time when the surrounding desert plains were very cold and dry as in the flinders ranges of south australia in the arid flinders ranges such valley fills were built up between 35 kyr and 15 kyr ago after which the return of the summer monsoon led to stream channel incision and the formation of a network of gullies often erroneously attributed to human activities understanding the causes of such accelerated erosion can prevent unnecessary and expensive attempts at restoration since the latter are based on the incorrect assumption that overgrazing and present day land use are responsible

environmental processes of the ice age land oceans glaciers epilog knowledge of the state of the earth at the last glacial maximum lgm an interval around 21 000 years ago is an important benchmark for understanding the sensitivity of global environmental systems to change much progress in understanding climates of the lgm has occurred in the 20 years since the end of the climap project of the 1970s climate long range investigation mapping and prediction here we review this progress based on presentations and discussion at a rst open science meeting of the epilog project environmental processes of the ice age land oceans glaciers held in delmenhorst germany may 1999 we outline key controversies and document protocols for epilog contributions so that a new synthesis of the lgm earth can emerge as an open project of the world s community of scientists 2001 elsevier science ltd all rights reserved

of droughts and flooding rains an alluvial loess record from central south australia spanning the last glacial cycle david haberlah peter glasby martin a j williams steven m hill frances williams edward j rhodes victor gostin anthony o flaherty and geraldine e jacobsen

partial rupture of a locked patch of the sumatra megathrust during the 2007 earthquake sequence the great sumatra andaman earthquake and tsunami of 2004 was a dramatic reminder of the importance of understanding the seismic and tsunami hazards of subduction zones 1 2 3 4 in march 2005 the sunda megathrust ruptured again producing an event 5 of moment magnitude mw 8 6 south of the 2004 rupture area which was the site of a similar event in 1861 ref 6 concern was then focused on the mentawai area where large earthquakes had occurred in 1797 mw 8 8 and 1833 mw 9 0 6 7 two earthquakes one of mw 8 4 and twelve hours later one of mw 7 9 indeed occurred there on 12 september 2007 here we show that these earthquakes ruptured only a fraction of the area ruptured in 1833 and consist of distinct asperities within a patch of the megathrust that had remained locked in the interseismic period this indicates that the same portion of a megathrust can rupture in different patterns depending on whether asperities break as isolated seismic events or cooperate to produce a larger rupture this variability probably arises from the influence of non permanent barriers zones with locally lower pre stress due to the past earthquakes the stress state of the portion of the sunda megathrust that had ruptured in 1833 and 1797 was probably not adequate for the development of a single large rupture in 2007 the moment released in 2007 amounts to only a fraction both of that released in 1833 and of the deficit of moment that had accumulated as a result of interseismic strain since 1833 the potential for a large megathrust event in the mentawai area thus remains large

scaling analysis of multipulsed turbidity current evolution with application to turbidite interpretation deposits of submarine turbidity currents turbidites commonly exhibit upward fining grain size profiles reflecting deposition under waning flow conditions however more complex grading patterns such as multiple cycles of inverse to normal grading are also seen and interpreted as recording deposition under cycles of waxing and waning flow such flows are termed multipulsed turbidity currents and their deposits pulsed or multipulsed turbidites pulsing may arise at flow initiation or following downstream flow combination prior work has shown that individual pulses within multipulsed flows are advected forward and merge such that complex longitudinal velocity profiles eventually become monotonically varying although transition length scales in natural settings could not be predicted here we detail the first high frequency spatial vertical streamwise and temporal measurements of flow velocity and density distribution in multipulsed gravity current experiments the data support both a process explanation of pulse merging and a phase space analysis of transition length scales in prototype systems the point of merging corresponds to the transition in any deposit from multipulsed to normally graded turbidites the scaling analysis is limited to quasi horizontal natural settings in which multipulsed flows are generated by sequences of relatively short sediment failures 10 km sequences of breaches or where pulsing arises from combination at confluences of single pulsed flows such flows may be responsible for the pulsing signatures seen in some distal turbidites 100 km from source

late quaternary lake level changes and climates of australia abstract spatial and temporal patterns in lake level data from 38 sites in australia and papua new guinea provide a basis for reconstructing changes in water balance and atmospheric circulation during the past 30 000 years the reconstructions are consistent with hydrological changes inferred from pollen analysis and palaeowind directions inferred from dunes generally wetter conditions between 30 000 and 24 000 bp are consistent with a strong walker circulation with the sta near its present position general aridity at the glacial maximum until 12 000 bp with higher than present lake levels in the southeastern interior of australia implies that the southern margin of the subtropical anticyclone belt was expanded southward and the southern westerlies were correspondingly displaced this southward shift appears in all gcm simulations of the 18 000 bp climate and may be a result of the increased vigour of the northern hemisphere circulation a northward migration of the belt of high lake levels between 11 000 and 6000 bp suggests that the sta shifted back equatorward to north of its present position relaxation to modern conditions occurred after 6000 bp interrupted by an unexplained dry phase 6000 5000 bp in tasmania and queensland

relationships between desert dunes during the late quaternary in the lake frome region strzelecki desert australia transverse and linear dunes near the ephemeral lake frome in the strzelecki desert of australia provide evidence for a genetic geomorphic relationship between desert dune types transverse dunes overlying palaeoshorelines lie upwind from linear dunes the sedimentology of both dune types is similar suggesting reworking or downwind transport of the same source material over time clay pellets from several horizons within the linear and transverse dunes provide evidence for fluctuating water tables and high evaporation rates during those periods of aeolian activity along with saltinflux associatedwith thedeflation oflakefrome weconclude thatthe nature andinitiation of dune activity is controlled not only by aridity but by local hydrology osl ages from both transverse and linear dunes indicate aeolian activity at 66 57ka and 22 11ka transverse dune building took place around 106 111ka linear dune activity initiated at least 66ka ago with reactivation around 43 28ka followed by pedogenesis in response to humid conditions widespread dune reactivation from around 22ka correlates broadly with the last glacial maximum and late glacial period consistent with evidence of cold arid conditions and dune activity in australia copyright 2007 john wiley sons ltd

fast and accurate depth and source mechanism estimation using p waveform modeling a tool for special event analysis event screening and regional calibration we have developed validated and applied a fast and accurate interactive easy to use tool for estimating seismic event depth and mechanism by modeling the initial p wave bundle significant features of this tool include its applicability over a broad band of frequencies f 2 hz and magnitudes mb 4 5 its ability to provide accurate high resolution depth estimates and its ability to provide constraints on event mechanism including isotropic contributions it also provides estimates of random and model errors and can be used to test hypotheses and investigate sensitivity to and trade offs between model parameters we validated this tool and its algorithms by showing that our estimated depths and mechanisms are in excellent agreement with ground truth depths and mechanisms based on local and regional data we find that depth can usually be estimated to an accuracy of a few km with a small number of stations although complete mechanisms are sometimes poorly resolved we find that two out of three of the mechanism parameters strike dip rake are usually well constrained we illustrate the potential of this technique for regional calibration special event analysis and event screening by comparing estimated depths and mechanisms of events in the middle east and north africa with those of the national earthquake information center neic and by comparing our depth and mechanism estimates for the may 11 1998 india nuclear explosion and a november 8 1991 earthquake that occurred in the same region

changes in vegetation and seasonal climate since the last full glacial at lake frome south australia abstract results are presented from stratigraphy radiocarbon and pollen analysis from lake frome south australia close to the summer winter rainfall boundary at 30 south latitude the pollen sequence shows that tree vegetation was minor around 18 000 yr b p the landscape was dominated by chenopod low shrublands and ephemeral tubuliflorae vegetation by 17 000 yr b p callitris moved in and rose to 25 of the pollen sum values of casuarina myrtaceous shrubs acacia dodonaea and cyperaceae also rose at about the same time between 17 000 and 14 500 yr b p callitris and eucalyptus dominated the tree vegetation with callitris reaching its maximum values eucalpt woodlands were associated with undershrubs belonging to myrtaceae acacia dodonaea and gyrostemonaceae whereas callitris woodlands had probably supported only a sparse understorey chenopodiaceae today distributed mainly in the winter rainfall zone continued to show high values 25 gramineae today associated with high summer rainfall generally remained below 20 the sporadic presence of a number of taxa which now grow in temperate areas further south suggest that average annual temperatures were a little lower than at present from 14 500 to 13 000 yr b p there was a sudden decline in the values of callitris and a more gradual decline in chenopodiaceae and dodonaea the rise of ephemeral vegetation together with a fall in chenopodiaceae would indicate that winter precipitation had started to decline between 13 000 and 4500 yr b p chenopodiaceae and tubuliflorae ephemerals declined and gramineae rose to its highest values tribulus pollen a subtropical tropical taxon first appeared 13 000 yr b p overall plants from the summer rainfall zone became more prominent and taxa from the temperate south declined summer monsoon incursions apparently strengthened and temperature increased during this phase since 4500 yr b p both chenopodiaceae and tubuliflorae returned to high values whereas gramineae declined values of acacia and myrtaceous shrubs rose but those of casuarina declined and callitris remained extremely low these changes were accompanied by the onset of playa environments which have since persisted vegetation during this phase suggests that summer precipitation declined and summer monsoon incursions became rare during the late holocene

the 2015 gorkha earthquake a large event illuminating the main himalayan thrust fault the 2015 gorkha earthquake sequence provides an outstanding opportunity to better characterize the geometry of the main himalayan thrust mht to overcome limitations due to unaccounted lateral heterogeneities we perform centroid moment tensor inversions in a 3 d earth model for the main shock and largest aftershocks in parallel we recompute s top and p to s receiver functions from the hi climb data set inverted centroid locations fall within a low velocity zone at 10 15 km depth and corresponding to the subhorizontal portion of the mht that ruptured during the gorkha earthquake north of the main shock hypocenter receiver functions indicate a north dipping feature that likely corresponds to the midcrustal ramp connecting the flat portion to the deep part of the mht our analysis of the main shock indicates that long period energy emanated updip of high frequency radiation sources previously inferred this frequency dependent rupture process might be explained by different factors such as fault geometry and the presence of fluids

imaging coseismic rupture in far field by slip patches summary since the end of the 1970s teleseismic waves are used routinely to infer the first order characteristics of the event location depth duration focal mechanism but finding the second order kinematic parameters spatial distribution of slip rupture velocity and more basically the discrimination between the fault plane and the other nodal plane of distant events remains a difficult task classically these events are studied by two different methods either they are seen as a succession of subevents each of which is considered as a point source or like in near field as extended sources where the kinematic parameters are retrieved on a grid the first approach is not physically satisfactory and can lead to erroneous interpretations of the

glacial and deglacial climatic patterns in australia and surrounding regions from 35 000 to 10 000 years ago reconstructed from terrestrial and near shore proxy data abstract this study forms part of a wider investigation of late quaternary environments in the southern hemisphere we here review the terrestrial and near shore proxy data from australia indonesia papua new guinea png new zealand and surrounding oceans during 35 10 ka an interval spanning the lead up to the last glacial maximum lgm the lgm proper 21 2 ka and the ensuing deglaciation sites selected for detailed discussion have a continuous or near continuous sedimentary record for this time interval a stratigraphically consistent chronology and one or more sources of proxy climatic data tropical australia indonesia and png had lgm mean annual temperatures 3 7 c below present values and summer precipitation reduced by at least 30 consistent with a weaker summer monsoon and a northward displacement of the intertropical convergence zone the summer monsoon was re established in northwest australia by 14 ka precipitation in northeast australia was reduced to less than 50 of present values until warmer and wetter conditions resumed at 17 16 ka followed by a second warmer wetter phase at 15 14 ka lgm temperatures were up to 8 c lower than today in mainland southeast australia and up to 4 c cooler in tasmania winter rainfall was much reduced throughout much of southern australia although periodic extreme flood events are evident in the fluvial record glacial advances in southeast australia are dated to 32 2 5 19 1 1 6 and 16 8 1 4 ka with periglacial activity concentrated towards 23 16 ka deglaciation was rapid in the snowy mountains which were ice free by 15 8 ka minimum effective precipitation in southern australia was from 14 to 12 ka in new zealand the glacial advances date to 28 21 5 and 19 ka with the onset of major cooling at 28 ka or well before the lgm there is no convincing evidence for a younger dryas cooling event in or around new zealand but there are signs of the antarctic cold reversal in and around new zealand and off southern australia there remain unresolved discrepancies between the climates inferred from pollen and those inferred from the beetle and chironomid fauna at a number of new zealand sites one explanation may be that pollen provides a generalised regional climatic signal in contrast to the finer local resolution offered by beetles and chironomids sea surface temperatures ssts were up to 5 c cooler during the lgm with rapid warming after 20 ka to attain present values by 15 ka the increase in summer monsoonal precipitation at or before 15 ka reflects higher insolation warmer ssts and steeper thermal gradients between land and sea the postglacial increase in winter rainfall in southern australia is probably related to the southward displacement of the westerlies as ssts around antarctica became warmer and the winter pack ice and antarctic convergence zone retreated to the south

on the equivocal fate of late pleistocene callitris vent cupressaceae woodlands in arid south australia fossil pollen assemblages suggest callitris cupressaceae dominated woodlands were prominent elements in landscapes near lake frome and lake eyre during latest pleistocene times callitris woodlands were present at lake eyre before 30 000 bp but became fragmented and disappeared in the lead up to the last glacial maximum callitris was again prominent from approximately 10 000 bp until about 5000 bp after which time it vanishes from the pollen record and presumably the region at lake frome callitris was abundant between 16 000 bp and 13 000 bp before declining to low modern levels from 11 000 bp at both sites the latest pleistocene or holocene decline in callitris occurrence and its eventual extinction in the vicinity of lake eyre broadly corresponds with archaeological indications of increasing human presence in the landscape in the absence of evidence of significant climatic changes at the times in question these observations lend tentative support to arguments that the composition and structure of modern zone vegetation has been significantly modified by aboriginal land management practices although the charcoal record is ambiguous fire is argued to be the principle agent of the changes wrought during human re colonisation of lands around lake frome and lake eyre

very fast characterization of focal mechanism parameters through w phase centroid inversion in the context of tsunami warning most of the tsunami potential seismic sources in the neam region are in a magnitude range of 6 5 le m w le 7 5 e g the tsunami triggered by the boumerdes earthquake of 2003 with m w 6 9 the centre d alerte aux tsunamis cenalt in operation since 2012 as the french national tsunami warning centre ntwc and candidate tsunami service provider ctsp has to issue warning messages within 15 min of earthquake origin time these warnings are based on the seismic source parameters m w magnitude focal depth and type of fault which are computed by focal mechanisms and centroid inversion methods the w phase method developed by kanamori and rivera allows quick computation of seismic source parameters due to the early arrival time between p waves and surface waves and is therefore particularly useful for monitoring we assess the w phase method with 29 events of magnitude m w ge 5 8 for the period 2010 2015 in the neam region results with 10 min of signal length are in good agreement compared to the global centroid moment tensor gcmt catalog

an approach to detect afterslips in giant earthquakes in the normal mode frequency band summary an approach to detect afterslips in the source process of giant earthquakes is presented in the normal mode frequency band 0 3 2 0 mhz the method is designed to avoid a potential systematic bias problem in the determination of earthquake moment by a typical normal mode approach the source of bias is the uncertainties in q modal attenuation parameter which varies by up to about 10 per cent among published studies a choice of q values within this range affects amplitudes in synthetic seismograms significantly if a long time series of about 5 7 d is used for analysis we present an alternative time domain approach that can reduce this problem by focusing on a shorter time span with a length of about 1 d application of this technique to four recent giant earthquakes is presented 1 the tohoku japan earthquake of 2011 march 11 2 the 2010 maule chile earthquake 3 the 2004 sumatra andaman earthquake and 4 the solomon earthquake of 2007 april 1 the global centroid moment tensor gcmt solution for the tohoku earthquake explains the normal mode frequency band quite well the analysis for the 2010 chile earthquake indicates that the moment is about 7 10 per cent higher than the moment determined by its gcmt solution but further analysis shows that there is little evidence of afterslip the deviation in moment can be explained by an increase of the dip angle from 18 in the gcmt solution to 19 this may be a simple trade off problem between the moment and dip angle but it may also be due to a deeper centroid in the normal mode frequency band data as a deeper source could have steeper dip angle due to changes in geometry of the benioff zone for the 2004 sumatra andaman earthquake the five point source solution by tsai et al explains most of the signals but a sixth point source with long duration improves the fit to the normal mode frequency band data the 2007 solomon earthquake shows that the high frequency part of our analysis above 1 mhz is compatible with the gcmt solution but the low frequency part requires afterslip to explain the increasing amplitude ratios towards lower frequency the required slip has the moment about 19 per cent of the gcmt solution and the rise time of 260 s the total moment of these earthquakes are 5 31 1022 n m tohoku 1 86 1 96 1022 n m chile 1 33 1023 n m sumatra and 1 86 1021 n m solomon the moment magnitudes are 9 08 8 78 8 79 9 35 and 8 11 respectively using kanamori s original formula between the moment and the moment magnitude however the trade off problem between the moment and dip angle can modify these estimates for moment up to about 40 50 per cent and the corresponding magnitude 0 1

the 17 july 2006 java tsunami earthquake the 17 july 2006 java earthquake involved thrust faulting in the java trench and excited a deadly tsunami 5 8 m that inundated the southern coast of java the earthquake s size estimates vary significantly with seismic wave period very long period signals 300 500 s indicate a seismic moment of 6 7 10 20 nm m w 7 8 m s 20 s 7 2 m b 1 s 6 2 while shaking intensities 3 10 hz were mmiv the large tsunami relative to ms characterizes this event as a tsunami earthquake like previous tsunami earthquakes the java event had an unusually low rupture speed of 1 0 1 5 km s and occurred near the up dip edge of the subduction zone thrust fault most large aftershocks involved normal faulting the rupture propagated 200 km along the trench with several pulses of shorter period seismic radiation superimposed on a smooth background rupture with an overall duration of 185 s

climatic patterns in equatorial and southern africa from 30 000 to 10 000 years ago reconstructed from terrestrial and near shore proxy data abstract as part of a wider study of last glacial and deglacial climates in the southern hemisphere continents we here review terrestrial and near shore marine records from equatorial and southern africa between 30 000 and 10 000 years ago 30 10 ka this time interval covers the lead up to the last glacial maximum lgm 21 2 ka the lgm proper and the ensuing deglacial records selected for review needed to meet three requirements continuity or near continuity over the period a well established chronology and at least one but preferably several unambiguous proxy ies we aim to show how regional climates of the sub continent have responded to orbital forcing as opposed to other global glacial interglacial boundary conditions and how they are related to high latitude climates sea and land surface conditions positions of the intertropical convergence zone itcz and of the westerly belt evidence of past climates derived from many independent proxies is given from west to southwest africa moisture from the atlantic ocean then from equatorial east africa to the southern subtropical summer rainfall domain moisture mainly from the indian ocean the lgm was cooler than today and generally drier in the tropics north of 8 9 s glacial to holocene increase in monsoonal precipitation primarily related to orbitally induced summer insolation in the northern hemisphere occurred by steps of increasing amplitude 17 16 14 5 11 5 ka major wet dry spells coincide with abrupt warm cold events in high northern latitudes and related itcz migrations in the southern tropics the main post glacial increase in tropical rainfall generally appears more gradual and in phase with antarctic warming data suggest a restricted northward migration of the itcz and concentration of tropical rainfall well south of the equator during the lgm and the younger dryas drier glacial conditions prevailed in southeastern africa while parts of southwestern africa point to enhanced humidity during the lgm suggesting that the winter westerly belt was either stronger than today or displaced further north possibly as a result of more extensive antarctic sea ice inferred african climatic fluctuations show the competing influences of tropical and high latitude climates of both hemispheres and suggest changes in both meridional and zonal circulation modes this review also reveals major geographical and methodological gaps and a number of unresolved issues providing pointers for future research

ten year recurrence time between two major earthquakes affecting the same fault segment earthquake ruptures stop when they encounter barriers impeding further propagation these barriers can theoretically originate from changes of geometry or nature of the seismic faults or from a strong lowering of the tectonic stresses typically due to the occurrence of a recent major earthquake we show here that this latter mechanism can be ineffective at stopping rupture expansion the 17 november 2013 magnitude 7 8 scotia sea earthquake has propagated into a 100 km long zone already ruptured 10 years ago by a magnitude 7 6 earthquake given the plate velocities between scotia and antarctic plates 8 9 mm yr simple recurrence models would have predicted that the segment affected by the 2003 earthquake could not be reruptured by a major earthquake during several hundreds of years this earthquake pair indicates that the variations of the tectonic stress during the seismic history of the fault are small compared to the stresses dynamically generated by a large earthquake

scardec a new technique for the rapid determination of seismic moment magnitude focal mechanism and source time functions for large earthquakes using body wave deconvolution accurate and fast magnitude determination for large shallow earthquakes is of key importance for post seismic response and tsumami alert purposes when no local real time data are available which is today the case for most subduction earthquakes the first information comes from teleseismic body waves standard body wave methods give accurate magnitudes for earthquakes up to mw 7 7 5 for larger earthquakes the analysis is more complex because of the non validity of the point source approximation and of the interaction between direct and surface reflected phases the latter effect acts as a strong high pass filter which complicates the magnitude determination we here propose an automated deconvolutive approach which does not impose any simplifying assumptions about the rupture process thus being well adapted to large earthquakes we first determine the source duration based on the length of the high frequency 1 3 hz signal content the deconvolution of synthetic double couple point source signals depending on the four earthquake parameters strike dip rake and depth from the windowed real data body wave signals including p pcp pp sh and scs waves gives the apparent source time function stf we search the optimal combination of these four parameters that respects the physical features of any stf causality positivity and stability of the seismic moment at all stations once this combination is retrieved the integration of the stfs gives directly the moment magnitude we apply this new approach referred as the scardec method to most of the major subduction earthquakes in the period 1990 2010 magnitude differences between the global centroid moment tensor cmt and the scardec method may reach 0 2 but values are found consistent if we take into account that the global cmt solutions for large shallow earthquakes suffer from a known trade off between dip and seismic moment we show by modelling long period surface waves of these events that the source parameters retrieved using the scardec method explain the observed surface waves as well as the global cmt parameters thus confirming the existing trade off for some well instrumented earthquakes our results are also supported by independent studies based on local geodetic or strong motion data this study is mainly focused on moment determination however the scardec method also informs us about the focal mechanism and source depth and can be a starting point to study systematically the complexity of the stf

a geospatial visualisation and chronological study of a late pleistocene fluvial wetland surface in the semi arid flinders ranges south australia abstract the semi arid flinders ranges of south australia contain abundant remnants of fine grained late pleistocene valley fills we have mapped these deposits using real time kinematic rtk gnss and topographic surveying techniques for data acquisition and integrate the surveyed data in a geographical information system gis to interpolate a 3 dimensional palaeo surface representing the uppermost remnant sediments of the late pleistocene floodplain our analysis of sedimentary and landscape profiles indicates a continuous surface and consistent westward slope suggesting that the remnants present today are still largely consistent with the original alluvial surface in addition secondary levels are identified and interpreted integration of the geospatial landscape characterisation with chronologies from selected sites microfossil and stable isotope data provides new evidence for the timing rates of aggradation and mode of deposition of the late pleistocene fine grained valley fill formation the use of gis for 2 d and 3 d data management analysis and visualisation provides a visual and quantitative model of landscape changes and helps to clarify how the valley fill deposits accumulated

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

empirical green function deconvolution of broadband surface waves rupture directivity of the 1992 landers california mw 7 3 earthquake we present a simple method to determine gross temporal and spatial characteristics of faulting that can uniquely define the fault plane for a relatively large earthquake the technique involves deconvolution of teleseismic and regional broadband surface waves and or body waves of a small event an empirical green function from the corresponding signals at the same stations for a large mainshock this deconvolution corrects each mainshock seismic record for propagation and instrument response and if the focal mechanisms and centroid depths are identical deconvolution provides relative source time functions for the mainshock azimuthal variations of source time function width or subevent interference reveal the mainshock rupture directivity changes in the source mechanism during rupture can be evaluated for some classes of events our empirical green function procedure is novel in its application to surface waves and its use for large m 7 earthquakes we perform synthetic tests to establish intrinsic limitations of the method the procedure requires very little data processing and can be applied in near real time with the current distribution of seismic stations that have dial up data retrieval capability it also provides a straightforward procedure for reducing bias in source duration estimates resulting from aspherical heterogeneity and for detecting anomalous long period radiation we apply the procedure to the 28 june 1992 landers california mw 7 3 earthquake the landers earthquake source duration lasted about 25 sec and was dominated by two subevents with predominantly north northwestward rupture extending 60 to 70 km the subevents show counter clockwise rotations of at least 12 in strike that correlate well with mapped surface rupture

coseismic and postseismic deformation of the 2016 mw 6 2 lampa earthquake southern peru constrained by interferometric synthetic aperture radar

heterogeneous structure around the rupture area of the 2003 tokachi oki earthquake mw 8 0 japan as revealed by aftershock observations using ocean bottom seismometers abstract large earthquakes have repeatedly occurred in the area off southeastern hokkaido island japan as the pacific plate subducts beneath the island which is on the north american plate the most recent large earthquake in this area the 2003 tokachi oki earthquake mw 8 0 occurred on september 26 2003 in order to investigate aftershock activity in the rupture area 47 ocean bottom seismometers obss were quickly deployed after the main shock in the present study we simultaneously estimate the hypocenters and 3 d seismic velocity models from the p and s wave arrivals of the aftershocks recorded by obss the subducting plate is clearly imaged as a northwest dipping zone in which vp is greater than 7 km s and the relocated hypocenters also show the subducting pacific plate the aftershock distribution reveals that the dip angle of the plate boundary increases abruptly around 90 km from the kuril trench the bending of the subducting plate corresponds to the southeastern edge of the rupture area the island arc crust on the overriding plate has p wave velocities of 6 7 km s and a vp vs of 1 73 a region of vp vs greater than 1 88 was found north of the epicenter of the main shock the depth of the high vp vs region extends about 10 km upward from the plate interface the plate boundary just below the high vp vs region has the largest slip at the main rupture a high vp anomaly 7 5 km s is found in the island arc crust in northeast part of the study area which we interpret as a structural boundary related to the arc arc collisional tectonics of the hokkaido region as the rupture of the main shock terminated at this high vp region we suggest that the plate interface geometry and the trench parallel velocity heterogeneity in the landward plate are principal factors in controlling the rupture area of the main shock

analysis of the 23 june 2001 mw 8 4 peru underthrusting earthquake and its aftershocks on 23 june 2001 a m w 8 4 underthrusting earthquake occurred in the southern peru subduction zone followed by several large aftershocks including 26 june m w 6 7 and 7 july m w 7 5 broadband analyses of seismic data for the largest of these earthquakes show southeastward rupture of 180 km along the portion of the subduction zone previously ruptured in 1868 m w 8 8 9 moment release distributions determined are consistent with aftershock location patterns earthquake rupture mode varies along southern peru from larger multi segment rupture in 1868 to several smaller segment ruptures in 2001 similar to rupture variation observed in northern peru and other subduction zones based on models of subduction zone segment interaction the 2001 earthquake sequence may suggest a shorter recurrence time for future earthquakes along this portion of the peru chile subduction zone

evolution of calcrete in palaeodrainages of the lake napperby area central australia abstract carbonate lithofacies developed along the trunk valley of palaeodrainage channels as well as those adjacent to gypsite facies in the lake napperby drainage basin in central australia show wide ranges of sedimentary characteristics reflecting significant variation in depositional environments sedimentological and geochemical characterization of the calcrete lithofacies in this drainage area indicate that whereas variations in bedrock morphology are important in overall distribution of the phreatic and vadose calcrete varieties faulting and basin adjustments since the early quaternary may also have played a significant role in redistribution of the hydrologic zones and hence the evolution of these calcretes accordingly phreatic calcretes which initially precipitated from laterally moving groundwaters along the palaeodrainage channels undergo systematic mineralogical changes due to direct evaporative precipitation and diagenetic displacement replacement processes mainly dolomitization and silicification under present hydro chemical conditions within the zone of grounwater fluctuations however lateral and downward shifts in groundwater flow due to excessive volumetric expansion and reduction in effective permeability of calcrete may ultimately result in isolation of the calcrete like those observed from the eastern margins of the lake the evolution of the vadose calcretes is thereafter topographically controlled and relates to mobilization and redistribution of earlier deposited calcretes under present meteorological conditions