persistent scatterer interferometric synthetic aperture radar for crustal deformation analysis with application to volcan alcedo galapagos 1 while conventional interferometric synthetic aperture radar insar is a very effective technique for measuring crustal deformation almost any interferogram includes large areas where the signals decorrelate and no measurement is possible persistent scatterer ps insar overcomes the decorrelation problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms existing ps methods have been very successful in analysis of urban areas where stable angular structures produce efficient reflectors that dominate background scattering however man made structures are absent from most of the earth s surface furthermore existing methods identify ps pixels based on the similarity of their phase history to an assumed model for how deformation varies with time whereas characterizing the temporal pattern of deformation is commonly one of the aims of any deformation study we describe here a method for ps analysis stamps that uses spatial correlation of interferogram phase to find pixels with low phase variance in all terrains with or without buildings prior knowledge of temporal variations in the deformation rate is not required for their identification we apply stamps to volcan alcedo where conventional insar fails because of dense vegetation on the upper volcano flanks that causes most pixels to decorrelate with time we detect two sources of deformation the first we model as a contracting pipe like body which we interpret to be a crystallizing magma chamber the second is downward and lateral motion on the inner slopes of the caldera which we interpret as landsliding

resolving three dimensional surface displacements from insar measurements a review abstract one dimensional measurement along the line of sight los direction has greatly limited the capability of insar technique in the investigation of surface displacements and their dynamics in recent years great efforts have been made to resolve complete three dimensional 3 d displacements from insar measurements this contribution is intended to provide a systematic review of the progress achieved in this field based on an analysis of the insar los measurements we first cover two commonly used techniques i e offset tracking and multi aperture insar mai with which the surface displacement in the azimuth direction can be measured together with the los displacement several methods for mapping 3 d displacements using insar measurements are subsequently presented and categorized into three groups i combination of multi pass los and azimuth measurements ii integration of insar and gps data and iii prior information assisted approaches the strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3 d displacement mapping cases in hope to provide a useful guidance in choosing a suitable approach accordingly finally suggestions for resolving the challenging issues and outlook of future research are given

degradation of the mitchell river fluvial megafan by alluvial gully erosion increased by post european land use change queensland australia along low gradient rivers in northern australia there is widespread gully erosion into unconfined alluvial deposits of active and inactive floodplains on the mitchell river fluvial megafan in northern queensland river incision and fan head trenching into pleistocene and holocene megafan units with sodic soils created the potential energy for a secondary cycle of erosion in this study rates of alluvial gully erosion into incipiently unstable channel banks and or pre existing floodplain features were quantified to assess the influence of land use change following european settlement alluvial gully scarp retreat rates were quantified at 18 sites across the megafan using recent gps surveys and historic air photos demonstrating rapid increases in gully area of 1 2 to 10 times their 1949 values extrapolation of gully area growth trends backward in time suggested that the current widespread phase of gullying initiated between 1880 and 1950 which is post european settlement this is supported by young optically stimulated luminescence osl dates of gully inset floodplain deposits lidar terrain analysis historic explorer accounts of earlier gully types and archival records of cattle numbers and land management it is deduced that intense cattle grazing and associated disturbance concentrated in the riparian zones during the dry season promoted gully erosion in the wet season along steep banks adjacent floodplain hollows and precursor gullies this is a result of reduced native grass cover increased physical disturbance of soils and the concentration of water runoff along cattle tracks in addition to fire regime modifications episodic drought and the establishment of exotic weed and grass species geomorphic processes operating over geologic time across the fluvial megafan predisposed the landscape to being pushed by land used change across an intrinsically close geomorphic threshold towards instability the evolution of these alluvial gullies is discussed in terms of their initiation development future growth and stabilisation and the numerous natural and anthropogenic factors influencing their erosion

atoll reef island formation and response to sea level change west island cocos keeling islands abstract reef islands around the margin of coral atolls generally comprise unconsolidated holocene sands and gravels overlying a reef flat or cemented conglomerate platform such islands have accreted within the last 3000 4000 years since sea level has reached a level close to present and the reef flat and conglomerate platform have formed island morphology consists of an oceanward ridge a less distinct lagoonward ridge and low lying central depression several alternative models of how such reef islands might have developed are examined in relation to chronology and sediment provenance particularly in the context of the cocos keeling islands where this issue has been debated since darwin visited the atoll which of these models appears most appropriate for an elongate reef island on the atoll margin is assessed using conventional radiocarbon dating of coral shingle and accelerator mass spectrometry ams radiocarbon dating of individual sand grains from pits across west island the dating results suggest that both coral clasts and individual grains of various components are generally reliable and replicable indicators of the chronology of island accumulation implying rapid transport of skeletal material after death of the contributing organisms across the reef flat zone and relatively little reworking the central part of west island appears to have formed first with oceanward accretion up until about 2000 years bp gradual oceanward accretion with lesser lagoonward extension has continued beyond 2000 years bp at the northern and southern ends of the island and a sequence of lagoonward recurving spits has formed adjacent to the inter island passage at the southern end of the island radiocarbon dating of fossil microatolls indicates a gradual fall of sea level over this period which appears to have had little effect on the pattern of island accretion

response of tide dominated mangrove shorelines in northern australia to anticipated sea level rise the exact response of mangrove shorelines to anticipated sea level rise will depend upon the balance between sedimentation and sea level change within the top end of the northern territory of australia there are extensive relatively unmodified tide dominated mangrove forests where tidal processes redistribute sediment harbours such as darwin harbour and tidal rivers such as the south alligator river with its associated coastal and estuarine plains represent opposite extremes in terms of holocene sedimentary infill and will respond differently to sea level rise in darwin harbour mangrove assemblages can be recognized in geomorphologically defined habitats similar topography within and between creeks implies morphodynamic equilibrium with tidal processes tidal reworking of sediment may maintain an equilibrial profile under gradually rising sea level with resuspension of lower intertidal and subtidal muds and their redeposition within upper intertidal mangrove habitats in contrast the plains along the coast and tidal rivers draining into van diemen gulf developed during the post glacial marine transgression and since sea level stabilized around 6000 years ago coastal plains have prograded these broad plains are presently not extensively influenced by salt water but are often at elevations close to or even below modern high tide levels they may therefore revert to saline conditions particularly rapidly if the sea rises the pattern of change may not be directly analogous to marine incursion experienced in the early holocene because broad plains have been able to prograde during the last 6000 years of relatively stable sea level

assessments of serious anthropogenic land subsidence in yunlin county of central taiwan from 1996 to 1999 by persistent scatterers insar article i nfo anthropogenic ground subsidence due to massive pumping of groundwater is one of the severe environmen tal hazards in taiwan the yunlin county located in the southwestern coastal region of taiwan is one of the most counties with serious land subsidence because of the agricultural needs in certain areas of the region the subsidence rate reaches as much as 14 3 cm yr the severe land subsidence gives rise to the risk of flood hazard and damage of infrastructures in this area we represented a persistent scatterers insar psinsar results deduced from 1996 to 1999 time span for monitoring of land subsidence in this area the psinsar results show that baojhou tuku and yuanchang townships reveal a maximum subsidence rate of about 7 8 cm yr along the los and lunbei township located on the northern yunlin reveals a subsidence rate of 3 5 cm yr which is quite coincident with the precise leveling result this result has proven that the effective reduction of labor and cost could be achieved by using this technique on monitoring land subsidence in

holocene reef growth in torres strait the platform and fringing reefs of torres strait are morphologically similar to reefs of the northern great barrier reef to the south except that several are elongated in the direction of the strong tidal currents between the coral sea and the gulf of carpentaria surface and subsurface investigations and radiocarbon dating on yam warraber and hammond islands reveal that the initiation and mode of holocene reef growth reflect antecedent topography and sea level history on the granitic yam island fringing reefs have established in some places over a pleistocene limestone at about 6 m depth around 7000 years bp emergent holocene microatolls of porites sp indicate that the reefs have prograded seawards while sea level has fallen gradually from at least 0 8 m above present about 5800 years bp on the warraber island reef platform drilling near the centre indicated a pleistocene limestone foundation at a depth of about 6 m over which reefs established around 6700 years bp reef growth lagged behind that on yam island microatolls on the mature reef flat indicate that the reef reached sea level around 5300 years bp when the sea was around 0 8 1 0 m above present on the reef flat on the western side of hammond island bedrock was encountered at 7 8 m depth overlain by terrigenous mud a progradational reef sequence of only 1 2 m thickness has built seaward over these muds as sea level has fallen over the past 5800 years reef flat progradation on these reefs is interpreted to have occurred by a series of stepwise buildouts marked by lines of microatolls parallel to the reef crest marking individual coalescing coral heads detrital infill has occurred between these this pattern of reef progradation is consistent with the radiocarbon dating results from these reefs and with seismic investigations on the torres reefs

environmental context for late holocene human occupation of the south wellesley archipelago gulf of carpentaria northern australia a 2400 year record of environmental change is reported from a wetland on bentinck island in the southern gulf of carpentaria northern australia three phases of wetland development are identified with a protected coastal setting from ca 2400 to 500 years ago transitioning into an estuarine mangrove forest from ca 500 years ago to the 1940s and finally to a freshwater swamp over the past 60 years this sequence reflects the influence of falling sea levels development of a coastal dune barrier system prograding shorelines and an extreme storm cyclone event in addition there is clear evidence of the impacts that human abandonment and resettlement have on the island s fire regimes and vegetation a dramatic increase in burning and vegetation thickening was observed after the cessation of traditional indigenous kaiadilt fire management practices in the 1940s and was then reversed when people returned to the island in the 1980s in terms of the longer context for human occupation of the south wellesley archipelago it is apparent that the mangrove phase provided a stable and productive environment that was conducive for human settlement of this region over the past 1000 years

holocene reef sequences and geochemistry britomart reef central great barrier reef australia holocene reef development was investigated by coring on britomart reef a mid shelf reef 23 km long and 8 km wide situated 120 km north of townsville in the central great barrier reef gbr two holes were drilled britomart 1 on a lagoon patch reef and britomart 2 on the windward reef crest the holocene reef 25 5 m is the thickest yet recorded in the gbr and overlies an uneven substrate of weathered pleistocene limestone mineralogical and geochemical analyses show that magnesian calcite and aragonite were converted to low mg calcite below the holocene pleistocene disconformity corals above the interface have 7500 8500 ppm sr but 1650 1500 ppm just below it decreasing to 400 800 ppm downwards the intermediate sr values could be due to partial replacement of aragonite by calcite or higher original sr content in the corals three units are recognized in the holocene 1 coral boundstone unit 2 coral framestone unit and 3 coral rudstone unit the coral boundstone unit forms the top 5 m of both cores and is algal bound coral rubble similar to the present reef top the coral framestone unit is composed of massive head corals diploastrea heliopora and porites sp and is currently forming in patch reefs situated in the lagoon and along the reef front the coral rudstone unit comprises coral rudstone and floatstone with unabraded and unbound coral clasts in muddy matrix this matrix may be up to 30 sponge chips radiocarbon dating indicates the reef grew more rapidly under the lagoon than under the reef front from 7000 to 5000 yr bp the rate of reef growth matched existing estimates of sea level rise but lagged approximately 1000 years 5 10 m behind it most of the reef mass accumulated between 8500 and 5000 yr bp as a mound of debris perhaps stabilized by seagrasses or algae accretion of the reef top in a windward direction between 5000 and 3000 yr bp created the present steep reef front profile

diagenetic history of the surma group sandstones miocene in the surma basin bangladesh abstract this study examines the various diagenetic controls of the miocene surma group sandstones encountered in petroleum exploration wells from the surma basin which is situated in the northeastern part of the bengal basin bangladesh the principal diagenetic minerals cements in the surma group sandstones are fe carbonates with fe calcite dominating quartz overgrowths and authigenic clays predominantly chlorite illite smectite and minor kaolin the isotopic composition of the carbonate cement revealed a narrow range of 18o values 10 3 to 12 4 and a wide range of 13c value 1 4 to 23 1 the 13c vpdb and 18o vpdb values of the carbonate cements reveal that carbon was most likely derived from the thermal maturation of organic matter during burial as well as from the dissolution of isolated carbonate clasts and precipitated from mixed marine meteoric pore waters the relationship between the intergranular volume igv versus cement volume indicates that compaction played a more significant role than cementation in destroying the primary porosity however cementation also played a major role in drastically reducing porosity and permeability in sandstones with poikilotopic pore filling blocky cements formed in early to intermediate and deep burial areas in addition to fe carbonate cements various clay minerals including illite smectite and chlorite occur as pore filling and pore lining authigenic phases significant secondary porosity has been generated at depths from 2500 m to 4728 m the best reservoir rocks found at depths of 2500 3300 m are well sorted relatively coarse grained more loosely packed and better rounded sandstones having good porosities 20 30 and high permeabilities 12 6000 md these good quality reservoir rocks are however not uniformly distributed and can be considered to be compartmentalized as a result of interbedding with sandstone layers of low to moderate porosities low permeabilities owing to poor sorting and extensive compaction and cementation

theoretical constraints and chronological evidence of holocene coastal development in central and southern new south wales australia abstract holocene coastal evolution in new south wales has been interpreted essentially as the unfolding of the impact of marine transgression sea level on this coast supposedly reached its present height at 6 6 5 ka and varied

origin of the rajmahal traps and the 85 e ridge preliminary reconstructions of the trace of the crozet hotspot the 85 e ridge is a buried aseismic ridge approximately parallel to and west of the ninetyeast ridge in the northeastern indian ocean it was previously shown to be of probable volcanic origin emplaced on very young oceanic crust but no satisfactory model of emplacement of the rocks was offered we propose a model of origin of the rajmahal traps of northeastern india the 85 e ridge and afanasy nikitin seamount as the trace of the hotspot that now lies beneath the crozet islands in the southern indian ocean this reconstruction places the kerguelen hotspot which formed the ninetyeast ridge at the triple junction between greater india australia and antarctica before the breakup of eastern gondwana

land subsidence in mashhad valley northeast iran results from insar levelling and gps summary significant land subsidence was recently recognized in northeast iran near the city of mashhad precise levelling surveys performed in 1995 2002 and 2005 indicate as much as 90 cm of subsidence during the 1995 2005 period continuous gps monitoring approximately 8 km northwest of mashhad city shows more than 20 cm yr 1 subsidence between 2005 and 2006 we use interferometric synthetic aperture radar insar measurements to detect the temporal and spatial pattern of this surface deformation 13 interferograms from 10 c band sar images acquired by the enivsat satellite from 2003 to 2005 are analysed and stacked our insar mapping suggests that subsidence occurs within a northwest southeast elongated ellipticshaped bowl along the axis of the mashhad valley with a peak amplitude of 28 30 cm yr 1 for the 2003 2005 time period the insar data indicate that approximately 70 km 2 in the valley floor including the northwestern part of mashhad city subsided at a rate exceeding 15 cm yr 1 between 2003 and 2005 and that the subsidence area is structurally controlled by the trends of quaternary faults cutting the valley floor analysis of piezometric records suggests that subsidence likely results from extensive overdrafting of the aquifer system in the valley that has caused as much as 65 m of water table decline since 1960s

a critical review of mid to late holocene sea level fluctuations on the eastern brazilian coastline abstract the eastern coast of brazil is 7000 km long and has been the subject of systematic paleo sea level investigations for more than 35 years more than 1000 samples have been radiocarbon dated and paleo sea level trends have been determined for 14 coastal sectors these trends have in common a mid holocene sea level maximum pmt above present sea level and a subsequent fall to the present time the time and elevation of the pmt the time when relative sea level rose above present mean sea level and the nature of late holocene sea level fall can however differ significantly discrepancies are observed not only between neighboring coastal sectors but also between different studies in a same coastal sector this paper discusses all the key radiocarbon dated samples used to establish regional trends in relative sea level on the eastern coast of brazil it is concluded that although many of the key sea level indicators are imprecise in time and space there is widespread evidence 30 of the data set for a progressive decline possibly with uneven rates of relative sea level since the end of the pmt

detection of aquifer system compaction and land subsidence using interferometric synthetic aperture radar antelope valley mojave desert california interferometric synthetic aperture radar insar has great potential to detect and quantify land subsidence caused by aquifer system compaction insar maps with high spatial detail and resolution of range displacement 10 mm in change of land surface elevation were developed for a groundwater basin 103 km2 in antelope valley california using radar data collected from the ers 1 satellite these data allow comprehensive comparison between recent 1993 1995 subsidence patterns and those detected historically 1926 1992 by more traditional methods the changed subsidence patterns are generally compatible with recent shifts in land and water use the insar detected patterns are generally consistent with predictions based on a coupled model of groundwater flow and aquifer system compaction the minor inconsistencies may reflect our imperfect knowledge of the distribution and properties of compressible sediments when used in conjunction with coincident measurements of groundwater levels and other geologic information insar data may be useful for constraining parameter estimates in simulations of aquifer system compaction

late pleistocene and holocene sea level change along the australian coast abstract tectonically the australian continent is relatively stable and as such it provides a good platform for studying late pleistocene and holocene sea level change the observations indicate that present sea level was reached at about 6000 years ago and that since then level has remained constant to within a few metres considerable spatial variability in the amplitude of the emergence and in the time at which sea levels first reached their present values have been observed spatial variability has also been observed in the sea level during the last glacial maximum and during the late phase of the holocene transgression much of this variaiblity is the result of the earth s adjustment to the glacial melting in the late pleistocene early holocene time and the concomitant distribution of this meltwater into the oceans conclusions that are drawn from matching observations with this glacio hydro isostatic model include the following 1 the mantle viscosity increases with depth the average upper mantle viscosity is about 2 3 10 20 pa s and the average lower mantle defined as below 670 km depth viscosity is about 10 22 pa s the average lithospheric thickness for the coastal and offshore region is about 70 80 km lateral variations in these mantle parameters are indicated 2 the addition of melwater into the oceans did not cease 6000 years ago but continued at a reduced rate up to more recent times adding an amount of water equivalent to a 3 m sea level rise in this interval 3 the amplitude of the holocene emergence is a function inter alia of coastal geometry and significant variations occur over distances of a few hundred kilometres and more holocene highstands of 1 2 m are generally well developed at the continental margins but are less well developed or do not developed at all at offshore islands and reefs 4 variations in the time of maximum emergence also occur being earlier at upstream tidal river sites than at coastal sites at offshore reefs or islands the sea level curve lags the coastal curves by 1000 years or more 5 considerable spatial variability occurs in the sea levels at the time of the last glacial maximum with variations of up to 30 m occurring across the continental shelves 6 there is generally no need to invoke tectonic movements to explain the sea level data along the australian coast but possible exceptions occur for the perth region and for tasmania

high precision u series dating of corals from western australia and implications for the timing and duration of the last interglacial abstract u series ages using methods of thermal ionisation mass spectrometry tims are reported for last interglacial fossil reefs along the stable coastal margin of western australia thorium isotope ratios were measured with superior precision using methods of charge collection high levels of precision in the measurement of both uranium and thorium isotopes has reduced the age uncertainty due to analytical errors excluding the uncertainty in the decay constants by a factor of four over the precisions reported by many earlier tims workers uncertainties in 234u t determined from both 230th 238u and 234u 238u are also significantly smaller than previously reported allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified strict criteria were adopted to screen the new western australian data reliable ages range from 127 to 122 ka published tims observations from other localities have been assessed using the same strict criteria when these are combined with glacio hydro isostatic sea level models they indicate that the last interglacial period occurred from at least 130 to 117 ka however these age constraints are largely determined from single data points and need to be verified with additional ages before considering them to be robust estimates for the timing of onset and termination of the last interglacial globally the main episode of reef growth appears to be confined to a narrow interval occurring from 127 to 122 ka in direct agreement with the narrow range in ages obtained from the western australian sites this may indicate that the last interglacial was of short duration extending from 127 to 122 ka only alternatively this interval may reflect a major reef building event in the middle of a longer duration 130 117 ka interglacial interval

holocene sea level change and coastal landscape evolution in the southern gulf of carpentaria australia a revised holocene sea level history for the southern gulf of carpentaria is presented based on new data from the south wellesley archipelago and age recalibration of previous research results confirm that rising sea levels during the most recent post glacial marine transgression breached the arafura sill ca 11 700 cal yr bp sea levels continued to rise to ca 30 m by 10 000 cal yr bp leading to full marine conditions by 7700 cal yr bp sea level reached present mean sea level pmsl and continued to rise to an elevation of between 1 5 m and 2 m above pmsl sea level remained ca 1 5 between 7000 and 4000 cal yr bp followed by rapid regression to within 0 5 m of pmsl by ca 3500 cal yr bp when placed into a wider regional context results from this study show that coastal landscape evolution in the tropical north of australia was not only dependent on sea level change but also show a direct correlation with holocene climate variability specifically the formation and preservation of beach rock deposits intertidal successions beach and chenier ridge systems hold valuable sea level and holocene climate proxies that can contribute to the growing research into lower latitude holocene sea level and climate histories

atmospheric effects in interferometric synthetic aperture radar surface deformation and topographic maps interferogram images derived from repeat pass spaceborne synthetic aperture radar systems exhibit artifacts due to the time and space variations of atmospheric water vapor other tropospheric variations such as pressure and temperature also induce distortions but the effects are smaller in magnitude and more evenly distributed throughout the interferogram than the wet troposphere term spatial and temporal changes of 20 in relative humidity lead to 10 cm errors in deformation products and perhaps 100 m of error in derived topographic maps for those pass pairs with unfavorable baseline geometries in wet regions such as hawaii these are by far the dominant errors in the spaceborne imaging radar c and x band synthetic aperature radar sir c x sar interferometric products the unknown time delay from tropospheric distortion is independent of frequency and thus multiwavelength measurements such as those commonly used to correct radar altimeter and global positioning system gps ionospheric biases cannot be used to rectify the error in the topographic case the errors may be mitigated by choosing interferometric pairs with relatively long baselines as the error amplitude is inversely proportional to the perpendicular component of the interferometer baseline for the sir c x sar hawaii data we found that the best longest baseline pair produced a map supporting 100 m contouring whereas the poorest baseline choice yielded an extremely noisy topographic map even at this coarse contour interval in the case of deformation map errors the result is either independent of baseline parameters or else very nearly so here the only solution is averaging of independent interferograms so in order to create accurate deformation products in wet regions many multiple passes may be required rules for designing optimal data acquisition and processing sequences for interferometric analyses in nondesert parts of the world are 1 to use the longest radar wavelengths possible within ionospheric scintillation and faraday rotation limits 2 for topography maximize interferometer baseline within decorrelation limits and 3 for surface deformation use multiple observations and average the derived products following the above recipe yields accuracies of 10 m for digital elevation models and 1 cm for deformation maps even in very wet regions such as hawaii

unroofing history of the eastern himalaya and the indo burman ranges heavy mineral study of cenozoic sediments from the bengal basin bangladesh abstract upper eocene to neogene fill of the bengal basin provides an earlier unroofing history of the eastern himalaya and indo burman ranges than that provided by drilling of the bengal fan and analysis of heavy minerals in these sequences provides useful provenance constraints quartzose sandstones of the eocene kopili and oligocene barail formations contain only 0 2 heavy minerals comprising abundant opaque minerals and stable minerals such as tourmaline garnet rutile and zircon this assemblage suggests sediment sources dominated by low to intermediate grade metamorphic silicic igneous and metasedimentary rocks the low heavy mineral content and abundance of stable minerals suggest intense chemical weathering these sediments may have been derived in part from incipient uplifts of the proto himalaya and or the indo burman ranges but a more likely source is the indian craton immediately to the west miocene sandstones of the surma group contain more abundant and more diverse heavy mineral assemblages than oligocene sandstones these include abundant opaque minerals and garnet mostly almandine and moderate to minor amounts of tourmaline kyanite zircon calcic amphibole rutile chlorite zoisite staurolite epidote sillimanite and clinopyroxene indicating a broad range of mostly metamorphic source rocks upper strata of the surma group also contain abundant blue green amphibole orthopyroxene and sparse chromite suggesting exhumation of arc and ophiolitic rocks sands and sandstones from the upper miocene to pliocene tipam group and the pliocene to pleistocene dupi tila formation contain assemblages similar to those of the underlying miocene sandstones along with more abundant orthopyroxene and sillimanite in dupi tila sands temporal variations in heavy mineral assemblages in the bengal basin suggest that orogenic detritus first appears in the eastern himalayan foredeep much later early miocene than in the western part of the foredeep eocene the appearance of high pressure phases in upper miocene strata reflects continued unroofing of deeper crustal metamorphic and silicic to ultramafic plutonic rocks

predicted and observed holocene sea levels on the australian coast what do they indicate about hydro isostatic models in far field sites data relating to holocene sea level elevations and ages obtained by radiocarbon dating of relict calcareous skeletons of intertidal organisms from widely spaced parts of the australian coast a far field region of comparative tectonic stability are divisible into two sets namely pre and post ca 3600 yr bp the older ages are from material consistently between 1 5 m and 2 2 m higher than present sea level whereas the younger ages ca 3600 1500 yr bp generally cluster around 1 m above present sea level the elevations do not display any decline in amplitude from north to south over an extensive transect contrary to predictions by hydro isostatic models also there appears to be little difference between time elevation results for the coasts of north queensland new south wales and the bass strait region adjacent to tasmania despite differences in the width of the continental shelf in these three locations and the expectation of some hydro isostatic warping of the continental shelf subsequent to the onset of the holocene transgression results from the south and southwest coasts of western australia also display similar elevations to the east coast for the same time periods there is sufficient evidence extending over 20 of latitude to suggest that north south differences related to hydro isostatic influence is limited or non existent there is insufficient data to test hydro isostatic models across continental shelves hydro isostasy and the lithological elasticity it reflects may not be as pronounced in far field sites with narrow continental shelves as models predict stable far field passive continental margins may be the best place to measure the ratio of inputs of eustatic and hydro isostatic influences on holocene relative sea levels copyright 2002 john wiley sons ltd journal of quaternary science

hydro isostasy and the sea level isobase of 5500 b p in north queensland australia abstract previous studies of holocene sea level in north queensland have been based on a variety of sea level related deposits with interpretations of mid holocene levels ranging from near zero up to 4 m above present we report data from 8 carefully controlled new sites located from the palm group northwards and extending into the gulf of carpentaria field evidence is from coral reef flats and prograded coastal deposits the highest sea level on inner shelf islands and mainland coast occurred 5500 yrs ago the results of this and of certain previous studies are reduced to a common reference surface or isobase which varies systematically in elevation across the region the isobase correlates strongly with predicted hydro isostatic deformation caused by postglacial sea level rise

sedimentation and tectonics of the sylhet trough bangladesh the sylhet trough a sub basin of the bengal basin in northeastern bangladesh contains a thick fill 12 to 16 km of late mesozoic and cenozoic strata that record its tectonic evolution stratigraphic sedimentologic and petrographic data collected from outcrops cores well logs and seismic lines are here used to reconstruct the history of this trough the sylhet trough occupied a slope basinal setting on a passive continental margin from late mesozoic through eocene time subsidence may have increased slightly in oligocene time when the trough was located in the distal part of a foreland basin paired to the indo burman ranges oligocene fluvial deltaic strata barail formation were derived from incipient uplifts in the eastern himalayas subsidence increased markedly in the miocene epoch in response to western encroachment of the indo burman ranges miocene to earliest pliocene sediments of the surma group were deposited in a large mud rich delta system that may have drained a significant proportion of the eastern himalayas subsidence rates in the sylhet trough increased dramatically 3 8 times from miocene to pliocene pleistocene time when the fluvial tipam sandstone and dupi tila formation were deposited this dramatic subsidence change is attributed to south directed overthrusting of the shillong plateau on the dauki fault for the following reasons 1 pliocene and pleistocene strata thin markedly away from the shillong plateau consistent with a crustal load emplaced on the northern basin margin 2 the shillong plateau is draped by mesozoic to miocene rocks but pliocene and younger strata are not represented suggesting that the massif was an uplifted block at this time 3 south directed overthrusting of the shillong plateau is consistent with gravity data and with recent seismotectonic observations sandstone in the tioam has a marked increase in sedimentary lithic fragments compared to older rocks reflecting uplift and erosion of the sedimentary cover of the shillong plateau if the dauki fault has a dip similar to that of other himalayan overthrusts then a few tens of kilometers of horizontal tectonic transport would be required to carry the shillong plateau to its present elevation uplift of the shillong plateau probably generated a major 300 km westward shift in the course of the brahmaputra river

fringing reef growth over a shallow last interglacial reef foundation at a mid shelf high island holbourne island central great barrier reef fringing reefs are rare on the mid shelf of the central great barrier reef with holocene development histories established for a few examples the paucity of reef growth records from mid shelf fringing reefs has limited opportunities for comparisons with inshore fringing reef growth records to better understand the influence of changes in environmental conditions on reef growth with distance offshore the long term development of the mid shelf fringing reef at holbourne island was reconstructed using nine percussion and drill cores that captured the entire holocene period of reef growth the cores were chronologically constrained by 16 high precision th 230 ages a weathered pleistocene reef substrate was u th dated as last interglacial open system age of 131 100 1000 cal ybp and this provides the underlying foundation upon which the holocene reef initiated prior to similar to 7520 20 cal ybp the last interglacial reef was encountered 5 9 m below the present reef surface and is the shallowest confirmed last interglacial reef in the central gbr region to date most of the holocene reef structure was emplaced within 1000 years of initiation the chronostratigraphy and contemporary geomorphology of the fringing reef at holboume island preserve evidence of re working and stripping of the reef structure by cyclones this evidence includes 1 an age hiatus in core data of similar to 3500 years 6238 18 to 2683 10 cal ybp 2 the abundance of detrital branching coral rubble material within the core facies 3 the surface elevations and ages of fossil microatolls which reveal that storm induced ponding of water during low tidal stages up to 55 cm deep has been active but intermittent across the reef flat for at least 600 years and is still active today and 4 long standing shingle ridges onshore and modern shingle ridges on the reef flat

late holocene higher sea level indicators from eastern australia abstract new age data from intertidal organisms exposed on coastal cliffs in northern new south wales suggest that in that area sea level was slightly more than 1 m higher about 3420 yrs b p and may have fallen to its present level since 1780 yrs b p these findings if regionally significant are important because they indicate that the tidally constructed zonations of organisms on high energy rocky coast could provide a more precise record of sea level behaviour than the study of constructional geomorphic features often related to storm events such as beach ridges chenier plains tidal deltas etc or mangrove peats

nonlinear subsidence rate estimation using permanent scatterers in differential sar interferometry discrete and temporarily stable natural reflectors or permanent scatterers ps can be identified from long temporal series of interferometric sar images even with baselines larger than the so called critical baseline this subset of image pixels can be exploited successfully for high accuracy differential measurements the authors discuss the use of ps in urban areas like pomona ca showing subsidence and absidence effects a new approach to the estimation of the atmospheric phase contributions and the local displacement field is proposed based on simple statistical assumptions new solutions are presented in order to cope with nonlinear motion of the targets

depositional facies of the subsurface neogene surma group in the sylhet trough of the bengal basin bangladesh record of tidal sedimentation the bengal basin in the north eastern part of the indian subcontinent contains a thick 22 km early cretaceous holocene sedimentary succession the neogene succession in the sylhet trough of the basin reaches a thickness of more than 6 km of which the surma group contains important sandstone reservoirs lithologically the group consists of a succession of alternating shales siltstones sandy shales and sandstones with minor conglomerates this research work is a sedimentological analysis of the subsurface neogene succession encountered in the petroleum exploration wells in the sylhet trough of the bengal basin detailed lithologic logs of the cores based on considering texture and sedimentary structure permit a subdivision into eight lithofacies e g a shale dominated facies interbedded fine sandstones and mudstones ripple laminated sandstones parallel laminated sandstones massive sandstones cross bedded sandstones cross bedded sandstones with pebble granule lag and conglomerates characteristic sedimentary structures of the surma group such as flaser wavy and lenticular bedding bipolarity of ripple cross stratification evenly laminated sand silt streaked shales reactivation surfaces within cross bedded sandstone sets mud drapes on foreset laminae and herringbone cross stratification as well as small scale vertical sequences several fining upward cycles are diagnostic for tidal influence on the basis of the lithofacies associations and prograding character of the deposits revealed from the electrofacies associations the surma group sediments have been interpreted as representing deposits of tide dominated deltaic depositional setting

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

new evidence for episodic post glacial sea level rise central great barrier reef australia abstract we present an extensive database of 364 radiocarbon dates from coastal and marine sediments of the central great barrier reef gbr shelf of which 110 are previously unpublished the elevation data have been reduced to a common datum australian height datum ahd and the various sources of error have been assessed using modern lithological and biological relationships with sea level the elements of the radiocarbon database have been converted into sea level indicators the upper bound of the assembled dataset corresponds to a best estimate sea level curve and the full dataset provides a narrow envelope for sea level rise on the gbr shelf for the last 11 12 kyr not including hydro isostatic crustal flexing the envelope is consistent with episodic rise in post glacial sea levels the rising post glacial sea level probably included stillstands or minor falls at ca 45 m ahd at ca 10 5 kyr b p 5 m 7 8 kyr b p 2 m ca 6 kyr b p and 1 7 m 5 5 kyr b p there is evidence for a significant fall in sea level between stillstands at 11 m 8 5 kyr b p and 17 m 8 2 kyr b p stillstand durations apparently ranged between the vertical spread in the derived sea level data is very wide the use of shell material for dating seems unreliable and prone to large and unpredictable errors data from bulk mangrove muds appear reliable for determination of ancient sea level but may at times result in sea level being placed up to 4 m below the true level in situ biogenic carbonates such as preserved oyster beds and coral micro atolls are the most reliable indicators of sea level position while deposits of mangrove mud give a useful first order approximation of ancient sea levels caution should be used in drawing sea level curves from few data points we conclude that the post 11 12 kyr b p relative rise in sea level was episodic on the central gbr continental margin more data are required to define clearly sea level change up to ca 20 m at 9 kyr b p

detailed documentation of a holocene sea level record in the perth region southern western australia abstract holocene prograded coastal sequences at becher rockingham southern western australia contain a detailed record of sea level over the last 6400 yr radiocarbon dating and use of a distinct stratigraphic indicator as a sea level marker permit reconstruction of sea level history and suggest that the sea was at least 2 5 m above present datum about 6400 yr b p before falling to its present level no evidence was found for eustatic fluctuations of the scale proposed by r w fairbridge 1961 in physics and chemistry of the earth l h ahrens f press k rankema and s k runcorn eds vol 4 pp 99 185 pergamon oxford the sea level record preserved on this coast can be explained by hydro isostasy tectonism or eustasy acting individually or in concert without a fixed reference point or analogous data from other locations a firm conclusion on which mechanism s has have operated could not be reached published sea level data from this and other coasts are often insufficiently detailed to compare with this study application of the techniques of this study to analogous sedimentary sequences elsewhere will provide data of comparable accuracy that would contribute to a more precise understanding of relative sea level movements in the late quaternary

surface deformation from persistent scatterers sar interferometry and fusion with leveling data a case study over the choushui river alluvial fan taiwan abstract the choushui river alluvial fan craf one of the most important agricultural areas in taiwan suffers severe subsidence caused by groundwater withdrawal we use 20 envisat images from 2006 to 2008 to derive vertical deformation over craf by persistent scatterer interferometry psi which effectively reduces errors affecting conventional dinsar techniques the pixel density over craf is 107 6 pixels km 2 compared to 0 19 points km 2 of the leveling benchmarks psi yields vertical displacements matching the leveling result to 0 6 cm year rms and provides a higher spatial resolution of subsidence than the latter we also develop a data fusion method that considers the high precision low point density leveling result as a smoothed correction to the psi result the combined field is more representative of overall deformation characteristics than the psi only or leveling only field and it is better suited for the assessment of the impact of subsidence over craf

a new method for measuring deformation on volcanoes and other natural terrains using insar persistent scatterers 1 we present here a new insar persistent scatterer ps method for analyzing episodic crustal deformation in non urban environments with application to volcanic settings our method for identifying ps pixels in a series of interferograms is based primarily on phase characteristics and finds low amplitude pixels with phase stability that are not identified by the existing amplitude based algorithm our method also uses the spatial correlation of the phases rather than a well defined phase history so that we can observe temporally variable processes e g volcanic deformation the algorithm involves removing the residual topographic component of flattened interferogram phase for each ps then unwrapping the ps phases both spatially and temporally our method finds scatterers with stable phase characteristics independent of amplitudes associated with man made objects and is applicable to areas where conventional insar fails due to complete decorrelation of the majority of scatterers yet a few stable scatterers are present

fifteen years of surface deformation in western taiwan insight from sar interferometry abstract geodetically measured surface displacements are produced by a combination of underlying deformation processes acting at different spatial and temporal scales a complete history of surface measurements in an area can help discriminate contributions from tectonic hydrologic and anthropogenic processes in this study we use synthetic aperture radar sar images of the active mountain front and adjacent coastal plain of southwestern taiwan to generate time series of surface deformation from 1995 to 2001 and from 2005 to 2008 based on the insar small baseline method the insar measurements agree well with los motions estimated from continuous gps measurements of 3d displacements between 2006 and 2008 a significant range increase in line of sight los is dominated by land subsidence in the coastal area of western and southwestern taiwan subsidence rates vary with annual periods and are highly correlated with seasonal precipitation which are likely associated with groundwater recharge and withdrawal the long term deformation is dominated by long term tectonic loading in sw taiwan during the interseismic period of the earthquake cycle including elastic strain along or continuous creep on the active faults our results show the ability of insar to reveal spatiotemporal crustal deformation in western taiwan with high spatial resolution and accuracy which is potentially important for evaluating seismic hazards

land subsidence in bangkok thailand abstract land subsidence from deep well pumping has been affecting bangkok for the past 35 years its impact is particularly critical because of the flat low lying topography and the presence of a thick soft clay layer at the ground surface that augment flood risk and foundation engineering problems respectively the subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 120 mm year the rate decreased in the subsequent period but the subsidence affected area expanded following the growth of the city despite various attempts implemented to remedy the crisis groundwater pumping from the thick aquifer system underneath the city continued to increase from 1 2 million m3 day in the early 1980s to more than 2 0 million m3 day at the turn of the century piezometric levels in the main aquifer layers had been drawn down by as much as 65 m monitoring data showed a clear correlation between the subsidence and piezometric drawdown the data suggested that for 1 m3 of groundwater pumped out in bangkok plain approximately 0 10 m3 of ground loss occurred at the surface significant development has been made in numerical methods for prediction of differential settlements between building foundations caused by the piezometric drawdown in the aquifers the strict mitigation measures adopted recently comprising a pricing policy for groundwater management an expansion of tap water supply and strict enforcement of groundwater laws have resulted in a marked drop in groundwater use however the land subsidence will continue for a long while owing to the time dependent consolidation behavior of the soft clay layer and clay aquitards

the hydrodynamic and sedimentary setting of nearshore coral reefs central great barrier reef shelf australia paluma shoals a case study the great barrier reef gbr shelf contains a range of coral reefs on the highly turbid shallow inner shelf where interaction occurs with terrigenous sediments the modern hydrodynamic and sedimentation regimes at paluma shoals a shore attached turbid zone coral reef and at phillips reef a fringing reef located 20 km offshore have been studied to document the mechanisms controlling turbidity at each reef waves currents and near bed turbidity were measured for a period of 1 month bed sediments were sampled at 135 sites on the inner shelf muddy sands are widespread with admixed terrigenous and carbonate gravel components close to the reefs and islands except on their relatively sheltered sw side where sandy silty clays occur at paluma shoals the coral assemblage is characteristic of inner shelf or sheltered habitats on the gbr shelf dominated by galaxea fascicularis up to 50 coral cover and is broadly similar to that at phillips reef further offshore and in deeper water the sediments of the paluma shoals reef flats consist of mixed terrigenous and calcareous gravels and sands with intermixed silts and clays whereas the reef slope is dominated by gravelly quartz sands the main turbidity generating process is wave driven resuspension and turbidity ranges up to 175 nephelometric turbidity units ntu in contrast at phillips reef turbidity is 40 ntu probably occurs for a total of 40 days each year and relatively little time is spent at intermediate turbidities 15 50 ntu the extended time spent at either low or high turbidities is consistent with the biological response of some species of corals to adopt two alternative mechanisms of functioning autotrophy and heterotrophy in response to different levels of turbidity sedimentation rates over periods of hours may reach the equivalent of 10 000 times the mean global background terrigenous flux btf of sediment to the sea floor i e 10 000 btf over three orders of magnitude greater than the holocene average for halifax bay of 3 btf as elsewhere along the nearshore zone of the central gbr dry season hydrodynamic conditions form a primary control upon turbidity and the distribution of bed sediments the location of modern nearshore coral reefs is controlled by the presence of suitable substrates which in halifax bay are pleistocene and early holocene coarse grained and relatively stable alluvial deposits

late holocene buried forests on the oregon coast deposits of late holocene beach sand buried conifer forests episodically emerge on beaches of the oregon coast simultaneously sand dunes buried late holocene forests growing on marine terraces landward of the beaches dune ramps up to 60 m in elevation connected the beach and dune deposits the average age of wood samples from stumps rooted on the shore platforms is 3 07 1 45 ka the average age of wood and charcoal samples embedded in forest soil on the marine terraces is 3 27 1 46 ka between 1994 and 2006 winter storm waves exposed more than 4 5 km2 of late holocene forest soil on shore platforms at 19 localities rooted stumps without soil were uncovered at an additional 14 localities once exposed wave action eroded the soil rapidly one to two years the intact forest soil and roots on the shore platforms must have been nearly continuously buried protected and preserved prior to recent exposure the late holocene buried forest provides the basis for a conceptual model of coastal evolution a three stage reversal of erosion and sand supply must have occurred 1 wave erosion switched to seaward advancement of forests 2 forest growth and soil development switched to burial beneath beach and dune sand and 3 burial and preservation switched to wave erosion truncation of dune ramps and landward retreat of sea cliffs copyright 2006 john wiley sons ltd

relative sea level records preserved in holocene beach ridge strandplains an example from tropical northeastern australia abstract northeastern queensland is a far field site from ice caps formed during the last glacial however the region has experienced glacio hydroisostatically driven coastal elevation change during the holocene that generated a distinctive relative sea level record we tested whether this subtle vertical movement of the coast is recorded in the morphology and stratigraphy of the beach ridge strandplain at cowley beach which comprises a series of 36 prominent and several subdued or truncated beach ridges previous studies have shown that the strandplain records the long term progradation of the coast with the ridges comprising coarse medium sand that was deposited during both fairweather foreshore and berm facies and tropical cyclone events erosional unconformities storm surge deposits over the past approximately 7 ka we utilised a fine scale digital elevation model of the strandplain to examine beach ridge morphology and to compare the elevation pattern with published holocene sea level data for the region the overall elevation pattern of the strandplain surface is consistent with the regional sea level history that includes a highstand at around 6 ka bp generated by isostatic uplift and the elevation of the berm facies matches well robust coral sea level indicator data we also modelled the strandplain topographic patterns that would result under stable and continually rising holocene sea levels the frequencies of elevation classes across the strandplain are normally distributed when the strandplain is deposited during a period of stable sea level and negatively skewed with a continually rising sea level consistent with the expected patterns the results indicate the sensitivity of the elevation of the top of the berm facies preserved in beach ridges to subtle changes in sea level tens of cm over a thousand years our results further underline the utility of beach ridge strandplains a globally distributed coastal landform for building relatively detailed regional records of sea level during the holocene at sites currently lacking this information

geology and depositional history of cenozoic sediments of the bengal basin of bangladesh abstract the bengal basin lies on the eastern side of the indian subcontinent and occupies the northern part of the bengal geosyncline sedimentation started with the breakup of gondwanaland cretaceous fluvial and deltaic sedimentation was slowly taken over by open marine and deep sea fan sedimentation by the mid eocene the basin was witnessing the maximum marine transgression and most of the stable shelf was in carbonate regime as part of the extended tethyan carbonate shelf the deeper part of the basin was dominated by deep sea fan sedimentation fed by clastic turbidites from the northeast with limited carbonate turbidites from the shelf the collision of the indian plate with the tibetan plate and with the burmese plate in the miocene resulted in a rapid switch in sedimentation pattern in the bengal basin the basin structure and sedimentation were both strongly influenced by the collision pattern of the plates and by the uplift of the himalayas with the miocene collision of the indian plate there was a change from flysch to molasse sedimentation the present day basin configuration with the ganges bramaputra delta on the north and the bengal deep sea fan on the south was established in the pliocene the stratigraphic and tectonic framework of the bengal basin suggest that the deposition of hydrocarbon source rocks was associated with the flysch sedimentation whereas formation of traps and deposition of most of the reservoir rocks in the basin was associated with mid pliocene tectonic movements and with the molasse sedimentation the pre mid miocene sediments now deeply buried in the deeper part of the bengal basin and in the eastern folded belt are the major source of gas of the eastern folded belt of the basin

late pleistocene and holocene sea level change in the australian region and mantle rheology summary spatial and temporal variations in sea level are produced by the melting of the late pleistocene ice and by the earth s response to the redistribution in surface loads by examining different parts of the sea level curves of the past 20 000 yr from geographically widely distributed regions it becomes possible to constrain models of the melting history of the ice sheets and of the earth s rheology observations from sites away from the former arctic ice sheets such as the australian and south pacific region are particularly important for constraining the total meltwater volumes added into the oceans in the past 20 000 yr and the rates at which this occurred these observations indicate that the antarctic ice sheets provided a significant contribution to the sea level rise at a rate that was approximately synchronous with the melting of the laurentide ice sheet except for the interval 9000 6000 yr ago when it may have lagged behind minor melting of the antarctic ice sheet appears to have continued throughout the late holocene differential observations of the late holocene sea level change recorded at sites in the same region are particularly useful for estimating parameters describing the earth s non elastic response to surface loading the effective parameters used here are a lithospheric thickness an upper mantle viscosity and a lower mantle viscosity describing the response below 670 km depth with the observations used here it is not possible to separate the lithospheric thickness h from the upper mantle viscosity and the viscosity results are based on the assumption that 50 h 100 km neither do these observations provide a resolution of the depth dependence of viscosity in the upper mantle and the resulting estimates are effective parameters only differential sea levels along continental margins and along the shores of large gulfs and bays constrain the effective upper mantle viscosity to be about 1 2 1020 pa s 1 while differential values from islands of different sizes are suggestive of a somewhat lower value the lower mantle taken to be below 670 km depth viscosity is about two orders of magnitude greater than this the estimated ice and rheological models explain many of the holocene sea level observations throughout the australian and southern pacific region the tilting of continental margins as exemplified by observations of variable amplitudes of the holocene high stands and the variable times at which sea levels first reached their present level along the north queensland coast and great barrier reef is well represented by these models differential holocene sea levels observed along the narrow spencers gulf of south australia are also well explained by the models and in neither case is it necessary to invoke tectonic motions predicted late holocene sea levels at small to medium sized islands are characterized by small amplitude high stands that reached their maximum values about 4000 2000 yr ago consistent with observations from the society cook and tuamotu islands

spatial analysis of surface deformation distribution detected by persistent scatterer interferometry in lanzhou region china persistent scatterer synthetic aperture radar interferometry ps insar is a remote sensing method that can be used to detect surface deformation which is an indicator of potential geohazards by capturing such deformations over time it is possible to obtain valuable information regarding geohazards such as landslides this study focused on the use of ps insar to investigate the distribution and causes of surface deformation in the lanzhou region of gansu province in china between 2003 and 2010 41 advanced synthetic aperture radar images were captured by the envisat satellite and analyzed using ps insar and the correlation between the observed surface deformation and topographic geologic and anthropogenic factors was derived based on a geographic information system platform it was found that the largest number and highest density of surface deformations occurred at elevations of 1486 1686 m it was also established that slope ranges of 25 30 and 35 40 are threshold values at which surface deformation changes abruptly and that slopes with north and northwest aspects are most prone to surface deformation the lithologies most susceptible to surface deformation are clay sandy soil and loess the normalized difference vegetation index indicated that surface deformation occurred most often in areas with sparse vegetation anthropogenic activities e g construction and wastewater discharge could be inferred as causal mechanisms of surface deformation comparison of the distributions of geohazards and surface deformation showed considerable consistency which proves surface deformation can induce geohazards these results could help governments improve urban planning and geohazard mitigation

a growing structure near the deformation front in sw taiwan as deduced from sar interferometry and geodetic observation 1 we apply the d insar technique to monitor the active growing structure on the tainan tableland near the deformation front in sw taiwan using ers sar images in the period of 1996 2000 interferometric processing of six sar images reveals the average slant range displacement srd to be 12 5 mm yr and it increases from the west edge of the tainan tableland and decreases across the houchiali fault the gps campaign data indicate an average horizontal movement of 12 4 mm yr in the direction of n44 w for the tainan tableland with respect to the western coastline five precise leveling surveys across the tainan tableland over two years show an uplift rate of 14 mm yr for the benchmarks on the tableland by combining the horizontal velocity of gps data and the srd of d insar we transfer the srd into vertical deformation and discuss the deformation pattern and seismic hazards in the tainan area

a new project to monitor land subsidence in the northern venice coastland italy the paper deals with the implementation of a levelling and global positioning system gps network to control land subsidence in the coastal area north of the venice lagoon about 480 km of levelling lines with 527 benchmarks 45 of which suited for differential gps measurements were established in 2004 a complete survey of the net was carried out in 2004 soon after its establishment the 2004 records have been compared with previous scattered data obtained by the use of levelling surveys dgps and sar interferometry the results show a trend in land settlement that increases from the lagoon margin to the north and jeopardize the venice coastland groundwater withdrawals for domestic agricultural and health spas uses peat oxidation of reclaimed marshlands for farming natural consolidation of the holocene deposits and tectonics of the pre quaternary basement are the causes of land subsidence in the study area since most of the area lies below the mean sea level and on account of the expected sea level rise due to global change a detailed monitoring of land displacements in the near future will be of paramount importance to plan necessary works for coastland protection

arctic ocean gravity geoid and sea ice freeboard heights from icesat and grace 1 icesat laser measurements provide a high resolution mapping of the sea ice surface of the arctic ocean which can be inverted to determine gravity anomalies and sea ice freeboard heights by a lowest level filtering scheme in this paper we use updated terrestrial gravity data from the arctic gravity project in combination with grace gravity field models to derive an improved arctic geoid model this model is then used to convert icesat measurements to sea ice freeboard heights with a coarse lowest level surface method the derived freeboard heights show a good qualitative agreement to the coverage of multi year sea ice however comparison to an airborne lidar underflight north of greenland shows that the lowest level filtering scheme may introduce a bias we finally use the icesat and grace results to derive new gravity anomalies by fourier inversion the satellite only gravity field shows all major tectonic features of the arctic ocean and has an accuracy of 6 mgal compared to recent airborne gravity data illustrating the usefulness of icesat data for gravity field determination

application of sar interferometry to a large thrust deformation the 1999 mw 7 6 chichi earthquake in central taiwan summary application of the interferometric method to four ers2 sar images acquired before and after the 1999 chichi earthquake has allowed determination of the coseismic surface displacement in the footwall area of the chelungpu fault the interferometric results revealed a relative shortening in the round trip distance between the radar antenna and the ground of the footwall side of chelungpu fault during the earthquake this shortening progressively increased from the west to the east and reaches the maximum amount of approximately 26 cm near the central segment of the chelungpu fault our interferometric results have been precisely examined using a dense gps network in the investigated area we mapped the gps coseismic measurements into the radar line of sight and implemented a forward simulation of sar interferogram from this synthesized result to control our unwrapping performance in this study these two observations are compared with a 3 d dislocation model of the fault finally a deformation analysis based on our interferometric result has indicated that a segment with irregular deformation behaviour can be distinguished in the footwall area of the chelungpu fault this segment may result from either the influence of inherited basement faults or the presence of a structural terrace that provide local opportunities for superficial deformation

spatial and temporal variability in the holocene sea level record of the south australian coastline abstract studies of past sea levels based on radiocarbon dated field samples suffer variously from compilation of information from disparate locations and the imprecise nature of the dated indicators geographic segregation and systematic elimination of poor samples from time depth data sets leads to improved interpretation of holocene sea level history an example is presented from southern australia where this is achieved through selection of higher resolution palaeoenvironmental indicators separation of transgressive from regressive populations and geographic regionalisation of data in southern australia fossil sea level indicators preserved in prograding coastal plain settings include seagrass sandflat mangrove samphire and chenier ridge organo sedimentary remains these provide sea level time depth data points with a variety of elevational and dating errors preserved organic remains at the transition from posidonia seagrass to intertidal sandflat environment and from sandflat to avicennia mangrove environment provide the most precise local data for tracing sea level change time depth plots of 233 dated sea level indicators from south australia generate a broad sea level envelope tracing the southern australian transgression from 10 000 to ca 6000 radiocarbon years bp followed by a more or less consistent level to the present finer details of sea level behaviour are only apparent after systematic selection separation and regionalisation of the data the data indicate a very rapid sea level rise in the early holocene at about 16 mm year reaching present levels at 6400 years bp this was followed by regionally variable regression and emergence of the land of 1 3 m a process that continues to the present the systematic increase from 1 to 3 m in the elevation of the 6400 year bp highstand with distance away from the shelf margin is consistent with a hydro isostatic origin for the emergence as predicted by geophysical models

evaluation of earthquake potential and surface deformation by differential interferometry abstract uncertainties in the length of active faults and the styles of deformation often hamper the evaluation of seismic potentials in a region in the area near chiayi city of southwestern taiwan where historically there have been many strong earthquakes complex fault and fold systems produced by regional tectonic forces and the subsequent deformation are frequently obscured by vegetation and anthropogenic effects and therefore detailed deformation information has not been available for evaluation of the seismic potential by stacking the results from differential interferometry and removing the ambiguity of interferograms using gps data we were able to retrieve surface deformation information about the area under consideration near chiayi city in our results we found that the meishan fault to the north of chiayi city extended 10 km to the west of its currently documented area and served as a geological boundary separating the northern part where sediments were thicker from the southern part of the westward extension of the meishan fault chiayi city was under active deformation by a double plunging fold with vertical uplift rate at approximately 1 cm yr frequent seismicity and active deformation allowed the tectonic stress to permute between strike slip and thrust in this area continuous folding of chiayi city and episodic large earthquakes along the meishan fault posed a serious threat of seismic hazards in this region and called for continuous monitoring of the area

geochemistry and detrital zircon u pb dating of pliocene pleistocene sandstones of the chittagong tripura fold belt bangladesh implications for provenance abstract the bengal basin originated during the collision of india with eurasia and burma the provenance analysis of the chittagong tripura fold belt ctfb which is the folded eastern flank of the bengal basin as well as the neogene belt of the indo burman ranges ibr is key to better understand the possible sources of sediment input from the complex interplay of the indian eurasian and burma plates we report new whole rock geochemical and detrital zircon u pb data from the upper neogene sandstones of tipam dupi tila formations pliocene to plio plestocene succession from the ctfb detrital zircon u pb age spectra show three predominant peaks at

coseismic deformation from the 2008 wenchuan china earthquake derived from alos palsar images abstract we analyzed alos palsar images along eight paths acquired before and after the mainshock of an earthquake in wenchuan in the sichuan province of china may 12 2008 we found entire coseismic deformation features and detected many fringes in an approximately 100 km wide region surrounding the longmen shan fault zone we found 6 7 broad elliptic fringes north of the epicenter which indicated around 70 80 cm increase in range distance between the ground and satellite this pattern corresponded to subsidence or eastward shift of ground which is often seen above the lower margin of a low angled thrust we also counted 8 9 fringes i e 90 100 cm range decrease between the fault zone and chengdu chengdu is located roughly 50 km away from the pengguan fault which is the southernmost trace of the longmen shan fault zone as this area is located on the footwall side the pattern suggested a westward shift of the earth s surface however we could not obtain high correlations due to large displacements in the about 240 km long belt along the surface faults several concentric fringes were found along the beichuan fault which is the central trace of the longmen shan fault zone this implied that the rupture process of this earthquake was complicated we also performed pixel matching to estimate offsets in the region of low correlation positive and negative range offsets larger than 2 m were found on the north and south sides of the beichuan fault respectively we observed a belt of negative range and azimuth offsets between the beichuan and pengguan faults we calculated an interferogram using a multi segment fault model with uniform slip along the beichuan and pengguan faults and estimated the slip distribution based on previous seismological studies we assumed that the southwestern part dipped toward the northwest by 33 degrees whereas the central and northeastern parts had a much steeper dip angle we found two regions of slips larger than 4 m in the southwest and central parts of the beichuan fault the pengguan segments may have much smaller slips around 1 m the southwestern segments of the beichuan fault and the entire pengguan fault had dominant thrust components whereas dextral slip prevailed in the central and northeastern segments of the beichuan fault the estimated geodetic moment was 5 87 1020nm mw 7 78

holocene sea levels in oceanic islands implications for the rheological structure of the earth s mantle abstract relative sea levels in oceanic islands that are situated sufficiently far from glaciated regions were studied in relation to the rheological structure of the earth s mantle the local hydro isostatic adjustment associated with the mantle flow from the oceanic side to an inland side depends on the size of the island the effective upper mantle viscosity and the elastic plate thickness the relative sea level has a significant dependence on the upper mantle rheology for islands with a radius larger than 10 km but it is almost independent of the upper mantle rheology for islands with a radius less than 10 km in other words the observed sea level changes in such small islands follow the global isostatic adjustment which depends strongly on the lower mantle viscosity in fact the relative sea levels in small oceanic islands impose important constraints on the lower mantle viscosity on the other hand the effective upper mantle viscosity and the elastic plate thickness are determined by analyzing the relative sea levels for islands greater than 10 km the observed sea level curves in japan and new zealand are consistent with the effective viscosity of the upper mantle equal to 2 to 6 10 21 poises the effective elastic plate thickness for japan and new zealand is estimated to be less than 50 km and greater than 100 km respectively the thickness of the lithosphere obtained by sea level curves in japan and new zealand is compatible with the results obtained by seismological studies

large sedimentation rate in the bengal delta magnetostratigraphic dating of cenozoic sediments from northeastern bangladesh a 4 3 km thick section of clastic sediments of the surma basin northeastern bangladesh that is exposed along the shari river was sampled for a magnetostratigraphic study miocene through pleistocene ages have been discussed previously however there has been no firm dating through biostratigraphy or radiometric or other methods primary paleomagnetic remanent magnetizations of normal or reversed polarity were determined for most of the 300 collected samples on the basis of assumptions of 1 constant sedimentation rates on average throughout the deposition of the sedimentary sequence 2 no major gaps in sedimentation and 3 a fairly young 2 ma age for the topmost dupi tila deposits we find good agreement between the measured profile and the geomagnetic polarity time scale if the entire sedimentary sequence is between 4 9 and 1 4 ma in age the upper marine shales an important seismic marker horizon are dated as 3 5 ma and are therefore 1 5 m y younger than previously assigned by biostratigraphic results the upper marine shales presumably correspond to the last pre pleistocene sea level highstand the dating of rock units below the upper marine shales is tentative because of a large gap in exposure the inferred sedimentation rate and thus the rate of delta subsidence of 1 2 m k y is much larger than previously assumed it appears to be one of the highest sedimentation rates in earth history that was sustained for millions of years

an overview of the sedimentary geology of the bengal basin in relation to the regional tectonic framework and basin fill history abstract the bengal basin in the northeastern part of indian subcontinent between the indian shield and indo burman ranges comprises three geo tectonic provinces 1 the stable shelf 2 the central deep basin extending from the sylhet trough in the northeast towards the hatia trough in the south and 3 the chittagong tripura fold belt due to location of the basin at the juncture of three interacting plates viz the indian burma and tibetan eurasian plates the basin fill history of these geo tectonic provinces varied considerably precambrian metasediments and permian carboniferous rocks have been encountered only in drill holes in the stable shelf province after precambrian peneplanation of the indian shield sedimentation in the bengal basin started in isolated graben controlled basins on the basement with the breakup of gondwanaland in the jurassic and cretaceous and northward movement of the indian plate the basin started downwarping in the early cretaceous and sedimentation started on the stable shelf and deep basin and since then sedimentation has been continuous for most of the basin subsidence of the basin can be attributed to differential adjustments of the crust collision with the various elements of south asia and uplift of the eastern himalayas and the indo burman ranges movements along several well established faults were initiated following the breakup of gondwanaland and during downwarping in the cretaceous by eocene because of a major marine transgression the stable shelf came under a carbonate regime whereas the deep basinal area was dominated by deep water sedimentation a major switch in sedimentation pattern over the bengal basin occurred during the middle eocene to early miocene as a result of collision of india with the burma and tibetan blocks the influx of clastic sediment into the basin from the himalayas to the north and the indo burman ranges to the east rapidly increased at this time and this was followed by an increase in the rate of subsidence of the basin at this stage deep marine sedimentation dominated in the deep basinal part while deep to shallow marine conditions prevailed in the eastern part of the basin by middle miocene with continuing collision events between the plates and uplift in the himalayas and indo burman ranges a huge influx of clastic sediments came into the basin from the northeast and east throughout the miocene the depositional settings continued to vary from deep marine in the basin to shallow and coastal marine in the marginal parts of the basin from pliocene onwards large amounts of sediment were filling the bengal basin from the west and northwest and major delta building processes continued to develop the present day delta morphology since the cretaceous architecture of the bengal basin has been changing due to the collision pattern and movements of the major plates in the region however three notable changes in basin configuration can be recognized that occurred during early eocene middle miocene and plio pleistocene times when both the paleogeographic settings and source areas changed the present basin configuration with the ganges brahmaputra delta system on the north and the bengal deep sea fan on the south was established during the later part of pliocene and pleistocene and delta progradation since then has been strongly affected by orogeny in the eastern himalayas pleistocene glacial activities in the north accompanied sea level changes in the bay of bengal

understanding the subsidence process of a quaternary plain by combining geological and hydrogeological modelling with satellite insar data the acque albule plain case study abstract this paper focuses on a multidisciplinary study carried out in an urban area affected by subsidence and related structural damages the study area is located about 20 km east of rome italy and is characterised by relevant groundwater exploitation for various purposes as well as by the presence of compressible soils immediately below the ground level extensive processing at different scales of sar satellite images ers and envisat provided by esa in the frame of a cat 1 project by means of a dinsar technique was performed the time histories of ground displacements have been analysed in combination with a detailed geological setting of the study area and with the hydrogeological changes occurred in the last decades as the response to the anthropic stress based on a large piezometric dataset this comprehensive dataset allowed us to describe the space and time distributions of the subsidence process the spatial pattern and deformation rate change is attributed to the following causes i the changes in the groundwater levels due to the intensification of mine exploitation requiring dewatering operations and ii the distribution and thickness of recent compressible deposits specifically it is derived that the groundwater level variations drive the timing of subsidence triggering over the area whereas the local geological conditions control the magnitude of the deformation process

a paleo brahmaputra subsurface lithofacies analysis of miocene deltaic sediments in the himalayan bengal system bangladesh abstract the bengal foreland basin contains a succession of up to 16 km of dominantly deltaic deposits eroded from the eastern himalayas and the indo burman ranges and carried by major river systems similar to the present day ganges and brahmaputra analysis of electric logs and core descriptions acquired during oil and gas exploration in bangladesh allows construction of lithofacies maps which constrain depositional patterns of miocene strata compilations of sand thickness and sand shale ratio of the miocene surma group show that lower to middle miocene strata of the bhuban formation accumulated in a large elongate trough sand thickness and percentage both decrease markedly away from this depocenter which describes a large scale bend running initially westward from rashidpur northeast bengal basin and curving southward toward the bengal fan middle to upper miocene strata of the boka bil formation show a similar geographic trend in deposition of coarsest and thickest sediment but the major depocenter had shifted northward relative to that of the bhuban formation by some 30 km passing near beani bazar these trends suggest that deltaic deposits of the surma group filled the sylhet trough of the northeast bengal basin from the east published seismic data from western bangladesh show that additional large channels also contributed materials to the bengal basin from the northwest during the late miocene but these channels resulted in very little accumulation in the northwestern part of the basin probably due to restricted subsidence of underlying continental crust this study suggests that there was a major drainage system similar to the modern brahmaputra river during miocene time which carried orogenic sediments eroded from the uplifted terranes of the eastern himalayas and indo burman ranges to the eastern bengal delta

geochemical investigation of the south wellesley island wetlands insight into wetland development during the holocene in tropical northern australia the south wellesley islands in the gulf of carpentaria northern australia were the recent focus of a palynological investigation which found vegetation change during the holocene was driven by coastal progradation and regional climate here we present new elemental data from x ray fluorescence core scanning which provides non destructive continuous and high resolution analysis from three wetlands across bentinck island the largest of the south wellesley islands elemental data and grain size analyses are combined with lead 210 210pb and accelerator mass spectrometry ams carbon 14 14c dates an open coastal environment was present 1250 cal a bp on the south east coast of bentinck island with sediment supply incorporating fluvial deposition and detrital input of titanium and iron from eroding lateritic bedrock prograding shorelines dune development and river diversion formed a series of swales parallel to the coast by 800 cal a bp forming the marralda wetlands wetlands developed at sites

alluvial gully erosion an example from the mitchell fluvial megafan queensland australia considerable attention has been focused on the role of gullies as a contributor to contemporary sediment loads of rivers in australia in southern australia rapid acceleration of hillslope gully erosion has been widely documented in the post european period last 200 years in the northern australian tropics however gully erosion processes operating along alluvial plains have not been well documented and can differ substantially from those gullies eroding into colluvium on hillslopes aerial reconnaissance surveys in 2004 along 13 500 km of the main stem rivers that drain into the gulf of carpentaria goc identified extensive areas of alluvial lands that have been impacted by a pervasive form of gully erosion more detailed remote sensing based mapping within the 31 000 km2 mitchell river fluvial megafan has identified that active gullying into alluvium occupies 0 4 129 km2 of the lower mitchell catchment these alluvial gullies are concentrated along main drainage channels and their scarp heights are highly correlated to the local relief between the floodplain and river thalweg while river incision into the megafan since the pleistocene has developed the relief potential for erosion other factors such as floodplain hydrology soil dispersibility and vegetation also influence the distribution of gullies in this paper we present a conceptual model of alluvial gullies and contend that they represent a distinct end member in the continuum of gully forms that have been described in the geomorphic literature an understanding of the processes driving this form of alluvial gullying can only be gained when they are differentiated from widely described colluvial hillslope gully models and theories we present evidence of type examples of alluvial gullying in the mitchell and through analysis of their distribution and morphology at different scales highlight some of the key mechanisms that are potentially initiating these features and driving their expansion copyright 2009 john wiley sons ltd

diagenesis and its impact on the reservoir quality of miocene sandstones surma group from the bengal basin bangladesh abstract rapid supply and deposition of 1000 s of meters of miocene and pliocene sediment tend to lead to a different set of controls on reservoir quality than older more slowly buried sandstones here we have studied miocene fluvial deltaic bhuban formation sandstones from the surma group bengal basin buried to 3 000 m and 110 c using a combination of petrographic geochemical and petrophysical methods in order to understand the controls on miocene sandstone reservoir quality to facilitate improved prediction of porosity and permeability the main conclusions of the study are that mechanical compaction processes are the dominant control on porosity loss although early calcite growth has led to locally negligible porosity in some sandstones mechanical compaction occurred by grain rearrangement ductile grain compaction and brittle grain fracturing calcite cement occupying up to 41 intergranular volume was derived from a combination of dissolved and recrystallized bioclasts an influx of organic derived carbon dioxide and plagioclase alteration clay minerals present include smectite illite kaolinite and chlorite the smectitic clay was probably restricted to low energy depositional environments and it locally diminishes permeability disproportionate to the degree of porosity loss kaolinite is probably the result of feldspar alteration resulting from the influx of organic derived carbon dioxide quartz cement is present in small amounts despite the relatively high temperature due to a combination of limited time available in these young sandstones grain coating chlorite and low water saturations in these gas bearing reservoir sandstones reservoir quality can now be predicted by considering primary sediment supply and primary depositional environment the magnitude of the detrital bioclast fraction and the influx of organic derived carbon dioxide

u series dates of great barrier reef corals suggest at least 0 7 m sea level 7000 years ago strong evidence from field observation and high precision tims u series dating of exposed in situ massive corals and exposed microatolls on magnetic island great barrier reef indicates that the relative sea level was at least 0 7 m higher than present 7000 calendar years cal yr ago and culminated to at least 1 6 m higher than present 5800 cal yr ago the present sea level was probably first reached around 7300 7100 cal yr ago together with the youngest age 2236 27 cal yr of an exposed microatoll colony the data suggest past sea level highstands occurred between 7200 and 2200 cal yr ago lasting for 5000 years this study represents the first attempt to date sea level indicators from the great barrier reef by the high precision u series method the results are broadly consistent with a sea level reconstruction based on a compilation and re examination of 115 calibrated 14c dates from eastern australia by lewis et al 2008

coral reefs and sea level change abstract coral reefs provide significant evidence for former sea level positions because of their geological preservation and suitability for dating interpretation of this evidence presumes an understanding of reef geomorphology modern reef organism distributions and environmental factors influencing them fossil reef terraces formed during the last interglacial marine oxygen isotope mis substage 5e 128 116 ka are prevalent on many tropical shorelines and there has been ongoing debate as to the height reached by sea level during that highstand observations from numerous last interglacial sites suggest that sea level was at least 3 m above present sea level implying less extensive icesheets than at present an elevation of 6 m has commonly been adopted when correcting tectonically active sites for uplift recent compilations suggest elevations up to 8 9 m but incorporate few observations from reefs where the last interglacial is found below sea level oscillation of sea level during mis 5e has been interpreted from several sites with recent studies inferring rapid rise of several metres at the end of the interglacial these interpretations are at the limits to the precision with which corals can currently be dated and their palaeo water depths inferred it is not surprising that constraining last interglacial sea level changes within uncertainties of less than 1 2 m remains controversial considering sea level variations recognised between reef sites in the holocene and observed geographical variation in isostatic or flexural adjustments fossil coral reefs on uplifting margins also provide clear evidence for mis substages 5c and 5a and those on huon peninsula indicate fluctuations related to heinrich events mis 3 interpretations show considerable variability between sites with still greater uncertainties about sea level timing and elevation during previous interglacials future study of extensive sequences of fossil reefs preserved on rapidly subsiding margins could address these uncertainties submerged reefs have already yielded important information about sea level rise during the last deglaciation coring around barbados and tahiti as well as on the huon peninsula has produced a broadly consistent picture of ice melt reflecting eustatic change since the last glacial maximum these studies have shown the sensitivity of reefs to rapid sea level rise associated with meltwater pulses with some reefs drowning while others back stepped integrated ocean drilling program iodp expeditions to tahiti and recently the great barrier reef extended these records but details of timing nature and impact of deglacial meltwater pulses remain elusive studies of holocene reefs have indicated different growth strategies some kept up with sea level while others caught up when sea level decelerated holocene sea level appears to have experienced a gradual rise up to present across the caribbean providing accommodation space for reefs to accrete vertically whereas in the indo pacific sea level has been near its present level since 7 ka with many reef flats emergent following a slight fall of sea level caused by ocean siphoning microatolls on reef flats provide perhaps the clearest evidence of past sea level position but in their absence novel biological or other sea level indicators are required to better constrain palaeo water depths there is an urgent need for further research from additional key reef locations not only to decipher processes driving past sea level change and its geographical variability but also to better understand how coral reefs will respond in the context of future sea level rise

sar monitoring of progressive and seasonal ground deformation using the permanent scatterers technique spaceborne differential radar interferometry has proven a remarkable potential for mapping ground deformation phenomena e g urban subsidence volcano dynamics coseismic and postseismic displacements along faults as well as slope instability however a full operational capability has not been achieved yet due to atmospheric disturbances and phase decorrelation phenomena these drawbacks can often be at least partially overcome by carrying out measurements on a subset of image pixels corresponding to natural or artificial stable reflectors permanent scatterers ps and exploiting long temporal series of interferometric data this approach allows one to push the measurement precision very close to its theoretical limit in the order of spl sim 1 mm for c band european remote sensing ers like sensors in this paper the detection of both time uniform and seasonal deformation phenomena is addressed and a first assessment of the precision achievable by means of the ps technique is discussed results highlighting deformation phenomena occurring in two test sites in california are reported fremont in the southern bay area and san jose in the santa clara valley

fault creep along the southern san andreas from interferometric synthetic aperture radar permanent scatterers and stacking 1 interferometric synthetic aperture radar insar provides a practical means of mapping creep along major strike slip faults the small amplitude of the creep signal 10 mm yr combined with its short wavelength makes it difficult to extract from long time span interferograms especially in agricultural or heavily vegetated areas we utilize two approaches to extract the fault creep signal from 37 ers sar images along the southern san andreas fault first amplitude stacking is utilized to identify permanent scatterers which are then used to weight the interferogram prior to spatial filtering this weighting improves correlation and also provides a mask for poorly correlated areas second the unwrapped phase is stacked to reduce tropospheric and other short wavelength noise this combined processing enables us to recover the near field 200 m slip signal across the fault due to shallow creep displacement maps from 60 interferograms reveal a diffuse secular strain buildup punctuated by localized interseismic creep of 4 6 mm yr line of sight los 12 18 mm yr horizontal with the exception of durmid hill this entire segment of the southern san andreas experienced right lateral triggered slip of up to 10 cm during the 3 5 year period spanning the 1992 landers earthquake the deformation change following the 1999 hector mine earthquake was much smaller 1 cm and broader than for the landers event profiles across the fault during the interseismic phase show peak to trough amplitude ranging from 15 to 25 mm yr horizontal component and the minimum misfit models show a range of creeping locking depth values that fit the data

transient deformation induced by groundwater change in taipei metropolitan area revealed by high resolution x band sar interferometry abstract we present precise deformation velocity maps for the two year period from september 2011 to july 2013 of the northern taiwan area taipei by using persistent scatterer interferometry psi technique for processing 18 high resolution x band synthetic aperture radar sar images archived from cosmo skymed csk constellation according to the result the highest subsidence rates are found in luzou and wuku area in which the rate is about 15 mm yr and 10 mm yr respectively in the whole dataset however dramatic change from serve subsidence to uplift in surface deformation was revealed in the taipei basin in two different time spans 2011 09 2012 09 and 2012 09 2013 07 this result shows good agreement with robust continuous gps measurement and precise leveling survey data across the central taipei basin moreover it also represents high correlation with groundwater table from 8 well data in the taipei basin the storativity is roughly constant across most of the aquifer with values between 0 5 10 4 and 1 6 10 3 in jingmei formation and 0 8 10 4 and 1 4 10 3 in wuku formation this high correlation indicated that one meter groundwater level change could induce about 9 and 16 mm surface deformation change in luzou and wuku area respectively which is about eight times faster the long term tectonic deformation rate in this area thus to access the activity of the shanchiao fault it is important to discriminate tectonic movement from anthropogenic or seasonal effect in the taipei basin to better understand the geohazards and mitigation in the taipei metropolitan area