latest miocene to quaternary horizontal and vertical displacement rates during simultaneous contraction and extension in the southern apennines orogen italy foreland contraction and hinterland extension in the southern apennines orogen of italy produced a complex spatial and temporal pattern of vertical and horizontal displacement remarkably late miocene to mid pleistocene foreland migration of the contractional front at 16 mm yr 1 was not accompanied by uplift and the frontal thrust belt remained at or below sea level only following a mid pleistocene reduction in horizontal displacement did the frontal thrust belt and foreland begin uplift at 0 5 mm yr 1 a rate that increased to 1 mm yr 1 after 125 ka although the extensional hinterland experienced net subsidence during formation of the tyrrhenian basin an extensional transition zone adjacent to the frontal thrust belt records sustained uplift at 0 3 mm yr 1 the interaction of preexisting crustal structure and deep tectonic processes resulted in time integrated displacement rates suggesting steady state deformation for periods of 106 years displacement rate changes were abrupt and occurred over intervals of 105 years or less

insar reveals coastal subsidence in the pearl river delta china summary the pearl river delta prd is one of the most important economic regions with the highest population densities in china with its dramatic increasing population and economy hazards associated with land subsidence frequently occur here that amplify the negative effect of sea level rise however land subsidence has not been regularly measured in this region here we use interferometric synthetic aperture radar insar to investigate the rate and extent of land subsidence in the prd region assuming purely vertical displacements multi track interferograms from different viewing geometries are combined to estimate the linear rate map and time series at a higher resolution in time than is possible with a single track the results show apparent subsidence along the coastal region of shenzhen associated with rapid urban development in recent years the average subsidence rate within 500 m of the coast is about 2 5 mm yr 1 and the maximum is up to about 6 mm yr 1 with respect to the central part of the city much of the land surface in the prd is less than 2 m above mean sea level high precision geodetic measurements throughout the prd region are therefore critical for conducting risk assessments considering the rate of about 2 3 mm yr 1 of current global sea level rise

source parameters and fault plane determinations of the 28 december 1999 northeastern cairo earthquakes abstract the velocity records of the 28 december 1999 northeastern cairo egypt earthquake sequence have been analyzed for relocation focal mechanism source parameters and rupture directivity a cross correlation analysis was performed to recognize the waveform similarity and to obtain relative location on the basis of small time delays between first arrivals the three events exhibit good correlation and similarity in focal mechanisms actually the fault plane solutions display normal faulting with strike slip component dynamic source parameters were estimated for the three events using p wave spectrum for 21 selected seismograms at the seven nearest stations the corner frequency fo low frequency amplitude o and the average attenuation path were simulated by nonlinear least square best fitting the mean of the obtained values shows that the mainshock occurred on a fault length of 822 m with relative displacement of 51 cm seismic moment of 5 59 1015 n m and stress drop of 5 9 mpa the azimuthal variation of the obtained low frequency spectrum amplitude was used to estimate the rupture velocity and direction the mean rupture velocity estimated to be eight tenths of the local shear wave velocity as well as the azimuthal variation provides an indication for the rupture directivities of the three events that are of 175 5 estimated rupture directions were incorporated with p wave focal mechanisms to identify the actual fault planes of these events therefore the preferred fault planes are those that have the strike of 137 148 and 132 dip of 59 45 and 51 and rake of 39 33 and 45 respectively in this case the slip component in strike direction indicates a left lateral motion along the nw fault the obtained results imply the reactivation of the oligocene deep seated faults in the gulf of suez red sea trend nw se

new model of reef island evolution maldives indian ocean a new model of reef island evolution based on detailed morphostratigraphic analysis and radiometric dating of three islands in south maalhosmadulu atoll maldives is presented islands initially formed on a foundation of lagoonal sediments between 5500 and 4500 yr b p when the reef surface was as much as 2 5 m below modern sea level islands accumulated rapidly during the following 1500 yr effectively reaching their current dimensions by 4000 yr b p since then the high circum island peripheral ridge has been subject to seasonal and longer term shoreline changes while the outer reef has grown upward reducing the energy window and confining the islands this new model has far reaching implications for island stability during a period of global warming and raised sea level which will partially reactivate the energy window although it is not expected to inhibit upward reef growth or compromise island stability

modes of fault reactivation from analogue modeling experiments implications for the seismotectonics of the southern adriatic foreland italy abstract the active tectonics at the front of the southern apennines and in the adriatic foreland is characterized by e w striking right lateral seismogenic faults interpreted as reactivated inherited discontinuities the best studied among these is the molise gondola shear zone mgsz the interaction of these shear zones with the apennines chain is not yet clear to address this open question we developed a set of scaled analogue experiments aimed at analyzing 1 how dextral strike slip motion along a pre existing zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge 2 the propagation of deformation as a function of increasing displacement 3 any insights on the active tectonics of southern italy our results stress the primary role played by these inherited structures when reactivated and confirm that regional e w dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the southern apennines

late quaternary reef growth and sea level in the maldives indian ocean abstract based on rotary drilling and radiometric and u series dating we present the first comprehensive data on holocene reef anatomy and sea level rise as well as nature and age of underlying pleistocene limestone in the maldives holocene reefs in rasdhoo atoll central maldives are composed of four facies including 1 robust branching coral facies 2 coralline algal facies 3 domal coral facies and 4 detrital sand and rubble facies branching coral and coralline algal facies predominate the marginal reefs and domal corals and detrital facies preferentially occur in a lagoon reef in addition microbialite crusts are found in lower core sections of marginal reefs microbialites formed during the early holocene in reef cavities holocene reef thickness ranges from 14 5 m to 22 m reef growth started as early as 8 5 kyr bp marginal reefs accreted in the keep up mode with rates of 15 m kyr rate of sea level rise significantly slowed down from 7 6 kyr bp and subsequently gradually rose with rates

monitoring landslides and tectonic motions with the permanent scatterers technique spaceborne differential synthetic aperture radar interferometry dinsar has already proven its potential for mapping ground deformation phenomena e g volcano dynamics however atmospheric disturbances as well as phase decorrelation have prevented hitherto this technique from achieving full operational capability these drawbacks are overcome by carrying out measurements on a subset of image pixels corresponding to pointwise stable reflectors permanent scatterers ps and exploiting long temporal series of interferometric data results obtained by processing 55 images acquired by the european space agency esa ers sar sensors over southern california show that the ps approach pushes measurement accuracy very close to its theoretical limit about 1 mm allowing the description of millimetric deformation phenomena occurring in a complex fault system a comparison with corresponding displacement time series relative to permanent gps stations of the southern california integrated gps network scign is carried out moreover the pixel by pixel character of the ps analysis allows the exploitation of individual phase stable radar targets in low coherence areas this makes spaceborne interferometric measurements possible in vegetated areas as long as a sufficient spatial density of individual isolated man made structures or exposed rocks is available the evolution of the ancona landslide central italy was analysed by processing 61 ers images acquired in the time span between june 1992 and december 2000 the results have been compared with deformation values detected during optical levelling campaigns ordered by the municipality of ancona the characteristics of ps gps and optical levelling surveying are to some extent complementary a synergistic use of the three techniques could strongly enhance quality and reliability of ground deformation monitoring d 2002 elsevier science b v all rights reserved

paleoseismic evidence of legendary earthquakes the apparition of archangel michael at monte sant angelo italy abstract the gargano promontory a carbonate massif belonging to the adria microplate the foreland of both the apenninic and dinaric mountain chains is a well known seismogenic area with historic earthquake up to i max x mcs july 30 1627 m 6 7 nevertheless paleoseismic data on the region are still scarce and no trench fault stratigraphy has been analysed along the major e w trending right lateral strike slip fault system that cuts through the whole massif the south gargano line sgl the over 60 km long on shore trace of the sgl the mattinata fault is clearly segmented this study focused on the eastern active fault segment the monte sant angelo fault msa to verify the associated seismic potential analysis of contemporary descriptions of the august 10 1893 earthquake m 5 2 coupled with field work allowed identification of surface faulting along the msa along the fault there is paleoseismic evidence of the occurrence of larger earthquakes after collecting geomorphic evidence of paleo earthquakes we selected two trench sites at the base of two prominent fault escarpments where the msa is characterized by significant vertical components of fault displacement the preliminary results demonstrate that i the recent vertical slip rate of the msa range between 0 2 0 3 and 0 7 mm yr ii the msa moves with incremental slip episodes with vertical surface offset up to several decimeters iii based on the stratigraphic and geomorphic evidence of surface faulting observed and assuming a rupture length of around 20 km the seismic potential of the msa segment would be similar to that displayed by the western sgl segment during the 1627 event a large earthquake on the msa is reported only in ancient legends the most relevant of which being the one describing the apparition of archangel michael at monte sant angelo traditionally dated ad 493 using a multidisciplinary approach combining paleoseismic and historical data it has been possible to interpret the legend and hereby identify an event of surface faulting before 8th century ad a recent scarplet up to 1 m high on the msa can be seen to be related to this legendary earthquake which in turn seems to correspond to the maximum possible magnitude geologic phenomena observed during the earthquake at the site of the sanctuary appear to lie at the very origin of the veneration of the place

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

co seismic displacements associated to the molise southern italy earthquake sequence of october november 2002 inferred from gps measurements abstract the 2002 earthquake sequence of october 31 and november 1 main shocks mw 5 7 struck an area of the molise region in southern italy in this paper we analyzed the co seismic deformation related to the molise seismic sequence inferred from gps data collected before and after the earthquake that ruptured a rather deep portion of crust releasing a moderate amount of seismic energy with no surface rupture the gps data have been reduced using two different processing strategies and softwares bernese and gipsy to have an increased control over the result accuracy since the expected surface displacements induced by the molise earthquake are in the order of the gps reliability the surface deformations obtained from the two approaches are statistically equivalent and show a displacement field consistent with the expected deformation mechanism and with no rupture at the surface in order to relate this observation with the seismic source an elastic modeling of fault dislocation rupture has been performed using seismological parameters as constraints to the model input and comparing calculated surface displacements with the observed ones the sum of the seismic moments 8 9 1017 nm of the two main events have been used as a constraint for the size and amount of slip on the model fault while its geometry has been constrained using the focal mechanisms and aftershocks locations since the two main shocks exhibit the same fault parameters strike of the plane dip and co seismic slip we modelled a single square fault size of 15 km 15 km assumed to accommodate the whole rupture of both events of the seismic sequence a vertical e w trending fault strike 266 has been modeled with a horizontal slip of 120 mm sensitivity tests have been performed to infer the slip distribution at depth the comparison between gps observations and displacement vectors predicted by the dislocation model is consistent with a source fault placed between 5 and 20 km of depth with a constant pure right lateral strike slip in agreement with fault slip distribution analyses using seismological information the gps strain field obtained doesn t require a geodetic moment release larger than the one inferred from the seismological information ruling out significant post seismic deformation or geodetic deformation released at frequencies not detectable by seismic instruments the molise sequence has a critical seismotectonic significance because it occurred in an area where no historical seismicity or seismogenic faults are reported the focal location of the sequence and the strike slip kinematics of main shocks allow to distinguish it from the shallower and extensional seismicity of the southern apennines being more likely related to the decoupling of the southern adriatic block from the northern one

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

tectonic contraction across los angeles after removal of groundwater pumping effects after the 1987 whittier narrows and 1994 northridge earthquakes revealed that blind thrust faults represent a significant threat to metropolitan los angeles a network of 250 continuously recording global positioning system gps stations was deployed to monitor displacements associated with deep slip on both blind and surface faults here we augment this gps data with interferometric synthetic aperture radar imagery to take into account the deformation associated with groundwater pumping and strike slip faulting after removing these non tectonic signals we are left with 4 4 mm yr 1 of uniaxial contraction across the los angeles basin oriented n 36 degrees e perpendicular to the major strike slip faults in the area this indicates that the contraction is primarily accommodated on thrust faults rather than on the northeast trending strike slip faults we have found that widespread groundwater and oil pumping obscures and in some cases mimics the tectonic signals expected from the blind thrust faults in the 40 km long santa ana basin groundwater withdrawal and re injection produces 12 mm yr 1 of long term subsidence accompanied by an unprecedented seasonal oscillation of 55 mm in the vertical direction and 7 mm horizontally

on the origin of late holocene sea level highstands within equatorial ocean basins abstract late holocene sea level highstands of amplitude 3 m are endemic to equatorial ocean basins these highstands imply an ongoing and moderate sub mm yr sea level fall in the far field of the late pleistocene ice cover that has long been linked to the process of glacial isostatic adjustment gia clark et al 1978 mitrovica and peltier 1991 coined the term equatorial ocean syphoning to describe the gia induced sea level fall and they provided the first physical explanation for the process they argued that water migrated away from far field equatorial ocean basins in order to fill space vacated by collapsing forebulges at the periphery of previously glaciated regions we provide a complete physical explanation for the origin of equatorial ocean syphoning and the associated development of sea level highstands using numerical solutions of the equation that governs meltwater redistribution on spherical viscoelastic earth models in particular we separate the total predicted sea level change into contributions associated with ice and meltwater loading effects and by doing so isolate a second mechanism that contributes significantly to the ocean syphoning process ocean loading at continental margins induces a levering of continents and a subsidence of offshore regions that has also long been recognized within the gia literature walcott 1972 we show that the influx of water into the volume created by this subsidence produces a sea level fall at locations distant from these margins indeed over the major ocean basins that is comparable in amplitude to the syphoning mechanism isolated by mitrovica and peltier 1991

the october november 2002 molise seismic sequence southern italy an expression of adria intraplate deformation a new seismotectonic model for the outer central southern apennines including the epicentral area of the 2002 molise seismic sequence and adjacent foreland is proposed the seismic sequence is related to foreland deformation affecting the adriatic lithosphere such deformation is characterized by active nw se compression resulting in the reactivation mainly as dextral strike slip faults of pre existing east west oriented structures both offshore and onshore one of these structures is interpreted to extend westward and to reach the epicentral area of the recent earthquakes nw se compression ultimately related with africa europe plate convergence and uplift would essentially control the active tectonics of the analysed region

holocene reef growth in the maldives evidence of a mid holocene sea level highstand in the central indian ocean radiometrically calibrated ages from three reef cores are used to develop a holocene reef growth chronostratigraphy and sea level history in the maldives central indian ocean last interglacial reef u series age 122 7 ka was encountered at 14 1 m below mean sea level an age of ca 8100 calibrated cal yr b p immediately overlying this pleistocene surface records the initiation of holocene reef growth massive in situ corals occur throughout the cores and the consistency of the three age depth plots indicate that the reef grew steadily between 8100 and 6500 cal yr b p and at a decreasing rate for the next 2 k y the position of modern sea level was first achieved ca 4500 cal yr b p and sea level reached at least 0 50 1 m higher from 4000 to 2100 cal yr b p before falling to present level emergent fossil microatolls provide evidence of this higher sea level results are significant to two long standing issues relating to maldivian sealevel history first the ambiguity of a late holocene highstand has been resolved with clear evidence of its existence reported here second the uncertainty of the regional pattern of sea level change in the central indian ocean has been clarified the maldivian results broadly agreeing with island records in the eastern rather than western indian ocean our results provide the first field evidence confirming geophysical model projections of a highstand 4 2 k y ago in the central indian ocean though the observed level 0 50 0 1 m is lower than that projected

the italian cmt dataset from 1977 to the present abstract the ingv harvard european mediterranean regional centroid moment tensor rcmt catalog collects solutions routinely computed since 1997 for earthquakes with moderate magnitude 4 5 m 5 5 in the mediterranean region the database represents an extension to smaller magnitudes of the harvard global cmt catalog based on analysis of seismograms recorded at regional distance and modeling of intermediate period surface waves the catalog includes about 600 events 200 of which in the italian region this study extends the catalog back in time for the italian region as long as made possible by available digital data i e since 1977 with the same analysis and inversion method used for current seismicity as a result we present here 65 new moment tensors for years between 1977 and 1997 these solutions represent 45 of the total number of events analyzed the existing seismograms being often too scarce to allow a stable solution the new dataset includes events in many seismic zones where moderate seismicity had previously been scarcely documented e g the po plain the central to southern apennines and the adriatic sea the complete dataset including previously determined rcmts and cmts represents the seismic deformation in the italian area during the last 25 years

seismotectonics of the southern apennines and adriatic foreland insights on active regional e w shear zones from analogue modeling 1 the active tectonics at the front of the southern apennines and in the adriatic foreland is characterized by e w striking right lateral seismogenic faults interpreted as reactivated inherited discontinuities the best studied among these is the molise gondola shear zone the interaction of these shear zones with the apennines chain is not yet clear to address this open question we developed a set of scaled analogue experiments aimed at analyzing 1 how dextral strike slip motion along a preexisting zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge 2 the propagation of deformation as a function of displacement and 3 any insights on the active tectonics of southern italy our results stress the primary role played by these inherited structures when reactivated and confirm that regional e w dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the southern apennines

scenarios of earthquake generated tsunamis for the italian coast of the adriatic sea we calculated the expected impact on the italian coast of the adriatic sea of a large set of tsunamis resulting from potential earthquakes generated by major fault zones our approach merges updated knowledge on the regional tectonics and scenario like calculations of expected tsunami impact we selected six elongated potential source zones for each of them we determined a maximum credible earthquake and the associated typical fault described by its size geometry and kinematics we then let the typical fault float along strike of its parent source zone and simulated all tsunamis it could generate simulations are based on the solution of the nonlinear shallow water equations through a finite difference technique for each run we calculated the wavefields at specified simulation times and the maximum water height field above mean sea level then generated travel time maps and maximum water height profiles along the target coastline maxima were also classified in a three level code of expected tsunami threat we found that the southern portion of apulia facing albania and the gargano promontory are especially prone to the tsunami threat we also found that some bathymetric features are crucial in determining the focalization defocalization of tsunami energy we suggest that our results be taken into account in the design of early warning strategies

permanent scatterer insar reveals seasonal and long term aquifer system response to groundwater pumping and artificial recharge received 4 may 2007 revised 30 july 2007 accepted 10 october 2007 published 5 february 2008 1 permanent scatterer insar psinsark p rovides an ew high resolution methodology for detecting and precisely measuring long term and seasonal aquifer system response to pumping and recharge in contrast to conventional insar the permanent scatterer methodology utilizes coherent radar phase data from thousands of individual radar reflectors on the ground to develop displacement time series and to produce velocity field maps that depict aquifer system response with a high degree of spatial detail in this study we present the first results of a prototype study in las vegas valley nevada that demonstrate how this methodology can be utilized in heavily pumped groundwater basins to analyze aquifer system response to long term and seasonal pumping we have developed a series of velocity field maps of the valley for the 1992 1996 1996 2000 and 2003 2005 time periods that show that despite rising water levels associated with an artificial recharge program long term residual inelastic aquifer system compaction subsidence is continuing in several parts of the valley in other areas however long term subsidence has been arrested and locally reversed the seasonal elastic responses to alternating pumping and recharge cycles were segregated from the long term trends and analyzed for spatial and temporal patterns the results show oscillations in which the maximum seasonal responses are associated with the late stages of the annual artificial recharge cycles and that similar seasonal subsidence signals are related to summer pumping cycles the differentiation of the seasonal response through the use of time series data further allows the estimation of elastic and inelastic skeletal storage coefficients providing a basis for future work that could characterize the storage properties of an aquifer system with a high degree of spatial resolution

strain accumulation across the gazikoy saros segment of the north anatolian fault inferred from persistent scatterer interferometry and gps measurements abstract we use a combination of persistent scatterer interferometry psi and gps observations to study interseismic crustal deformation on the gazikoy saros segment ganos fault of the north anatolian fault naf zone northwestern turkey the data include 44 c band radar images collected by the ers1 and ers2 satellites in descending orbits between 1992 and 2003 over the study area and campaign gps horizontal velocities from 7 stations the resultant secular velocity field is inverted using a nonlinear minimization algorithm to estimate parameters of two interseismic deformation models aseismic deep slip in a purely elastic earth model elastic half space rheology and viscoelastic flow in an elastic viscoelastic earth model viscoelastic coupling rheology the following conclusions are drawn 1 the fault locking depth is estimated in the range of 8 17 km 95 confidence interval regardless of the rheological model 2 the elastic half space model implies an upper bound of 20 27 mm yr for the slip rate on the ganos fault 3 models incorporating viscoelastic rheology and seismic cycle effects suggest a lower slip rate of 18 24 mm yr which agrees more closely with geological estimates however these values are slightly sensitive to the assumed earthquake recurrence interval 4 a bootstrap analysis of deformation data yields average crust upper mantle viscosities of 1 3 10 19 3 6 10 20 pa s for the ganos area

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

structural analysis and miocene to present tectonic evolution of a lithospheric scale transcurrent lineament the sciacca fault sicilian channel central mediterranean sea abstract seismo stratigraphic and structural analysis of a large number of multichannel seismic reflection profiles acquired in the northern part of the sicilian channel allowed a 3 d reconstruction of a regional ns trending transfer zone which displays a transcurrent tectonic regime and that is of broad relevance for its seismotectonic and geodynamic implications it is constituted of two major transcurrent faults delimiting a 30 km wide mostly undeformed basin the western fault capo granitola does not show clear evidence of present day tectonic activity and toward the south it is connected with the volcanic area of the graham bank the eastern fault sciacca is structurally more complex showing active deformation at the sea floor particularly evident along the nerita bank the sciacca fault is constituted of a master and splay faults compatible with a right lateral kinematics sciacca fault is superimposed on an inherited weakness zone a mesozoic carbonate ramp which borders to the east a 2 5 km thick plio quaternary basin and that was reactivated during the pliocene a set of scaled claybox analogue models was carried out in order to better understand the tectonic processes that led to the structural setting displayed by seismic data tectonic structures and uplift subsidence patterns generated by the models are compatible with the 3 d model obtained from seismic reflection profiles the best fit between the tectonic setting deriving from the interpretation of seismic profiles and the analogue models was obtained considering a right lateral movement for the sciacca fault nevertheless the stress field in the study area derived from gps measurements does not support the present day modelled right lateral kinematics along the sciacca fault moreover seismic events along this fault show focal mechanisms with a left lateral component we ascribe the slip change along the sciacca fault from a right lateral transcurrent regime to the present day left lateral kinematics to a change of principal horizontal stress direction starting from late pliocene

source analysis of the 2002 molise southern italy twin earthquakes 10 31 and 11 01 1 on october 31 2002 a moderate size earthquake mw 5 8 occurred in molise region southern italy causing loss of young human lives in a school collapse and destructions in several villages the day after a slightly smaller earthquake happened a few kilometers westward from the first one without making strong damage we use a complete set of seismological data global regional and local including both body and surface waves to better understand the source process of these two events we show that the two earthquakes are similar in terms of hypocentral depth focal mechanism and source kinematics moreover the imaged slip zones are almost contiguous which makes the time delay between the two shocks 29 hours an open question the identified updip rupture propagation has amplified the radiation usually created by such mw 5 8 earthquakes at 15 20 km depth we model a maximum acceleration zone in agreement with location of damaged villages

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

influence of erosion and sedimentation on strike slip fault systems insights from analogue models abstract we describe 18 experiments on the formation of strike slip fault systems in sand all models were in a rectangular box a piston imparted strike slip motion along a basal cut in some experiments uplifted areas underwent erosion in others all areas were subject to sedimentation in experiments without erosion or sedimentation first to develop were r faults at 16 to the basal cut at later stages p faults and y faults took over in section faults splayed upward forming flower structures the splays had reverse components of slip this was due to dilation which reached 7 within fault splays in experiments with erosion but no sedimentation faults were less steep and accumulated greater amounts of reverse slip in experiments with erosion and sedimentation some faults propagated through their syn kinematic cover others became buried and inactive whilst yet others were exposed by erosion therefore the average fault dip increased significantly in experiments with sedimentation but no erosion early faults propagated whereas others became buried flower structures in nature have similar features in areas of sedimentation fault splays with gentle dips die out at depth whereas steeper faults penetrate higher in areas of erosion strike slip systems exhibit large amounts of reverse slip on steep bounding faults

quaternary geomorphological evolution of the tremiti islands puglia italy abstract the archipelago of the tremiti islands situated in the centre of the adriatic sea is considered nationally and internationally a very important geological laboratory in the area of connection between the central and southern apennines already rich in cenozoic stratigraphic structural and seismological data this study discusses structural geomorphologic data with particular attention to features useful to define the islands quaternary evolution the identification of the main morphogenic events is based on the study of landforms that are spatially and chronologically comparable with depositional erosional features of the quaternary continental succession analysis of geomorphology and quaternary continental deposits supported by radiometric dating allows reconstruction of the islands quaternary evolution and provides some contributions at a regional scale

sea level and coral atolls late holocene emergence in the indian ocean the cocos keeling islands in the eastern indian ocean were visited by charles darwin who described geomorphological evidence that he considered supported his subsidence theory of coral reef development however several other accounts of the reef islands have questioned darwin9s interpretation and have suggested that a conglomerate platform that underlies most of the reef islands may indicate recent emergence of the atoll radiocarbon ages on corals from this conglomerate platform reported here indicate that it formed in the late holocene fossil in situ microatolls above present upper coral growth limits the elevation of associated beachrock and the morphological similarity of the conglomerate platform to the present reef flat deposits indicate a late holocene sea level above the present relative to the atoll the atoll has undergone at least 0 5 m of emergence since about 3000 yr b p this represents the first radiometrically dated evidence of holocene emergence from islands in the eastern or central indian ocean

repeated gps surveys across the ionian sea evidence of crustal deformations summary geodetic evidence of crustal deformation in the ionian area detected by gps surveys is given in this paper a network consisting of nine geodetic sites crossing the ionian sea from calabria southern italy to northwestern greece was repeatedly surveyed starting in 1991 within the framework of the tyrgeonet project the results obtained from processing data from three gps campaigns performed on the same network in 1991 1994 and recently in 1995 show significant changes in the positions of five sites the deformations in terms of displacements coordinate differences are obtained by applying a rigorous statistical approach that analyses their significance by an original iterative procedure based on the classical f fisher test although more substantial geophysical conclusions require more observations the estimated relative displacement pattern is generally coherent with the features of the main tectonic structures identified for this area the detected deformations for the greek sites confirm the activity of the kephalonia right lateral transform fault and a rightlateral motion of the mattinata fault northern apulia seems to have been detected by the italian sites moreover within the time span analysed the site of matera shows a different behaviour from the three adriatic sites tremiti m s angelo and specchia cristi since relative displacements among matera and these sites were detected this fact may indicate the weakness of the assumption reported in some papers that matera could be a representative site of the motion of the whole adriatic plate furthermore the site of specchia cristi shows the maximum relative displacement in the network with a vector magnitude of about 5 cm with a 3 cm confidence interval at the 95 per cent level therefore even if some additional gps observations are needed to achieve a clearer picture of the tectonic behaviour of the ionian sea area the detected relative displacement pattern of the italian sites agrees with a possible rotational behaviour of the apulian platform with respect to the adriatic plate as already hypothesized by finetti 1982

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

interactions between mantle upwelling drainage evolution and active normal faulting an example from the central apennines italy summary in this paper we show that the processes that have shaped the quaternary surface development of the apennines in central italy are all consequences of a single subcrustal process the upwelling of the mantle the relationship between gravity and topography shows that mantle convection is responsible for a long wavelength 150 200 km topographic bulge over the central apennines and stratigraphic evidence suggests this bulge developed in the quaternary active normal faulting is localized at the crest of this bulge and produces internally draining fault bounded basins these basins have been progressively captured by the aggressive headward erosion of major streams that cut down to the sea on the flanks of the regional bulge the only surviving closed basins are those on the apennine watershed most distant from the marine base level where continued normal faulting is still able to provide local subsidence that defeats their capture by the regional drainage network understanding the competition between regional capture and local fault related subsidence of intermontane basins is crucial for recognizing potentially hazardous active faults in the landscape and also for interpreting the sediment supply to adjacent offshore regions central italy provides a good modern analogue for processes that are probably common in the geological record particularly on rifted margins and intracontinental rifts but may not have been fully appreciated

solution slip and separations on strike slip fault zones theory and application to the mattinata fault italy we present a set of relationships to determine the component of slip and separations generated by the cleavage controlled volume contraction in strike slip fault zones the fault walls can translate toward each other along the cleavage normal axis of maximum shortening as rock is dissolved by pressure solution along patterned cleavage surfaces within strike slip fault zones the fault zone shortening produces an apparent slip and possible separations of reference stratigraphic surfaces across the fault zone solution related slip and separations can differ in magnitude and have either the same or the opposite sense these discrepancies depend upon the amount of fault zone shortening and upon the angles between the fault and the shortening axis and between the fault and the reference stratigraphic surface separations can be considerable at any scales even for very low amounts of fault zone thinning apparent slip can be appreciable for large amounts of fault zone thinning and or high fault to cleavage incidence angles with the proper geometrical conversions the relationships here presented can apply to any fault type the application of this technique to the left lateral mattinata fault italy demonstrated that both left and right lateral strike separations can occur along the fault even for low amounts of fault zone contraction by rock dissolution q 2002 elsevier science ltd all rights reserved

discrimination of geophysical phenomena in satellite radar interferograms various geophysical phenomena are recorded in the interference patterns formed by differencing two synthetic aperture radar sar images the fringes generated by the topographic relief can be removed using a digital elevation model dem the remaining fringes map the change in satellite to ground range which occurred between the acquisition times of the two images by comparing different pairs of images spanning different intervals of time it is possible to discriminate between geophysical signal and interferometric artifact here we apply this pair wise logic to the area around the 1992 landers california earthquake using sar images acquired by the ers 1 satellite the range varies with time as a constant step impulsive or sloping function examples of each type include a dem error an aftershock two atmospheric perturbations and postseismic afterslip respectively their signatures are identified and separated using the pair wise logic

locating distributed faulting contributions from insar imaging to probabilistic fault displacement hazard analysis pfdha abstract prediction of location and amount of slip for distributed faulting associated to strong earthquakes is a recently explored issue with major implications in terms of hazard assessment currently the best practice involves the applications of probabilistic fault displacement hazard analysis pfdha whose results fit sufficiently well real data in the near range of the primary fault but show considerable inaccuracies in the far range we believe that this inaccuracy descends from the biased earthquake databases used for regression analysis whose data relative to old earthquakes were largely collected only by field surveys focused close to the primary fault i e near range remotely sensed data i e interferometric radar imaging insar offer the opportunity to precisely measure the surface deformation induced by strong earthquakes and thus to explore its possible relation with distributed faulting we analyze the l aquila earthquake case study 29th april 2009 mw 6 3 and explore the correlation between location and slip on distributed faulting and insar derived deformation field we find a significant correlation between occurrence of distributed faulting and profile curvature of the dislocation field in spite of the distance from the primary fault moreover distributed faults tend to occur within the area deformed by the earthquake as imaged by insar data and whose extent is directly proportional to the earthquake magnitude mw according to a dataset of 30 recent earthquakes we then propose that these observations have to be incorporated into the present pfdha practice as limit boundaries to possible scenarios of probabilistic analysis and that an integrated use of field based and remotely data collection have to be implemented following strong earthquakes

thrust wrench interference between major active faults in the gulf of cadiz africa eurasia plate boundary offshore sw iberia tectonic implications from coupled analog and numerical modeling abstract analog and numerical modeling experiments were carried out to investigate the tectonic interference between intersecting major active strike slip and thrust faults in the gulf of cadiz africa eurasia plate boundary offshore sw iberia the obtained results show that newly mapped tectonic features located in the fault intersection area corner zone consist mostly in oblique dextral reverse faults that accommodate significant strain partitioning modeling of this corner zone faults show that they have endured some degree of rotation displaying successive evolving geometries and kinematics numerical modeling results further show that an interbedded shallow soft layer accounting for a regional late miocene gravitational chaotic unit could explain the mild bathymetric expression of the fault pattern in the corner zone moreover a recognized depth discrepancy between the upper crust interference fault pattern and the lithospheric mantle seismicity is interpreted as a manifestation of similar thrust wrench tectonic interference at different lithospheric depths accordingly an intermediate lower crust upper mantle aseismic i e softened depth domain could be explained by pervasive alteration serpentinization prompted by fluid percolation through fault related fractures associated with the newly revealed corner zone fault network overall obtained results reinforce the relevance of a thrust wrench multi rupture seismic scenario as the main cause for the moderate seismicity mw

different foreland basins in italy examples from the central and southern adriatic sea abstract the central adriatic basin cab and the southern adriatic basin sab are foreland or foredeep basins relative to the non coeval apenninic and dinaric hellenic orogenic systems and currently characterized by different physiographies these are separated by a major forebulge of the adriatic lithosphere running throughout the adriatic region from istria to the gargano promontory the clastic basin filling of the cab is mostly plio pleistocene whereas it is upper oligocene pleistocene in the sab stratigraphy reveals that the cab has experienced an overfilling regime throughout the plio pleistocene whereas the sab has been probably continuously underfilled during the same time span in the cab the foreland plate dips westward at an average angle of 5 6 whereas in the sab the basement dips to the east at an angle of 1 2 this discrepancy is congruent with the already noticed distinction between east and west dipping subduction systems and possibly has geodynamical implications in the cab the non homogeneous distribution of thrust sheets suggests strike slip tectonic movements along roughly ne trending lineaments that occurred up to the middle late pliocene on the western part of the sab the overall structural assemblage recalls the fabric typical to strike slip regimes and includesboth extensional and contractional structures it is proposed that the messinian salinity crisis and relative eustatic lowstand affected the subsequent tectono sedimentary evolution of the cab in terms of subsidence rate and depositional style one still tentative hypothesis is that water and sediment removal in the basin lasted for a sufficient time span to promote viscoelastic relaxation temporary migration of the forebulge towards the thrust belt and downwarping of the foreland plate

space geodesy subsidence and flooding in new orleans a subsidence map of the city offers insight into the failure of the levees during hurricane katrina

land subsidence in houston texas measured by radar interferometry and constrained by extensometers 1 we present results from a radar interferometry study over the houston galveston texas gulf coast region from the nearly 60 potential interferograms considered an atmospheric artifact assessment is performed and a tractable set of interferograms selected for detailed processing and error analysis the subsequent interferogram time series spanning 1996 1998 is constrained by coincident extensometer data with root mean square error less than 2 5 mm the interferogram time series confirms that historic subsidence in east houston has stopped consistent with current groundwater use patterns broad scale subsidence bowls are observed in west and northwest houston where maximum subsidence rates are in excess of 2 and 4 cm yr 1 respectively linear interferogram phase signatures associated with approximately 1 cm of differential subsidence across faults including the long point fault in northwest houston are observed near the seabrook extensometer a hereto unidentified subsidence bowl with a maximum subsidence rate in excess of 3 cm yr 1 is revealed this study demonstrates that when used in conjunction with a set of traditional geodetic measurements radar interferometry can measure the spatial and temporal evolution of urban land subsidence within even the most challenging of environments

a bayesian seismic hazard analysis for the city of naples in this paper we explore the feasibility of formulating the hazard assessment procedure to include the information of past earthquakes into the probabilistic seismic hazard analysis together with the use of an ensemble modeling technique this strategy allows on one hand to enlarge the information used in the evaluation of the hazard from alternative models for the earthquake generation process to past shaking and on the other hand to explicitly account for the uncertainties the bayesian scheme we propose is applied to evaluate the seismic hazard of naples the framework in which we have embedded the tools is flexible to include all types of uncertainties here we focus on a sensitive study of the earthquake occurrence by implementing models that span from random to cluster type temporal behavior and models that include quasi periodic occurrence of earthquakes on faults we implement 5 different spatio temporal models to parameterize the occurrence of earthquakes potentially dangerous for naples subsequently we combine these hazard curves with shakemaps of past earthquakes that have been felt in naples since 1200 a d the results are posterior ensemble hazard curves for three exposure times e g 5 10 and 50 years in a dense grid that cover the municipality of naples considering rocky soil and including the site amplification our results show the importance to include the data from past shaking since the difference between the prior and the posterior is about 8 15 for the different exposure times

tropospheric corrections of sar interferograms with strong topography application to etna the accuracy of spaceborne geodetic techniques including sar interferometry is limited by the time and spatial variation and altitude dependance of the propagation delay of electomagnetic waves in the lower troposphere particularly in mountainous areas in this paper we use a 1d model developed for tropospheric corrections of gps and doris measurements to correct sar data the differential tropospheric delay is computed at each pixel of the interferogram from ground temperature humidity and pressure using two empirical parameters calibrated from several radio soundings acquired in various latitude and climate conditions it is shown that with such a model given the 3300 meters topography of etna tropospheric variations can generate up to 4 phase rotations between the top and the bottom of the volcano in 16 out of the 20 interferograms processed with images acquired between august 1992 and october 1993 correction of the tropospheric effect reduces the number of fringes associated with the 1991 93 eruption from previous estimates the remaining deformation is consistant with a deforming source located at a depth of 14 1 km during the second half of the eruption the subsidence rate at the top of the volcano is roughly stable at 13 3 mm month these values are in good agreement with tiltmeter data collected on etna during the same period and with the estimated volume of erupted material no significant deformation can be observed during the last month of eruption inflation of the volcano seems to resume immediately after the end of the eruption at a rate of 3 mm month

active tectonic deformation of the western indian plate boundary a case study from the chaman fault system abstract collision of the eurasian and indian plates has resulted in two spatially offset subduction zones the makran subduction zone to the south and the himalayan convergent margin to the north these zones are linked by a system of left lateral strike slip faults known as the chaman fault system 1200 km which spans along western pakistan although this is one of the greatest strike slip faults yet temporal and spatial variation in displacement has not been adequately defined along this fault system this study conducted geomorphic and geodetic investigations along the chaman fault in a search for evidence of spatial variations in motion four study areas were selected over the span of the chaman fault 1 tarnak rud area over the tarnak rud valley 2 spinatizha area over the spinatizha mountain range 3 nushki area over the nushki basin and 4 kharan area over the northern tip of the central makran mountains remote sensing data allowed for in depth mapping of different components and faults within the kohjak group wind and water gap pairs along with offset rivers were identified using high resolution imagery and digital elevation models to show displacement for the four study areas the mountain front sinuosity ratio valley height to width ratio and the stream length gradient index were calculated and used to determine the relative tectonic activity of each area these geomorphic indices suggest that the kharan area is the most active and the tarnak rud area is the least active gps data were processed into a stable indian plate reference frame and analyzed fault parallel velocity versus fault normal distance yielded a 8 10 mm yr displacement rate along the chaman fault just north of the spinatizha area insar data were also integrated to assess displacement rates along the fault system geodetic data support that ultra slow earthquakes similar to those that strike along other major strike slip faults such as the san andreas fault system are possible along the northern segments of the chaman fault zone geomorphic data suggest that the chaman fault along southern part is not very active now but may have gone through high tectonic activity in the past

pleistocene changes in the central apennine fault kinematics a key to decipher active tectonics in central italy integrated structural geomorphological and stratigraphic data have permitted the definition of the quaternary structural evolution of some tectonically generated basins in the central apennines available data indicate that some n130 140 trending quaternary normal faults have not been active since the middle pleistocene while along some other faults with the same trend left lateral strike slip or oblique slip movements are superimposed on normal movements pure normal movements were found to affect only n125 to e w trending faults this structural evolution indicates that fault kinematics in the central apennines changed markedly between the early and middle pleistocene current models infer that this change may have been a response to the bending which caused the arcuate shape of the apennine orogen the deformation related to the bending added to the effects of the regional stress field as a result post early pleistocene fault kinematics were due to an extension that locally was not perfectly perpendicular to the inherited normal faults and that is consistent with models of oblique slip tectonics processes of arc formation and related incompatibility between inherited quaternary faults and post early pleistocene extension have significant implications regarding research on active tectonics in fact some nonactive faults show misleading features typical of recent activity while some active faults are poorly visible owing to the recent age of the present regime this kinematic evolution therefore represents one of the major factors others being the low slip rates and the fragmented structural setting which hinders the definition of reliable active faulting schemes for the apennine chain

seasonal subsidence and rebound in las vegas valley nevada observed by synthetic aperture radar interferometry analyses of areal variations in the subsidence and rebound occurring over stressed aquifer systems in conjunction with measurements of the hydraulic head fluctuations causing these displacements can yield valuable information about the compressibility and storage properties of the aquifer system historically stress strain relationships have been derived from paired extensometer piezometer installations which provide only point source data because of the general unavailability of spatially detailed deformation data areal stress strain relations and their variability are not commonly considered in constraining conceptual and numerical models of aquifer systems interferometric synthetic aperture radar insar techniques can map ground displacements at a spatial scale of tens of meters over 100 km wide swaths insar has been used previously to characterize larger magnitude generally permanent aquifer system compaction and land subsidence at yearly and longer timescales caused by sustained drawdown of groundwater levels that produces intergranular stresses consistently greater than the maximum historical stress we present insar measurements of the typically small magnitude generally recoverable deformations of the las vegas valley aquifer system occurring at seasonal timescales from these we derive estimates of the elastic storage coefficient for the aquifer system at several locations in las vegas valley these high resolution measurements offer great potential for future investigations into the mechanics of aquifer systems and the spatial heterogeneity of aquifer system structure and material properties as well as for monitoring ongoing aquifer system compaction and land subsidence

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

deep structure of the campanian lucanian arc southern apennine italy abstract recent exploration activities and successful discovery of large oil fields in the upper val d agri area southern apennine italy have encouraged the collection of large quantities of geological and geophysical data and their integration into comprehensive geological models here we present a series of structural profiles based on several hundred kilometres of seismic lines two and three dimensional and the results of many deep wells the best seismic lines have been extensively reprocessed and also tied to magnetotelluric data geological interpretations of those lines have been interactively tested and verified by gravity and magnetic modelling and structural balancing the wells and seismic data demonstrate that the fundamental tracts of the deep architecture of the orogen as it appears today were developed only at the end of the late pliocene the final closure of the ensialic shear zone responsible for the subduction of at least 150 km of continental lithosphere originally underlying the lagonegro basin can be dated as early pliocene the involvement of the inner apulian platform in the core of the belt and the activation of a new and more external left lateral oblique ensialic shear zone can be constrained to the late pliocene pleistocene the seismic profiles clearly show the underthrusting of the outer apulian platform unit beneath the inner apulian platform unit the thick skinned character of the plio pleistocene contractional structures is evident from the structural profiles this geometry is constrained by gravity magnetic data and structural considerations according to the relatively steep angle of dip about 10 of the apulian foreland beneath the chain the structural profiles depict the general architecture of the campanian lucanian arc the apennine platform and lagonegro unit are largely allochthonous and a part of the lagonegro basement could be buried below the apennine platform sole thrust the neogene plastic successions of the apennine platform and lagonegro basin were detached and now outcrop in the bradanic foredeep the inner apulian platform constitutes a huge thrust sheet structured as a wide antiform in the core of the belt its regional culmination roughly corresponds to the val d agri area extensional and transtensional structures cross cut the pre existing compressional structures as shown by the quaternary valleys of vallo di diano and val d agri the profiles shown also highlight the existing contrast between the deep structures in the core of the belt and the tectonic style of the lagonegro liguride and sicilide units these units were in fact subjected to brittle ductile deformation under metamorphic part of liguridi units and deep diagenetic to anchizonal conditions lagonegro units and were affected by a general overthrust shear directed towards the ne the inner apulian platform was on the contrary involved in the thrust belt together with its basement whereas the outer apulian platform affected by a subduction underwent a regional bending with associated normal faulting

analogue modelling of different angle thrust wrench fault interference in a brittle medium analogue modelling experiments of thrust wrench fault interference in a brittle medium are presented and discussed simultaneous reactivation of confining strike slip and thrust faults bounding a corner zone of interference defined by the angle between the two fault systems is simulated instead of previously reported discrete time and space superposition of alternating thrust and strike slip events the influence of different considered interference angles of 60 90 and 120 is investigated through comparison between the obtained structural configurations in each case it is shown that under these conditions a characteristic morpho structural pattern with a deltoid shape resembling a tie knot consistently forms in the corner zone between the two fault systems the specific structural configuration of a such tie knot structure tks varies significantly as a function of the prescribed fault interference angle which determines the orientation of the displacement vector shear component ds along the main frontal thrust system and critically controls the geometry and kinematics of the tks comparison with three natural examples shows remarkable geometric and kinematic similarity confirming model predictions and suggesting the existence of common underlying dynamic processes governing the specific tks structural configuration of different thrust wrench fault interference corner zones in nature

opposite verging chains sharing the same foreland kinematics and interactions through analogue models central po plain italy abstract in this study we investigate the potential role played by different geological factors on the development of a thrust system in particular our goal is to analyze how pre existing compressional structures located in the foreland of a thrust and fold belt may affect the kinematics of a thrust system we studied such circumstances both in a natural case and through analogue models as a natural case we selected the central po plain italy where the buried external fronts of the northern apennines and southern alps are very close to each other starting from a regional cross section representative of this tectonic setting we reconstructed the post messinian development of the apennines thrust fronts which includes out of sequence thrusting then we modeled this evolution through a set of analogue experiments to evaluate the possible relationships of the out of sequence thrusting with the burial of the syntectonic sediments and or the existence of the outer fronts of an opposite verging chain in its foreland the comparison between natural case and models highlights that the presence of opposite verging thrust fronts in the foreland of a belt limits the propagation of new thrusts favoring the out of sequence reactivation of inner thrusts an analysis of the study area with respect to adjacent tectonic settings coupled with analogue models revealed that syntectonic sedimentation as well has a role in the reactivation of the inner fronts although secondary in the po plain specific case this implies that the presence of the buried southern alps fronts affects the northern apennines kinematics even if the two fronts did not collide yet

reactivation of deep faults beneath southern apennines evidence from the 1990 1991 potenza seismic sequences we relocate the 1990 1991 potenza southern apennines belt italy sequences and calculate focal mechanisms this seismicity clusters along an e w dextral strike slip structure second order clusters are also present and reflect the activation of minor shears the depth distribution of earthquakes evidences a peak between 14 and 20 km within the basement of the subducting apulian plate the analysed seismicity does not mirror that of southern apennines which include nw se striking normal faults and earthquakes concentrated within the first 15 km of the crust we suggest that the e w faults affecting the foreland region of apennine propagate up to 25 km of depth the potenza earthquakes reflect the reactivation of a deep preexisting fault system we conclude that the seismotectonic setting of apennines is characterized by nw se normal faults affecting the upper 15 km of the crust and by e w deeper strike slip faults cutting the crystalline basement of the chain

microatolls as sea level indicators on a mid ocean atoll microatolls are discoid corals with flat upper surfaces that develop when upward coral growth is constrained by exposure at low tide they have been widely viewed as important and relatively precise indicators of modern and paleo sea level positions because of their sensitivity to the water air interface though this has rarely been directly established by survey to a precise datum this study involved an accurate survey of 282 microatolls growing in a range of intertidal environments open reef flats interisland passages lagoons across the cocos keeling islands a mid ocean atoll in the indian ocean the upper surface elevation of modern microatolls was found to vary through more than 40 cm across the environments in which these corals occur on cocos representing more than 30 of the spring tide range much of the variation reflects subtle ponding at low water levels across extensive low gradient reef surfaces associated with interisland passages microatolls in open reef flat habitats are typically constrained within the narrowest and most consistent elevation range around the atoll the environment in which individual fossil microatolls occurred when they were alive is significant in reconstructing former sea levels

permanent scatterer investigation of land subsidence in greater cairo egypt summary land subsidence is a major geomorphic problem commonly associated with densely populated areas such as the greater cairo area prior to this study rates and patterns of land subsidence in greater cairo were not known the permanent scatterer interferometric approach has been applied in this study to detect and measure the magnitude and the spatial and temporal variations of subsidence in greater cairo thirty four interferometric synthetic aperture radar insar images acquired by the european radar satellites ers 1 and ers 2 during 1993 2000 have been used in this investigation the main contributing factors to the rate of land subsidence in greater cairo include natural sediment compaction tectonic activity and groundwater pumping however the measured rate of land subsidence is found significantly impacted by anthropogenic factors rather than natural factors the average measured rate of subsidence is approximately 7 mm yr 1 during the period of observation and the spatial and temporal patterns of land subsidence are demonstrated by a time series of surface deformation maps insar results show differential surface displacements along the major surface and subsurface faults and indicate pumping induced subsidence which is characterized by bowl shapes in districts of high population density the detected pattern of land subsidence in greater cairo implies a considerable contribution from the subway network as well the results from this interferometric investigation can be used to help mitigate the environmental impacts and potential consequences of land subsidence in the region

rapid subsidence over oil fields measured by sar interferometry the lost hills and belridge oilfields are in the san joaquin valley california the major oil reservoir is high porosity and low permeability diatomite extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction forming a surface subsidence bowl we measure this subsidence from space using interferometric analysis of sar synthetic aperture radar data collected by the european space agency remote sensing satellites ers 1 and ers 2 maximum subsidence rates are as high as 40 mm in 35 days or 400 mm yr measured from interferograms with time separations ranging from one day to 26 months the 8 and 26 month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ers sar but shows increased detail in areas of less rapid subsidence synoptic mapping of subsidence distribution from satellite data powerfully complements ground based techniques permits measurements where access is difficult and aids identification of underlying causes

modelling of structural complexity in sedimentary basins the role of pre existing faults in thrust tectonics abstract analogue and numerical models have been used to study the role of pre existing faults in compressive regimes from a theoretical point of view reactivation is mainly controlled by fault attitude stress regime and frictional properties of fault planes in scaled down sandbox experiments precut faults are introduced in the homogeneous granular media with a nylon wire which is forced through the sand cake producing a thin planar disturbed zone systematic experiments of thrust inversion with various dips and strikes of such planar discontinuities have been modelled comparison of experimental results with theoretical diagrams indicate that disturbed zones have a friction angle which is 10 20 lower than the homogeneous sand and that the compressive regime in the sandbox has a shape factor close to 0 4 the static analysis of fault reactivation is in accordance with the experimental observations except for pre existing faults dipping at very low angle however numerical modelling using the udec code shows that low angle faults can be reactivated as a result of stress concentration in the lower part of the fault in addition sandbox experiments indicate that in thrust systems reactivation of pre existing faults is not only dependent on their attitude but also on their spacing and location relative to the thrust system

recent subsidence and northeast tilting of the nile delta egypt abstract sediment borings collected in the nile delta of egypt many of them radiocarbon dated indicate that the entire northern sector of this major depositional center in the eastern mediterranean is presently subsiding mapping of the base of the holocene deltaic facies which is dated at about 8000 6500 yrs b p reveals that differential lowering of the northern delta plain is preferentially accentuated toward the northeast long term subsidence rates at or near the coast averaged for the mid to upper holocene range from about 0 1 to 0 25 cm yr between alexandria and the north central delta margin rates increase markedly eastward to a maximum of about 0 5 cm yr in the port said manzala lagoon region and this rapid lowering explains the presence of thick marine delta lobe sequences of holocene age in cores in the northeastern delta in contrast only reworked remnants of holocene marine delta lobe deposits of the earlier river nile branches which once flowed to the north and northwest are preserved seaward of the present north delta coast subsidence has induced marked environmental changes particularly with respect to coastal erosion and salt water incursion the asymmetric pattern of saline ground water here attributed in part to the northeast tilt of the delta plain has serious implications for agricultural development in this intensely cultivated region

subsidence in the northeastern nile delta rapid rates possible causes and consequences holocene fluvial and marine deposits have accumulated in a graben like structure on the northeastern margin of the nile delta this part of the delta which includes lake manzala port said and the northern suez canal has subsided rapidly at rates of up to 0 5 centimeter per year since about 7500 years ago this subsidence has diverted at last four major distributaries of the nile river into this region the combined effects of continued subsidence and sea level rise may flood a large part of the northern delta plain by as much as 1 meter by the year 2100 the impact of continued subsidence now occurring when sediment input along the coast has been sharply reduced because of the aswan high dam is likely to be substantial particularly in the port said area and as far inland as south of lake manzala