constraining the slip distribution and fault geometry of the mw 7 9 3 november 2002 denali fault earthquake with interferometric synthetic aperture radar and global positioning system data the m w 7 9 denali fault earthquake dfe is the largest continental strike slip earthquake to occur since the development of interferometric synthetic aperture radar insar we use five interferograms constructed using radar images from the canadian radarsat 1 satellite to map the surface deformation at the western end of the fault rupture additional geodetic data are provided by displacements observed at 40 campaign and continuous global positioning system gps sites we use the data to determine the geometry of the susitna glacier fault thrusting on which initiated the dfe and to determine a slip model for the entire event that is consistent with both the insar and gps data we find there was an average of 7 3 0 4 m slip on the susitna glacier fault between 1 and 9 5 km depth on a 29 km long fault that dips north at 41 0 7 and has a surface projection close to the mapped rupture on the denali fault a simple model with large slip patches finds a maximum of 8 7 0 7 m of slip between the surface and 14 3 0 2 km depth a more complex distributed slip model finds a peak of 12 5 0 8 m in the upper 4 km significantly higher than the observed surface slip we estimate a geodetic moment of 670 10 10 18 n m m w 7 9 consistent with seismic estimates lack of preseismic data resulted in an absence of insar coverage for the eastern half of the dfe rupture a dedicated geodetic insar mission could obviate coverage problems in the future

ability of a global three dimensional model to locate regional events 1 we assess the ability of a global three dimensional 3d seismic model of the crust and upper mantle cub2 0 to locate seismic events using regional travel time data alone epicentral distances 20 assessments are based on a ground truth gt database comprising nearly 1000 uncommonly well located events which occur in 23 event clusters across eurasia and north africa groomed p and pn arrival time data observed at regional distances from individual events and 1000 empirical phase path anomalies produced from event clusters evidence is presented that supports the conversion of the shear velocities vs in cub2 0 to compressional velocities vp in the upper mantle using the thermoelastic properties of an assumed mantle composition rather than traditional empirical scaling relationships two principal results are presented first this 3d vp model fits the empirical p and pn phase path anomalies very well in both pattern and absolute level second location assessments demonstrate that intrinsic regional location accuracy is 5 km using the 3d vp model and 10 km using the 1d model ak135 these findings highlight the importance of gt databases in assessing regional travel time models and establish that a global 3d vs model together with vp inferred from it provides a solid basis on which to build improvements in regional location capabilities

lithification of peritidal carbonates by continental brines at fisherman bay south australia to form a megapolygon spelean limestone association abstract groundwater springs in the supratidal zone at fisherman bay south australia are the sites of aragonite precipitation and cementation of holocene marine carbonates lithification which commenced less than 3000 years bp and is still active has formed a cavernous limestone containing megapolygons tepees and speleothems including pisoliths floe aragonite and aragonitic pool deposits the emerging waters are from a continental source and have evolved from low alkalinity waters of pleistocene sand and clay coastal plain aquifers which have passed through an underlying tertiary marine carbonate aquifer the resulting waters have high pco2 total carbonate ca and sulphate concentrations they are close to saturation with respect to aragonite and their mmg2 mca2 ratios approach or exceed the critical aragonite precipitation value aragonite is precipitated from these waters when they approach the surface and evolve co2 features which taken together may diagnose ancient examples of this process include 1 primary aragonitic cements with high msr2 mca2 values 2 nonmarine 34s values in associated gypsum 3 two superimposed networks of surface polygons one delineated by extensional boundaries the other by tepees 4 high water vadose zone isopachous grain cements 5 interconnected speleothem lined cavities and 6 the presence of evaporites only in surface sediments possible ancient examples of peritidal carbonate lithification by saline spring waters rising from confined aquifers are recognized in descriptions of carbonates from west texas lombardy and the atlas mountains the areal extent of each of these deposits suggests that the process may be a geologically important feature and its products may be diagnostic of semi arid or arid zone paralic sedimentation

the structural evolution of active fault and fold systems in central otago new zealand evidence revealed by drainage patterns abstract central otago in new zealand is an area of active continental shortening in which a peneplain surface cut into schist has been deformed by folds which are developed above buried reverse faults we use the drainage patterns in this region to demonstrate various processes in fold and fault growth and interaction that would be difficult to identify by other means in particular we show 1 how simple asymmetric folds can develop into box folds 2 how apparently continuous ridges were formed by the coalescing of quite separate propagating fold and fault segments 3 evidence for the relative ages or relative uplift rates of adjacent structures and 4 evidence for the propagation direction of folds or faults as they grow the few quantitative estimates we obtain for fault propagation rates suggest an increase in length of 10 50 m per earthquake on faults about 20 km long these estimates are very uncertain but are similar in magnitude to an estimate made in nevada for a normal fault of similar size and are also similar to predicted estimates from theoretical growth models they raise the question of whether fault growth earthquake recurrence rates and climate change can interact to produce semi regular discrete features in an active landscape

a luminescence method for dating dirty pedogenic carbonates for paleoenvironmental reconstruction pedogenic carbonates are sensitive paleoclimatic and paleomonsoonal indicators stratigraphic markers and important sources and sinks in the global co budget establishing a chronology of such carbonates has been difficult due to their open system behaviour with respect to the radioisotopes used for dating a luminescence method for chronometric dating of carbonates is proposed which is less susceptible to post depositional changes and uses subtle changes in the radiation flux to a mineral grain on being carbonated this change is estimated by measuring luminescence signals of carbonated and uncarbonated mineral separates from the sediment strata and can be related to the age of the carbonate formation such ages of pedogenic carbonates from thar desert india conform with paleoclimatic and stable isotopic data and show that they formed in thar ca 17 ka 5 ka and 2 ka ago since the last glacial epoch

epicentre accuracy based on seismic network criteria summary we establish reliable and conservative estimates for epicentre location accuracy using data that are readily available in published seismic bulletins a large variety of seismic studies rely on catalogues of event locations making proper assessment of location uncertainty critical event location and uncertainty parameters in most global regional and national earthquake catalogues are obtained from traditional linearized inversion methods using a 1 d earth model to predict traveltimes reported catalogue uncertainties are based on the assumption that error processes are gaussian zero mean and uncorrelated unfortunately these assumptions are commonly violated leading to the underestimation of true location uncertainty especially at high confidence levels we find that catalogue location accuracy is most reliably estimated by station geometry we make use of two explosions with exactly known epicentres to develop local network location 0 2 5 accuracy criteria using monte carlo simulations of network geometry we find that local network locations are accurate to within 5 km with a 95 per cent confidence level when the network meets the following criteria 1 there are 10 or more stations all within 250 km 2 an azimuthal gap of less than 110 3 a secondary azimuthal gap of less than 160 and 4 at least one station within 30 km to derive location accuracy criteria for near regional 2 5 10 regional 2 5 20 and teleseismic 28 91 networks we use a large data set of exceptionally well located earthquakes and nuclear explosions beyond local distances we find that the secondary azimuthal gap is sufficient to constrain epicentre accuracy and location error increases when the secondary azimuthal gap exceeds 120 when station coverage meets the criterion of a secondary azimuth gap of less than 120 near regional networks provide 20 km accuracy at the 90 per cent confidence level while regional and teleseismic networks provide 25 km accuracy at the 90 per cent confidence level

u series isochron dating a generalized method employing total sample dissolution the age of a sedimentary deposit can be determined by measuring 238u 234u 232th and 230th in two or more samples of the deposit with the requirement that these samples have different u th ratios but an identical 230th232th ratio when deposited this paper presents the theoretical and experimental aspects of the dating method the latter involves techniques for securing samples of varied u th ratios from the same deposit plotting isochrons of the radiochemical data obtained on totally dissolved samples for age analysis and estimating the errors involved although applications to impure carbonates and lacustrine evaporite sediments are given as examples in this paper the method potentially can be generalized for dating a variety of authigenic deposits such as rock varnish peat opal sulfate minerals and marine phosphorites

speleothem evidence from oman for continental pluvial events during interglacial periods growth periods and stable isotope analyses of speleothems from hoti cave in northern oman provide a record of continental pluvial periods extending back over the past four of earth s glacial interglacial cycles rapid speleothem growth occurred during the early to middle holocene 6 10 5 ka b p 78 82 ka b p 120 135 ka b p 180 200 ka b p and 300 325 ka b p the speleothem calcite deposited during each of these episodes is highly depleted in 18 o compared to modern speleothems the d 18 o values for calcite deposited within pluvial periods generally fall in the range of 24 to 28 relative to the vienna peedee belemnite standard whereas modern speleothems range from 21 to 23 the growth and isotopic records indicate that during peak interglacial periods the limit of the monsoon rainfall was shifted far north of its present location and each pluvial period was coincident with an interglacial stage of the marine oxygen isotope record the association of continental pluvial periods with peak interglacial conditions suggests that glacial boundary conditions and not changes in solar radiation are the primary control on continental wetness on glacial interglacial time scales

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

the growth of geological structures by repeated earthquakes 2 field examples of continental dip slip faults a strong test of our understanding of the earthquake cycle is the ability to reproduce extant fault bounded geological structures such as basins and ranges which are built by repeated cycles of deformation along strike slip faults the coseismic and interseismic deformation can be nearly equal in magnitude and opposite in sign resulting in little permanent deformation except for the fault offset for dip slip faults portions of the crust are lifted and dropped and so buoyancy forces are exerted the seismic and interseismic deformations do not balance and structures grow and become subject to erosion and deposition we consider three examples for which the structure and fault geometry are well known the white wolf reverse fault in california site of the 1952 kern county m 7 3 earthquake the lost river normal fault in idaho site of the 1983 borah peak m 7 0 earthquake and the cricket mountain normal fault in utah site of quaternary slip events basin stratigraphy and seismic reflection records are used to profile the structure and coseismic deformation measured by leveling surveys is used to estimate the fault geometry to reproduce these structures we add the deformation associated with the earthquake cycle the coseismic slip and postseismic relaxation to the flexure caused by the observed sediment load treating the crust as a thin elastic plate overlying a fluid substrate the cumulative deformation is principally dependent on the elastic plate thickness modestly sensitive to the sediment substrate density difference and insensitive to the fluid viscosity for the 4 to 8 ma structures we deduce a longterm flexural rigidity of 2 15 1019 nm this is equivalent to an elastic plate thickness of 2 4 km for a young s modulus of 2 5 1010 nm 2 this value is found where independent estimates of the elastic thickness from the coherence between surface topography and gravity yield values of about 4 km but where coseismic fault slip extends to a depth of 10 15 km thus much of the seismogenic crust must weaken substantially during the life of active faults causing the fault bounded basins to narrow over time

the 1994 sefidabeh eastern iran earthquakes revisited new evidence from satellite radar interferometry and carbonate dating about the growth of an active fold above a blind thrust fault in 1994 three shallow earthquakes of mw 6 occurred close together on blind thrusts near sefidabeh in eastern iran in an earlier study of the teleseismic waveforms the geomorphology and the faulting in the epicentral region it was suggested that these earthquakes were associated with the growth of a ridge above a blind thrust fault system whose activity could be detected by its effect on the surface drainage in this study we present a sar interferogram that precisely determines the location and amount of coseismic surface displacements showing that the earthquakes in the sefidabeh sequence probably occurred on en echelon fault segments associated with three stepping ridges we also present u th dates of 100 ka for lake deposits uplifted by the growing ridge from the cumulative dated uplift and knowledge of the surface displacements due to an earthquake sequence we estimate that 120 such events have occurred in the past 100 ka with an average recurrence interval of 830 yr and an average convergence rate of 1 5 mm yr 1 on the sefidabeh thrust each estimate has an uncertainty of a factor of two either way we argue that the sefidabeh fault originally formed by coalescence of many small fault segments and has grown in length at about 2 cm yr 1 in the past 100 ka though the coseismic surface deformation observed in the sar interferogram closely resembles folding the overall topography does not because of inherited topography associated with earlier geological deformation in spite of this the activity of the buried thrust fault can easily be detected by its effect on the surface drainage a significant lesson when interpreting landscapes that are not entirely due to the present day deformation

gulf stream thermal fronts detected by synthetic aperture radar 1 our purpose is to detect ocean surface features specifically oceanic thermal fronts through analysis of sar synthetic aperture radar derived wind stress fields fine resolution measurements of near surface wind speeds over the gulf stream region of the northwest atlantic were made using sar images collected by radarsat 2 linear statistical relationships between the wind stress curl and divergence to the crosswind and downwind components of the sst gradient field were used to derive a new method for detecting gulf stream thermal fronts from synthetic aperture radar sar imagery in particular sea surface temperature front features as suggested by corresponding avhrr and modis images are evident in both of the wind stress curl and divergence fields the importance of this methodology is that clouds are often present in the northwest atlantic in autumn and winter months and they obscure avhrr and modis images whereas sar can penetrate clouds

u series dating of impure carbonates an isochron technique using total sample dissolution abstract u series dating is a well established technique for age determination of late quaternary carbonates materials of sufficient purity for nominal dating however are not as common as materials with mechanically inseparable aluminosilicate detritus detritus contaminates the sample with extraneous th we propose that correction for contamination is best accomplished with the isochron technique using total sample dissolution tsd experiments were conducted on artificial mixtures of natural detritus and carbonate and on an impure carbonate of known age results show that significant and unpredictable transfer of radionuclides occur from the detritus to the leachate in commonly used selective leaching procedures the effects of correcting via leachate residue pairs and isochron plots were assessed isochrons using tsd gave best results followed by isochron plots of leachates only

oxygen isotopes in meteoric calcite cements as indicators of continental paleoclimate because meteoric water 18 o values decrease with decreasing ambient temperature and increasing latitude 18 o values of meteoric calcite cement should exhibit a similar relation with paleolatitude and be an indicator of continental paleotemperatures to test this we compiled isotopic and paleolatitude data for 20 meteoric cements and nine speleothems ranging in age from devonian to modern and in paleolatitude from 3 5 to 83 mean 18 o values for meteoric cements and speleothems both show the same negative correlation with paleolatitude the 18 o vs latitude trend for these carbonates is almost identical to that predicted for modern inland environments but differs from the trend for coastal environments this suggests that the ground water controlling the ultimate composition of meteoric cement is derived predominantly from inland recharge if it is assumed that the modern meteoric water 18 o vs temperature relation is valid for the past and that insignificant evaporation occurred prior to carbonate precipitation then coastal and inland paleotemperatures can be calculated from the 18 o values of meteoric calcite 18 o mcl and seawater 18 o sw by using the equations t coastal 13 3 32 6 0 231 0 0613 18 o mcl 18 o sw and t inland 17 8 16 2 0 572 0 1233 18 o mcl 18 o sw where t is temperature in c calcite precipitated from coastal meteoric water at temperatures between 0 and 25 c will exhibit a narrow range in 18 o 6 to 4 where 18 o sw 0 the 18 o of calcite precipitated from inland meteoric water will be sensitive to paleotemperature ranging from 14 to 5 where 18 o sw 0 for temperatures of 0 to 25 c

uranium series dating uranium decays through a number of radioactive daughter isotopes some of which have half lives comparable to the time scale of prehistoric archaeology the growth of these isotopes in naturally occurring materials at archaeological sites can be used to determine the age of sites the growth of 230th from its parent 234u can be used over a time range from a few hundred to half a million years calcite precipitated from running or dripping water in springs and caves as well as marls and soil deposited calcretes may be spatio temporally associated with archaeological materials they can be dated by 230th 234u and 234u 238u measurements with a precision of 5 10 of the age by alpha counting or 1 by mass spectrometry bones teeth mollusk and egg shells are also datable but present problems due to migration of parent u in and out of the samples during their burial history

active tectonics and late cenozoic strain distribution in central and eastern iran 1 right lateral shear between central iran and afghanistan is accommodated on n s right lateral strike slip faults surrounding the aseismic dasht e lut north of 34 n the right lateral shear is accommodated on left lateral faults that rotate clockwise about vertical axes little is known of the late tertiary and younger offsets and slip rates on the active fault systems results that are important for understanding the regional tectonics we use observations from satellite imagery to identify displaced geological and geomorphological markers which we use in conjunction with the overall morphology and orientation of the active fault systems to estimate the total cumulative right lateral shear estimates of cumulative fault movements from offset features and inferred vertical axis rotation of fault bounded blocks suggest that the late cenozoic strain is concentrated toward the eastern margin of iran along the sistan shear zone where bedrock offsets of at least 70 km are observed across the active faults the geomorphology of the deh shir anar and great kavir strike slip faults in central iran suggest that although little shortening is accommodated across this region they might still be active and hence capable of producing earthquakes present day activity on these faults in central iran would not be expected from distributions of instrumental and historical earthquakes although speculative the late tertiary strain distribution described in this paper is consistent with what we know of the present day rates of shear in eastern iran and provides a framework to which later more detailed work can be added

recognition of paleoearthquakes on the puente hills blind thrust fault california borehole data from young sediments folded above the puente hills blind thrust fault beneath los angeles reveal that the folding extends to the surface as a discrete zone 145 meters wide buried fold scarps within an upward narrowing zone of deformation which extends from the upward termination of the thrust ramp at 3 kilometers depth to the surface document the occurrence of at least four large moment magnitude 7 2 to 7 5 earthquakes on this fault during the past 11 000 years future events of this type pose a seismic hazard to metropolitan los angeles moreover the methods developed in this study can be used to refine seismic hazard assessments of blind thrusts in other metropolitan regions

offset and evolution of the gowk fault s e iran a major intra continental strike slip system abstract we use drainage reconstructions to estimate long term offsets on the gowk fault an oblique right lateral strike slip fault in eastern iran on which there have been a number of recent large earthquakes a 3 km horizontal offset is inferred from well preserved geomorphology we further identify a total cumulative offset of 12 km which produces a simple reconstruction of geomorphology across the fault filling in pull apart basins restoring rivers to linear courses across the fault trace and aligning structural and bed rock features the probable age of the gowk fault and k ar dating of offset basalts north of the study region suggest an overall slip rate of 1 5 2 4 mm year this is small compared with the overall 10 20 mm year of shear expected between central iran and afghanistan and the deficit is likely to have been accommodated on other faults east of the gowk fault drainage displaced by dextral movement leads to the development of a series of basins along the fault and a longitudinal topographic profile that resembles an asymmetric saw tooth the geomorphic evolution of the fault zone at the surface includes both normal and reverse faulting components reflecting a probable ramp and flat structure in cross section this interpretation is consistent with evidence from the analysis of seismological radar and surface rupture data in recent earthquakes

uranium series dating of quaternary deposits abstract this is a review of u series dating methods as applicable to terrestrial sedimentary materials alpha counting techniques allow the dating of carbonates and phosphates with a precision of 5 to 10 over the time range from 1 ka to 350 ka atom counting methods mass spectrometry and ams substantially increase precision and may increase the range problems of contamination and open system behavior are discussed correction for detrital contaminant is demonstrated in the dating of speleothem from a cave in italy

three dimensional υp and υp υs structure of the hengill triple junction and geothermal area iceland and the repeatability of tomographic inversion we investigate the crustal structure of the hengill triple junction in southwestern iceland applying tomographic methods to local earthquake data recorded in two field experiments with different network geometries and instrumentation data from the two experiments enable us to derive three dimensional models of the compressional wave speed p and the wave speed ratio p s well resolved high p bodies correlate with sites of gabbroic intrusions a small reduction in p s associated with the high temperature part of the geothermal area is probably due to mineral alteration or supercritical fluids the rms difference between the two p models about 0 26 km s 1 indicates the approximate repeatability that may be expected of good tomographic inversions

active tectonics at wheeler ridge southern san joaquin valley california wheeler ridge is an east west trending anticline that is actively deforming on the upper plate of the pleito wheeler ridge thrust fault system holocene and late pleistocene deformation is demonstrated at the eastern end of the anticline where salt creek crosses the anticlinal axis uplift tilting and faulting associated with the eastward growth of the anticline are documented by geomorphic surfaces that are higher and older to the west faulting and associated folding is propagating eastward as indicated by increases in both the degree of surface dissection and the degree of soil development from east to west distinct topographic areas having distinct degrees of surface dissection bounded by tear faults suggest that faulting and folding have propagated eastward in discrete segments numerical dates indicate 1 the anticline is propagating eastward at a rate of about 30 mm yr about 10 times the rate of uplift 2 folding was initiated about 400 ka 3 a prominent wind gap was formed during q3 time about 60 ka when an antecedent stream was defeated forcing the stream east around the nose of the fold today drainage through the ridge is by way of two antecedent streams water gaps east of the wind gap and 4 the rate of uplift at the easternmost and youngest past 1 k y part of the fold is at least 3 mm yr investigations of the tectonic geomorphology of wheeler ridge support the hypothesis that climatic perturbations are primarily responsible for producing geomorphic surfaces such as alluvial fan segments and river terraces tectonic perturbations deform the surfaces

speleothem based paleoclimate record from northern oman u th age dating and stable isotope measurements of speleothems from hoti cave in northern oman yield paleoclimate information from the region extending to 125 ka the results 1 provide further confirmation of an early holocene wet period in southern arabia extending from some time prior to 9 7 ka and ending at 6 2 ka 2 demonstrate a second period of wetness closely coinciding with the last interglacial period marine isotope stage mis 5e 3 indicate that during mis 5e southern arabia was considerably wetter than during the early holocene and 4 demonstrate that periods of increased monsoon wind strength based on data from marine sediments do not always coincide with evidence of greatly increased precipitation even from nearby continental areas

a healing reloading feedback control on the growth rate of seismogenic faults spatial and temporal variations in the growth rates of faults are explained in terms of a stress feedback mechanism operating in the seismogenic upper crust it is based on the idea that seismic rupture of a fault perturbs the surrounding stress field advancing the occurrence of future earthquakes on some faults that are optimally oriented while relaxing stress levels on others if post slip healing is geologically rapid then the earthquakes that are thus induced will contribute to reloading along the earlier rupture zone because of the symmetry of the optimal geometry a positive feedback is set up so that even in areas that are undergoing uniform tectonic straining some faults develop higher displacement rates and grow more rapidly while others experience reduced rates or become inactive using a thin plate elastic model for lithospheric scale faulting it is shown that this healing reloading feedback mechanism drives rapid localisation and the formation of major through going faults moving at plate boundary velocities enhanced displacement rates compared to an isolated fault develop shortly after the onset of deformation along those faults which are optimally positioned in the overall fault population thus the formation of a new plate boundary fault zone is predetermined and is a consequence of rather than the precursor of preferentially high displacement rates also fault segments located at points of rupture symmetry e g the central portion of a fault zone are reloaded more frequently and develop higher displacement rates and consequently have longer segment lengths and or larger displacement to length ratios episodic fault movement through time is a general feature of the model these predictions are consistent with available field observations over a wide range of scales thus elastic brittle failure and healing appear to be important rheological components of the lithosphere on long time scales 104 106 y as well as on the time scale of earthquake recurrence

source parameters of the 1 october 1995 dinar turkey earthquake from sar interferometry and seismic bodywave modelling abstract the 1 october 1995 m s 6 1 dinar earthquake ruptured a 10 km section of the nw se dinar civril fault there are discrepancies between the published source parameters from seismic data with seismic moments in disagreement by over a factor of two we use both sar interferometry and seismic bodywave modelling to determine earthquake source parameters an interferogram generated from ers 1 2 sar imagery spanning the event and separated by 5 months is used to derive source parameters by a downhill simplex inversion with multiple monte carlo restarts we model the displacements in the satellite line of sight initially using uniform slip on a rectangular dislocation in an elastic half space the resultant model fault plane agrees in strike and location with the observed surface break but systematic residuals exist in the line of sight deformation field resulting in a r m s residual of 20 mm in the interferogram the residuals are reduced if the depth distribution of slip is allowed to vary spatially in four segments along a continuous fault plane our best fitting solution with a r m s misfit of 8 mm reveals two distinct areas of slip on the fault plane strike 145 dip 49 rake 270 a main rupture slipping by 1 44 m between depths of 1 and 8 km becoming deeper to the se and matching the observed surface rupture and an along strike continuation to the nw of the same fault plane but between depths of 8 and 13 km and not associated with a surface break the total geodetic moment 4 5 0 1 10 18 nm is more than twice as large as published seismic moments based on the inversion of p waveforms alone but close to the harvard cmt moment 4 7 10 18 nm we use sh waveforms in addition to the p waves used previously to determine an alternative seismic source mechanism sh waves constrain the depth to be shallower than solutions based on p waves alone agreeing with the depths from the interferometric inversion and resulting in a larger moment 3 1 0 4 10 18 nm than the previous bodywave estimates 2 2 1 10 18 nm the cmt moment reduces in magnitude to a similar size 3 3 10 18 nm if the centroid depth and fault dip are constrained to the values determined from bodywave modelling and interferometry thus the geodetic moment is 40 bigger than the moment determined from seismology

present day crustal deformation and plate kinematics in the middle east constrained by gps measurements in iran and northern oman summary a network of 27 gps sites was implemented in iran and northern oman to measure displacements in this part of the alpine himalayan mountain belt we present and interpret the results of two surveys performed in 1999 september and 2001 october gps sites in oman show northward motion of the arabian plate relative to eurasia slower than the nuvel 1a estimates e g 22 2m m yr 1 at n8 5 e instead of 30 5 mm yr 1 at n6 e at bahrain longitude we define a gps arabia eurasia euler vector of 27 9 0 5 n 19 5 1 4 e 0 41 0 1 myr 1 the arabia eurasia convergence is accommodated differently in eastern and western iran east of 58 e most of the shortening is accommodated by the makran subduction zone 19 5 2m m yr 1 and less by the kopet dag 6 5 2m m yr 1 west of 58 e the deformation is distributed in separate fold and thrust belts at the longitude of tehran the zagros and the alborz mountain ranges accommodate 6 5 2m m yr 1 and 8 2m m yr 1 respectively the right lateral displacement along the main recent fault in the northern zagros is about 3 2m m yr 1 smaller than what was generally expected by contrast large rightlateral displacement takes place in northwestern iran up to 8 mm yr 1 the central iranian block is characterized by coherent plate motion internal deformation 2m m yr 1 sites east of 61 e show very low displacements relative to eurasia the kinematic contrast between eastern and western iran is accommodated by strike slip motions along the lut block to the south the transition zone between zagros and makran is under transpression with right lateral displacements of 11 2m m yr 1

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

field examples of strike slip fault terminations in mongolia and their tectonic significance deformation at the ends of large intracontinental strike slip faults that do not simply link other major structures often involves rotations about a vertical axis we use earthquake slip vectors surface rupture in earthquakes and geomorphology to examine the ends of three major strike slip faults in mongolia in these places a simple pattern is seen consisting of a thrust fault on one side with a displacement that decreases away from the strike slip fault consistent with local rotational deformation strike slip faults that terminate in this way allow the style of faulting to change spatially within a deforming area for example from dominantly strike slip to dominantly dip slip while still accommodating the overall deformation required by larger scale regional motions such a change in fault style should also be accompanied by a change in the rotation rate about a vertical axis which may be detected paleomagnetically the kind of strike slip fault termination described here may have consequences for how large strike slip fxaults evolve and grow and for the variation in displacement along their length

growth of faults by accumulation of seismic slip the accommodation of large strains in the upper crust is largely achieved by the accumulation of displacement on faults observation shows that as a fault accumulates displacement it grows in size i e its surface area and its length increase here we address the question for an increase in the amount of displacement on a fault by how much would the length of the fault change it is argued by cowie and scholz 1992a that the displacement on a fault is linearly related to the length of the fault this simple result is expanded upon in this paper by assuming that a fault accumulates displacement by repeated earthquakes two different approaches are presented the first approach considers the balance that must be achieved between the energy available for deformation and the work involved in creating new fault surface area as the fault grows the available energy is provided by changes in strain energy when the fault slips the second approach is to construct a geometrical model for fault growth using the scaling relationship between the slip during a single earthquake and the length of the rupture the total displacement on a fault is the sum of the slips contributed by many earthquakes the usefulness of these two approaches is that the growth of a fault over geologic time can be described by parameters that can be obtained from earthquake and fault data the models presented here predict that 1 the maximum amount a fault can grow in a single earthquake that ruptures the entire fault is of the order of 1 of its previous length and 2 the work of faulting may account for 10 of the total energy available during an earthquake the energy lost from the system is accounted for by work done against friction and seismic radiation consequences of fault growth for the segmentation and thus seismogenic potential of a fault over geologic time are discussed using predictions of the theory