the structure and fault activity of the makran accretionary prism the makran subduction zone has the highest incoming sediment thickness up to 7 5 km of any subduction zone these sediments have formed a wide accretionary prism 400 km seismicity in the makran is generally low however the margin experienced an mw 8 1 earthquake in 1945 which generated a significant regional tsunami seismic reflection data and swath bathymetry data from offshore pakistan are used to analyze the structure and fault activity of the outer accretionary prism the outer prism has a simple structure of seaward verging imbricate thrust faults many continuous for over 100 km along strike fault activity is analyzed using basin stratigraphy and fault geometry revealing a frontal continuously active zone a central intermittently active zone and a landward inactive zone over 75 of the faults in the seaward 70 km of the prism show evidence for recent activity the decollement occurs within the lower sediment section but steps onto the top basement surface in regions of elevated basement topography fault spacing 6 km and taper 4 5 are comparable to other margins such as s hikurangi cascadia and nankai suggesting that high sediment input is not leading to an unusual prism structure the decollement is unreflective which is unexpected considering other prism characteristics predicting a weak surface and may suggest a potentially stronger decollement than previously predicted this study provides a significant advance in our understanding of the structure of an end member convergent margin and demonstrates that systematic analyses of accretionary prism structure can help to elucidate subduction zone dynamics with ultimate relevance to seismogenic potential

the 2013 mw 7 7 balochistan earthquake seismic potential of an accretionary wedge great earthquakes rarely occur within active accretionary prisms despite the intense long term deformation associated with the formation of these geologic structures this paucity of earthquakes is often attributed to partitioning of deformation across multiple structures as well as aseismic deformation within and at the base of the prism davis et al 1983 we use teleseismic data and satellite optical and radar imaging of the 2013 m w 7 7 earthquake that occurred on the southeastern edge of the makran plate boundary zone to study this unexpected earthquake we first compute a multiple point source solution from w phase waveforms to estimate fault geometry and rupture duration and timing we then derive the distribution of subsurface fault slip from geodetic coseismic offsets we sample for the slip posterior probability density function using a bayesian approach including a full description of the data covariance and accounting for errors in the elastic structure of the crust the rupture nucleated on a subvertical segment branching out of the chaman fault system and grew into a major earthquake along a 50 north dipping thrust fault with significant along strike curvature fault slip propagated at an average speed of 3 0 km s for about 180 km and is concentrated in the top 10 km with no displacement on the underlying decollement this earthquake does not exhibit significant slip deficit near the surface nor is there significant segmentation of the rupture we propose that complex interaction between the subduction accommodating the arabia eurasia convergence to the south and the ornach nal fault plate boundary between india and eurasia resulted in the significant strain gradient observed prior to this earthquake convergence in this region is accommodated both along the subduction megathrust and as internal deformation of the accretionary wedge

ball and socket tectonic rotation during the 2013 mw7 7 balochistan earthquake abstract the september 2013 m w 7 7 balochistan earthquake ruptured a 200 km long segment of the curved hoshab fault in southern pakistan with 10 0 2 m of peak sinistral and 1 7 0 8 m of dip slip this rupture is unusual because the fault dips 60 15 towards the focus of a small circle centered in northwest pakistan and despite a 30 increase in obliquity along strike the ratios of strike and dip slip remain relatively uniform surface displacements and geodetic and teleseismic source inversions quantify a bilateral rupture that propagated rapidly at shallow depths from a transtensional jog near the northern end of the rupture static friction prior to rupture was unusually weak 0 05 and friction may have approached zero during dynamic rupture here we show that the inward dipping hoshab fault defines the northern rim of a structural unit in southeast makran that rotates akin to a 2 d ball and socket joint counter clockwise in response to india s penetration into the eurasian plate this rotation accounts for complexity in the chaman fault system and in principle reduces seismic potential near karachi nonetheless these findings highlight deficiencies in strong ground motion equations and tectonic models that invoke anderson byerlee faulting predictions

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

global compilation of interferometric synthetic aperture radar earthquake source models 1 comparisons with seismic catalogs 1 while many earthquakes have now been studied using interferometric synthetic aperture radar insar data a full assessment of the quality and additional value of insar source parameters compared to seismological techniques is still lacking we compile a catalog of source models obtained using insar and estimate the corresponding centroid moment tensor cmt parameters we refer to this compilation as the icmt archive we compare source parameters from over 70 insar studies of 57 global earthquakes with those in the global cmt gcmt international seismological centre isc and engdahl hilst buland ehb seismic catalogs we find an overall good agreement between fault strike dip and rake values in the gcmt and icmt archives likewise the differences in seismic moment between these two archives are relatively small and we do not find support for previously suggested trends of insar leading to larger moments than seismic data however epicentral locations show substantial discrepancies which are larger for the gcmt median differences of 21 km than for the ehb and isc catalogs median differences of 10 km since insar data have a high spatial resolution and thus should map epicentral locations accurately this allows us to obtain a first independent estimate of epicentral location errors in the seismic catalogs earthquake depths from insar are systematically shallower than those in the ehb catalog with a median of differences of 5 km while this trend may be partly due to unmodeled crustal complexity it is also compatible with the observation that the rupture of crustal earthquakes tends to propagate upward in the seismogenic layer

the diffuse transition between the zagros continental collision and the makran oceanic subduction iran microearthquake seismicity and crustal structure summary the nature of the transition between the zagros intra continental collision and the makran oceanic subduction is a matter of debate either a major fault cutting the whole lithosphere or a more progressive transition associated with a shallow gently dipping fault restricted to the crust microearthquake seismicity located around the transition between the transition zone is restricted to the west of the jaz murian depression and the jiroft fault no shallow micro earthquakes seem to be related to the nnw sse trending zendan minab palami active fault system most of the shallow seismicity is related either to the zagros mountain belt located in the west or to the ns trending sabzevaran jiroft fault system located in the north the depth of microearthquakes increases northeastwards to an unusually deep value for the zagros of 40 km two dominant types of focal mechanisms are observed in this region low angle thrust faulting mostly restricted to the lower crust and strike slip at shallow depths both consistent with ns shortening the 3 d inversion of p traveltimes suggests a high velocity body dipping northeastwards to a depth of 25 km this high velocity body probably related to the lower crust is associated with the deepest earthquakes showing reverse faulting we propose that the transition between the zagros collision and the makran subduction is not a sharp lithospheric scale transform fault associated with the zendan minab palami fault system instead it is a progressive transition located in the lower crust the oblique collision results in partial partitioning between strike slip and shortening components within the shallow brittle crust because of the weakness of the pre existing zendan minab palami faults

precise relative earthquake magnitudes from cross correlation abstract we present a method to estimate precise relative magnitudes using cross correlation of seismic waveforms our method incorporates the intercorrelation of all events in a group of earthquakes as opposed to individual event pairings relative to a reference event this method works well when a reliable reference event does not exist we illustrate the method using vertical strike slip earthquakes located in the northeast pacific and panama fracture zone regions our results are generally consistent with the global centroid moment tensor catalog which we use to establish a baseline for the relative event sizes online material supplementary description and formulation of uncertainty and tables of relative magnitudes

high frequency radiation from earthquake sources in laterally varying layered structures point sources situated in a 2 d model of the earth s crust are presented special attention is devoted to faulting sources of finite extent with arbitrary spatial variations of rupture velocity and slip velocity intensity factor over a curved fault inserting gaussian beams and or paraxial ray approximations into the representation theorem leads to expressions which may be evaluated in several ways for situations in which the involved parameters vary smoothly along the fault the narrow beam approach may be used within the region on the fault illuminated by a beam the variation of parameters may be substituted by their taylor expansion and the expressions resulting from the representation theorem may be evaluated easily if any of the involved parameters do not change smoothly along the fault the broadbeam approach may be used in which the slip function is expanded into gaussian envelope functions several other modifications and or combinations of these approaches are proposed none of the mentioned algorithms requires a two point ray tracing moreover synthetic ground motions generated by different faulting models may under certain circumstances be computed using the same system of rays without repeating the relatively timeconsuming ray tracing this makes proposed algorithms more effective

floodplain evolution in the east midlands united kingdom the lateglacial and flandrian alluvial record from the soar and nene valleys this paper describes and interprets the floodplain stratigraphy of two low energy rivers in the east midlands u k and goes on to present an appropriate model of floodplain evolution that may be applicable to other lowland rivers in temperate mid latitudes work has been undertaken at the reach level to try and characterize the entire system in general only laterally extensive exposures have been used and detailed stratigraphic and microstratigraphic recording has been used to facilitate process interpretations all the sites have been radiocarbon dated the dataset consists of three sites in the soar valley and five sites in the larger nene valley the most common sedimentary architecture is a basal gravel with occasional shallow channels covered by a mixed loam sand silt clay of variable thickness with landsurfaces and evidence of bioturbation this loam is frequently interrupted by palaeochannels and finally all these sediments are buried by a massive silt clay unit most of the palaeochannels were abandoned in the early flandrian or between ca 3500 years bp and 2000 years bp the superficial silty clay is diachronous largely because of the irregular topography of the floodplain onto which it was deposited dates from non palaeochannel sections range from ca 3500 bp to ca 2100 years bp the floodplain stratigraphy has been profoundly influenced by soil development and sub aerial processes especially tree throw which has produced distinctive sedimentary structures the loam unit is interpreted as a soil which developed in between both silting palaeochannels and active channels the landsurfaces are both earlier and contemporaneous with the later phase of channel abandonment there is some evidence ca 5000 4000 bp of a rise in floodplain watertables an evolutionary model is proposed which can account for the stratigraphic evidence reported here it is based upon the development of an anastomosing stable multiple channel system from an initial braided river topography and its eventual conversion to a predominantly single channel system due to floodplain and channel siltation the reduction of channels is compensated for by a change in channel types and capacities while the floodplain aggrades this is the stable bed aggrading banks sbab model which necessitates no changes in discharges it is suggested that the sub meandering or straight to sinuous nature of many lowland u k channels may be due to their evolution from an anastomosing pattern where the least meandering channels survived typically with a box s shape planform and at the edges of the floodplain the sites also show that the lateglacial fluvial history of the two catchments seems to have been very different with incision and subsequent aggradation occurring during the younger dryas in the nene but not in the soar given the proximity and similarity of the two catchments this suggests that relatively minor local factors may have been able to push some catchments across fluvial thresholds in contrast the flandrian history of the two rivers has been broadly similar although there is evidence of greater lateral instability and floodplain reworking in the soar which may be due to hydrogeological factors or a different landuse history this work strongly suggests that new process based interpretations of floodplain stratigraphy and new models of floodplain evolution may be required before alluvial history can be easily related to the changing lateglacial and flandrian climate of lowland u k

linearized inversion for fault rupture behavior application to the 1984 morgan hill california earthquake we present a technique to infer the rupture history of an earthquake from near source records of ground motion unlike most previous studies each point on the fault is assumed to slip only once when the rupture front passes with a spatially variable slip intensity in this parameterization the data are linearly related to slip intensity but nonlinearly related to rupture time we perform a linearized inversion for slip intensity and rupture time by iteratively perturbing an assumed starting model the inverse problem for the model perturbation is solved using a tomographic back projection technique smoothing and inequality constraints are applied to ensure that the resulting solution is stable and feasible asymptotic ray theory is used to calculate theoretical seismograms and partial derivatives with respect to model parameters in test cases with noisy synthetic data sets we found that it is possible to distinguish between rupture models having variable slip amplitude and models having variable rupture velocity provided the station coverage is adequate we apply the technique to recordings of the april 24 1984 morgan hill earthquake the results indicate that slip amplitude on the fault plane was extremely variable and that the rupture front did not propagate uniformly away from the hypocenter in particular rupture was delayed on a 12 km2 section of the fault approximately 14 km to the southeast of the hypocenter the rupture front surrounded the region which subsequently failed with a component of rupture propagation back toward the hypocenter similar behavior has been observed in dynamic rupture models with stress or strength inhomogeneities this segment of the fault ruptured with a large slip amplitude releasing 12 of the total seismic moment from 4 of the total area of the aftershock zone the surface trace of this section of the fault is characterized by a complex left step that could act to increase the normal stress acting across the fault however the distribution of aftershocks suggests that the fault at depth is simpler and that it may bend to the right in either case our rupture model suggests that this segment of the fault represents an asperity which initially resisted rupture but eventually ruptured massively we estimate the shear fracture energy for this earthquake to be 2 106 j m2

a new asymptotic method for the modeling of near field accelerograms we study high frequency radiation from a dislocation model of rupture propagation at the earthquake source we demonstrate that in this case all the radiation emanates from the rupture front and by a change of variables that at any instant of time the high frequency waves reaching an observer come from a line on the fault plane that we call isochrone an asymptotic approximation to near source velocity and acceleration is obtained that involves a simple integration along the isochrones for every time step it is shown that wave front discontinuities critical or stopping phases are radiated every time an isochrone becomes tangent to a barrier this leads to what we call the critical ray approximation which is given in a closed form the previous results are compared with discrete wavenumber synthetics obtained by bouchon 1982 for the gilroy 6 recording of the coyote lake earthquake of 1980 the fit between the asymptotic and full numerical method is extremely good the critical ray approximation permits the identification of different phases in bouchon s synthetics and the prediction of the behavior of the signal in the vicinity of their arrival time

precise relative earthquake location using surface waves 1 earthquake locations provide a fundamental tool for seismological investigations while dense seismic networks can provide robust locations accuracy and precision of these locations suffer outside dense networks this is particularly true in offshore areas where location analysis relies heavily on distant seismic observations we present a method for estimating precise relative seismic source epicentroid locations using surface waves several reasons including lower velocities and strength of the signal at distance make use of surface waves for event location appealing we focus on the panama fracture zone region and relocate 81 strike slip earthquakes to produce tectonically consistent epicentroid locations the resulting pattern of earthquakes more clearly delineates recently active regional structures than original body wave locations the mean shift between the us geological survey national earthquake information center epicenter and our epicentroids is about 14 km the median is about 11 km and typical origin time changes are generally less than 2 s we find that north of 6 5 n the plate boundary motion is split across two roughly north south striking structures the panama and balboa fracture zones for the last 36 years slip along these two structures roughly matches slip along the panama fracture zone to the south from 4 5 n to 6 25 n but the balboa fracture zone has roughly three times the moment than the northern panama fracture zone our analyses show that observed rayleigh wave signal to noise ratios for moderate to large shallow earthquakes are suitable for applying the procedure and that rayleigh wave observations form a self consistent set of constraints on the relative location of earthquake centroids

locations of selected small earthquakes in the zagros mountains the zagros mountains of southern iran are marked by a zone of high seismicity and accommodate a significant portion of the convergence between arabia and eurasia due to the lack of dense local seismic or geodetic networks the inferred kinematics of the collision in iran is mainly based on catalogs of teleseismically determined earthquake locations we surveyed all mw 4 5 earthquakes in the harvard centroid moment tensor hcmt and international seismological centre isc catalogs that occurred in the zagros mountains during the period 1992 2002 and that were spanned by interferometric synthetic aperture radar insar images from the ers 1 and 2 satellites we invert the observed deformation for the best fitting point source single fault plane and distributed fault slip for four earthquakes and one unexplained deformation event we find that we can precisely locate earthquakes that are too small to be well located by either the hcmt or isc catalogs allowing us to tie specific earthquakes to active geologic structures

the 2013 balochistan earthquake an extraordinary or completely ordinary event the 2013 balochistan earthquake a predominantly strike slip event occurred on the arcuate hoshab fault in the eastern makran linking an area of mainly left lateral shear in the east to one of shortening in the west the difficulty of reconciling predominantly strike slip motion with this shortening has led to a wide range of unconventional kinematic and dynamic models here we determine the vertical component of motion on the fault using a 1 m resolution elevation model derived from postearthquake pleiades satellite imagery we find a constant local ratio of vertical to horizontal slip through multiple past earthquakes suggesting the kinematic style of the hoshab fault has remained constant throughout the late quaternary we also find evidence for active faulting on a series of nearby subparallel faults showing that failure in large distributed and rare earthquakes is the likely method of faulting across the eastern makran reconciling geodetic and long term records of strain accumulation

crustal stress map of iran insight from seismic and geodetic computations we used the focal mechanisms of crustal earthquakes depth 40 km in the period 1909 2012 and the available gps velocities derived from the data collected between 1999 to 2011 to estimate the magnitude and directions of maximum principal stress and strain rates in iran the pearson product moment correlation was used to find the correlation between the stress field obtained from the focal mechanism stress inversion and that obtained using the seismic and geodetic strain rates our assumption is that stresses in a continuum are produced by tectonic forces and the consequent deformation on the crustal scale therefore the direction of the stress and strain or strain rate are ideally to be the same our results show a strong correlation between the directions of the principal components of stress and strain rate obtained using the different data methods using weighted average analysis we present a new stress map for iran

rupture processes of the 2013 2014 minab earthquake sequence iran we constrain epicentroid locations magnitudes and depths of moderate magnitude earthquakes in the 2013 2014 minab sequence using surface wave cross correlations surfacewave spectra and teleseismic body wave modelling we estimate precise relative locations of 54 mw 3 8 earthquakes using 48 409 teleseismic intermediate period rayleigh and lovewave cross correlation measurements to reduce significant regional biases in our relative locations we shift the relative locations to align the mw 6 2 main shock centroid to a location derived from an independent insar fault model our relocations suggest that the events lie along a roughly east west trend that is consistent with the faulting geometry in the gcmt catalogue the results support previous studies that suggest the sequence consists of leftlateral strain release but better defines the main shock fault length and shows that most of the mw 5 0 aftershocks occurred on one or two similarly oriented structures we also show that aftershock activity migrated westwards along strike away from the main shock suggesting that coulomb stress transfer played a role in the fault failure we estimate the magnitudes of the relocated events using surface wave cross correlation amplitudes and find good agreement with the gcmt moment magnitudes for the larger events and underestimation of small event size by catalogue ms in addition to clarifying details of the minab sequence the results demonstrate that even in tectonically complex regions relative relocation using teleseismic surface waves greatly improves the precision of relative earthquake epicentroid locations and can facilitate detailed tectonic analyses of remote earthquake sequences

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

on finding and using repeating seismic events in and near china 1 a comprehensive search for repeating seismic events was performed using cross correlation on waveforms for 17 898 seismic events in and near china reported in the annual bulletin of chinese earthquakes from 1985 to 2005 we define a repeat as an event pair having a high cross correlation 0 8 for a particular bandwidth 0 5 to 5 hz and time window 5 s before p arrival to 40 s after lg arrival such events typically have hypocenters separated by no more than about 1 km this result enables a determination of median relative location error of around 15 km for global and regional catalogs that locate events in this study one at a time using phase picks the maximum location error is on the order of hundreds of kilometers we use nonnormalized cross correlation values to measure relative amplitudes of event pairs the standard deviation is about 0 06 magnitude units much better than the precision of relative magnitudes for doublet events which we estimate for the chinese catalog to have a standard deviation of 0 36 magnitude units two thousand three hundred and seventy nine events out of the 17 898 or 13 of the events in this catalog are classified as repeats with later years showing an increase in the percentage about half the repeats occur as isolated doublets the rest as multiplets of three or larger up to a 92 event multiplet most of the events appear to be triggered or are due to some earthquake interaction since their recurrence intervals are significantly shorter than would be estimated from tectonic loading

effects of three dimensional crustal structure on the estimated slip history and ground motion of the loma prieta earthquake abstract the strong ground motion of the loma prieta earthquake is synthesized using a known three dimensional 3d crustal model of the region a rupture model determined under the assumption of laterally homogeneous structure and green9s functions computed by superposition of gaussian beams compared to results obtained assuming a laterally homogeneous crust stations within 30 km of the hypocenter and 5 km of the fault trace are predicted to be strongly focused by factors up to 10 or more while stations lying at the northeastern edge of the santa clara valley are predicted to be weakly defocused by factors of 0 5 the focusing is caused by low velocities lying between the zayante and san andreas faults and the defocusing is caused by a wedge of high velocity material between the san andreas and sargent faults the magnitude of amplitude variations resulting from known 3d structure is similar to that incorporated in site effects resulting from variations in surface impedance and shallow structure beneath receivers the existence of these effects add to the uncertainty in estimates of future strong ground motion the strong path dependence of the effects makes it possible to include them in estimates of future ground motions only by knowing both the 3d structure and the sites of localized high slip in future earthquakes to match observed waveforms with the structure model of eberhart phillips et al 1990 the slip model of beroza 1991 is modified by reducing the magnitude of the northwest maximum in slip by a factor of 0 7 and increasing the magnitude of the southeast maximum slip by a factor of 2 5 these modifications are in the range of variations in the estimated slip history published by investigators using different data sets and inversion procedures

modeling of short period surface wave propagation in southern california abstract for the 1992 landers mainshock the lateral heterogeneity of the lithosphere combined with an extended earthquake source may account for the complexity of the strong motion observations that cannot be easily interpreted by a simplified point source model in a laterally homogeneous medium both the effect of an extended source and that of lateral heterogeneity are examined using a forward modeling technique that combines distributed nonuniform slip on a fault plane in a 3d medium surface wave synthetics are constructed using surface wave gaussian beam method which allows for a mild degree of lateral heterogeneity we analyze the amplitude and waveform data of the landers strong motion recordings in southern california in order to identify the path effects and the effect of an extended source the overall source parameters of the landers earthquake are obtained by comparing synthetics with recordings at near source stations which lie within relatively homogeneous path structures this procedure yields a unilateral rupture propagating northwesterly over two distinct rupture segments with somewhat different focal mechanisms the surface wave phase velocity map is modified to fit the data recorded at larger hypocentral distances the final improved model generates a very good agreement between observations and synthetics in the presence of lateral heterogeneity the focusing defocusing and multipath interference are found to contribute significantly to the strong motion shaking in a 3d basin