rupture directivity of the 2011 mw 5 2 lorca earthquake spain 1 on may 11th 2011 a rather small earthquake caused nine fatalities in the city of lorca se spain we analyze seismograms from a dense network to characterize the source of this earthquake we estimate an oblique reverse faulting mechanism moment magnitude of 5 2 and a shallow hypocenter 4 6 km at only 5 5 km epicentral distance from the city center double difference relocations yield a 5 km long ne sw trending distribution of aftershocks sw of the mainshock suggesting a sw propagating rupture along the alhama de murcia fault we use the mw 4 6 foreshock and an mw 3 9 aftershock as empirical greens functions to estimate apparent source time functions observing a clear directivity effect we model apparent durations with a unilateral and asymmetric bilateral rupture in both cases obtaining rupture directivity of n220 e towards lorca in addition to the near epicenter and shallow depth directivity may have contributed to the significant impact

stress evolution in southern california and triggering of moderate small and micro size earthquakes we calculate the evolution of stresses in southern california extending the study of deng and sykes 1997 by increasing from 6 to 36 the number of earthquakes for which coseismic changes in stress are computed and by expanding from m 6 to m 1 8 the range of magnitudes m of events whose focal mechanism solutions are examined in the context of the evolving stress field the cumulative stress on a given date is calculated with respect to an arbitrary zero baseline just before the 1812 wrightwood earthquake by taking into account the long term stress loading associated with 98 fault segments and coseismic stress changes for 36 significant earthquakes our calculations indicate that more than 85 of m 5 earthquakes from 1932 1995 occurred in regions of positive change in coulomb failure function cff most of the remaining about 15 earthquakes that occurred in areas of negative cff fall very close to boundaries between positive and negative cff some of which are sensitive to the less well controlled slip distributions of the earliest historic events calculations also show that from 1981 until just before the 1992 landers earthquake more than 85 of small m 3 and micro size m 1 8 shocks in the seeber and armbruster 1995 catalog with mechanisms involving either nw trending right lateral or ne trending left lateral strike slip faulting occurred in regions of positive cff the ratio of encouraged to all small and micro size events reaches a high value of about 88 if an apparent coefficient of friction between 0 0 and 0 6 is used the highest percentage of earthquakes occurred in areas where stress is about 1 mpa above the 1812 baseline most 66 events occurred in regions of cff between 0 0 and 2 0 mpa the upper limit indicates that the approximate range of stress variation in the earthquake cycle is of the order of 2 0 mpa the fact that the locations of most moderate small and micro size earthquakes are still related to stress changes remaining from large historical events might be used to constrain slip distribution of some of those earthquakes and to constrain the locations of future significant events

stress sensitivity of fault seismicity a comparison between limited offset oblique and major strike slip faults we present a new three dimensional inventory of the southern san francisco bay area faults and use it to calculate stress applied principally by the 1989 m 7 1 loma prieta earthquake and to compare fault seismicity rates before and after 1989 the major high angle right lateral faults exhibit a different response to the stress change than do minor oblique right lateral thrust faults seismicity on oblique slip faults in the southern santa clara valley thrust belt increased where the faults were unclamped the strong dependence of seismicity change on normal stress change implies a high coefficient of static friction in contrast we observe that faults with significant offset 50 100 km behave differently microseismicity on the hayward fault diminished where right lateral shear stress was reduced and where it was unclamped by the loma prieta earthquake we observe a similar response on the san andreas fault zone in southern california after the landers earthquake sequence additionally the offshore san gregorio fault shows a seismicity rate increase where right lateral oblique shear stress was increased by the loma prieta earthquake despite also being clamped by it these responses are consistent with either a low coefficient of static friction or high pore fluid pressures within the fault zones we can explain the different behavior of the two styles of faults if those with large cumulative offset become impermeable through gouge buildup coseismically pressurized pore fluids could be trapped and negate imposed normal stress changes whereas in more limited offset faults fluids could rapidly escape the difference in behavior between minor and major faults may explain why frictional failure criteria that apply intermediate coefficients of static friction can be effective in describing the broad distributions of aftershocks that follow large earthquakes since many of these events occur both inside and outside major fault zones

the effects of double fault bends on rupture propagation a geometrical parameter study we use the 2d finite element method to determine how geometrical parameters determine whether rupture will propagate across a linked stepover in a strike slip fault the end segments of the fault system are aligned in the direction of maximum shear and the length and angle of the linking segment are allowed to vary we observe that ruptures propagate through extensional stepovers with steeper angles and longer linking segments than otherwise equivalent compressional step overs these different rupture behaviors form distinct regions in angle stepover length parameter space the boundary between these regions takes the shape of an asymptotic curve in both the extensional and compressional cases models in which the size of the entire fault system was made larger or smaller revealed that the location of the bound aries between regions of different rupture behavior do not scale linearly with the system size it was easier to rupture steeper and relatively longer stepovers in fault systems that were larger overall a separate set of models in which the stress field is rotated so that the parallel end segments were optimally aligned for rupture significantly altered the rupture behavior curves in this stress field it was easier to rupture compressional stepovers with steeper angles and longer linking segments than it was to rupture equivalent extensional stepovers in both the case in which the end segments are aligned with the direction of maximum shear and the case in which the end segments are optimally oriented for rupture the angles at which rupture could no longer propagate through the entire fault corresponded with peaks in the fault s s value

from extension to transpression quaternary reorganization of an extensional related drainage network by the alhama de murcia strike slip fault eastern betics abstract the complex present day drainage network of the lorca totana area records the changing tectonic setting from extension to transpression in the eastern betics through a detailed morphometric analysis we evaluate the topographic response to this major change in the tectonic setting and the influence in the drainage of miocene extension and middle pleistocene to present day transpression the present day drainage network preserves geomorphic features inherited from late miocene extension that are being overprinted by a new transverse fluvial system this new system advanced towards the nw since the middle pleistocene in response to a localized base level drop related to the ne sw oriented alhama de murcia sinistral reverse fault geomorphic indexes calculated in this work suggest the present day activity of the alhama de murcia fault and the sierra de la tercia anticline the two major tectonic structures in the area the landscape rejuvenation associated with this process results in contrasting mountain front sinuosity values between old and new mountain fronts high slk index anomalies convex shaped and complex hypsometric curves knickpoints in river profiles contrasting slope area plots and high steepness index values this fluvial reorganization was driven progressively by successive fluvial captures preserved as wind gaps in the present day drainage network

refining seismic parameters in low seismicity areas by 3d trenching the alhama de murcia fault se iberia three dimensional paleoseismology in strike slip faults with slip rates less than 1 mm per year involves a great methodological challenge we adapted 3d trenching to track buried channels offset by the alhama de murcia seismogenic left lateral strike slip fault se iberia a fault net slip of 0 9 0 1 mm yr was determined using statistical analysis of piercing lines for one buried channel whose age is constrained between 15 2 1 1 ka and 21 9 22 3 cal bp this value is larger and more accurate than the previously published slip rates for this fault the minimum number of five paleo earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka the combination of both seismic parameters yields a maximum slip per event between 5 3 and 6 3 m we show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas

earthquake ruptures with strongly rate weakening friction and off fault plasticity part 1 planar faults abstract observations demonstrate that faults are fractal surfaces with deviations from planarity at all scales we study dynamic rupture propagation on self similar faults having root mean square rms height fluctuations of order 10 3 to 10 2 times the profile length our 2d plane strain models feature strongly rate weakening fault friction and off fault drucker prager viscoplasticity the latter bounds otherwise unreasonably large stress concentrations in the vicinity of bends our choice of a cohesionless yield function prevents tensile stress states and thus fault opening a consequence of strongly rate weakening friction is the existence of a critical background stress level above which self sustaining rupture propagation in the form of self healing slip pulses first becomes possible around this level at which natural faults are expected to operate ruptures become extremely sensitive to fault roughness and exhibit substantial fluctuations in rupture velocity except for shallow inclinations of the maximum compressive stress to the fault less than about 20 the fluctuations are anticorrelated with the local fault slope these accelerations and decelerations of the rupture together with naturally emerging slip heterogeneity excite waves of all wavelengths and result in ground acceleration spectra that are flat at high frequency consistent with observed strong motion records

detection of a locked zone at depth on the parkfield california segment of the san andreas fault the parkfield california segment of the san andreas fault is transitional in character between the creeping segment of the fault to the northwest and the locked carrizo plain segment to the southeast the rate of shallow fault slip decreases from 25 30 mm yr northwest of the epicenter of the 1966 parkfield earthquake to zero at the southeastern end of the 1966 rupture zone data from a network of trilateration lines spanning the san andreas fault near parkfield and extending to the pacific coast near san luis obispo shed light on the rate of fault slip at depth since the 1966 earthquake in this study average rates of line length change and shallow fault slip were inverted to determine the slip rate at depth on the parkfield fault segment the fault is taken to be a vertical surface with unknown distribution of strike slip displacement in an elastic half space a striking result of the inversions is that all solutions providing acceptable fits to the data exhibit a locked zone essentially coincident with the rupture surface of the 1966 parkfield earthquake the data require that the locked zone extend nearly as far north as the 1966 epicenter however the vertical extent of the locked zone is not well resolved over much of the parkfield segment the fault is slipping faster at the earth s surface than it is at seismogenic depths in order to fit the trilateration measurements it is necessary to include a component of contraction normal to the trend of the san andreas the inversion results suggest a spatially uniform normal strain of 0 06 strain yr the orientation of the contraction is compatible with geologic and seismic evidence of active folding and reverse faulting in the region the magnitude of the contraction is consistent with convergence rates inferred from global plate motion models

significance of euxinic condition in the middle eocene paleo arctic basin a geochemical study on the iodp arctic coring expedition 302 sediments article 34 s on the early to middle eocene section of the acex cores the ts were high in all the examined intervals and the sedimentary sulfur occurred mainly as framboidal pyrite indicating that sufficient sulfate indicative of seawater was present in the deep layer of the paleo arctic basin and that the pyrite was formed in the sediments under sufficient iron input the high ts values with low 34 s values also indicate the continuous existence and supply of seawater the high accumulation of sulfide in unit 1 6 was due to a significant increase of toc supply which increased sulfate reduction rates by bacteria the toc ts diagram shows excess sulfur content relative to the toc suggesting euxinic condition of the bottom water during the studied period such an oxygen depleted environment was brought about by salinity stratification and restricted water circulation the patterns observed in the acex data can be comparable with the mediterranean sapropels the global 34

insar and gps derived coseismic deformation and fault model of the 2017 ms7 0 jiuzhaigou earthquake in the northeast bayanhar block abstract on 8 august 2017 a ms7 0 earthquake stroke the city of jiuzhaigou sichuan china the jiuzhaigou earthquake occurred on a buried fault in the vicinity of three well known active faults and this event offers a unique opportunity to study tectonic structures in the epicentral region and stress transferring here we present coseismic displacement field maps for this earthquake using descending and ascending sentinel 1a interferometric synthetic aperture radar insar data deformation covered an area of approximately 50 50 km with a maximum line of sight los displacement of 22 cm in ascending and 14 cm in descending observations on the west side of the source fault based on insar and global positioning system gps measurements both separately and jointly we constructed a one segment model to invert the coseismic slip distribution and dip angle of this event our final fault slip model suggests that slip was concentrated at an upper depth of 15 km there was a maximum slip of 1 3 m and the rupture was dominated by a left lateral strike slip motion the inverted geodetic moment was approximately 6 75 1018 nm corresponding to a moment magnitude of mw6 5 consistent with seismological results the calculated static coulomb stress changes indicate that most aftershocks occurred in stress increasing zones caused by the mainshock rupture the jiuzhaigou earthquake has brought the western part of the tazang fault 0 1 0 4 mpa closer to failure indicating an increasing seismic hazard in this region the coulomb stress changes caused by the 2008 mw7 8 wenchuan earthquake suggest that stress loading from this event acted as a trigger for the jiuzhaigou earthquake

the vertical separation of mainshock rupture and microseismicity at qeshm island in the zagros fold and thrust belt iran we investigate the depth and geometry of faulting within a cluster of buried reverse faulting earthquakes that struck qeshm island in the zagros fold and thrust belt over a four year period between november 2005 and july 2009 of particular interest is our observation that there was a vertical separation between the largest two earthquakes mw 5 8 and 5 9 which ruptured the lower parts of a 10 km thick sedimentary cover and microseismicity recorded by a local network after the first mw 5 8 event which was concentrated within the underlying basement at depths of 10 20 km although measured in different ways the largest three earthquakes using radar interferometry moderate sized events with teleseismically recorded long period waveforms and the microseismicity using data from a local seismic network we used consistent velocity and elastic parameters in all our modelling and the observed vertical separation is robust and resolvable we suggest that it reflects the influence of the proterozoic hormuz salt a weak layer at the base of the sedimentary cover across which rupture failed to propagate because the full thickness of the seismogenic layer failed to rupture during the largest earthquakes in the sequence the lower unruptured part may constitute a continued seismic hazard to the region considering the rarity of earthquakes larger than mw 6 2 in the zagros simply folded belt we suggest that the hormuz salt forms an important regional barrier to rupture not just a local one finally we note that buried faulting involved in the largest earthquakes is almost perpendicular to the trend of an anticline exposed at the surface immediately above them this suggests that locally faulting and folding are decoupled probably along a weak layer of marls or evaporites in the middle part of the sedimentary cover

neogene basin inversion and recent slip rate distribution of the northern termination of the alhama de murcia fault eastern betic shear zone se spain the alhama de murcia fault is one of the main active structures of the eastern betic shear zone se spain characterized by the presence along its trace of neogene basins developed under early to late miocene extensional tectonics a dominant nnw sse shortening direction is active from late miocene driven by the present day plate convergence we present the structural analysis of the northeastern section of this fault where reliable estimations of slip rates were unknown due to the lack of geomorphological evidence of recent activity the recent tectonic evolution and reactivation of the northeastern section is closely related to the fortuna basin development and tectonic inversion we approach the structural analysis through the interpretation of seismic reflection profiles well data fieldwork and 3d geological modeling we estimated a maximum long term slip rate of 0 32 0 18 0 13 mm yr in the librilla sector last 4 8 7 6 ma based on cross section restorations and assuming current motion trends from gps data according to the results from the cross sections restored along the section and a vertical displacement analysis based on a 3d model the slip rate distribution shows a decrease of activity toward the northeastern tip of the studied fault section this supports a transference of deformation between the alhama de murcia fault and the carrascoy fault which seems to absorb part of the shortening during the plio quaternary explaining the lower relief created by the activity of the northeastern section the slip rates obtained have important implications in seismic hazard assessments and in the distribution of deformation along the region

glacioeustasy during the middle eocene insights from the stratigraphy of the hampshire basin uk the sedimentary strata of the hampshire basin constitute some of the best preserved palaeogene sequences worldwide and include the traditional unit stratotype for the bartonian 36 9 41 4 ma the barton clay formation at alum bay on the isle of wight iow was studied to assess the evidence for middle eocene sea level variation in records of grain size sediment properties faunal assemblage foraminiferal diversity indices and foraminiferal stable isotopes sedimentary cycles of 1 10 myr third order and 0 2 0 5 myr fourth order duration are reported and interpreted to reflect 20 60 metre variations in water depth additionally an integrated magneto bio chemostratigraphical age model for the succession at alum bay is presented and new and published litho and bio stratigraphical markers are used to correlate additional successions based on this age model it appears that during the late lutetian and early bartonian 42 38 ma water depth variation identified within the basin was synchronous sedimentary and fossil evidence supports episodic uplift in the eastern part of the hampshire basin during the bartonian which at present precludes the calculation of eustatic sea level however the amplitude and frequency of water depth variations identified in the barton clay formation and correlations to published sea level curves are consistent with a component of these changes being glacioeustatic during the middle eocene there is also evidence for a large excursion delta 18o 1 per mille sign in the mono specific benthic foraminiferal oxygen isotope record alum bay 39 9 ma which is correlated to the isotope excursion at the middle eocene climatic optimum previously reported in the southern ocean and other localities a contemporaneous water depth increase of 40 m at alum bay may indicate that a component of this global oxygen isotope excursion results from a reduction in continental ice storage

depth segmentation of the seismogenic continental crust the 2008 and 2009 qaidam earthquakes 1 the seismic hazard in the immediate vicinity of an earthquake is usually assumed to be reduced after rupture of a continental fault with along strike portions being brought closer to failure and aftershocks being significantly smaller this period of reduced hazard will persist as strain re accumulates over decades or centuries however this is only realised if the entire seismogenic layer ruptured in the event here we use satellite radar measurements to show the ruptures of two mw 6 3 earthquakes occurring in almost the same epicentral location ten months apart in the qaidam region china were nearly coplanar the 2008 earthquake ruptured the lower half of the seismogenic layer the 2009 event the upper half fault segmentation with depth allows a significant seismic hazard to remain even after a moderate and potentially devastating earthquake this depth segmentation possibly exists in the case of the 2003 bam earthquake where satellite radar and aftershock measurements showed that it ruptured only the upper half of the 15 20 km deep seismogenic region jackson et al 2006 and that the lower unruptured part may remain as a continuing seismic hazard

triggering effect of m 4 5 earthquakes on the earthquake cycle of repeating events at parkfield california stress perturbations influence earthquake recurrence and are of funda mental importance to understanding the earthquake cycle and determining earthquake hazard the large population of repeating earthquakes on the san andreas fault at parkfield california provides a unique opportunity to examine the response of the repeating events to the occurrence of moderate earthquakes using 187 m 0 4 to 1 7 repeating earthquake sequences from the high resolution seismic network cat alog we find that the time to recurrence of repeating events subsequent to nearby m 4 5 earthquakes is shortened suggesting triggering by major events the triggering effect is found to be most evident within a distance of 5 km corresponding to static coseismic stress changes of 0 6 26 6 kpa and decays with distance we also find coherently reduced recurrence intervals from 1993 to 1998 this enduring recurrence acceleration over several years reflects accelerated fault slip and thus loading rates during the early 1990s online material figures of event chronologies of res estimates of dt and coseismic static stress changes

directivity detection and source properties of the 11 may 2011 mw 5 2 lorca spain earthquake a kinematic finite source study of the 11 may 2011 m w 5 2 lorca spain earthquake has been performed using broadband data from the spanish national network the nodal plane ambiguity of the double couple solution was resolved from finite source analysis and a rupture velocity of 1 8 km s 1 and the northeast southwest striking northwest dipping plane was found to best fit the data this fault plane corresponds to the central sector of the alhama de murcia fault amf the resulting slip distribution has a maximum of 19 3 cm and a total seismic moment of 6 25 1016 n m a jackknife test has been performed to estimate the fault plane errors and their consequences in the slip distribution also synthetic tests have been performed to evaluate the errors in the finite source modeling from this model a prediction of the strong ground motion near the fault corrected for soil amplification is given in terms of peak ground velocity pgv which fits with the observed value at the accelerograph in the city of lorca we also compared the pgv converted to modified mercalli intensity at the surface with the intensity distribution also showing good agreement finally we extracted the directivity pulse from the strong ground motion record at lorca with 0 5 s period in the transverse component to the amf direction and 33 cm s 1 pgv to further analyze the directivity effect we estimate the duration and azimuthal amplitude distribution of the source time functions finding them to be shorter and of greater amplitude in the direction of rupture and longer and smaller in amplitude in the opposite direction

the alhama de murcia fault se spain a seismogenic fault in a diffuse plate boundary seismotectonic implications for the ibero magrebian region received 20 december 2002 revised 15 september 2003 accepted 26 september 2003 published 2 january 2004 1 the shortening between the african and the iberian plates is absorbed by a number of faults distributed over a very wide zone with very low slip rates and long periods of seismic loading thus a seismotectonic map based only on faults associated with seismicity or with expressive geomorphic features is incomplete it is possible to characterize seismogenic faults using paleoseismology first paleoseismological results based on trenching analysis in the eastern betics lorca totana segment of the alhama de murcia fault are presented the main paleoseismic parameters of this fault segment are 1 a minimum of two to three mw 6 5 7 earthquakes in the last 27 kyr shortly before 1650 a d between 830 and 2130 b c and shortly before 16 7 ka respectively with a mean recurrence period of 14 kyr and a very short elapsed time and 2 a net slip rate of 0 07 0 6 mm yr during the last 30 kyr these results were extrapolated to the rest of the known active faults in the eastern betics and were added to the slip rates of the active faults at the african margin the total slip rate of the transect which crosses de alhama de murcia fault in spain and reaches the cheliff basin algeria would represent 21 82 of the total shortening between africa and eurasia estimated from plate motion models and seismic moment summation a number of factors could account for this discrepancy 1 hidden seismogenic faults in the emerged areas 2 absence of correlation between current and late pleistocene slip rates 3 extensive small faults that are undetected and that absorb a significant amount of the deformation and 4 possible overestimation of the convergence rates index terms 7221 seismology paleoseismology 7230 seismology seismicity and seismotectonics 7215 seismology earthquake parameters 8150 tectonophysics plate boundary general 3040 keywords eastern betics alhama de murcia fault paleoseismology trenching seismotectonics plate boundary

an exceptionally long paleoseismic record of a slow moving fault the alhama de murcia fault eastern betic shear zone spain most catastrophic earthquakes occur along fast moving faults although some of them are triggered by slow moving ones long paleoseismic histories are infrequent in the latter faults here an exceptionally long paleoseismic record more than 300 k y of a slow moving structure is presented for the southern tip of the alhama de murcia fault eastern betic shear zone which is characterized by morphological expression of current tectonic activity and by a lack of historical seismicity at its tip the fault divides into a splay with two main faults bounding the gonar fault system at this area the condensed sedimentation and the distribution of the deformation in several structures provided us with more opportunities to obtain a complete paleoseismic record than at other segments of the fault the tectonic deformation of the system was studied by an integrated structural geomorphological and paleoseismological approach stratigraphic and tectonic features at six paleoseismic trenches indicate that old alluvial units have been repeatedly folded and thrusted over younger ones along the different traces of the structure the correlation of the event timing inferred for each of these trenches and the application of an improved protocol for the infrared stimulated luminescence irsl dating of k feldspar allowed us to constrain a paleoseismic record as old as 325 ka we identified a minimum of six possible paleoearthquakes of m w 6 7 and a maximum mean recurrence interval of 29 k y this provides compelling evidence for the underestimation of the seismic hazard in the region

resolution of rupture directivity in weak events 1 d versus 2 d source parameterizations for the 2011 mw 4 6 and 5 2 lorca earthquakes spain resolving robustly source parameters of small moderate magnitude earthquakes is still a challenge in seismology we infer directivity from apparent source time functions astfs at regional distance and quantify the associated uncertainties astfs are used for i modeling a propagating 1d line source from the duration data and ii inverting the 2d slip distribution from the full signals slip inversion is performed through a popperian scheme where random trial models are either falsified on account of large misfit or else become members of the solution set of the inverse problem we assess the resolution of rupture directivity representing centroid shifts from the solution set in a rose diagram using as example an event with well studied rupture directivity the 2011 mw 5 2 lorca spain earthquake 1d and 2d parameterizations yield similar estimates for direction n213 e and n220 e respectively and asymmetry 67 33 65 35 of rupture propagation as well as rupture length 2 1 km 2 7 km and speed 3 5 km s 3 25 km s the high rupture velocity 90 vs may be held primarily responsible for the strong directivity effect of this earthquake we show that inversion of apparent source durations is intrinsically unable to resolve highly asymmetric bilateral ruptures while inversion of full astfs misses part of the signal s complexity suggesting the presence of deconvolution artifacts we extend the analysis to the mw 4 6 foreshock of the lorca earthquake inferring similar directivity parameters and slip pattern as for the mainshock the rupture towards sw of both earthquakes suggests that this direction could be inherent to the fault segment

genetic stratigraphic sequences in basin analysis ii application to northwest gulf of mexico cenozoic basin the northwest gulf of mexico cenozoic sedimentary wedge illustrates the application of genetic stratigraphic sequence analysis and documents several general conclusions 1 sequences defined by regional marine flooding are the principal genetic stratigraphic units of the basin fill continental margins are characterized by repetitive episodes of basin margin offlap punctuated by periods of transgression and marine flooding of the depositional platform 2 continental margin outbuilding is concentrated at one or more shelf edge deltaic depocenters separated by interdeltaic bights depocenters remain fixed during a depositional episode but commonly relocate during transgression and flooding 3 a distinct syndepositional structural style in prograding continental margins results in sporadic uplift of a basin fringing peripheral bulge and accentuates preservation of shelf margin facies along zones of extensional normal faulting and enhanced subsidence 4 genetic stratigraphic sequences commonly reflect an evolving interplay among two or even three variables for example early cenozoic gulf sequences are most closely related to tectonic events of the intraplate source terrane which in turn affect rate and location of sediment supply and basin margin response to loading late cenozoic sequences more closely reflect proposed eustatic cycles

earthquake rupture propagation inferred from the spatial distribution of fault rock frictional properties abstract the frictional properties of fault rocks that rupture during earthquakes are expected to affect the nucleation and propagation of seismic slip but these properties and their variation under in situ earthquake conditions are typically unknown here we present experimental results on the variation of frictional properties of fault rocks from the alhama de murcia fault amf in se spain which ruptured in the 2011 lorca earthquake in the epicentral area the fault zone is characterized by the presence of abundant phyllosilicate rich gouges that surround more competent fractured lenses of the phyllitic basement measurements of lineaments and orientations of r shears in the gouges are consistent with cmt solutions of the 2011 lorca earthquake suggesting that the bulk of displacement on the amf was accommodated within similar gouges at depth in order to evaluate the frictional properties of the fault rocks of the amf we performed rotary shear experiments under hydrothermal conditions of samples obtained from surface outcrops of the amf zone progressively simulating deeper levels in the crust by stepping temperature effective normal stress and fluid pressure a negative velocity dependence of friction expressed as a negative value of the rate and state friction rsf parameter a b and which is a prerequisite for the nucleation of an instability was observed only for samples derived from competent lenses under hydrothermal conditions gouge derived samples exhibited only velocity strengthening properties i e positive values of a b which increase with deeper conditions in particular with increasing effective normal stress combined with our outcrop observation of the anastomosing nature of gouges surrounding more competent lenses of fractured protolith our results suggest that the 2011 lorca earthquake nucleated in the competent lenses followed by propagation of slip into the frictionally weaker gouges the inferred upward propagation direction of the 2011 lorca earthquake is consistent with propagation of the rupture into the velocity strengthening gouges which at shallower levels provide a smaller barrier to seismic slip due to lower values of effective normal stress and a b our results suggest that the spatial variation of the frictional properties along the amf was an important factor controlling the nucleation and propagation of seismic slip which together with the shallow hypocenter close to the city of lorca led to serious damage we infer that understanding of such variations in frictional properties may significantly improve seismic hazard evaluations in tectonically active regions

superficial simplicity of the 2010 el mayor cucapah earthquake of baja california in mexico the geometry of faults is usually thought to be more complicated at the surface than at depth and to control the initiation propagation and arrest of seismic ruptures the fault system that runs from southern california into mexico is a simple strike slip boundary the west side of california and mexico moves northwards with respect to the east however the m w 7 2 2010 el mayor cucapah earthquake on this fault system produced a pattern of seismic waves that indicates a far more complex source than slip on a planar strike slip fault here we use geodetic remote sensing and seismological data to reconstruct the fault geometry and history of slip during this earthquake we find that the earthquake produced a straight 120 km long fault trace that cut through the cucapah mountain range and across the colorado river delta however at depth the fault is made up of two different segments connected by a small extensional fault both segments strike n130 e but dip in opposite directions the earthquake was initiated on the connecting extensional fault and 15 s later ruptured the two main segments with dominantly strike slip motion we show that complexities in the fault geometry at depth explain well the complex pattern of radiated seismic waves we conclude that the location and detailed characteristics of the earthquake could not have been anticipated on the basis of observations of surface geology alone

relation between continental strike slip earthquake segmentation and thickness of the crust 1 high resolution maps of large continental strike slip earthquake surface ruptures show that they are formed of fault segments these segments are bounded by fault bends step overs or combinations of the two the lowest limit in size for such segments may not be relevant in the understanding of earthquake mechanics as it pertains to the granular properties of fault zones the maximum limit in segment length however is important as it is directly relates to the maximum extent of seismic rupture to measure the length of the segments a new quantitative method based on piecewise linear fitting is developed and is used to automatically retrieve segments from earthquake rupture maps next this approach is tested against a set of ten continental strike slip earthquake ruptures derived from similar high quality maps the test suggests that segments have a maximum length of 18 km independent of regional tectonic setting slip inversions for earthquakes based on seismological and or geodetic data most often are not unique and can show some variability even for one particular event some basic characteristics however such as total moment release or general source geometry seem to persist that are relevant to earthquake mechanics measurements of the maximum horizontal extent of individual slip patches derived from seismic source inversion for strike slip ruptures show that their strike dimension does not increase infinitely with magnitude but instead reaches a maximum value of 25 km these two independent lines of observations complemented by earlier data and analog experiments suggest that it is the thickness of the seismogenic crust that controls the structural scaling of the length of seismic segments and that it is independent of the ultimate size of individual earthquakes

construction of a palaeogene tide dominated shelf influence of top chalk topography and sediment supply wessex basin uk palaeogene siliciclastic sediments reading and london clay formations in the wessex basin record an upward change through four tidally influenced deposition systems the lowest reading formation was deposited in estuarine and coastal plain environments the overlying london clay records discrete upward changes from deltaic to mixed tidal flat to tidal sandsheet bagshot sands erosional topography on the top chalk surface had an important control on deposition 1 topographic lows controlled the initial sites of marine flooding and sedimentation 2 lows would have acted as conduits for sediment delivery 3 lows created additional accommodation by the compaction of thick mud fills 4 lows may have formed preferential sites for delta growth as topography was reduced by sediment infill depositional units tended toward more sheet like geometries heavy minerals reveal that an upward progradational aggradational trend and the development of more sand rich facies are related to a change in provenance toward sand rich cornubian sources

earthquake damage orientation to infer seismic parameters in archaeological sites and historical earthquakes abstract studies to provide information concerning seismic parameters and seismic sources of historical and archaeological seismic events are used to better evaluate the seismic hazard of a region this is of especial interest when no surface rupture is recorded or the seismogenic fault cannot be identified the orientation pattern of the earthquake damage ed e g fallen columns dropped key stones that affected architectonic elements of cities after earthquakes has been traditionally used in historical and archaeoseismological studies to infer seismic parameters however in the literature depending on the authors the parameters that can be obtained are contradictory it has been proposed the epicenter location the orientation of the p waves the orientation of the compressional strain and the fault kinematics and authors even question these relations with the earthquake damage the earthquakes of lorca in 2011 christchurch in 2011 and emilia romagna in 2012 present an opportunity to measure systematically a large number and wide variety of earthquake damage in historical buildings the same structures that are used in historical and archaeological studies the damage pattern orientation has been compared with modern instrumental data which is not possible in historical and archaeoseismological studies from measurements and quantification of the orientation patterns in the studied earthquakes it is observed that there is a systematic pattern of the earthquake damage orientation edo in the proximity of the seismic source fault trace

the 2010 mw 6 8 yushu qinghai china earthquake constraints provided by insar and body wave seismology 1 by combining observations from satellite radar body wave seismology and optical imagery we have determined the fault segmentation and sequence of ruptures for the 2010 mw 6 8 yushu china earthquake we have mapped the fault trace using displacements from sar image matching interferometric phase and coherence and 2 5 m spot 5 satellite images modeling the event as an elastic dislocation with three segments fitted to the fault trace suggests that the southeast and northwest segments are near vertical with the central segment dipping 70 to the southwest slip occurs mainly in the upper 10 km with a maximum slip of 1 5 m at a depth of 4 km on the southeastern segment the maximum slip in the top 1 km i e near surface is up to 1 2 m and inferred locations of significant surface rupture are consistent with displacements from sar image matching and field observations the radar interferograms show rupture over a distance of almost 80 km much larger than initial seismological and field estimates of the length of the fault part of this difference can be attributed to slip on the northwestern segment of the fault being due to an mw 6 1 aftershock two hours after the main event the remaining difference can be explained by a non uniform slip distribution with much of the moment release occurring at depths of less than 10 km the rupture on the central and southeastern segments of the fault in the main shock propagated at a speed of 2 5 km s southeastward toward the town of yushu located at the end of this segment accounting for the considerable building damage strain accumulation since the last earthquake on the fault segment beyond yushu is equivalent to an mw 6 5 earthquake

landscape response to strike slip faulting linked to collisional settings quaternary tectonics and basin formation in the eastern betics southeastern spain abstract neotectonic behaviour of the eastern betics southeastern spain has been controlled by the presence of a large left lateral shear zone this is an intraplate transcurrent zone probably decoupled by a mid crustal detachment horizon the morphological expression of this crustal structure is a sigmoidal corridor in which the main quaternary basins are located three types of morphostructural domains can be distinguished in the sigmoidal corridor the central segment and the northern and southern terminal splays the central segment is characterized by wrench tectonics whilst the southern and northern terminal splays are controlled by transtensional and transpressional tectonics respectively the quaternary morphostructural pattern is only the more recent picture of the tectonic processes that have controlled the late orogenic evolution of the eastern betics the indentation of the aguilas arc accompanied by thin skinned thrusting and tectonic escape in its easternmost sector and extensional collapse accompanied by thin skinned stretching in its westernmost sector

langfjordjokelen a rapidly shrinking glacier in northern norway in this paper we document changes of langfjordjokelen a small ice cap in northern norway surface mass balance measurements have been carried out on an east facing part 3 2 km 2 o f the ice cap since 1989 measurements reveal a strong thinning the balance year 2008 09 was the 13th successive year with significant negative annual balance 0 30 m w e the average annual deficit was 0 9 m w e over 1989 2009 the recent thinning of langfjordjokelen is stronger than observed for any other glacier in mainland norway maps from 1966 1994 and 2008 show that the whole ice cap is shrinking the total volume loss over 1966 2008 was 0 264 km 3 the east facing part has been greatly reduced in volume 46 area 38 and length 20 for this part over 1994 2008 the cumulative direct mass balance 14 5 m w e is less negative than the geodetic mass balance 17 7 m w e a surface mass balance model using upper air meteorological data was used to reconstruct annual balances back to 1948 and to reconstruct unmeasured years 1994 and 1995 sensitivity of annual balance to 18c warming is 0 76 m w e and to 10 increase in precipitation is 0 20 m w e

slip maxima at fault junctions and rupturing of barriers during the 2008 wenchuan earthquake the devastating wenchuan earthquake in 2008 struck along a fault zone that showed low rates of deformation analysis of gps and insar data suggests that as structural barriers failed during a single earthquake the rupture cascaded across multiple fault segments which may explain the high magnitude of the event

dynamics of fault interaction parallel strike slip faults we use a two dimensional finite difference computer program to study the effect of fault steps on dynamic ruptures our results indicate that a strike slip earthquake is unlikely to jump a fault step wider than 5 km in correlation with field observations of moderate to great sized earthquakes we also find that dynamically propagating ruptures can jump both compressional and dilational fault steps although wider dilational fault steps can be jumped dilational steps tend to delay the rupture for a longer time than compressional steps do this delay leads to a slower apparent rupture velocity in the vicinity of dilational steps these dry cases assumed hydrostatic or greater pore pressures but did not include the effects of changing pore pressures in an additional study we simulated the dynamic effects of a fault rupture on undrained pore fluids to test sibson s 1985 1986 suggestion that wet dilational steps are a barrier to rupture propagation our numerical results validate sibson s hypothesis by demonstrating that the effect of the rupture on the undrained pore fluids is to inhibit the rupture from jumping dilational stepovers the basis of our result differs from sibson s hypothesis in that our model is purely elastic and does not necessitate the opening of extension fractures between the fault segments

quaternary tectonic activity of the carboneras fault in the la serrata range se iberia geomorphological and chronological constraints the eastern betic shear zone ebsz in southern iberia is known to accommodate part of the 4 5 mm yr convergence between africa and iberia but its seismic hazard is not sufficiently understood for an accurate risk assessment one of the main structures of the ebsz the left lateral 150 km long carboneras fault displays no clear instrumental and historical activity despite being morphologically expressive detailed geomorphological mapping geochronological analysis and structural observation on the la serrata segment of the carboneras fault were designed to investigate its recent evolution quaternary sediments and geomorphic features were targeted and 42 new numerical ages were obtained based on 66 samples thermoluminescence u series 14c 10be the chronological framework of la serrata was constructed by combining these numerical ages with a conceptual model previously developed in the region which assumes that alluvial fan aggradation was produced during cold and dry periods glacials and stadials whereas stability and phases of calcrete formation were favored during warm and wetter periods interglacials and interstadials the spatial distribution of dated alluvial fans suggests an early phase of uplift that probably occurred between 1 ma and 56 6 ka in the northeastern portion of the study area whereas in the southwest sector the main uplift phase occurred later than 110 3 ka a decline in fault activity would have taken place after 30 8 ka vertically offset dated units indicate minimum dip slip rates of 0 05 mm yr and 0 18 mm yr averaged for the last 1 ma and the last 110 3 ka respectively deflected channels and associated dated units yield a minimum left lateral strike slip rate of 1 31 mm yr averaged for the last 110 3 ka the most recent fault movement of the fault could be younger than ad 637 our results suggest therefore that the carboneras fault is among the fastest in iberia and should be considered in future hazard analyses

twenty year advanced dinsar analysis of severe land subsidence the alto guadalentin basin spain case study a twenty year period of severe land subsidence evolution in the alto guadalentin basin southeast spain is monitored using multi sensor sar images processed by advanced differential interferometric synthetic aperture radar dinsar techniques the sar images used in this study consist of four datasets acquired by ers 1 2 envisat alos and cosmo skymed satellites between 1992 and 2012 the integration of ground surface displacement maps retrieved for different time periods allows us to quantify up to 2 50 m of cumulated displacements that occurred between 1992 and 2012 in the alto guadalentin basin dinsar results were locally compared with global positioning system gps data available for two continuous stations located in the study area demonstrating the high consistency of local vertical motion measurements between the two different surveying techniques an average absolute error of 4 6 4 mm for the alos data and of 4 8 3 5 mm for the cosmo skymed data confirmed the reliability of the analysis the spatial analysis of dinsar ground surface displacement reveals a direct correlation with the thickness of the compressible alluvial deposits detected ground subsidence in the past 20 years is most likely a consequence of a 100 200 m groundwater level drop that has persisted since the 1970s due to the overexploitation of the alto guadalentin aquifer system the negative gradient of the pore pressure is responsible for the extremely slow consolidation of a very thick 100 m layer of fine grained silt and clay layers with low vertical hydraulic permeability approximately 50 mm h wherein the maximum settlement has still not been reached

some thoughts on the use of insar data to constrain models of surface deformation noise structure and data downsampling repeat pass interferometric synthetic aperture radar insar provides spatially dense maps of surface deformation with potentially tens of millions of data points here we estimate the actual covariance structure of noise in insar data we compare the results for several independent interferograms with a large ensemble of gps observations of tropospheric delay and discuss how the common approaches used during processing of insar data affects the inferred covariance structure motivated by computational concerns associated with numerical modeling of deformation sources we then combine the data covariance information with the inherent resolution of an assumed source model to develop an efficient algorithm for spatially variable data resampling or averaging we illustrate these technical developments with two earthquake scenarios at different ends of the earthquake magnitude spectrum for the larger events our goal is to invert for the coseismic fault slip distribution for smaller events we infer the hypocenter location and moment we compare the results of inversions using several different resampling algorithms and we assess the importance of using the full noise covariance matrix

application of the analytic model of general triclinic transpression with oblique extrusion to an active deformation zone the alhama de murcia fault se iberian peninsula abstract we have applied the analytic model of general triclinic transpression with oblique extrusion to an active shear zone in southeastern spain this study opens a new methodological approach in the study of active fault zones we are able to constrain the triclinic transpression model with absolute measures of active deformation such as gps velocity gradients and have exhaustively explored the predictions of the model and compared them to the orientation data of field kinematic markers fault slip data and reorientation of fold hinges during progressive deformation gps data and the kinematic study of the fault gouge that is developed at the alhama de murcia fault the combined analysis allows the values of the kinematic vorticity number the orientation of the vorticity vector the orientation of the local and regional convergence vectors the angle of extrusion in the shear zone and the amount of extrusion to be constrained the results point to a highly partitioned heterogeneous shear zone with domains deforming in response to the same boundary conditions but are displaying different kinematic responses that reflect both their intrinsic properties and geometric effects related to competency contrasts we propose that the alhama de murcia fault is an incompletely coupled fault zone with two different domains a low competency domain comprising the fault gouge ductilely deformed with low vorticity values which probably experienced a steady state aseismic slip that reflects regional convergence vectors convergence eurasia nubia and a domain outside of the fault gouge with episodic brittle failure with higher vorticity values and showing convergence vectors which are parallel to the local convergence vectors calculated from the gps velocity field

modelling earthquake rupture rates in fault systems for seismic hazard assessment the eastern betics shear zone abstract earthquake surface fault ruptures can show very complex geometries and involve different faults simultaneously consequently modern fault based probabilistic seismic hazard assessments psha need to account for such complexities in order to achieve more realistic modellings that treat fault systems as a whole and consider the occurrence of earthquake ruptures as aleatory uncertainties we use sherifs a recent approach of modelling annual rates of complex multi fault ruptures to obtain system level magnitude frequency distributions mfds for the eastern betics shear zone ebsz spain considering four fault rupture hypotheses we then analyze the consistency of each scenario based on data from the earthquake catalogue and paleoseismic studies the definition of the different rupture hypotheses was discussed within the frame of fault2sha esc working group and critical fault input data is extracted from previous published studies the four rupture hypotheses are defined as incremental scenarios based on fault geometry and kinematics with lengths varying from minimal fault sections to a rupture of nearly the whole system the results suggest that multi fault ruptures involving lengths up to single to several whole faults are consistent with the annual rates from both the instrumental catalogue and paleoseismic record the method does not allow to completely discard any hypothesis but it allows to weight the different models in a logic tree for seismic hazard assessment the approach is revealed as a practical tool for obtaining fault system mfds and as a useful tool for highlighting limitations and uncertainties in geological and paleoseismic data to be assessed this study aims to constitute a step forward in the consideration of complex multi fault ruptures for future seismic hazard assessments in the region

slip in the 2010 2011 canterbury earthquakes new zealand the 3rd september 2010 mw 7 1 darfield and 21st february 2011 mw 6 3 christchurch new zealand earthquakes occurred on previously unknown faults we use insar ground displacements sar amplitude offsets field mapping aerial photographs satellite optical imagery a lidar dem and teleseismic body wave modeling to constrain the pattern of faulting in these earthquakes the insar measurements reveal slip on multiple strike slip segments and secondary reverse faults associated with the darfield main shock fault orientations are consistent with those expected from the gps derived strain field the insar line of sight displacement field indicates the main fault rupture is about 45 km long and is confined largely to the upper 10 km of the crust slip on the individual fault segments of up to 8 m at 4 km depth indicate stress drops of 6 10 mpa in each event rupture initiated on a reverse fault segment before continuing onto a strike slip segment the non double couple seismological moment tensors for each event are matched well by the sum of double couple equivalent moment tensors for fault slip determined by insar the slip distributions derived from insar observations of both the darfield and christchurch events show a 15 km long gap in fault slip south west of christchurch which may present a continuing seismic hazard if a further unknown fault structure of significant size should exist there

impacts of sediment connectivity on holocene alluvial records across a mediterranean basin guadalentin river se spain two contiguous alluvial valleys maria and guadalupe sectors of the upper guadalentin river se spain show distinct holocene alluvial architecture cut and fill nested and stepped fill terraces revealing a strong control of valley morphology and bedrock barriers on sediment delivery storage and preservation the headwater valley maria sector preserves four morphosedimentary alluvial units corresponding to two palaeogeographic stages morphosedimentary unit msu1 the most extensive is a major depositional valley infill dominated by sand and silt texture showing three stratigraphic sets dated 9000 8500 5300 4800 4000 3000 cal bp this vertically stacked alluvial accumulation occurs upstream of a narrow bedrock channel that limited sediment connectivity with the downstream guadalupe sector between 3000 and 2350 cal bp a 15 m deep incision on msu1 occurred and subsequent cut and fill cycles generated three alluvial terraces dated at 2350 1900 cal bp msu2 1800 700 cal bp msu3 and post 400 years msu4 in the downstream valley guadalupe sector six flights of alluvial terraces msug1 to msug6 were formed by episodic aggradation and quasi continuous incision in response to baselevel changes of the lower guadalentin river during the holocene alluvial chronologies in these two contiguous valleys show out of phase sedimentation periods under low connectivity conditions 9 3 ka and in phase cut and fill cycles after valley re connection post 3 0 ka the late holocene alluvial activity periods also coincide with morpho stratigraphic data from the lower guadalentin indicating that fluvial connectivity throughout the catchment was only completed in the late holocene

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

stress field variation related to fault interaction in a reverse oblique slip fault the alhama de murcia fault betic cordillera spain abstract the interpretation of kinematic data from microstructural observations has led many authors to propose a complex dynamic development for the eastern betic cordillera from the late miocene to the present in which different and sometimes contradictory stress fields explain the generation of the same structures the main aim of this work is to determine whether the dynamic variability of the study area observed during the neotectonic period is coherent with a single regional stress field the structure of the area was analysed through the detailed mapping of the alhama de murcia fault amf and the associated structures further microtectonic data from shear veins in an interaction zone between the main and secondary faults were studied by the stress inversion method of reches tectonics 6 1987 849 a hierarchy is proposed for stress fields and their interpretation with respect to the interaction between structures of different scales relative movements of fault bounded blocks with different sizes produce this hierarchy these movements depend on boundary conditions of blocks and their position relative to the alhama fault zone the study shows that adequate cartography and understanding the context of micro and mesotectonic data is necessary for determining the dynamic significance of microtectonic data the use of stress inversion methods without taking the local tectonic context into consideration can give rise to incorrect interpretations incorrect processing of previous data and extrapolations inappropriate at other scales

new insights on speleoseismology the geothermal gradient and heat flow values in caves for the study of active faults abstract normally in paleoseismology the study of the tectonic slip rate is performed in trenches on the fault scarp or by the estimation of fault movements from the geomorphic features in this work we have carried out a paleoseismic analysis of the benis fault located in southeast spain combined with a geothermal analysis inside a deep cave related to the fault 350 m thus we have estimated the last earthquake magnitude and time of occurrence from evidence of ceiling collapse and displaced carbonate blocks inside a cave which is developed across the fault the magnitude was obtained from the application of the empirical relationship of the fault parameters and coseismic vertical displacement yielding a value ranging between m 5 9 and m 6 5 moreover we dated this paleoearthquake by the paleontological record of a lynx pardinus spelaea with an age of 65 18 ka bp additionally we have measured the thermal profile of the benis cave 350 m of depth from single rock point temperature measurements during 2 years the temperature profile shows three different parts inside the cave the shallow heterogeneous thermal zone till 50 m depth the homogeneous thermal zone 150 m till with constant temperature and the hetero thermal deep zone deeper than 150 m and till the deepest zone 350 m furthermore we have estimated the vertical geothermal gradient 1 85 c 100 m for the deepest zone 150 290 m the temperature increases with depth showing a reverse thermal profile in comparison with normal gradients in deep caves finally we have calculated the heat flux of 0 46 mwm 2

increased terrestrial carbon storage across the palaeocene eocene boundary abstract a rapid short lived global warming event at the close of the palaeocene ca 55 5 million years ago ma was associated with the addition of massive amounts of carbon to the exogenic carbon cycle and major benthic extinctions evaluation of the response of the terrestrial biosphere to this transient ancient greenhouse world with a process based terrestrial carbon cycle model and global palaeoclimate simulations indicates the sequestration of ca 1112 gt c into the vegetation and soil carbon pools a largely independent global carbon isotope mass balance analysis also points to the strong potential for the terrestrial biosphere to sequester substantial amounts of carbon at this time with the increase being calculated at between 2107 and 3060 gt c this analysis suggests that some other feature of global environmental change across the palaeocene eocene boundary may have been forcing terrestrial carbon cycle dynamics at this time however even a minimum increase of 1112 gt c would have been sufficiently large to implicate the response of the terrestrial carbon cycle as a negative feedback mechanism on climate at 55 5 ma possibly reducing global temperatures by up to 2 5 c

obtaining suitable logic tree weights for probabilistic earthquake induced landslide hazard analyses abstract in this study an inventory of landslides induced by the 2011 lorca earthquake mw 5 1 has been used in order to develop a new procedure to obtain objective logic tree weights for a probabilistic earthquake induced landslide hazard analysis the 2011 lorca earthquake triggered more than 250 landslides mainly of disrupted type the logic tree was designed having regard to variability of relevant geotechnical parameters involved in the problem and uncertainties associated with the use of several empirical relationships in order to compute newmark displacements for the purpose the resulting hazard maps were compared with this landslide inventory and weights estimated for each branch of the logic tree based on these results the best model for seismic landslide hazard mapping for a moderate earthquake correctly identifies around 72 of landslide areas based on the set of parameters that comprises depth of failure surface specific weight cohesion friction angle and newmark displacement model the corresponding weights were objectively established these weights are reliable enough for the obtaining seismic landslide hazard maps and may be implemented in similar environments characterized by moderate low magnitude earthquakes mw

fault branching and rupture directivity 1 could the directivity of a complex earthquake be inferred from the ruptured fault branches it created typically branches develop in forward orientation making acute angles relative to the propagation direction direct backward branching of the same style as the main rupture e g both right lateral is disallowed by the stress field at the rupture front here we propose another mechanism of backward branching in that mechanism rupture stops along one fault strand radiates stress to a neighboring strand nucleates there and develops bilaterally generating a backward branch such makes diagnosing directivity of a past earthquake difficult without detailed knowledge of the branching process as a field example in the landers 1992 earthquake rupture stopped at the northern end of the kickapoo fault jumped onto the homestead valley fault and developed bilaterally there nnw to continue the main rupture but also sse for 4 km forming a backward branch we develop theoretical principles underlying such rupture transitions partly from elastostatic stress analysis and then simulate the landers example numerically using a two dimensional elastodynamic boundary integral equation formulation incorporating slip weakening rupture this reproduces the proposed backward branching mechanism based on realistic if simplified fault geometries prestress orientation corresponding to the region standard lab friction values for peak strength and fracture energies characteristic of the landers event we also show that the seismic s ratio controls the jumpable distance and that curving of a fault toward its compressional side like locally along the southeastern homestead valley fault induces near tip increase of compressive normal stress that slows rupture propagation

esi 07 shakemaps for instrumental and historical events in the betic cordillera se spain an approach based on geological data and applied to seismic hazard abstract this work presents high resolution shakemaps for three earthquakes occurred in the betic cordillera se spain the 2011 ce lorca event viii esi 07 the 1863 ce huercal overa event viii esi 07 and the 1829 ce torrevieja event x esi 07 detailed field characterizations and mapping of their coseismic environmental effects eees are catalogued and classified following the esi 07 scale the resulting macroseismic information reaches up to ten times the existing information based on conventional damage based scales e g ems 98 providing a better constrain towards more realistic ground motion scenarios the 2011 lorca earthquake has been used as a calibration event since there is a relevant record of instrumental measures on source and ground motion parameters allowing a direct comparison with the modelled pga values from a methodological standpoint the obtained shakemaps follow the basic guidelines and methodology proposed by the usgs shakemap program the two historical earthquakes analysed in this paper produced a wide variety of secondary eees but no surface faulting was reported these effects need to be properly identified by high resolution dtms 5 m pixel far from the c 900 m pixel terrain models used by usgs program additionally the proposed esi 07 shakemaps incorporate correction factors to solve inconsistencies derived from the large scale terrain models considered in standard usgs program workflows 1 empirical slope derived v s 30 models result in overestimations of the pga values in flat terrains in absence of unconsolidated deposits 2 the topographic amplification factor included here explains the occurrence of rock falls and landslides in steep areas where ground motion is underestimated by the sole use of slope derived v s 30 models basic geological and geomorphological information need to be implemented in the modelling workflow in both cases to prevent pga overestimations in flat terrains a correction factor related to the spatial distribution and thickness of the quaternary unconsolidated deposits has been incorporated i e isopach maps to correct pga underestimations in steep terrains an amplification factor was modelled following standard guidelines of seismic topographic amplification the comparison via iteration of the spatial distribution of both esi effects and ems macroseismic data with the obtained ground motion spatial distribution enables a better definition of the geological parameters for the studied historical earthquakes a more accurate location and or size of the suspect seismic sources are obtained for these historical earthquakes providing scenarios more realistic than those resulting from old intensity maps quaternary geology and geomorphology are behind the implementation of the proposed esi 07 shakemaps being especially useful when exploring historic or ancient moderate earthquakes with scarce damage based macroseismic data but with sufficient paleoseismic or archaeoseismic records in summary the methodological workflow proposed here contemplates the implementation of a computational configuration seismologically relevant and able to test repeated seismic scenarios with different parametric data in a controlled gis environment useful to reproduce historical events

seismotectonic rupture process and earthquake hazard aspects of the 2003 december 26 bam iran earthquake summary the catastrophic 2003 m w 6 6 bam earthquake in southern iran attracted much attention and has been studied with an abundance of observations from synthetic aperture radar teleseismic seismology aftershock studies strong ground motion geomorphology remote sensing and surface field work many reports have focused on the details of one or other data type producing interpretations that either conflict with other data or leave questions unanswered this paper is an attempt to look at all the available data types together to produce a coherent picture of the coseismic faulting in 2003 and to examine its consequences for active tectonics and continuing seismic hazard in the region we conclude that more than 80 per cent of the moment release in the main shock occurred on a near vertical right lateral strike slip fault extending from the city of bam southwards for about 15 km with slip of up t o2mb utmostly restricted to the depth range 2 7 km analysis of the strong ground motion record at bam is consistent with this view and indicates that the extreme damage in the city can be attributed at least in part to the enhancement of ground motion in bam because of its position at the end of the northward propagating rupture little of the slip in the main shock reached the earth s surface and more importantly aftershocks reveal that 12 km vertical extent of a deeper part of the fault system remained unruptured beneath the coseismic rupture plane at depths of 8 20 km this may represent a substantial remaining seismic hazard to the reconstructed city of bam we believe that some oblique reverse slip up to 2 m and less than 20 per cent of the released seismic moment occurred at a restricted depth of 5 7 km on a blind west dipping fault that projects to the surface at the bam baravat escarpment an asymmetric anticline ridge that is the most prominent geomorphological feature in the area this fault did not rupture significantly at shallow levels in 2003 and it may also represent a continuing seismic hazard widespread distributed surface ruptures north of the city are apparently unrelated to substantial slip at depth and may be the result of enhanced ground motion related to northward propagation of the rupture the faulting at bam may be in the early stages of a spatial separation partitioning between the reverse and strike slip components of an oblique convergence across the zone such a separation is common on the continents though in this case the slip vectors between the two faults differ only by 20 as a substantial strike slip component remains on the obliquereverse fault the bam earthquake is one in a series of large earthquakes involving faulting along the western edge of the lut desert in addition to the unruptured parts of the faults near bam itself continuing and substantial hazard is represented by unruptured neighbouring faults particularly blind thrusts along the jebel barez mountains to the south and strike slip faulting at sarvestan to the west

crustal deformation in eastern betics from cuateneo gps network abstract the eastern betic cordillera spain is the most seismically active area within the iberian peninsula we present a global positioning system gps derived horizontal crustal deformation obtained from five occupations of the cuateneo gps network 1997 2002 2006 2009 and 2011 that clearly shows continuing tectonic activity in the se betics the most prominent feature of the gps velocity field is the nw oriented motion of the majority of the stations at rates ranging from 2 mm yr near the coast to 0 5 mm yr inland this type of deformation indicates that the main driving force responsible for the observed velocities is related to the on going convergence between nubia and eurasia plates the calculated deformation field shows evidence for localized deformation related to active faults within the area most of the deformation is concentrated on the alhama de murcia fault the source of the 2011 lorca earthquake m w 5 2 we estimate a reverse sinistral geodetic slip rate of 1 5 0 3 mm yr for this fault our crustal deformation field and analyses are important contributions to estimating seismic hazard for the eastern betics since it is the first time crustal deformation rates at this scale are presented

complex rupture mechanism and topography control symmetry of mass wasting pattern 2010 haiti earthquake the 12 january 2010 mw 7 0 haiti earthquake occurred in a complex deformation zone at the boundary between the north american and caribbean plates combined geodetic geological and seismological data posited that surface deformation was driven by rupture on the leog ne blind thrust fault while part of the rupture occurred as deep lateral slip on the enriquillo plantain garden fault epgf the earthquake triggered 4490 landslides mainly shallow disrupted rock falls debris soil falls and slides and a few lateral spreads over an area of 2150 km2 the regional distribution of these slope failures defies those of most similar earthquake triggered landslide episodes reported previously most of the coseismic landslides did not proliferate in the hanging wall of the main rupture but clustered instead at the junction of the blind leog ne and epgf ruptures where topographic relief and hillslope steepness are above average also low relief areas subjected to high coseismic uplift were prone to lesser hanging wall slope instability than previous studies would suggest we argue that a combined effect of complex rupture dynamics and topography primarily control this previously rarely documented landslide pattern compared to recent thrust fault earthquakes of similar magnitudes elsewhere we conclude that lower static stress drop mean fault displacement and blind ruptures of the 2010 haiti earthquake resulted in fewer smaller and more symmetrically distributed landslides than previous studies would suggest our findings caution against overly relying on across the board models of slope stability response to seismic ground shaking

distinguishing barriers and asperities in near source ground motion we investigate the ground motion produced by rupture propagation through circular barriers and asperities in an otherwise homogeneous earthquake rupture using a three dimensional finite difference method we analyze the effect of asperity radius strength and depth in a dynamic model with fixed rupture velocity we gradually add complexity to the model eventually approaching the behavior of a spontaneous dynamic rupture to determine the origin of each feature in the ground motion a barrier initially resists rupture which induces rupture front curvature these effects focus energy on and off the fault leading to a concentrated pulse from the barrier region and higher velocities at the surface finally we investigate the scaling laws in a spontaneous dynamic model we find that dynamic stress drop determines fault parallel static offset while the time it takes the barrier to break is a measure of fracture energy thus given sufficiently strong heterogeneity the prestress and yield stress relative to sliding friction of the barrier can both be determined from ground motion measurements in addition we find that models with constraints on rupture velocity have less ground motion than constraint free spontaneous dynamic models with equivalent stress drops this suggests that kinematic models with such constraints overestimate the actual stress heterogeneity of earthquakes

speculations on the geometry of the initiation and termination processes of earthquake rupture and its relation to morphology and geological structure earthquake initiation and termination processes are commonly described in terms of barriers and asperities barriers fall into two classes geometric barriers are associated with places where the orientation of a failure surface changes and relaxation barriers where stress is low because aseismic creep processes outpace tectonic loading geometric barriers fall into conservative and nonconservative subgroups according to whether finite fault motion can proceed without the creation of new structures or whether it demands the creation of new faulting or void space the multiple faulting or fragmentation associated with some nonconservative barriers can disrupt fault planes and form asperities by means of selected examples it is shown that a description in terms of these barriers can help one to visualise the processes of earthquake rupture and its relation to the geological environment

ground motion measurement in the lake mead area nevada by differential synthetic aperture radar interferometry time series analysis probing the lithosphere rheological structure 1 we measure ground motion around the lake mead nevada using synthetic aperture radar interferometry the lake water level has fluctuated through time since impoundment in 1935 to quantify the deformation due to water level variations over the past decade and to constrain the crust and mantle rheological parameters in the lake area we analyze 241 interferograms based on 43 ers images acquired between 1992 and 2002 all interferograms have a high coherence due to arid conditions most of them show strong atmospheric artefacts tropospheric phase delays are estimated and corrected for each interferogram by analyzing the phase elevation correlation corrections are validated using data from the era40 global atmospheric reanalysis corrected interferograms are inverted pixel by pixel to solve for the time series of ground motion in the lake area temporal smoothing is added to reduce random atmospheric artefacts the observed deformation is nonlinear in time and spreads over a 50 50 km2 area we observe a 16 mm subsidence between 1995 and 1998 due to an 11 m water level increase followed by an uplift due to the water level drop after 2000 we model the deformation taking into account the loading history of the lake since 1935 a simple elastic model with parameters constrained by seismic wave velocities does not explain the amplitude of the observed motion the two layer viscoelastic model proposed by kaufmann and amelung 2000 with a mantle viscosity of 1018 pa s adjusts well the data amplitude and its spatiotemporal shape

the application of geomorphic indices in terrain analysis for ground engineering practice abstract terrain analysis studies for long linear engineering projects provide critical engineering geological and geomorphological data that inform project design options route selection and construction methodologies this paper introduces the use of geomorphic indices alongside methods of aerial photograph interpretation and remote sensing in the desk study phase of engineering terrain evaluations in the identification of landscape changes and geohazards in active tectonic regions three geomorphic indices hypsometry river long profile analysis and stream length gradient index are applied to freely available dem data in order to develop the qualitative and quantitative relative to study area understanding of how the hillslope and river systems respond to the effects of tectonic activity and climate change a hypothetical pre feasibility study corridor 10 km width located in the sorbas basin se spain is used to develop the methods of application which could represent a proposed rail road or pipeline routing the results of the scaled indices approach from catchment to reach i e section of uninterrupted river channel investigations indicate a variable response of landscape processes active erosional conditions are found in the central and northern limits of the basin relating to a known zone of tectonic deformation the infierno marchalico lineament and also to the effects of a river capture related base level lowering active conditions are typically linked to an increased occurrence of landslides and badland formation stable conditions are more common in the west and east of the basin where drainage channels are effectively coupled to base level the combined results of geomorphic indices and aerial photograph interpretation are used in the identification of engineering constraints and geohazards as related to gully development badland formation and the formation of landslides a simple geohazard constraints map is produced which demonstrates ground related hazard to the wider project team and can be used to target field investigations and further inform construction methodologies and limitations

topographic controls on production and deposition of tidal cool water carbonates uzes basin se france we document an example of a cool water carbonate deposit interpreted as a flood tidal delta formed during sea level fall in the uzes basin french miocene foreland basin in the miocene it was a peripheral basin connected to the open sea by a narrow 15 km long seaway the studied uzes formation is a 50 m thick tidal bioclastic carbonate body formed at the junction between the uzes basin and the seaway it is composed dominantly of rhodalgal packstones that are interpreted to have been produced inside the basin however most of the deposit was built out by bidirectional hydraulic dunes suggesting that accumulation of carbonate grains was not controlled by production but rather by tidal currents the deposit is thickest and coarsest grained and exhibits the larger dunes at the inlet of the seaway where currents are expected to have been fastest the deposit is thinner finer grained and more bioturbated away from the inlet toward the basin that is interpreted as a result of a decrease of current velocity due to flow expansion the main deposit exhibits a general upward increase in thickness and grain size of cross beds together with a decrease of faunal diversity from bivalve rich to rhodalgal facies consistent with progressive tidal flow acceleration in the seaway resulting from sea level fall lime mud is pervasive in the matrix of even the highest energy facies this suggests that one cannot draw any average correlation between permeability and architecture of the deposit also this could favor the observed early marine diagenesis of the deposit and give it a high preservation potential in the stratigraphic record

the enigma of the arthur s pass new zealand earthquake 2 the aftershock distribution and its relation to regional and induced stress fields the aftershock distribution of the 1994 arthur s pass earthquake mw6 7 is unusual for a reverse faulting event in that it extends 12 km nnw and 30 km sse of the actual fault plane which strikes ne sw we have used several methods to infer the regional stress field in the region including geodetic results earthquake mechanisms and inversion of p wave polarity data for the stress tensor orientation the inversion method is new and does not require the focal mechanisms of the events used it also incorporates the coulomb failure criterion all results point to a stress field favoring strike slip faulting not thrusting with near horizontal 1 and 3 principal axes striking at 298 and 28 using dislocation theory we calculate the stress induced by the arthur s pass earthquake and its largest aftershock a strike slip event and add this to the regional field there is a fair correspondence between the hypocenters of aftershocks away from the mainshock fault plane and regions of high induced coulomb failure stress cfs on optimally oriented fault planes however there are regions of high induced cfs that are devoid of aftershocks it appears that earthquake slip in this region of oblique 19 plate convergence is as observed elsewhere partitioned into components parallel and perpendicular to the plate margin most of the slip is parallel as occurs on the nearby dextral alpine fault the boundary between the pacific and australian plates however occasional reverse events such as the arthur s pass earthquake account for at least some of the perpendicular component of slip and the uplift that produced the southern alps

drought driven transient aquifer compaction imaged using multitemporal satellite radar interferometry in unconsolidated heterogeneous aquifer systems low rates of pore pressure diffusion of applied effective stresses due to the drainage of thick low permeability clay rich layers with time constants of decades to centuries cause delayed residual permanent compaction and land subsidence current application of satellite differential radar interferometry dinsar differential interferometric synthetic aperture radar to estimate aquifer hydraulic properties compressibility and or storage in these systems is limited by the temporal availability of synthetic aperture radar data 1992 present in this paper we study the degree of aquifer compaction due to water extraction using dinsar through an example in southeast spain ground deformation data indicate large scale deformation and in particular the discovery of the highest rates of groundwater related land subsidence recorded in europe 10 cm yr affecting the guadalentin river basin 200 km 2 the largest tributary of the segura river modeling of the ground surface time series of the guadalentin basin indicates that deformation is mainly driven by nonlinear time delayed flow processes in the underlying aquifer after a drought period 1990 1995 the aquifer responded with an exponential decay of the land subsidence lasting 8 yr suggesting transient groundwater pore pressure flow we show that multitemporal satellite radar interferometry analysis and its modeling can be a stimulating way to study nonlinear soil mechanics and groundwater flows at aquifers a deeper understanding of such processes could help the management of water resources and land subsidence of unconsolidated coastal and quaternary alluvial aquifers in a highly evolving climate region the mediterranean sea and elsewhere

comparison of various inversion techniques as applied to the determination of a geophysical deformation model for the 1983 borah peak earthquake abstract a number of techniques are employed to overcome nonuniqueness and instability inherent in linear inverse problems to test the factors that enter into the selection of an inversion technique for fault slip distribution we used a penalty function with smoothness pf s a damped least squares method dls damped least squares method with a positivity constraint dls p and a penalty function with smoothness and a positivity constraint pf s p for inverting the elevation changes for slip associated with the 1983 borah peak earthquake unlike solving an ill posed inverse problem using a gradient technique ward and barrientos 1986 we have restored the well posed character between the elevation changes and normal slip distribution studies showed that the constraints based on sound understanding of the physical nature of the problem are crucial in the derivation of a meaningful solution and dictates primarily the selection of a particular inversion technique all available geological and geophysical information were used to determine a geophysical deformation model for the earthquake it is suggested that the pf s p solution for a fault length of 75 km is the preferred model the long wavelength features in the estimated slip distribution are similar to those obtained by ward and barrientos 1986 whereas the shorter wavelength features differ between two solutions the fault dips 49 to the southwest the slipped zones deepen from the surface at the northwest to about 20 km downdip depth at the southeast the fault extends to the southeast beyond the epicenter of the mainshock it is also shown that only the long wavelength features of the slip distribution are well resolved the resolution is better at shallower levels than at deeper levels the resolution deteriorates when the deformation sources are away from the leveling lines smoothness constraints provide better resolution than damping does at depth the addition of a positivity constraint significantly improves the model resolution

stress transferred by the 1995 mw 6 9 kobe japan shock effect on aftershocks and future earthquake probabilities the kobe earthquake struck at the edge of the densely populated osaka kyoto corridor in southwest japan we investigate how the earthquake transferred stress to nearby faults altering their proximity to failure and thus changing earthquake probabilities we find that relative to the pre kobe seismicity kobe aftershocks were concentrated in regions of calculated coulomb stress increase and less common in regions of stress decrease we quantify this relationship by forming the spatial correlation between the seismicity rate change and the coulomb stress change the correlation is significant for stress changes greater than 0 2 1 0 bars 0 02 0 1 mpa and the nonlinear dependence of seismicity rate change on stress change is compatible with a state and rate dependent formulation for earthquake occurrence we extend this analysis to future mainshocks by resolving the stress changes on major faults within 100 km of kobe and calculating the change in probability caused by these stress changes transient effects of the stress changes are incorporated by the state dependent constitutive relation which amplifies the permanent stress changes during the aftershock period earthquake probability framed in this manner is highly time dependent much more so than is assumed in current practice because the probabilities depend on several poorly known parameters of the major faults we estimate uncertainties of the probabilities by monte carlo simulation this enables us to include uncertainties on the elapsed time since the last earthquake the repeat time and its variability and the period of aftershock decay we estimate that a calculated 3 bar 0 3 mpa stress increase on the eastern section of the arima takatsuki tectonic line attl near kyoto causes fivefold increase in the 30 year probability of a subsequent large earthquake near kyoto a 2 bar 0 2 mpa stress decrease on the western section of the attl results in a reduction in probability by a factor of 140 to 2000 the probability of a mw 6 9 earthquake within 50 km of osaka during 1997 2007 is estimated to have risen from 5 6 before the kobe earthquake to 7 11 afterward during 1997 2027 it is estimated to have risen from 14 16 before kobe to 16 22

high resolution satellite imagery mapping of the surface rupture and slip distribution of the mw 7 8 14 november 2001 kokoxili earthquake kunlun fault northern tibet china the mw 7 8 kokoxili earthquake of 14 november 2001 which ruptured a 450 km long stretch of the sinistral kunlun strike slip fault at the northeastern edge of the tibet plateau china ranks as the largest strike slip event ever recorded instrumentally in asia newly available high resolution satellite hrs images pixel size 1 m acquired in the months following the earthquake proved a powerful tool to complement field investigations and to produce the most accurate map to date of the coseismic displacements along the central kusai hu segment of the rupture the coseismic rupture geometry south and west of buka daban feng near the earthquake epicenter was also investigated in detail along the kusai hu segment slip parti tioning is for the first time observed to occur simultaneously during a single event with two parallel strands 2 km apart localizing almost pure strike slip and normal faulting in all 83 new hrs coseismic offset measurements some of which calibrated by field work show large well constrained variations 100 of the slip function over distances of only25 km tension cracks opening ahead of the shear dislocation and later offset by the upward propagating strike slip rupture were observed dem onstrating that the rupture front propagated faster at depth than near the surface the triple junction between the central kusai hu segment the kunlun pass fault where the rupture ended and the xidatan dongdatan segment which could be the next segment to fail along the main kunlun fault acted as a strong barrier implying that direct triggering of earthquake rupture on the xidatan dongdatan segment by kokoxili type earthquakes may not be the rule

coseismic deformation from the 1999 mw 7 1 hector mine california earthquake as inferred from insar and gps observations we use interferometric synthetic aperture radar insar and global positioning system gps observations to investigate static deformation due to the 1999 m w 7 1 hector mine earthquake that occurred in the eastern california shear zone interferometric decorrelation phase and azimuth offset measurements indicate regions of surface and near surface slip which we use to constrain the geometry of surface rupture the inferred geometry is spatially complex with multiple strands the southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a n45 w direction the central segment is the simplest with a single strand crossing the bullion mountains and a strike of n10 w the northern third of the rupture zone is characterized by multiple splays with directions subparallel to strikes in the southern and central the average strike for the entire rupture is about n30 w the interferograms indicate significant along strike variations in strain which are consistent with variations in the ground based slip measurements using a variable resolution data sampling routine to reduce the computational burden we invert the insar and gps data for the fault geometry and distribution of slip we compare results from assuming an elastic half space and a layered elastic space results from these two elastic models are similar although the layered space model predicts more slip at depth than does the half space model the layered model predicts a maximum coseismic slip of more than 5 m at a depth of 3 to 6 km contrary to preliminary reports the northern part of the hector mine rupture accommodates the maximum slip our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models the inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake

how much nubia eurasia convergence is accommodated by the ne end of the eastern betic shear zone se spain constraints from gps velocities this research was funded by the spanish ministry of economy and competitiveness research project cgl2011 30153 c02 02 university of alicante research project vigrob053 university of jaen paiuja 2019 2020 ceactierra and rnm282 research group of junta de andalucia

tectonic and seismic implications of an intersegment rupture the damaging may 11th 2011 mw 5 2 lorca spain earthquake on may 11th 2011 a mw 5 2 earthquake stroke the city of lorca in the se spain this event caused 9 fatalities 300 injuries and serious damage on the city and the surrounding areas the lorca earthquake occurred in the vicinity of a region bounding two well known segments of a large active fault the alhama de murcia fault amf the lorca earthquake offers a unique opportunity to study how strain is accommodated in an intersegment region of a large strike slip fault we map recent tectonic structures in the epicentral region and we use radar interferometry to analyze the coseismic deformation combining these data with seismological observations of lorca seismic sequence we first model the source of the earthquake then we analyze the influence of our preferred model in the adjacent segments by coulomb failure stress modeling the proposed earthquake source model suggests that this event ruptured an area of 4 3 km within the complex structure that limits the gonar lorca and lorca totana segments of the amf the induced static stress change on the adjacent segments of the fault represents a seismic cycle advance equivalent to 200 to 1000 years of tectonic loading

topography of the top chalk surface on and offshore denmark abstract a time structure map of the top of the upper cretaceous danian chalk group the top chalk surface in the entire danish sector is presented the present topography of the top chalk surface is a result of various erosional and tectonic events taking place during the cenozoic the analysis shows that the cenozoic is characterised by significant reactivation of the mesozoic structural elements of which the central graben the ringkobing fyn high and the sorgenfrei tornquist zone are the most important a tectonically controlled relief caused the generation of widespread sheet like erosion on the ringkobing fyn high and incisions along the margins of ringkobing fyn high during the mid paleocene incisions in the northern part of the danish sector formed valleys which probably transported sediment towards the west the present topography of top chalk in the eastern part of the danish sector is highly influenced by the late cenozoic erosion of the uplifted eastern margin of the north sea basin the topography of top chalk also reflects the distribution of mobile zechstein salt as collapse structures follow the pitch out line of mobile salt onto the ringkobing fyn high and numerous salt structures deformed the top chalk surface

localised and distributed deformation in the lithosphere modelling the dead sea region in 3 dimensions article i nfo the earth s lithosphere behaves as a strain softening elasto plastic material in the laboratory such materials are known to deform in a brittle or a ductile manner depending on the applied geometric boundary conditions in the lithosphere however the importance of boundary conditions in controlling the deformation style has been largely ignored under general boundary conditions both laboratory and field scale observations show that only part of the deformation can localise on through going faults while the rest must remain distributed in process zones where spatially varying shear directions inhibit localisation conventional modelling methods finite difference finite or discrete elements use rheologies deduced from laboratory experiments that are not constrained as a function of the geometry of the applied boundary conditions in this paper we propose an alternative modelling method that is based on the use of an appropriate distribution of dislocation sources to create the deformation field this approach because it does not rely on integrating differential equations from more or less well constrained boundary conditions does not require making assumptions on the parameters controlling the level and distribution of stresses within the lithosphere it only supposes that strain accumulates linearly away from the dislocation singularities satisfying the compatibility equations we verify that this model explains important and hitherto unexplained features of the topography of the dead sea region following the idea that strain can only localise under specific conditions as inferred from laboratory and field scale observations we use our model of deformation to predict where deformation can localise and where it has to remain distributed we find that 65 of the deformation in the dead sea region can localise on kinematically stable through going strike slip faults while the remaining 35 has to remain distributed observations suggest that distributed deformation occurs at stress levels that can be ten times greater than that associated with motion on well localised faults thus although only representing a minor part of the total deformation distributed deformation should provide the greatest source of resistance to motion along this part of the levant plate these results can change dramatically our view of the behaviour of this and other plate boundaries if the lithosphere can be regarded as a strain softening elasto plastic material then similar behaviour should occur throughout with important implications not only for its mechanical behaviour but also for heat generation and related issues like metamorphism or magma genesis