spatial and temporal variations in growth rates along active normal fault systems an example from the lazio abruzzo apennines central italy abstract the geometry kinematics and rates of active extension in lazio abruzzo italian apennines have been measured in order to gain a better understanding of the spatial and temporal variations in fault growth rates and seismic hazards associated with active normal fault systems we present fault map traces throws throw rates and slip directions for 17 parallel en echelon or end on active normal faults whose 20 40 km lengths combine to form a soft linked fault array ca 155 km in length and ca 55 km across strike throw rates derived from observations of faulted late glacial features and holocene soils show that both maximum throw rates and throw rate gradients are greater on centrally located faults along the strike of the array total throws and throw gradients show similar spatial variations but with weaker relationships with distance along strike when summed across strike throw rates are increasingly high towards the centre of the array relative to summed throws we interpret the above to suggest that throw rates have changed in the recent past ca 0 7 ma from spatially random fault growth rates initiating at 2 5 3 3 ma to growth rates that are greater on centrally located faults we interpret this as evidence for fault interaction producing throw rate variations that drive throw profile readjustment on these crustal scale soft linked faults the results are used to discuss seismic hazards in the region which are quantified in a second paper in this issue

a recent tectonic reorganization in the south central mediterranean abstract new geodetic data combined with seismicity geologic and geochemical information document a major tectonic reorganization in the central mediterranean around 0 8 0 5 ma when rapid trench migration and consequent tyrrhenian back arc extension which dominated the region s evolution since the tortonian 10 8 ma essentially stopped in response the african convergence in sicily was transferred to a back thrust in the southern tyrrhenian characterized by frequent m5 6 earthquakes in the last 20 years a diffuse transform boundary formed across northeastern sicily to connect the sicilian and calabrian plate boundaries causing opening of the messina straits home to large historical earthquakes and unusual volcanism in the aeolian island arc and the intraplate mount etna a divergence of the ionian region from the main part of africa with northeastward motions that reflect the joint influence of african push and hellenic slab pull and are transmitted to calabria and adria could explain motions observed in the sicily channel calabria and apulia as well as the high level of southeastern sicilian seismic activity

transient landscapes at fault tips 1 fault growth produces patterns of displacement and slip rate that are highly variable in both space and time this transience is most pronounced near fault tips where along strike displacement gradients vary in time as the fault array lengthens we use a set of statistical and field observations to quantify the response of catchments and their associated fans in three large normal fault arrays to transient patterns of displacement and slip rate catchments near the fault tips show distinct scaling of channel slope with drainage area compared with catchments near the strike center this scaling becomes uniform beyond about 10 km from the fault tips and is therefore like footwall relief largely decoupled from the fault displacement profile the estimated catchment response times to a change in slip rate also vary between fault tips and strike center the response times for tip catchments are much longer than the inferred time since fault activity began indicating that they are unlikely to be in equilibrium with the current fault displacement field this disequilibrium combined with the decoupling of slope area scaling from displacement indicates that landscapes are most sensitive to fault activity near fault tips active faults characterized by along strike variation in slip rate thus provide excellent opportunities to explore the transient response of landscapes to tectonic forcing

regional uplift and local tectonic deformation recorded by the quaternary marine terraces on the ionian coast of northern calabria southern italy abstract the setting of a flight of marine terraces along a 65 km long section of the ionian coast of northern calabria is the result of the interaction between interglacial sea levels regional uplift and local fault related elevation changes seven terraces with corresponding palaeoshoreline angles at elevations ranging from 12 m to 420 m were recognised by aerial photo interpretation and field surveying the terraces were correlated to the oxygen isotope stages 1 5a 5c 5e 7 9 15 which correspond to the 7 81 102 124 215 330 and 600 ka highstands of the palaeosea level curve the 600 ka long regional ascent of the terraces took place at an average uplift rate of 0 67 mm yr this value slightly but progressively increases southward along the coastline the elevation of the strandlines is related to the activity of tectonic structures three cases were analysed allowing us 1 to recognise the height anomalies of the terraces on the sibari plain as the result of cumulated coseismic deformation caused by the normal castrovillari fault and on this basis calculate a minimum slip rate and a mean recurrence time for a single event of deformation 2 to exclude the presence of significant vertical deformations and consequently activity on the easternmost section of the normal pollino fault and 3 to hypothesise the presence of an hitherto unknown active fault responsible for the strong vertical displacements of the flight of terraces near the river avena finally we find the ratio of the rate of regional uplift to the average rates of local tectonic deformation to be 2 to 3 1

the significance of marine boreal molluscs in the early pleistocene faunas of the mediterranean area abstract repeated migration of boreal guests into the mediterranean during the early pleistocene has been considered a weak paleoclimatic oceanographic tool this attitude is partly held because the plio pleistocene boundary as defined in the mediterranean does not seem to coincide with isotopic events more important than those of the piacenzian an analysis of their present biogeographical distributions suggests that the successful migration of the boreal elements into the early pleistocene mediterranean was caused by the establishment of a climatic phase of high seasonality with winter temperatures lower than 9 10 c and summer temperatures not lower than 20 c such a situation would also have been suitable for the taxa of warm affinity that characterize the present mediterranean moroccan bioprovince this hypothesis applies mainly to the first phase of migration santernian substage which is the best known from a malacological point of view the available paleoclimatic and isotopic record seems in agreement with the hypothesis

contribution of structural analysis to understanding the geodynamic evolution of the calabrian arc southern italy abstract a marked curvature of crustal structures characterizes the calabrian arc in southern italy the overall deformation of the arc seems mostly controlled by the sangineto shear zone to the north and by the mt kumeta alcantara shear zone to the south which both separate different crustal sectors other important fault systems cut the iblean foreland scicli ragusa fault zone and many others dissect the crystalline units of central calabria neotectonic structural analyses have been carried out in order to recognize the character of the plio pleistocene tectonic phases and their bearing on the present configuration of the arc after the middle miocene extensional phase an early middle pliocene compressional phase is detectable in many parts of the arc right and left lateral displacements respectively characterize the mt kumeta alcantara and sangineto shear zones and right lateral movements are also detectable within the scicli ragusa fault system finally the pleistocene tensional regime seems to have been controlled mainly by uplift the structural and neotectonic data allow us to propose a model of the recent evolution of the arc which was bent mainly as a result of opposed wrench faulting along the sangineto and mt kumeta alcantara shear zones

evidence for sea level oscillations by the characteristic thickness of marine deposits from raised terraces of southern calabria italy abstract clastic deposits associated with marine terraces can provide evidence for detecting eustatic oscillations the method is based on the characteristic thickness ct of beach formations which are generally deposited on a wave cut platform between the breakpoint and the swash upper limit on any present day coast ct reflects equilibrium related to current shore processes with a constant sea level it represents a local threshold t cr as when sea level rises ct increases by a value equal to the rise amplitude this amount is reduced in uplifted areas by the magnitude of coeval uplifting the amplitude of sea level variations detected by ct can be calculated knowing ct t cr uplift rate and the duration of an oscillation the method is applied to the clastic deposits of 23 marine terraces stepped between 52 and 172 m and shaped over the mis 5 mis 4 period along the calabria coast of the messina strait not only the great orbital oscillations mis 5 5 mis 5 3 mis 5 1 and mis 3 are recorded but also several rapid and low amplitude events are detected into each substage the most surprising result is the ten small oscillations during mis 5 5 the duration of which ranges between 2 ka and less than 1 ka while sea level oscillates from 0 5 to 12 m in amplitude by calculating initial relative sea level highstands and also lowstands preceding them detailed eustatic oscillations of the curve are drawn

beyond threshold hillslopes channel adjustment to base level fall in tectonically active mountain ranges numerous empirical and model based studies argue that in general hillslopes and river channels increase their gradients to accommodate high rates of base level fall to date however few data sets show the dynamic range of both these relationships needed to test theoretical models of hillslope evolution and river incision here we utilize concentrations of 10 be in quartz extracted from river sand on the eastern margin of the tibetan plateau to explore relationships among short term 10 2 10 5 a erosion rate hillslope gradient and channel steepness our data illustrate nonlinear behavior and a threshold in the relationship between erosion rate and mean hillslope gradient confi rming the generalization that hillslopes around the world are limited by slope stability and cease to provide a metric for erosion at high rates 0 2 mm a the relationship between channel steepness index and erosion rate is also nonlinear but channels continue to steepen beyond the point where threshold hillslopes emerge up to at least 0 6 mm a demonstrating that channel steepness is a more reliable topographic metric than mean hillslope gradient for erosion rate and that channels ultimately drive landscape adjustment to increasing rates of base level fall in tectonically active settings

pliocene lower pleistocene chronostratigraphy a re evaluation of mediterranean type sections the pliocene pleistocene stages defined for the mediterranean region are generally used as the standard chronostratigraphic units for the upper neogene and quaternary the recently developed calcareous plankton bio chronology based on results from ocean drilling program leg 107 and numerous outcrop sections provides the necessary time control for evaluating the ages and stratigraphic relationships for the various pliocene pleistocene stages and their associated stratotypes our results indicate that the currently accepted stratotypes do not provide a continuous stratigraphic representation for all of pliocene early pleistocene time on the basis of these findings we propose a revised chronostratigraphic scheme for this time period a tripartite subdivision is proposed for the pliocene series the zanclean stage is retained for the lower pliocene representing the interval from the miocene pliocene boundary ca 4 93 ma to ca 3 5 ma the middle pliocene is represented by the piacenzian stage and it incorporates strata deposited from ca 3 5 to 2 5 ma none of the currently used pliocene stages fully represents the upper pliocene ca 2 5 to 1 6 ma as a result late pliocene time lacks an adequately defined chronostratigraphic unit the selinuntian stage appears to be the most appropriate stage for the lower pleistocene ca 1 6 to 0 8 ma it can be divided into three stratigraphically continuous substages santernian emilian and sicilian the calabrian stage which is commonly used to designate the lowest part of the pleistocene should be abandoned because its stratotype does not include a record of the first 500 000 yr of pleistocene time

fault parameters in the messina strait southern italy and relations with the seismogenic source abstract the messina strait is characterized by strong deformations in pliocene and pleistocene times but considering the historical seismicity significant uncertainity exists as to whether any of the surface fault systems reflects the location geometry and mechanisms of the seismogenic source based on field data and structural analyses the parameters length l displacement d age of activity t minimum slip rate min and total geological moment m g have been derived for all the faults exposed on the sicilian and calabrian sides of the strait the analysis of these parameters shows that the highest rates of activity pertain to interconnected faults of different orientation and length which bound the uplifted crystalline basement relative to the pliocene pleistocene foundered zones of the calabrian side the comparison between the fault slip rates and the regional uplift rates shows that each single fault contributes for a limited fraction only to the whole deformation release in the area the contribution of the whole fault population expressed as cumulative m g release is still one order of magnitude less than the seismic moment release taking into account the underestimation of the geological parameters the lack of information on the offshore faults and the role of anelastic deformation by aseismic creep the data suggest that the long term recurrence of seismic breaks is partitioned at the surface in a complex array of interconnected faults some of these faults might represent basement inherited structures repeatedly and preferentially reactivated over geological time

landscape form and millennial erosion rates in the san gabriel mountains ca abstract it has been long hypothesized that topography as well as climate and rock strength exert first order controls on erosion rates here we use detrital cosmogenic 10 be from 50 basins ranging in size from 1 to 150 km 2 to measure millennial erosion rates across the san gabriel mountains in southern california where a strong e w gradient in relief compared to weak variation in precipitation and lithology allow us to isolate the relationship between topographic form and erosion rate our erosion rates range from 35 to 1100 m ma and generally agree with both decadal sediment fluxes and long term exhumation rates inferred from low temperature thermochronometry catchment mean hillslope angle increases with erosion rate until 300 m ma at which point slopes become invariant with erosion rate although this sort of relation has been offered as support for non linear models of soil transport we use 1 d analytical hillslope profiles derived from existing soil transport laws to show that a model with soil flux linear in slope but including a slope stability threshold is indistinguishable from a non linear law within the scatter of our data catchment mean normalized channel steepness index increases monotonically though non linearly with erosion rate throughout the san gabriel mountains even where catchment mean hillslope angles have reached a threshold this non linearity can be mostly accounted for by a stochastic threshold incision model though additional factors likely contribute to the observed relationship between channel steepness and erosion rate these findings substantiate the claim that the normalized channel steepness index is an important topographic metric in active ranges

transient fluvial incision in the headwaters of the yellow river northeastern tibet china 1 we utilize topographic analysis of channel profiles combined with field measurements of erosion rates to explore the distribution of channel incision in the anyemaqen shan a broad mountainous region in the northeastern tibetan plateau tributary channels to the yellow river display systematic downstream increases in channel gradient associated with convex upward longitudinal profiles steep lower reaches of channels are associated with rapid 1 m ka incision rates along the yellow river while upstream reaches are associated with relatively slow 0 05 0 1 m ka erosion of soil mantled uplands covariance between erosion rates and channel steepness indices suggest that channels are adjusted to match long wavelength differential rock uplift across the range geologic constraints indicate that rapid incision downstream of the range is associated with excavation of basin fill driven by changes in relative base level farther downstream the upstream limit of this wave of transient incision is marked by a series of knickpoints that are found at nearly the same elevation throughout the watershed consistent with knickpoint migration as a kinematic rather than diffusional wave tributary channel gradients downstream of knickpoints however display a progressive adjustment to increased incision rates that may reflect the influence of increased sediment flux comparison of observed channel profiles to a stream power model of fluvial behavior reveals that the rate of knickpoint propagation can only be explained if the erosional efficiency coefficient k increases during incision our results thus highlight the utility of channel profile analysis to reconstruct the fluvial response to both active tectonism and external changes in base level

quantifying the slip rates spatial distribution and evolution of active normal faults from geomorphic analysis field examples from an oblique extensional graben southern turkey abstract quantifying the extent to which geomorphic features can be used to extract tectonic signals is a key challenge in the earth sciences here we analyse the drainage patterns geomorphic impact and long profiles of bedrock rivers that drain across and around normal faults in a regionally significant oblique extensional graben hatay graben in southern turkey that has been mapped geologically but for which there are poor constraints on the activity slip rates and plio pleistocene evolution of basin bounding faults we show that drainage in the hatay graben is strongly asymmetric and by mapping the distribution of wind gaps we are able to evaluate how the drainage network has evolved through time by comparing the presence size and distribution of long profile convexities we demonstrate that the northern margin of the graben is tectonically quiescent whereas the southern margin is bounded by active faults our analysis suggests that rivers crossing these latter faults are undergoing a transient response to ongoing tectonic uplift and this interpretation is supported by classic signals of transience such as gorge formation and hill slope rejuvenation within the convex reach additionally we show that the height of long profile convexities varies systematically along the strike of the southern margin faults and we argue that this effect is best explained if fault linkage has led to an increase in slip rate on the faults through time from 0 1 to 0 45 mm yr by measuring the average length of the original fault segments we estimate the slip rate enhancement along the faults and thus calculate the range of times for which fault acceleration could have occurred given geological estimates of fault throw these values are compared with the times and slip rates required to grow the documented long profile convexities enabling us to quantify both the present day slip rate on the fault 0 45 0 05 mm yr and the timing of fault acceleration 1 4 0 2 ma our results have substantial implications for predicting earthquake hazard in this densely populated area calculated potential mw 6 0 6 6 enable us to constrain the tectonic evolution of the graben through time and more widely demonstrate that geomorphic analysis can be used as an effective tool for estimating fault slip rates over time periods 106 years even in the absence of direct geodetic constraints

geometry kinematics and deformation rates along the active normal fault system in the southern apennines implications for fault growth throw rates throws and kinematic data have been collected from a localised system of active normal faults in the southern apennines italy to assess how its growth history differs from that for a distributed fault system in the central apennines both show evidence for fault interaction in that 1 faults located centrally along strike have higher throws and throw rates than distal faults and 2 cumulative throw and throw rate profiles summed across strike show central maxima with values decreasing to zero at fault system tips however although throw rates increased through time in the central apennines we are unable to resolve such changes if they exist for the southern apennines specifically throw rates derived from offsets of 18 ka geomorphic surfaces are consistent with total throws in the southern apennines when extrapolated back through time but overestimate total throws in the central apennines by a factor of 2 4 suggesting an increase in throw rate through time for the latter we discuss why some fault systems appear to have throw rates that are constant through time whilst others accelerate during growth interaction

active faulting and seismicity along the siculo calabrian rift zone southern italy abstract southern italy is dominated by extensional tectonics that in the calabrian arc and eastern sicily produced the development of the siculo calabrian rift zone scrz this zone is represented by a 370 km long fault belt consisting of 10 to 50 km long distinct fault segments which extend both offshore and on land being also responsible of the crustal seismicity of this region the geological and morphological observations indicate that the active normal faults of the scrz are characterized by throw rates ranging from 0 7 to 3 1 mm a they accommodate an almost uniform horizontal extension rate of about 3 0 mm a along a wnw ese regional extension direction based on our field observations and following empirical relationships between magnitude and surface rupture length connections between large crustal earthquakes and distinct fault segments of the scrz have been also tentatively tested our data indicate moreover that the magnitudes m of the historical and instrumental earthquakes are consistent with the estimated values and that the geometry and kinematics of the fault segments and the related different crustal features of the scrz control the different seismic behaviours of adjacent portions of the active rift zone

paleoseismology along the cittanova fault implications for seismotectonics and earthquake recurrence in calabria southern italy 1 this paper focuses on the seismogenic structure responsible for the 5 february 1783 earthquake m 7 calabria southern italy in particular the slip rate and recurrence time along the cittanova fault thus giving new insights on the seismic hazards and seismotectonics of the region the 1783 earthquake one of the strongest earthquake of the mediterranean area caused more than 30 000 casualties and radically changed the physiography of the local landscape until now the cittanova fault or aspromonte fault has been generally identified as the surficial expression of the seismogenetic structure even though its youthful activity has never been demonstrated recently the shortage of geologic evidence of middle upper pleistocene activity on this fault led some authors to locate the 1783 fault elsewhere in our study we used a multidisciplinary approach paleoseismology geomorphology historical seismology archaeoseismology our analysis of contemporary literary sources strengthened our interpretation of the coseismic origin of many geological features and sometimes oriented our field research toward specific areas in particular we excavated trenches and pits at three different sites along the trace of the cittanova fault for paleoseismological analysis and 14 c dating our data document the holocene and present activity of the cittanova fault providing a minimum vertical slip rate of 0 44 mm yr and a possible return time of 1350 1800 years for earthquakes similar to 1783 the penultimate event has been dated to the 4th century a d a time when southern calabria and eastern sicily were devastated by an earthquake documented by archaeoseismic analyses

geomorphic constraints on landscape sensitivity to climate in tectonically active areas abstract the geomorphology of fluvial landscapes is known to record information about uplift rate spatial patterns of faulting and tectonic history data is far less available when addressing the sensitivity of common geomorphological metrics such as channel steepness to climatic boundary conditions we test the relationship between channel steepness and precipitation rate by measuring a large number of channels in different mountainous areas these regions exhibit a tenfold variation in precipitation rate between them 100 1000 mm y 1 but have similar uplift rates allowing the tectonic variable to be controlled by accounting for the orographic coupling of rainfall with uplifted topography we find that channel steepness is significantly suppressed by higher precipitation rates in a measurable way that conforms to simple stream power erosion laws and empirical constraints on their parameters we demonstrate this using modern and estimated glacial precipitation rates and climate emerges as an important quantifiable control on channel geometry these findings help to explain why highly variable measurements of channel steepness are reported from different locations and provide important empirical constraints on how climate shapes tectonically active landscapes

the implications of revised quaternary palaeoshoreline chronologies for the rates of active extension and uplift in the upper plate of subduction zones we demonstrate a synchronous correlation technique to determine the chronology of quaternary palaeoshorelines to test proposed relationships between tectonics climate and sea level change the elevations of marine palaeoshorelines in calabria around the active vibo normal fault have been measured from tin dem 10 m data and fieldwork and correlated with global sea level curves a synchronous correlation method and new u th dates are used to ascertain how the slip rate on the fault relates to uplift rates across the region regional uplift possibly associated with subduction along the calabrian trench or due to the cumulative effect of closely spaced active normal faults is rapid enough to uplift even the hangingwall of the vibo normal fault the actual value for the rate of background uplift can only be ascertained once the rate of slip on the vibo fault is subtracted synchronous correlation of multiple palaeoshorelines sampled along 29 elevation profiles with global sea levels shows that the resultant uplift rate background uplift minus local hangingwall subsidence is constant through time from 0 to 340 ka and not fluctuating by a factor of 4 as previously suggested the uplift rate increases from 0 4 mm yr at the centre of the hangingwall of the fault to 1 75 mm yr in the hangingwall in the vicinity of the fault tip palaeoshorelines can be traced from the hangingwall to the footwall around the fault tip and hence correlated across the fault the throw rate on the fault averaged over 340 ka decreases from a maximum at the centre of the fault 1 mm yr to zero at the tip this gradient in throw rate explains the spatial variation in resultant uplift rates along the fault we interpret the 1 75 mm yr resultant uplift rate at and beyond the fault tip as the signature of a regional uplift presumably related to subduction although we cannot exclude the possibility that other local faults influence this uplift the lower uplift rates in the hangingwall of the fault are due to interaction between regional uplift and subsidence associated with the local active normal faulting we discuss a how our synchronous correlation technique should trigger a re appraisal of palaeoshoreline chronologies worldwide and b the implications for the tectonics and seismic hazard of calabria suggesting that perturbations in the uplift rate field are a key criterion to map the locations of active faults their deformation rates and hence seismic hazard above subduction zones

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

the vallo di diano and auletta extensional basins in the southern apennines italy a simple model for a complex setting this work has been developed within the 2005 2008 firb project research and development of new technologies for protection and defence of territory from natural risks w p c3 crustal imaging in italy coordinated by p montone funded by the italian ministry of uni versity and research

the growth of fault bounded tilt blocks a series of uniformly tilted fault bounded blocks is a common feature in actively extending regions such as the basin and range province if the tilted blocks were produced by rigid domino style rotation one would predict large voids at either end of a series of these blocks using tilt data and a simple flexural calculation we suggest that much of the apparent rigid behavior could also be produced by internal block deformation in our model of normal fault growth isostatic elastic uplift of the footwall is coupled with hanging wall downdrop within the region between faults resulting in the appearance of a tilted rigid block we present tilt data sampled at varying distances from several block defining faults within the northeast basin and range province tilt measurements between a series of 30 km spaced block defining faults are found to be uniform while tilts between more widely spaced faults exhibit a pattern of tilt that diminishes to zero in less than 30 km using a simple flexural calculation for internal block deformation we show that for this region the patterns of tilt are consistent with a flexural length scale of 8 12 km and deflections of 2 4 km these estimates are compatible with both the lower limit to seismicity and basin depth determined from earthquake and seismic reflection studies

knickpoint initiation and distribution within fluvial networks 236 waterfalls in the waipaoa river north island new zealand if knickpoints transmit signals of base level fall in river networks then improvements in our understanding of their retreat rate and basin wide distribution helps constrain the transient response following perturbation many studies of knickpoint retreat focus on the response of trunk streams to base level fall here we examine the response of an entire fluvial network as recorded by 236 active knickpoints distributed within the waipaoa river on the north island of new zealand base level fall within the waipaoa catchment initiated 18 000 years ago in response to a climatically triggered and tectonically exacerbated pulse of incision using observations from field work aerial photo analysis and a digital elevation model dem we study the knickpoint positions within the network we find that 70 of the knickpoints are located at drainage areas between 1 10 5 m 2 and 1 10 6 m 2 and more than half are b1 km upstream of a large change in drainage area for the knickpoints b1 km upstream of large tributary junctions we find that the retreat distances were well correlated with the tributaries drainage areas in order to determine how a pulse of incision distributes itself throughout a fluvial network we develop two simple end member models and compare their behavior to the observed knickpoint distribution in the waipaoa in the first model we propose that a knickpoint initiated at the basin outlet retreats upstream and distributes the signal throughout the network at a rate that is a power law function of drainage area in the second model we propose that knickpoints form near a threshold drainage area below which channels cannot incise with the same efficiency as possible in downstream reaches though neither model addresses the along stream variability in substrate or knickpoint form the misfit between the modeled and the observed knickpoints along stream positions are surprisingly low b1 km 1 25 of the total stream length for knickpoints with drainage areas b1 10 6 m 2 large misfits up to 3 5 km are observed for knickpoints with present day drainage areas greater than 1 10 6 m 2 the large single step in channel elevation that characterizes knickpoints presently observed in tributaries of the waipaoa river may not characterize the base level fall signal that propagated through the trunk streams evidence for progressive rather than instantaneous incision in the trunk streams the knickpoints vicinities to tributary junctions and the equivalent success of the two end member models lead us to conclude that the present positions of the 236 observed knickpoints are largely a consequence of thresholds in channel incision at low drainage areas

a 125 kyr long geological record of seismic source repeatability the messina straits southern italy and the 1908 earthquake ms7 2 the occurrence of characteristic earthquakes along segments of major active belts has been described as early as the beginning of the century the large 1908 messina straits blind normal faulting earthquake provides an opportunity to investigate the repetition of characteristic earthquakes and the persistency of the main features of the fault zone over a time scale in the order of 100 kyr we have compared seismological and geodetic descriptions of the 1908 rupture process with long term crustal deformation recorded at different stratigraphic levels by marine terraces marine sedimentary units and landscape features the wealth of elevated coastal features in and around a region affected by large normal faulting earthquakes indicates that coseismic strain is superimposed on much faster uplift on a regional scale we investigated in detail the pattern of deformation of the 125 kyr old lowest emergent terrace and found that it mimics the pattern of elevation changes observed following the earthquake this suggests 1 that the 1908 earthquake is characteristic 2 that its segment boundaries have been stationary during the past 125 kyr and 3 that even the locations of the regions of largest coseismic release do not change through many seismic cycles based on a comparison between observed heights of the 125 kyr terrace and 1908 displacements we estimated an average repeat time of 1000 yr for a 1908 type earthquake we also investigated the height position age and state of deformation of older terraces and found 1 that uplift of the region started about 1 ma and has since continued rather uniformly at 0 9 1 4 mm yr 1 2 that during this time the straits have narrowed at a rate of 10 20 mm yr 1 and 3 that all the main geomorphic features of the messina straits result from the interaction of fast regional uplift 1908 type coseismic subsidence and global sea level fluctuations

footwall topographic development during continental extension 1 we examine the progressive development of footwall topography associated with a set of active normal faults in the northeastern basin and range province of the western united states fault length and displacement increase monotonically from northeast to southwest in the study area allowing us to track both variations in footwall morphology with increasing displacement and along strike changes in morphology on a single fault we show that patterns of catchment area footwall relief and catchment outlet spacing vary predictably and are related to the growth of the range bounding normal fault array in this semiarid region full parsing of footwall drainage area and removal of antecedent topography do not occur until fault arrays grow beyond two crustal scale segments multiple segment faults with lengths of up to 150 km have footwall relief that is limited to 1000 m in the center of the footwall and that decays to zero at the fault tips over a length scale of 15 km we hypothesize that this relatively uniform footwall relief is erosionally limited and reflects the efficacy of surface processes in removing footwall material in the center of the footwall if the fault array grows by relatively steady propagation of the tips we suggest that the 15 km length scale required to reach uniform relief is related to a timescale of relief generation by the fault tip propagation rate while such propagation rates are poorly known an average rate of 10 mm yr 1 would imply footwall relief generation over a timescale of 1 myr

bedrock channel adjustment to tectonic forcing implications for predicting river incision rates we present detailed data of channel morphology for a river undergoing a transient response to active normal faulting where excellent constraints exist on spatial and temporal variations in fault slip rates we show that traditional hydraulic scaling laws break down in this situation and that channel widths become decoupled from drainage area upstream of the fault unit stream powers are 4 times higher than those predicted by current scaling paradigms and imply that incision rates for rivers responding to active tectonics may be significantly higher than those heretofore modeled the loss of hydraulic scaling cannot be explained by increasing channel roughness and is an intrinsic response to tectonic forcing we show that channel aspect ratio is a strongly nonlinear function of local slope and demonstrate that fault induced adjustment of channel geometries has reset hillslope gradients the results give new insight into how rivers maintain their course in the face of tectonic uplift and illustrate the first order control the fluvial system exerts on the locus and magnitude of sediment supply to basins

landscape response to tectonic forcing digital elevation model analysis of stream profiles in the mendocino triple junction region northern california the topographic evolution of orogens is fundamentally dictated by rates and patterns of bedrock channel incision quantitative field assessments of process based laws are needed to accurately describe landscape uplift and denudation in response to tectonics and climate we evaluate and calibrate the shear stress or similar unit stream power bedrock incision model by studying stream profiles in a tectonically active mountain range previous work on emergent marine terraces in the mendocino triple junction region of northern california provides spatial and temporal control on rock uplift rates digital elevation models and field data are used to quantify differences in landscape morphology associated with along strike northwest to southeast changes in tectonic and climatic conditions analysis of longitudinal profiles supports the hypothesis that the study area channels are in equilibrium with current uplift and climatic conditions consistent with theoretical calculations of system response time based on the shear stress model within uncertainty the profile concavity of the trunk streams is constant throughout the study area 0 43 as predicted by the model channel steepness correlates with uplift rate these data help constrain the two key unknown model parameters the coefficient of erosion k and the exponent associated with channel gradient n this analysis shows that k cannot be treated as a constant throughout the study area despite generally homogeneous substrate properties for a reasonable range of slope exponent values n best fit values of k are positively correlated with uplift rate this correlation has important implications for landscape evolution models and likely reflects dynamic adjustment of k to tectonic changes due to variations in orographic precipitation and perhaps channel width sediment load and frequency of debris flows the apparent variation in k makes a unique value of n impossible to constrain with present data

mechanics of continental rift architecture continental rifts are long narrow features bounded on one or both sides by normal faults along which several kilometers of displacement has occurred resulting in deep rift valleys that form sedimentary basins continental rifts all share the same geometrical features they have widths that are characteristic of the region in which they form they are predominantly asymmetric and they are segmented along axes at a length scale that is also characteristic of the region we describe a very simple mechanical model to explain these three features the rift initiates with the formation of a conjugate set of normal faults that intersect at the center of the seismogenic layer one of these becomes the boundary fault system the other the failed conjugate fault being offset by the former becomes locked early in the rifting history hence an asymmetric graben is formed which is the basic building block of rifts the failed conjugate fault has distinctive properties that allow it to be easily distinguished from other faults examples of these faults from the tanganyika and malawi rifts show excellent agreement with predictions about their positions with respect to the boundary fault system and their net displacement and slip history the width of the asymmetric graben is a simple function of seismogenic thickness the net displacement on the boundary fault system is limited by the resistive friction and the flexural restoring force we calculate this limiting boundary fault system displacement and using the displacement length scaling law for normal faults suggest that this controls the along axis segmentation length both maximum fault slip and segmentation length are functions of the seismogenic thickness and the effective elastic thickness of the crust these calculations agree very well with observations of segmentation from the african rifts and the maximum length of range fronting normal faults in nevada

structural and geomorphological constraints on active normal faulting and landscape evolution in calabria italy calabria is one of the fastest uplifting and most seismically active regions in the mediterranean yet the time averaged c 10 6 years rates of normal faulting remain poorly constrained here we use digital elevation model analysis geological cross sections and a compilation of published data to quantify systematically along strike the fault throws and time averaged throw rates of the serre cittanova armo east crati and west crati faults we show that regional uplift has uplifted both their hanging wall and footwall blocks by c 200 400 m and the aspromonte massif by up to c 1150 1300 m we find that these faults have throws between c 640 and 1430 m and throw rates between c 0 6 and 1 4 mm a 1 their footwall ranges have variable proportions of inherited relief up to c 300 800 m the channels draining these ranges reflect the active normal faulting and relief in their steepness indices becoming c 5 8 m 0 9 steeper for each 0 1 mm a 1 throw rate increment and each 100 m relief increase finally the presence of knickpoints suggests that these channels are transiently responding to changes in relative base level which could be due to fault linkage or regional strain rate increases for the southern calabrian faults and to regional uplift acceleration in the case of the crati faults supplementary material topographic profiles of the marine terraces and long profiles of rivers are available at https doi org 10 6084 m9 figshare c 3689464

recent deformations and the seismogenic source in the messina strait southern italy abstract the relationships between mechanisms and mode of faulting in pliocene and pleistocene times and seismic release are the basis for an interpretation of the growth of deformation energy in the messina strait the major fault systems trending in ne sw nw se and e w directions divide blocks subjected to high mobility in concurrence with greater uplifting of the calabrian side with respect to sicily across the two sides of the strait as revealed by structural analyses the tectonic features of the area are dominated by normal faulting many synsedimentary features seem to indicate repeated and intermittent pulses of high velocity fault slippage possibly related to seismic shaking when considering the seismic record it seems that the strongest shocks are generated by preferential strain accumulations along the nne ssw fault systems from a geological standpoint it seems clear that the largest events may be alternately related to either the nne ssw e w or nw se fault systems which dissect an extremely cataclastic upper crust the recent deformations of the messina strait can be related to the large scale processes induced by the overthrusting of the thinned tyrrhenian crust over the thickened african crust as suggested by seismic refraction profiles along the inner margin of the calabrian arc the deep deformation mechanisms are reflected by contrasting vertical movements between a stretched and downfaulted tyrrhenian domain and an uplifted chain with resulting large strain accumulations and seismic failure in the brittle upper crust

the southern tyrrhenian subduction zone deep geometry magmatism and plio pleistocene evolution abstract we report on a high resolution vp vp vs and qp model of the southern tyrrhenian subduction zone obtained by the inversion of p and s wave arrival times and t values from intraslab seismicity the arcuate shape of the southern apennines calabrian arc sicilian maghrebides is perfectly mirrored by two rather continuous low and high vp bands lying beneath the belt system at ca 25 and 100 km respectively between 100 and 300 km two independent high vp slabs lie beneath the neapolitan region and the southern tyrrhenian sea separated by unperturbed mantle we suggest that the ca 150 km wide slab window beneath the southern apennines opened after a tear occurring within a composite subduction system formed by the apulian continental lithosphere and the ionian oceanic slab the abrupt slab rupture induced ultrafast southeastward retreat of the ionian slab and the 19 cm yr spreading of the back arc oceanic marsili basin between ca 2 1 and 1 6 ma ago the 25 km low vp zone beneath the arc denotes continental upper crustal rocks below the chain its striking continuity requires a unique orogenic wedge at 25 km depth below the southern apennines the calabrian arc and the sicilian maghrebides the alternative explanation would imply the ubiquitous occurrence of autochthonous lower plate rocks at 25 km depth i e a puzzling autochthonous continental calabria the ionian slab beneath calabria shows high vp high qp and low vp vs anomalies typical of old oceanic lithosphere intermediate depth seismicity is concentrated within its thin oceanic crust suggesting the occurrence of vigorous metamorphism the slab dehydration promotes the melting of the overlying mantle as testified by high vp vs and low qp anomalies between the slab and the aeolian magmatic arc

hanging valleys in fluvial systems controls on occurrence and implications for landscape evolution 1 we document and characterize hanging valleys in a fluvially eroded landscape in eastern taiwan our conceptual model for the initiation of hanging valleys builds on a recently proposed model of bedrock incision in which erosion actually becomes less efficient on very steep channel gradients if a pulse of incision in the main stem outpaces the tributary response the gradients at tributary mouths may therefore pass a threshold value beyond which erosional efficiency declines giving rise to a mismatch between trunk and tributary erosion rates this mismatch is expected at junctions with small tributaries where a step function decrease in drainage area also leads to sharp contrasts in water and sediment flux between trunk and tributary channels the occurrence of hanging valleys in actively uplifting fluvial landscapes such as the central range of taiwan suggests that the most common parameterizations of bedrock erosion which typically assume a monotonic positive correlation between channel gradient and incision rate may be violated in very steep channels in addition hanging valleys could greatly increase the response time of landscapes to tectonic perturbations since catchments above these tributary mouths will be insulated from these perturbations until a new suite of processes e g weathering and rock mass failure wear through the hanging valley lip the results of this study underscore the need for a more complete understanding of bedrock erosion processes and the incorporation of process transitions and threshold conditions into landscape evolution models

forearc extension and slow rollback of the calabrian arc from gps measurements 1 here we describe the horizontal velocities of continuous gps stations in the calabrian arc ca and surrounding regions the appropriate reference frame to evaluate the crustal motion of the ca is considered by assessing the internal deformation and the relative motion of the crustal blocks in the foreland of the apennines ionian maghrebides subduction system we propose that the motion of ca relative to the subducting ionian lower plate is most properly assessed by minimizing the gps velocities in apulia in this reference frame the significant 2 mm yr southeastward motion of the stations on the ionian flank of the ca shows that the arc is still moving towards the trench in agreement with the observations of active shortening in the ioanian wedge this southeastward migration is associated to 1 4 0 3 mm yr e w extension of the forearc in northern calabria comparable with the seismic strain averaged in the last 500 years the limited subaerial exposure decreases the resolution on locking of the subduction interface but the distribution and direction of crustal extension along the ca impose important constraints on geodynamic interpretations of the area

deformed streams reveal growth and linkage of a normal fault array in the canyonlands graben utah we use the deformation of streams by the growth of active normal faults within the canyonlands graben of southeastern utah to constrain the displacement evolution of a fault array during segment interaction and linkage coupling fault displacement data with geomorphic analysis of present day streams and paleostreams permits sequential reconstruction of a three segment fault array from initial component segments to its final displacement geometry our results show that although segment interaction causes enhanced displacement addition at overlap zones postlinkage displacement accumulation is significant and permits array equilibration to a displacement length ratio characteristic of a single fault evidence of stream disequilibrium indicates that this postlinkage displacement addition was rapid compared to that during the fault interaction phase

development and response of a coupled catchment fan system under changing tectonic and climatic forcing sediment fans are a potentially useful and underexploited recorder of earth s climatic and tectonic history but historical observations have led to conflicting views on the importance of tectonic climatic and lithologic variables in controlling fan morphology and deposition a one dimensional model of a sediment fan and its associated catchment is used to explore the sensitivity of such simple sediment routing systems to perturbations in fault slip and precipitation rates a transport limited catchment is coupled to a fan whose surface slope is set by the balance between catchment sediment efflux and the available tectonically generated basin accommodation rock uplift rate is spatially variable across the model space increasing the fault slip rate or decreasing the precipitation rate leads to an increase in fan slope temporary back stepping of the fan toe and a pronounced angular unconformity conversely a decrease in slip rate or an increase in precipitation rate results in a decrease in fan slope and progradation and eventual stabilization of the fan toe once perturbed the system evolves toward a new equilibrium state with time constants of 0 5 to 2 myr these response times are insensitive to slip rate but are strongly dependent on precipitation rate variations in fan slope are well described by a dimensionless parameter that expresses equilibrium slope as a function of slip rate precipitation rate system size and catchment lithology this parameter holds promise as a predictive tool in inverting the morphology of natural fans for environmental variables

geomorphic constraints on fault throw rates and linkage times examples from the northern gulf of evia greece we evaluate how the growth and interaction of active normal faults in the sperchios basin and northern gulf of evia greece are recorded by the landscape we demonstrate that patterns in footwall relief along the faults reflect fault segmentation and we show that in this study area fault throw is 2 to 3 times the maximum footwall relief rivers crossing the faults typically have two knickpoints which are unrelated to lithology however their heights measured from the active fault trace vary systematically the height of the upper set of knickpoints scales linearly with the footwall relief of the faults and is typically 85 of the maximum relief the height of the lower set of knickpoints also scales with footwall relief but the heights are consistently lower the existence of two sets of knickpoints suggests that the rivers have been perturbed by two changes in tectonic rates during faulting we interpret the upper knickpoints to represent the initiation and growth of fault generated topography while the lower set of knickpoints reflects a throw rate increase due to fault linkage estimates of throw rate enhancement factor derived from fault interaction theory suggest that the faults increased their rate by a factor of 3 when they linked this constraint combined with the distribution of knickpoint heights allows us to estimate the throw rate and linkage time for the faults the sperchios fault has a maximum throw rate of 1 5 2 0 mm yr while the coastal fault has a maximum throw rate of 0 8 1 2 mm yr

interpretation of radon anomalies in seismotectonic and tectonic gravitational settings the south eastern crati graben northern calabria italy the study area is located in the south eastern part of the crati valley northern calabria italy which is a graben bordered by n s trending normal faults and crossed by nw se normal left lateral faults numerous severe crustal earthquakes have affected the area in historical time present day seismic activity is mainly related to the n s faults located along the eastern border of the graben in this area much seismically induced deep seated deformation has also been recognised in the present paper radon concentrations in soil gas have been measured and compared with a lithology b quaternary faults c historical and instrumental seismicity and d deep seated deformation the results highlight the following a there is no evidence of a strong correlation between lithology and the radon anomalies b a clear correlation between the n s geometry of radon anomalies and the orientation of main fault systems has been recognised except in the southernmost part of the area where the radon concentrations are strongly affected by the superposition of the n s and the nw se fault systems c epicentral zones of instrumental and historical earthquakes correspond to the highest values of radon concentrations probably indicating recent activated fault segments in particular high radon values occur in the zones struck by earthquakes in 1835 1854 and 1870 d deep seated gravitational deformation generally coincides with zones characterised by low radon concentrations in the studied area the anisotropic distribution of radon concentrations is congruent with the presence of neotectonic features and deep seated gravitational phenomena the method used in this study could profitably contribute towards either seismic risk or deep seated gravitational deformation analyses

holocene activity of the scilla fault southern calabria insights from coastal morphological and structural investigations abstract integration of on land and offshore geomorphological and structural investigations coupled to extensive radiometric dating of co seismically uplifted holocene beaches allows characterization of the geometry kinematics and seismotectonics of the scilla fault which borders the eastern side of the messina strait in calabria southern italy this region has been struck by destructive historical earthquakes but knowledge of geologically based source parameters for active faults is relatively poor particularly for those running mostly offshore as the scilla fault does the 30 km long normal fault may be divided into three segments of 10 km individual length with the central and southern segments split in at least two strands the central and northern segments are submerged and in this area marine geophysical data indicate a youthful morphology and locally evidence for active faulting the on land strand of the western segment displaces marine terraces of the last interglacial 124 to 83 ka but seismic reflection profiles suggest a full quaternary activity structural data collected on bedrock faults exposed along the on land segment provide evidence for normal slip and nw se extension which is consistent with focal mechanisms of large earthquakes and gps velocity fields in the region detailed mapping of raised holocene marine deposits exposed at the coastline straddling of the northern and central segments supplies evidence for two co seismic displacements at 1 9 and 3 5 ka and a possible previous event at 5 ka co seismic displacements show a consistent site value and pattern of along strike variation suggestive of characteristic type behaviour for the fault the 1 5 2 0 m average co seismic slips during these events document me 6 9 7 0 earthquakes with 1 6 1 7 ka recurrence time because hanging wall subsidence cannot be included into slip magnitude computation these slips reflect footwall uplift and represent minimum average estimates the palaeoseismological record based on the palaeo shorelines suggests that the last rupture on the scilla fault during the february 6 1783 mw 5 9 6 3 earthquake was at the expected time but it may have not entirely released the loaded stress since the last great event at 1 9 ka comparison of the estimated co seismic extension rate based on the holocene shoreline record with available gps velocities indicates that the scilla fault accounts for at least 15 20 of the contemporary geodetic extension across the messina strait

widespread syn eruptive volcaniclastic deposits in the pleistocenic basins of south western calabria abstract since late tortonian depositional sequences developed along the southern calabrian forearc inside the half graben depressions of the mesima gioia tauro and reggio calabria basins in these basins volcaniclastic sedimentation took place during lower to middle pleistocene volcaniclastic deposits consist of isolated pumice swarms ash layers and thick successions of lapilli and ash in this paper we describe and discuss the depositional characteristics of these volcanogenic sediments and the morphology mineralogy and chemistry of pumices shards lithics and crystal fragments these deposits all have the characteristics of a proximal tephra fall deposit from a plinian plume which has been reworked in a shore environment in the mesima basin the deposits reach 6 m in thickness and in the gioia tauro plain 21 m of pumiceous sediments have been cored in a drill hole the compositional homogeneity of fragments and the absence of non volcanic detritus as well as of soil or organic matter suggest that the deposits were quickly reworked after their primary emplacements all the tephra deposits exhibit calc alkaline affinity and dacitic to rhyolitic composition the mineralogical assemblage including orthopyroxene as phenocryst indicates provenance from magmatic arc volcanism icp ms and la icp ms analyses of crystals and glass point to a common origin probably from a single eruption this makes these volcaniclastic layers a very useful tool for stratighaphic reconstructions at a regional scale the geological setting of the deposits their petrological and geochemical signature and the occurrence of large size clasts suggest a provenance from explosive eruptions preceding the emplacement of the 50 ka dacitic lava dome of the island of panarea aeolian archipelago however a provenance from a different calc alkaline volcanic system cannot be excluded these deposits can therefore represent the only evidence of a large explosive eruption in the southern tyrrhenian sea whose very proximal equivalent is not preserved

the geometrical evolution of normal fault systems abstract the purpose of this paper is to examine the kinematic behaviour of normal fault systems and see what general conditions govern their geometrical evolution we pay particular attention to seismological and surface data from regions of present day active normal faulting as the instantaneous three dimensional geometry at the time of fault movement is better known in active regions than in areas where the faults are now static most normal faults are concave upward or listric this shape can be produced by geometric constraints either because the faults reactivate curved thrusts or because they must be curved to accommodate rotations another effect which will produce curved faults is the variation of rheology with depth brittle failure at shallow depths produces less fault rotation than does distributed creep in the lower part of the crust an important geometric feature of normal faulting is the uplift of the footwall the amount of such uplift is related not only to the elastic properties of the lithosphere but also to the throw and dip of the fault a striking feature of active normal faults is that they occur in groups in which all the faults dip in the same direction this behaviour arises because the faults cannot intersect if they do one must cease to be active the rotation which such fault systems produce reduces the dip of the faults until a new steeply dipping fault is formed once a new fault cuts pre existing faults the earlier faults become locked and a new set of faults must propagate rapidly across the whole region involved many of these geometric constraints also apply to thrust faulting

structure of the hanmer strike slip basin hope fault new zealand hanmer basin 10 x 20 km located in northern south island new zealand is evolving where two major segments of the dextral strike slip hope fault are projected to converge across a 6 to 7 km wide releasing step over the structural geometry and development of hanmer basin does not conform to traditional pull apart basin models the respective fault segments do not overlap but are indirectly linked along the southwest margin of the basin by an oblique normal fault the hope river segment terminates in an array of oblique normal faults along the northwestern basin range front and east west striking normal faults on the west hanmer plain faulted holocene alluvial fan surfaces indicate west hanmer basin is actively subsiding evolving under north south extension the conway segment along the southeastern margin of the basin terminates in a complex series of active fault traces small pop up ridges and graben depressions early basin fill sediments of pleistocene age are being folded elevated and dissected as the eastern part of hanmer basin is progressively inverted and destroyed by north south contraction the north margin of the basin is defined by a series of topographic steps caused by normal faulting outside of the area of the releasing step over these normal faults we interpret to reflect large scale upper crustal collapse of the hanging wall side of the hope fault new seismic reflection data and geologic mapping reveal a persistent longitudinal and lateral asymmetry to basin development four seismic stratigraphic sequences identified in the eastern sector of the basin thicken and are tilted southward with insequence lateral onlaps occurring to the north and east and also onto basement near the fault controlled basin margins the basin depocenter currently contains 1000 m of sediment adjacent to the south margin and is disrupted by faulting only at depth in the western part of the basin the sediment fill is thinner today the rate of basin deepening under transtension at the western end is matched by its progressive inversion and destruction under transpression in the eastern sector with the oldest basin fill now being recycled we propose a hybrid model for hanmer strike slip basin one in which geometric elements of a fault wedge basin downward and upward tipped spindle shaped ends are combined with those of a pull apart basin step over region between the major fault segments we also conclude that changes in fault geometry releasing and restraining bends and step overs at a variety of scales and over short distances control the development of the extensile and contractile parts of the basin and three dimensional basin asymmetry strain partitioning is complex and cannot be related simply to local reorientation of the regional stress field

fission track analysis of the crystalline basement rocks of the calabrian arc southern italy evidence of oligo miocene late orogenic extension and erosion abstract fission track analysis is used to provide low temperature and time constraints on the late orogenic cooling and exhumational history of the crystalline basement rocks of the calabrian arc southern italy 65 samples yielded 57 apatite fission track ages 54 zircon fission track ages and 25 apatite confined fission track length distributions interpretation of this data reveals a phase of increased cooling rates related to exhumation between approximately 35 ma mid oligocene and 15 ma middle miocene evidence from the sedimentary record indicates significant oligo miocene erosion related to this period of exhumation new chronological constraints are also applied to localised late orogenic extensional tectonism that has recently been identified within the basement rocks of the calabrian arc this information is used to produce a new model of the oligo miocene tectonic evolution of the calabrian arc it proposes that the crystalline basement rocks were part of a critical orogenic wedge between the mid oligocene and the middle miocene

tectonic and climatic controls on knickpoint retreat rates and landscape response times 1 the rate at which transient knickpoints propagate through a landscape fundamentally controls the rate of geomorphic response to tectonic and climatic perturbation here we present knickpoint retreat rates upstream of active faults for 19 bedrock catchments in turkey and 11 bedrock catchments in italy where we have very good constraints on both the magnitude and timing of the tectonic perturbation and where climate histories are well documented we show that the knickpoints have average retreat rates of between 0 2 and 2 mm yr for catchments with drainage areas between 6 and 65 km2 and we test whether differences in rock mass strength and catchment size are sufficient to explain this range in retreat rates our analysis suggests that even accounting for these two variables knickpoint propagation velocities differ markedly and we show that channels crossing faults with higher throw rates have knickpoints that are retreating faster the dependence of knickpoint retreat velocity on throw rate is at least as important as catchment drainage area these results indicate counterintuitively that landscapes forced by large amplitude tectonic perturbations will have shorter response times than those perturbed by smaller amplitude changes the link between the knickpoint propagation velocity and throw rate is largely but not completely explained by channel narrowing in areas of high uplift rate channel steepening upstream of the active faults may explain all of the residual dependency of knickpoint retreat rate on fault throw rate but only if the slope exponent n in the standard stream power model is greater than 1 3 however we cannot rule out a role for sediment supply in driving enhanced knickpoint retreat rate in addition to the well documented channel narrowing effect finally we find that mean knickpoints retreat rates in turkey are only half of those in italy for catchments of equivalent size crossing faults with similar throw rates this difference in fluvial response time is accounted for by long term differences in the ratio of precipitation to infiltration in the two areas over the last 1 my

the architecture of brittle postorogenic extension results from an integrated structural and paleomagnetic study in north calabria southern italy an integrated structural and paleomagnetic study was carried out on neogene quaternary clastic sedimentary sequences exposed in north calabria to define the brittle postorogenic evolution of the inner sector of the calabrian arc the structural mineralogical and magnetic fabric data presented in this paper suggest that the post orogenic basins of north calabria originated and developed under an extensional tectonic regime that has been active since the middle miocene results were used to define the spatial and temporal evolution of the extensional fault systems in the framework of extensional processes active in the backarc region of the southeastward migrating apennine subduction system our data indicate that regional backarc extension operated in the brittle crust and the data trace a continuous evolution from low to high angle extensional faulting paleomagnetic data show that this continuous extensional process was accompanied by complex interactions among fault bounded crustal blocks in fact the extensional domain is subdivided into different structural compartments separated by the adjustment in the fault strike imposed by the regional rotation pattern

low slip rates and multimillennial return times for mw 7 earthquake faults in southern calabria italy the calabrian arc is the epicentral region of one third of the strongest earthquakes of italy mw 7 0 these are confined within a narrow peninsula which is the emerging portion of a slab related accretionary wedge and all occurred in the past four centuries therefore here more than anywhere in italy historical seismicity alone is not sufficient for seismic hazard assessment we carried out geological and paleoseismological studies in southern calabria that allowed characterizing the seismogenic behavior of the cittanova fault which was responsible for one of the most catastrophic earthquakes to ever occur in europe the mw 7 0 5 february 1783 event we have found out conclusive evidence for four holocene earthquakes prior to 1783 with a recurrence time longer 3 2 kyr than the other apennine faults 0 3 2 4 kyr we have also estimated a robust slip rate for the late upper pleistocene 0 6 mm yr and an extension rate 0 4 mm yr that could reflect the residual back arc opening of the tyrrhenian basin

the growth of geological structures by repeated earthquakes 1 conceptual framework in many places earthquakes with similar characteristics have been shown to recur if this is common then relatively small deformations associated with individual earthquake cycles should accumulate over time to create geological structures following this paradigm we show that existing models developed to describe leveling line changes associated with the seismic cycle can be adapted to explain geological features associated with a fault in these models an elastic layer containing the fault overlies a viscous half space with a different density fault motion associated with an earthquake results in immediate deformation followed by a long period of readjustment as stresses relax in the viscous layer and isostatic equilibrium is restored deformation is also caused as a result of the loading and unloading due to sediment deposition and erosion in this paper the parameters that control the growth of dip slip structures are identified we find that the flexural rigidity of the crust or the apparent elastic thickness provides the main control of the width of a structure the loading due to erosion and deposition of sediment determines the ratio of uplift to subsidence between the two sides of the fault the flexure due to sediment load is much more important in this respect than whether the fault is normal or reverse in character we find that in general real structures are associated with apparent elastic thicknesses of 4 km or less and thus with very low flexural rigidities

how collision triggers backarc extension insight into mediterranean style of extension from 3 d numerical models the formation and evolution of a backarc basin are linked to the dynamics of the subduction system the opening of the central mediterranean basins is a well documented example of backarc extension characterized by short lived episodes of spreading the underlying reasons for this episodicity are obscured by the complexity of this subduction system in which multiple continental blocks enter the subduction zone we present results from three dimensional numerical models of laterally varying subduction to explain the mechanism of backarc basin opening and the episodic style of spreading our results show that efficient backarc extension can be obtained with an along trench variation in slab buoyancy that produces localized deformation within the overriding plate we observe peaks in the trench retreating velocity corresponding first to the opening of the backarc basin and later to the formation of slab windows we suggest that the observed episodic trench retreat behavior in the central mediterranean is caused by the formation of slab windows

modeling fluvial incision and transient landscape evolution influence of dynamic channel adjustment 1 channel geometry exerts a fundamental control on fluvial processes recent work has shown that bedrock channel width depends on a number of parameters including channel slope and is not solely a function of drainage area as is commonly assumed the present work represents the first attempt to investigate the consequences of dynamic gradient sensitive channel adjustment for drainage basin evolution we use the channel hillslope integrated landscape development child model to analyze the response of a catchment to a given tectonic perturbation using as a template the topography of a well documented catchment in the footwall of an active normal fault in the apennines italy that is known to be undergoing a transient response to tectonic forcing we show that the observed transient response can be reproduced to first order with a simple detachment limited fluvial incision law transient landscape is characterized by gentler gradients and a shorter response time when dynamic channel adjustment is allowed the differences in predicted channel geometry between the static case width dependent solely on upstream area and dynamic case width dependent on both drainage area and channel slope lead to contrasting landscape morphologies when integrated at the scale of a whole catchment particularly in presence of strong tilting and or pronounced slip rate acceleration our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution they stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution particularly when the relative uplift field is nonuniform

quaternary normal faulting in southeastern sicily italy a seismic source for the 1693 large earthquake summary we present geological and morphological data combined with an analysis of seismic reflection lines across the ionian ovshore zone and information on historical earthquakes in order to yield new constraints on active faulting in southeastern sicily this region one of the most seismically active of the mediterranean is avected by wnw ese regional extension producing normal faulting of the southern edge of the siculo calabrian rift zone our data describe two systems of quaternary normal faults characterized by diverent ages and related to distinct tectonic processes the older nw se trending normal fault segments developed up to 400 kyr ago and striking perpendicular to the main front of the maghrebian thrust belt bound the small basins occurring along the eastern coast of the hyblean plateau the younger fault system is represented by prominent nnw sse trending normal fault segments and extends along the ionian ovshore zone following the ne sw trending avola and rosolini ispica normal faults these faults are characterized by vertical slip rates of 0 7 3 3 mm yr 1 and might be associated with the large seismic events of january 1693 we suggest that the main shock of the january 1693 earthquakes m 7 could be related to a 45 km long normal fault with a right lateral component of motion a long term net slip rate of about 3 7 mm yr 1 is calculated and a recurrence interval of about 550 50 yr is proposed for large events similar to that of january 1693

development of symmetrical and asymmetrical fabrics in sheet like igneous bodies the role of magma flow and wall rock displacements in theoretical and natural cases abstract two orientations of fabrics are recognised in vertical dykes a symmetric orientation associated with magma injected into non deforming wall rocks and an asymmetric orientation usually associated with external non coaxial shearing or magma injected into an active fault the notion of two fabric arrangements stems from two planes of symmetry the dyke symmetry plane dsp and the fabric symmetry plane fsp this paper uses conceptual models to simulate all possible orientations of magma flow indicators that might be produced within a vertical dyke emplaced under coeval internal and external stresses the effect of magmatic buoyancy related stresses are portrayed in terms of magma flow velocities mfv and the external non coaxial tectonic related stresses in terms of wall displacement velocities divided by two wmv 2 the tectonic setting is that of a sinistral transcurrent fault using these assumptions five cases are proposed mfv wdv 2 mfv wdv 2 mfv wdv 2 mfv

displacement gradients on fault surfaces abstract the maximum displacements and the dimensions of single faults are systematically related and the variation in displacement from a maximum at the centre of a fault to zero at an elliptical tip line loop is described by a simple theoretically derived expression these relationships are used to examine the theoretical ranges and distributions of rates of change of displacement on fault surfaces the dimensions and maximum displacement of a fault can be estimated from a limited number of displacement gradient measurements estimates are further constrained by a knowledge of the effective shear modulus of the rocks containing a fault an understanding of displacement gradients can be applied to problems commonly encountered in mining operations and in the interpretation and use of seismic reflection data in addition to field problems a comparison of theoretical displacement gradients with measured displacement gradients from british coalfield faults shows that i fault surface ellipticities are between 1 5 and 2 5 and ii gross displacement gradients expressed as the ratio of maximum displacement long axis radius of the fault ellipse range from 0 02 to 0 002 the measured displacement gradients indicate that the shear moduli of the faulted rocks range from 3 to 11 gpa which is within the known range for coal measure rocks displacement gradients along an array of fault segments are similar to those of single faults for analysis of displacement gradients it is necessary to sum the discontinuous and continuous components of displacement in extreme cases all the displacement may be accommodated by continuous deformation

implications of sediment flux dependent river incision models for landscape evolution 1 developing a quantitative understanding of the factors that control the rate of river incision into bedrock is critical to studies of landscape evolution and the linkages between climate erosion and tectonics current models of long term river network incision differ significantly in their treatment of the role of sediment flux we analyze the implications of various sediment flux dependent incision models for large scale topography in an attempt 1 to identify quantifiable and diagnostic differences between models that could be detected from topographic data or from the transient responses of perturbed systems and 2 to explain the apparent ubiquity of mixed bedrock alluvial channels in active orogens although certain forms of the various models can be discarded as inconsistent with morphological data we find that the relative intrinsic concavity indices of detachment and transport limited systems defined herein largely dictate whether the various models can be tied to distinctive steady state morphologies preliminary data suggest that no such diagnostic differences may exist and other methods must be developed to test models accordingly we develop and explore differences in the scaling behavior of topographic relief and the extent of detachment versus transport limited channels as a function of rock uplift rate that may allow discrimination among various models further we explore potentially diagnostic differences in the rates and patterns of transient channel response to changes in rock uplift rate in addition to general differences between detachment and transport limited systems our analysis identifies an interesting hysteresis in landscape evolution hybrid channels at the threshold between detachment and transport limited conditions are expected to act as detachment limited systems in response to an increase in rock uplift rate or base level fall and as transport limited systems in response to a decrease in rock uplift rate especially during postorogenic topographic decline the analyses presented set the stage for field studies designed to test quantitatively the various river incision models that have been proposed

the capo vaticano calabria coastal terraces and the 1905 m7 earthquake the geomorphological signature of regional uplift and coseismic slip in southern italy terra nova 22 378 389 2010 abstract the elevation of the capo vaticano coastal terraces tyrrhenian coast central calabria is the result of a combination of regional uplift and repeated coseismic displacement we subtract the regional uplift from the total uplift maximum average uplift rates 0 81 0 97 mm a 1 since c 0 7 ma and obtain the residual fault related displacement then we model the residual displacement to provide constraints on the location and geometry of the seismogenic source of the 1905 m7 earthquake the strongest and still poorly understood earthquake of the instrumental era in this area we try four different potential sources for the dislocation modelling and find that 1 three sources are not compatible with the displacement observed along the terraces and 2 the only source consistent with the local deformation is the 100 striking coccorino fault we calculate average long term vertical slip rates of 0 2 0 3 mm a 1 on the coccorino fault and estimate an average recurrence time of one millennium for a 1905 type earthquake

topography of the calabria subduction zone southern italy clues for the origin of mt etna 1 calabria represents an ideal site to analyze the topography of a subduction zone as it is located on top of a narrow active wadati benioff zone and shows evidence of rapid uplift we analyzed a pattern of surface deformation using elevation data with different filters and showed the existence of a long wavelength 100 km relatively positive topographic signal at the slab edges the elevation of mis 5 5 stage marine terraces supports this pattern although the record is incomplete and partly masked by the variable denudation rate we performed structural analyses along the major active or recently reactivated normal faults showing that the extensional direction varies along the calabrian arc and laterally switches from arc normal within the active portion of the slab to arc oblique or even arc parallel along the northern and southern slab edges this surface deformation pattern was compared with a recent high resolution p wave tomographic model showing that the high seismic velocity anomaly is continuous only within the active wadati benioff zone whereas the northern and southwestern sides are marked by low velocity anomalies suggesting that large scale topographic bulges volcanism and uplift could have been produced by mantle upwelling we present numerical simulations to visualize the three dimensional mantle circulation around a narrow retreating slab ideally similar to the one presently subducting beneath calabria we emphasize that mantle upwelling and surface deformation are expected at the edges of the slab where return flows may eventually drive decompression melting and the mount etna volcanism

interaction between regional and local tectonic forcing along a complex quaternary extensional basin upper tiber valley northern apennines italy abstract in extending areas undergoing regional tectonic uplift the persistence of subsidence at a normal fault hanging wall depends on the competition between regional and local tectonic effects when regional uplift exceeds the subsidence of the hanging wall block denudation prevails at both the hanging wall and the foot wall when local tectonic subsidence exceeds regional uplift sedimentation occurs over the hanging wall block supplied by foot wall erosion we analyzed a pliocene quaternary continental basin currently crossed by the tiber river in italy the tectono sedimentary evolution of the basin developed at the hanging wall of a regional low angle extensional detachment the alto tiberina fault in the axial region of the northern apennines of italy this area is affected by regional uplift on the order of 0 5 1 0 mm yr the present day activity of the fault is revealed by both microseismicity and geodetic gps data we investigated the mid 10 100 ka and long term 0 5 3 0 ma evolution of the three depocenters by studying the continental pleistocene succession infilling the basin as well as fluvial terraces and higher paleosurfaces carved into the pleistocene deposits by using surficial geologic data and an interpretation of a set of seismic reflection profiles we show that the three depocenters experienced a fairly similar evolution during the pliocene early pleistocene when a 1000 m thick continental succession was deposited on the contrary geomorphological observations indicate that at the beginning of the middle pleistocene a switch occurred in the evolution of the three depocenters in the northernmost sansepolcro sub basin bounding normal faults are active and hanging wall subsidence outpaces regional uplift concurrently in the umbertide and ponte pattoli sub basins uplift dominates over the hanging wall subsidence promoting river incision and exhumation of the pleistocene deposits for these two depocenters by means of terrace river correlations we estimate that the incision rate is 0 3 0 35 mm yr suggesting a maximum tectonic subsidence of 0 2 mm yr the identification of a heterogeneous uplift pattern along the hanging wall of the alto tiberina fault driven by different displacement rates of its fault splays allowed us to characterize fault segments with different activities and possibly different seismic behaviors

crustal motion along the eurasia nubia plate boundary in the calabrian arc and sicily and active extension in the messina straits from gps measurements 1 we investigate crustal deformation along the eurasia nubia plate boundary in calabria and sicily revealed by the gps velocity field obtained by the combination of continuous site velocities with previous results from episodic campaigns we recognize two distinct crustal domains characterized by different motions and styles of deformation convergence in sicily is taken up by crustal shortening along the former tyrrhenian back arc passive margin in agreement with seismological data and geological evidence of recent cessation of deformation along the plio pleistocene subduction front the analysis of the gps data and the consistency between earthquake slip vectors and convergence direction suggest that eu nu convergence in sicily does not require intermediate crustal blocks significant eurasia 3 mm yr to nne and nubia fixed 5 mm yr to ese residual velocities in calabria suggest instead the presence of an intermediate crustal block which can be interpreted as a forearc sliver or as an independent ionian block according to the first hypothesis subduction is still active in the ionian wedge although we find no evidence for active back arc spreading in the tyrrhenian sea the n115 e oriented sicily calabria gps relative motion is consistent with the extension observed during the 1908 mw 7 1 messina earthquake we suggest that up to 3 mm yr 80 of this estimated relative motion between sicily and the calabrian arc may be taken up in the messina straits

the gubbio normal fault central italy geometry displacement distribution and tectonic evolution abstract normal faults within orogenic belts can be pre syn or post orogenic features we studied the gubbio normal fault central italy which is an example of a pre orogenic fault reactivated in a post orogenic stage the gubbio fault is a 22 km long fault bordering a quaternary basin and part of an active faults system in the umbria marche region central italy the interpretation of a set of seismic profiles enables us to reconstruct the fault geometry in detail and to measure displacement and throw distributions along the fault strike seismic data indicate that the gubbio fault represents an example of multiple reactivation at least a portion of the fault was active in the miocene and only a part of the total displacement was achieved in the quaternary the reconstruction of the fault geometry at depth shows that the fault is characterised by listric geometry the fault is also characterised by a bend along strike and structure contours show that this geometry is maintained at depth as the fault is commonly addressed as presently active the maximum fault dimensions are correlated to the maximum expected earthquake and the presence of the fault bend is discussed as a possible barrier to seismic ruptures propagation

a quantitative evaluation of playfair s law and its use in testing long term stream erosion models playfair s law j playfair illustrations of the huttonian theory of the earth 1802 requires any two tributaries in a river network to lower at the same rate near their junction although this law holds exactly at the junction it is unclear how well it holds in the vicinity of the junction this issue has practical importance because playfair s law has been used to estimate parameters for detachment limited models of erosion if the incision rate of a stream is modelled as amsn where is an erodibility parameter a is the area drained by the stream and s is the local gradient of the channel then the ratio of the parameters m n can be estimated from junctions by assuming that playfair s law holds over the distance used to determine s for each tributary in this paper playfair s law and associated m n estimates are evaluated for simulated basins with constant and temporally varying uplift rates or baselevel lowering rates the results demonstrate that estimates of m n may be biased for basins with upward concave stream profiles because the local slope must be approximated with an average upstream slope in addition when uplift rate varies temporally knickpoints are shown to travel through the basins with constant vertical velocity because incision rates vary within the basin playfair s law only holds exactly at the junctions these effects are more important when slopes are measured over longer distances finally measurement techniques are presented which address these potential biases copyright 2001 john wiley sons ltd

uplift history of the sila massif southern italy deciphered from cosmogenic 10be erosion rates and river longitudinal profile analysis 1 the sila massif in the calabrian arc southern italy is a key site to study the response of a landscape to rock uplift here an uplift rate of 1 mm yr has imparted a deep imprint on the sila landscape recorded by a high standing low relief surface on top of the massif deeply incised fluvial valleys along its flanks and flights of marine terraces in the coastal belt in this framework we combined river longitudinal profile analysis with hillslope erosion rates calculated by 10be content in modern fluvial sediments to reconstruct the long term uplift history of the massif cosmogenic data show a large variation in erosion rates marking two main domains the samples collected in the high standing low relief surface atop sila provide low erosion rates from 0 09 0 01 to 0 13 0 01 mm yr conversely high values of erosion rate up to 0 92 0 08 mm yr characterize the incised fluvial valleys on the massif flanks the analyzed river profiles exhibit a wide range of shapes diverging from the commonly accepted equilibrium concave up form generally the studied river profiles show two or more frequently three concave up segments bounded by knickpoints and characterized by different values of concavity and steepness indices the wide variation in cosmogenic erosion rates and the non equilibrated river profiles indicate that the sila landscape is in a transient state of disequilibrium in response to a strong and unsteady uplift not yet counterbalanced by erosion

decoding temporal and spatial patterns of fault uplift using transient river long profiles we present detailed observations of rivers crossing active normal faults in the central apennines italy where excellent constraints exist on the temporal and spatial history of fault movement we demonstrate that rivers with drainage areas 10 km2 and crossing faults that have undergone an increase in throw rate within the last 1 my have significant long profile convexities in contrast channels that cross faults that have had a constant slip rate for 3 my have concave up profiles and have similar concavities and steepness indices to rivers that do not cross any active fault structures this trend is consistent across the central apennines and cannot be explained by appeal to lithology or regional base level change the data challenge the belief that active faulting must always be reflected in river profiles instead the long profile convexities are best explained as a transient response of the river system to a change in tectonic uplift rate moreover for these rivers we demonstrate that the height of the profile convexity as measured from the fault scales with the magnitude of the uplift rate increase on the fault and we establish that this relationship holds for throw rate variation along strike for the same fault segment as well as between faults these findings are shown to be consistent with predictions of channel response to changing uplift rate rates using a detachment limited fluvial erosion model and they illustrate that analysis of the magnitude of profile convexities has considerable predictive potential for extracting tectonic information we also demonstrate that the migration rate of the profile convexities varies from 1 5 10 mm y and is a function of the slip rate increase as well as the drainage area this is consistent with n 1 for the slope exponent in a classical detachment limited stream power erosion law but could potentially be explained by incorporating an erosion threshold or an explicit role for sediment in enhancing erosion rates finally we show that for rivers in extensional settings where the response times to tectonic perturbation are long in this case 1 my attempts to extract tectonic uplift rates from normalised steepness indices are likely to be flawed because topographic steady state has not yet been achieved

sediment and rock strength controls on river incision into bedrock recent theoretical investigations suggest that the rate of river incision into bedrock depends nonlinearly on sediment supply challenging the common assumption that incision rate is simply proportional to stream power our measurements from laboratory abrasion mills support the hypothesis that sediment promotes erosion at low supply rates by providing tools for abrasion but inhibits erosion at high supply rates by burying underlying bedrock beneath transient deposits maximum erosion rates occur at a critical level of coarse grained sediment supply where the bedrock is only partially exposed fine grained sediments provide poor abrasive tools for lowering bedrock river beds because they tend to travel in suspension experiments also reveal that rock resistance to fluvial erosion scales with the square of rock tensile strength our results suggest that spatial and temporal variations in the extent of bedrock exposure provide incising rivers with a previously unrecognized degree of freedom in adjusting to changes in rock uplift rate and climate furthermore we conclude that the grain size distribution of sediment supplied by hillslopes to the channel network is a fundamental control on bedrock channel gradients and topographic relief

overlapping faults intrabasin highs and the growth of normal faults normal fault systems bounding extensional basins are typically adjoined by a series of subbasins separated by intrabasin highs the strata within these basins form syndepositional anticlines and synclines whose axes are transverse to the strike of the main bounding fault one possible explanation for these intrabasin highs is that they result from persistent along strike deficits in fault displacement such deficits are incompatible with scaling relationships observed between fault displacement and length based on large populations of faults we present data from active normal faults within the basin and range province and from inactive normal faults of the newark basin of eastern north america demonstrating a clear correlation between the along strike position of overlapping splay faults and the location of intrabasin highs as well as syndepositional transverse folds summed displacements for all faults within an intrabasin high are comparable to the displacements on faults bounding flanking subbasins o

seismic potential of southern italy abstract to improve estimates of the long term average seismic potential of the slowly straining south central mediterranean plate boundary zone we integrate constraints on tectonic style and deformation rates from geodetic and geologic data with the traditional constraints from seismicity catalogs we express seismic potential long term average earthquake recurrence rates as a function of magnitude in the form of truncated gutenberg richter distributions for seven seismotectonic source zones seismic coupling seems to be large or even complete in most zones an exception is the southern tyrrhenian thrust zone where most of the african european convergence is accommodated here aseismic deformation is estimated to range from at least 25 along the western part to almost 100 aseismic slip around the aeolian islands even so seismic potential of this zone has previously been significantly underestimated due to the low levels of recorded past seismicity by contrast the series of 19 m6 7 earthquakes that hit calabria in the 18th and 19th century released tectonic strain rates accumulated over time spans up to several times the catalog duration and seismic potential is revised downward the southern tyrrhenian thrust zone and the extensional calabrian faults as well as the northeastern sicilian transtensional zone between them which includes the messina straits where a destructive m7 event occurred in 1908 all have a similar seismic potential with minimum recurrence times of m 6 5 of 150 220 years this potential is lower than that of the southern apennines m 6 5 recurring every 60 to 140 years but higher than that of southeastern sicily minimum m 6 5 recurrence times of 400 years the high seismicity levels recorded in southeastern sicily indicate some clustering and are most compatible with a tectonic scenario where the ionian deforms internally and motions at the calabrian trench are small the estimated seismic potential for the calabrian trench and central and western sicily are the lowest minimum m 6 5 recurrence times of 550 800 years most zones are probably capable of generating earthquakes up to magnitudes 7 7 5 with the exception of central and western sicily where maximum events sizes most likely do not exceed 7

an alternative model for the growth of faults conventional growth models suggest that faults become larger due to systematic increases in both maximum displacement and length we propose an alternative growth model where fault lengths are near constant from an early stage and growth is achieved mainly by increase in cumulative displacement the model reconciles the scaling properties of faults and earthquakes and predicts a progressive increase in fault displacement to length ratios as a fault system matures this growth scheme is directly applicable to reactivated fault systems in which fault lengths were inherited from underlying structure and established rapidly the model may also apply to some non reactivated fault systems near constant fault lengths during subsequent growth are attributed to retardation of lateral propagation by interaction between fault tips the model is validated using kinematic constraints from growth strata which are displaced by a system of reactivated normal faults in the timor sea nw australia

from collisional to rifted basins an example from the southern calabrian arc italy structural interpretation of available geological and geophysical data carried out along a regional transect extending across the southern calabrian arc from the tyrrhenian margins to the ionian off shore demonstrates that a complex interplay between compressional and extensional processes has controlled the evolution of upper miocene pleistocene sedimentary basins developing in this region our data indicate that an upper miocene lower pliocene succession outcropping in the southern calabrian arc represents the infilling of perched basins developed between crystalline basement thrust sheets a similar tectonic pattern characterises the plio pleistocene basins occurring on the frontal part of the arc in the ionian off shore upper pliocene pleistocene sediments outcropping along the tyrrhenian side of the arc reveal that they in fact represent the infilling of extension related basins time space migration of compressional and extensional related sedimentary basins can be explained as the result of different tectonic processes developing on the upper plate as a result of the underplating of the ionian domain beneath the calabrian block in this framework upper miocene lower pliocene and upper pliocene pleistocene perched basins represent therefore fore arc basins developed on the frontal accretionary wedge and or on the hangingwall buttress of the arc during its southeastwards migration late pliocene early pleistocene extensional tectonics occurring along the tyrrhenian side of the arc may indeed be related to accommodation processes which characterised the rear of the wedge to maintain a stable geometry as a result of the underplating of the ionian crust

recent and active tectonics in the calabrian arc southern italy normal faulting which has developed since the middle pleistocene with an overall ese wnw extension is the dominant mode of deformation which has characterized the calabrian arc up to the present quaternary normal faults extend for a total length of about 180 km along the inner side of the arc the different normal fault segments which during the pleistocene controlled the evolution of the main marine sedimentary basins are varying in length from 10 to 20 km and have fault escarpments showing a very young morphology which define the fronts of the major mountain ranges of the arc the morphological features of the fault escarpments suggest slip rates of 0 8 1 1 mm yr for the last 700 k y and values of 0 6 0 9 mm yr for the last 120 k y indicating a uniform rate of faulting since the middle pleistocene crustal seismicity and the mesoseismic areas of historical large events 6 5 m 7 1 which occurred in the calabrian arc are located within a narrow belt along the hanging walls of the quaternary normal fault segments this suggests that the normal faults which dissect the inner side of the calabrian arc may be seismically active

fault propagation in a seismic gap area northern calabria italy implications for seismic hazard abstract the crati basin is a tectonic depression developed between the coastal range and the sila massif and is characterised by a sedimentary succession ranging between late miocene to holocene age basin cover can be subdivided into a series of stratigraphic intervals bounded by angular unconformities the general basin architecture is mainly controlled by n s striking normal faults the crati fault system cropping out along both basin margins these faults formed since the middle pliocene in the southern part of the basin and propagated northwards where they developed during middle late pleistocene the occurrence of several earthquakes along n s striking faults suggest their still ongoing activity the northernmost part of the crati basin bordered by the 30 km long pollino fault is thought to be characterised by an important seismic gap this contrasts with the geological evidences of quaternary fault activation of both the central part of the pollino fault and some nnw sse striking normal faults we propose that the nnw sse striking faults represent the northernmost prolongation of the crati fault system a large scale active crustal rift related to the tyrrhenian spreading these faults mechanically interacted with the neogene pollino fault and determined the almost contemporary activation of the central part of this structure because of stress triggering phenomena as suggested by the coulomb failure stress changes

sand waves echinocardium traces and their bathyal depositional setting monte torre palaeostrait plio pleistocene southern italy stacked cross sets up to 2 5 m thick produced by sand wave migration and meniscate trace fossils produced by echinocardium cordatum both considered in the literature as typical of shallow water marine depositional settings commonly occur in the bathyal plio pleistocene deposits of monte torre calabria southern italy the plio pleistocene sediments form two coarsening upward depositional sequences separated by an unconformity and by a palaeobathymetric gap of at least 300 m the lower sequence passes upwards from hemipelagic marls and thin bedded turbidites to thick bedded sandy turbidites then to sand wave deposits alternated with sandy turbidites and finally to base of slope megabreccias facies characteristics and relationships and the occurrence of deep sea faunal associations indicate deposition in the bathyal zone the facies of the upper sequence reflect a fan delta environment no deeper than a few tens of metres the depositional setting of the lower sequence where the sand wave deposits and meniscate trace fossils occur appears to have been a tectonically controlled seaway connecting the tyrrhenian and ionian seas this seaway became progressively narrower with time evolving into a strait the overall coarsening upward trend reflects the upward transition from a low to a high energy environment possibly caused by the tectonic narrowing of the seaway deposition and erosion from high concentration turbidity currents and from tidal bottom currents were important processes periods of tectonic activity producing first the uplift of the seaway margins and culminating with the uplift of the strait sequence itself are marked by scattered rockfall deposits the strait setting causing the development of powerful oxygenated bottom currents produced optimal conditions in the bathyal zone for the colonization of sandy bottoms by a single infaunal r selected species echinocardium sp

formation of segmented normal faults a 3 d perspective the interpretation of fault kinematics from geometric data is an essential step in developing an understanding of the growth of fault systems constraints on fault geometry are however often restricted to 2 d maps or cross sections in this article we consider the extent to which kinematic interpretations of faulting benefit from a 3 d rather than 2 d geometrical perspective concentrating on relay zones and segmented normal fault arrays we suggest that very different interpretations of their evolution arise from the recognition that the propagation directions of faults and fault segments will rarely be contained within the inspection plane of 2 d data a 3 d perspective favours an interpretation in which the segments of a fault array are kinematically interrelated from their initiation individual segments in such systems may link into a single fault surface out of the plane of inspection or may be unconnected in 3 d we argue that this interpretation which conflicts with the often suggested model of incidental overlap of originally isolated faults should be the preferred model for the generation and growth of segmented normal fault arrays

late quaternary tectonics of the vallo di diano basin southern apennines italy italian ministry of university and research project firb research and development of new technologies for protection and defence of territory from natural risks w p c3 crustal imaging in italy

faulting and earthquake triggering during the 1783 calabria seismic sequence summary between the 1783 february 5 and 1783 march 28 five earthquakes struck the southern part of calabria the main shock february 5 and the first aftershock february 6 devastated the region ene of the messina strait the greatest damage occurred along the foot of the aspromonte mountains south of san giorgio morgeto and along the tyrrhenian coast south of palmi a surface break about 18 km long with several feet of downthrow to the west formed along the cittanova santa cristina fault as a result of the main shock on february 7 a third large shock ruined villages at the foot of the serre mountains north of san giorgio morgeto morphological and structural evidence combined with a reassessment of observations made at the time of the earthquakes suggest that these three shocks were shallow 20 km and related to slip on the west dipping ne striking cittanova sant eufemia palmi scilla and serre normal faults respectively which juxtapose the basement of the aspromonte and serre mountains with the pleistocene deposits of the gioia tauro and mesima basins and border the palmi coastal high the three faults belong to an active rift that stretches from northern calabria to offshore the ionian coast of sicily the spatial coupling between the 1783 events is investigated by resolving changes of coulomb failure stress the main shock 1783 february 5 m 7 on the cittanova and sant eufemia faults increased that stress by several bars on the scilla fault triggering the 1783 february 6 earthquake m 6 5 the cumulative effect of these two shocks was to raise the coulomb stress by more than 1 bar on the sw part of the serre fault which was subsequently the site of the 1783 february 7 shock m 6 5 in turn the first three events increased the stress by about 1 bar on the ne part of this latter fault leading to the 1783 march 1 shock m 5 7 the gap between the 1783 february 7 and 1783 march 1 events may be related to the previous occurrence of an earthquake 124 yr before 1659 november 5 m 6 which had already released stress locally the occurrence of the last 1783 event 28 march is not as simply accounted for by coulomb modelling in part because it remains unclear which fault slipped and how deep this event was overall the 1783 sequence increased the coulomb failure stress by several bars south of the messina strait and north of the epicentral region of the 1693 se sicily catania noto earthquakes 125 yr later this same region was the site of the 1908 messina earthquake also a normal faulting event our study thus provides one convincing example in which coulomb stress modelling brings insight into the spatial dynamics of seismic sequences