palaeoseismology review of the state of the art abstract historical seismicity provides only a partial indication of the seismotectonic character i e earthquake potential of a given region even in italy where a relatively long historical record exists available catalogues are generally unsatisfactory for this purpose fortunately strong earthquakes often leave geological evidence herein referred to as seismites that are mainly related to surface faulting folding or other deformation and occasionally to secondary ground failures e g landslides liquefaction features etc these features may be preserved and therefore palaeoseismological studies may detect and date them thereby permitting extension of knowledge beyond the local historical threshold up to 2000 years in the most fortunate cases this paper provides a summary of criteria which may aid in the identification of areas suitable for palaeo earthquake investigation historical seismicity and the presence of well developed tectonic geomorphic features are recognized as the most reliable criteria for identifying active faulting however lack of these characteristics cannot be considered conclusive evidence for lack of activity palaeoseismological techniques aim at identifying not only the obvious effects of surface faulting such as offset of young geologic units but also the more subtle tectonic or non tectonic features including liquefaction structures gravity features and coseismic uplift and or subsidence finally we discuss some questions that pertain to palaeoseismicity evaluation techniques among these are the reliability of the quaternary dating techniques the evaluation of the seismic energy released minimum magnitude and principally the unequivocal identification of a seismic origin for the considered geological structures

the northeast brazilian rift system the northeast brazilian rift basins provide important data critical to the understanding of continental rifting processes associated with the opening of the south atlantic these basins represent the locus of intersection of the southern and equatorial branches and some basins yield substantial chronostratigraphic data that constrain the temporal and spatial interaction of the rift phases similar data are not found in its counterpart in africa especially for the neocomian these early cretaceous rift basins of northeast brazil illustrate key three dimensional geometries of intracontinental rift systems mainly controlled by the basement structural framework during the main rift phase syn rift ii neocomian early barremian extensional deformation was distributed over three main rift axes 1 the gabon sergipe alagoas gsa trend 2 the reconcavo tucano jatoba rtj trend and 3 the cariri potiguar cp trend during this phase extensional deformation jumped west from the easternmost basins gsa trend to a series of ne trending intracratonic basins rtj and cp trends characterized by a set of asymmetric half grabens separated by basement highs transfer faults and or accommodation zones these basins are typically a few tens of kilometers wide and trend ne sw roughly perpendicular to the main extension direction during the neocomian preexisting upper crustal weakness zones like the dominantly ne sw trending shear zones of the brazilian pan african orogeny controlled the development of intracrustal listric normal faults internal transverse structures such as transfer faults and accommodation zones were also controlled by the local basement structural framework the megashear zones of pernambuco brazil and ngaundere africa seem to have behaved like a huge accommodation zone accommodating extensional deformation along the rtj gsa trends with simultaneous extension along the cp trend during the late barremian syn rift phase iii a significant change in rifting kinematics occurred when the cp trend was aborted and major rifting initiated at the equatorial branch during the aptian while the equatorial branch and benue trough africa experienced the main rift phase the rtj trend was aborted and the gsa trend developed a transitional phase between the rift and drift stage the gsa trend and the offshore potiguar basin represent the site of continued evolution into passive margin basins following the main rift episode

low permeability rocks laboratory measurements and three dimensional microstructural analysis traditional techniques for measuring permeability and traditional models relating permeability to porosity are inadequate for low permeability or 10 sup 18 m sup 2 geologic materials special techniques have been developed for measuring fluid flow through such rock samples and for quantifying their three dimensional pore microstructure permeability is measured by a modified transient pulse technique pore structure is quantified using a computerized microgeometric modeling system and portable three dimensional display is produced by an optical imaging system results of applying this processing to a low porosity tight gas sandstone from the cotton valley formation agree with the well documented diagenetic history of these samples we find that the porosity distribution is very inhomogeneous and skewed the pore system is slightly anisotropic which is consistent with the differences in permeability measured in two orthogonal directions we indicate how such data could be used to develop more geologically and geometrically realistic models relating porosity and permeability in low permeability gas formations

modelling seismites with a digital shaking table abstract soft sediment deformation structures induced by seismically triggered liquefaction and or fluidization seismites have been reproduced with a digital shaking table we have used natural sediments with variable granulometric ranges clay silt and sand and an earthquake simulator that is able to reproduce real tridimensional seismograms acceleration and pore pressure recording allowed us to follow liquefaction and or fluidization processes in unconsolidated sediments during earthquakes different types of seismites were produced by variations in the tested sedimentary column

earthquake magnitude frequency epicentral distance and soft sediment deformation in sedimentary basins abstract empirical equations available for earthquake magnitude frequency and the maximum epicentral distance of liquefied sites versus magnitude are combined with the characteristic instantaneous sediment deposition rate at a station in a sedimentary basin to form a model for the local stratigraphic frequency of earthquake induced soft sediment deformation structures both the style of sedimentation and the characteristics of the earthquake source combine to determine the pattern of incidence of the structures in a basin the model is probably most directly applicable to the geodynamic interpretation of fluvial basins in which substantial volumes of readily liquefied sands accumulate at high local short term rates

late pleistocene seismites from lake issyk kul the tien shan range kyrghyzstan abstract the aim of the study is to record the occurrence of sediment deformation structures in one of the tectonically most active areas on the globe the tien shan range in central asia and to examine the significance of the deformations as indicators of palaeoseismicity soft sediment deformation structures in form of balls and pseudo nodules are exposed in the issyk kul basin within interfingering beds of shallow lacustrine beach and fluviatile origin additional deformation structures that were encountered are a complex and chaotic folded structure giant balls and a pillar structure which has not been previously reported where marl intrudes down into coarse pebbley sand and forms pillar morphology liquefaction features and bedforms related to storm and breaking waves were not encountered neither was there evidence of turbidites seven field criteria for relating soft sediment deformation to palaeoseismic triggering provide strong evidence for a seismic origin of the deformation structures empirical relationships between magnitude and the maximum distance from an epicenter to liquefaction sites make the active epicentral zone north of lake issyk kul with its frequent high magnitude events the most favorable source for the deformation structures luminescence dating of the sediments gives a time window of 26 2 1 to 10 5 0 7 ka bp indicating latest pleistocene seismic activity

paleo earthquakes in passive margin settings an example from the paleocene of the golfo san jorge basin argentina abstract paleocene sedimentary rocks in the golfo san jorge basin include the marine salamanca formation and the continental rio chico formation both units contain soft sediment deformation features and evidence of contemporary tectonics which include 1 sediment filled fissures hosted in muddy marine sediments of the salamanca formation fragmentosa section where the sandy infill of the fissures took place from above 2 synsedimentary normal faults in the uppermost levels of the salamanca formation with vertical throws rarely exceeding 1 m 3 fault graded beds in the banco negro inferior marine continental transition which show a deformed sequence with small scale normal faults at the bottom and intraformational breccias on top and 4 liquefaction and or fluidization pillars v or funnel shaped with vertical extension of up to 5 m and preserved into fluvial channels of the rio chico formation deformed strata are bounded by undisturbed horizons and some of these features can be correlated along 60 km of exposures the suite of soft sediment deformation structures is considered a secondary evidence of synsedimentary paleo earthquakes seismites in this portion of the south american passive margin this work shows new evidence of syndepositional tectonic activity in the lowermost paleogene of the golfo san jorge basin

paleosubsidence and active subsidence due to evaporite dissolution in the zaragoza area huerva river valley ne spain processes spatial distribution and protection measures for transport routes abstract the lowest 17 km long reach of the huerva river valley down to its confluence with the ebro river in zaragoza city flows across salt bearing evaporites of the ebro tertiary basin ne spain upstream the horizontally lying miocene evaporites are interfingered with non soluble distal alluvial fan facies shales and sandstones the proportion of soluble facies in the huerva river valley increases in a downstream direction towards the basin depocenter on the basis of the type and magnitude of the paleosubsidence features the valley has been divided into four reaches along reach i undeformed terrace deposits less than 4 m thick rest on insoluble detrital bedrock in reaches ii and iii dissolution at the alluvium bedrock boundary has generated local thickening deformation and paleocollapse structures which only affect the alluvial mantle in reach iv terrace deposits thicken to over 60 m resulting from a large scale synsedimentary subsidence in this sector subsidence locally affects to both the alluvium and the underlying bedrock this indicates that dissolution acts at the rockhead beneath the alluvial cover alluvial karst and within the evaporitic substratum interstratal karst the development of an intraevaporitic karst in reach iv is attributed to gypsum and salt dissolution irregular terrace gravel bodies gravel pockets embedded in a fine grained matrix associated with paleocollapse structures have been interpreted as liquefaction fluidization structures resulting from ground acceleration and suction induced by catastrophic collapses subsidence is currently active in the region affecting areas with a thin alluvial cover in reaches iii and iv the low subsidence activity in most of zaragoza city is explained by the presence of thickened around 50 m and indurated alluvial deposits in the surrounding area numerous buildings in cadrete and santa fe villages have been severely damaged by subsidence natural and human induced subsidence favours the development of slope movements in the gypsum scarp overlooking cadrete village several transport routes including the imperial canal irrigation canal and the recently completed madrid barcelona high speed railway are affected by human induced sinkholes the paleocollapse structures exposed in the trenches of this railway and a ring road under construction point to hazardous locations underlain by cavities and collapse structures where special protection measures should be applied rigid structures are recommended beneath the high speed railway with sufficient strength to span the larger sinkholes with no deformation electronic monitoring devices linked to a warning system can detect subtle subsidence induced deformations in carriageways or railways this research demonstrates that the study of the paleokarst helps to understand the processes involved in the present day subsidence phenomena and their general spatial distribution

3 d geometry and luminescence chronology of quaternary soft sediment deformation structures in gravels northeastern brazil abstract this paper reports and describes soft sediment deformation in gravels and gravelly sediments in quaternary alluvial deposits of the potiguar basin northeastern brazil deformation structures were measured in terms of geometry size and relationship with sedimentary bedding using geological mapping and ground penetrating radar tl and osl irsl methods following mar and sar protocols were used to date sediments and soft sediment deformation events our results indicate that soft sediment deformation structures are widely distributed in several stratigraphic intervals of alluvial channel deposits in a low lying topographic valley depending on their geometry and composition two types of soft sediment deformation structures occur pockets and dome like load structures these structures resulted from the shaking of sediments with a reverse density gradient system which caused collapse and realignment of pebbles these features are similar in morphology and size to modern examples of seismically induced soft sediment deformation in coarse sediments tl and osl ages indicate that sediment deposition and associated soft sediment deformation occurred at least six times from 352 ka to 9 ka

back scattered electron imagery of the tectonic fabrics of some fine grained sediments implications for fabric nomenclature and deformation processes back scattered electron investigations of argille scagliose mudstones from the barbados forearc sampled during ocean drilling program leg 110 and the matrix of the okitsu melange southwest japan indicate a variety of microfabric geometries and deformation mechanisms despite the similarity of their mesoscopic scaly fabrics in the okitsu melange the scaly fabric is the mesoscopic expression of an anastomosing microfabric whereas the detailed geometry of scaly fabrics is unrelated to the microfabric in the argille scagliose and leg 110 mudstones care must be taken in the classification and interpretation of scaly fabrics in light of these data and future studies should focus on microstructural investigations

the significance of giant seismites in the plio pleistocene baza palaeo lake s spain terra nova 22 172 179 2010 abstract giant load type seismites uncommon in the geological record are described in plio pleistocene lacustrine deposits of the baza basin betic cordillera s iberia deformed beds of the marginal lacustrine and distal alluvial facies of the baza palaeo lake can be traced continuously for several kilometres soft sediment deformation is represented by load type structures of large dimensions pillows around 4 m in width and 2 m in height three dimensional exposures show ellipsoidal pillows separated by fluidized channels without any preferred orientation the final size of these load type seismites is strongly influenced by sedimentary factors such as the presence of a reverse density gradient in sediments and the bed thickness the giant seismites of the baza basin are located in a region which is unlikely to have been subjected to high magnitude earthquakes maximum around 7 0 therefore magnitude is not the main factor that controls the size of these load type structures

soft sediment deformation in a tectonically active area the plio pleistocene zarzal formation in the cauca valley western colombia abstract the plio pleistocene zarzal formation corresponds to fluvio lacustrine sediments deposited in an intramontane depression within the colombian andes associated with the cauca romeral fault system it crops out mainly in the cauca valley where numerous field sections have permitted the mapping of the vertical and lateral lithological variations lacustrine deposits of sands silts clays and diatomites are interbedded with fluvial sand and gravel beds and fluvio volcanic mass flows derived from the volcanic central cordillera numerous soft sediment deformation structures are encountered in this formation particularly in fine to medium grained sands silts and clays load structures load casts flame structures pseudonodules water escape structures water escape cusps dish and pillar and pocket and pillar structures soft sediment intrusions clastic sills and dykes disturbed laminites convolute laminations slumps and synsedimentary faulting deformation mechanisms and driving forces are related essentially to gravitational instabilities dewatering liquidization and brittle deformations field and regional geological data show that most of these deformations are related to seismicity and can be interpreted as seismites this area has a geological and recent seismic history and outcrops show both syn and post depositional faulting related to the transpressional regime of this part of the colombian andes which generates strike slip faults and associated local normal faults the drainage pattern within the zarzal formation shows the signature of neotectonics moreover the fine to coarse grained sands of the zarzal formation are lithologies prone to liquefaction when affected by seismic waves the intercalation of the deformed intervals within undisturbed strata confirms the catastrophic nature of the events finally the large areal extent of the deformations and the type of structures are compatible with seismites consequently the existence of seismites in the zarzal formation represents corroboration of tectonic activity in this area during the pleistocene earthquakes with a magnitude higher than 5 can be postulated based upon the proximity of active faults and the types of deformations

liquefaction induced structures in quaternary alluvial gravels and gravelly sediments ne brazil abstract we have identified numerous well preserved elutriation and fluidization structures probably induced by liquefaction in quaternary gravels and gravelly sediments of braided fluvial channel deposits in the rio grande do norte and ceara states northeastern brazil they show evidence of upward directed water escape after sediment deposition and before sediment compaction among the several types of structures observed the most frequent are pillars pockets and dikes these structures range in width from a few centimeters to as much as 4 m and in height from 60 cm to 4 m dikes pillars and pockets are systematically associated clastic dikes vented large quantities of sand to the upper layers or the surface pebbles and cobbles from the host rock sank into the dikes and formed pillars and pockets pockets form the root part pillars form the intermediate part and dike the upper part of the composite structure the morphology of the structures in sectional and plan views indicates a 3d geometry composed of a tabular dike and pillar that present a downward continuous transition to a bowl shaped pocket this stratigraphy of liquefaction features is different from that usually presented in the current literature field data suggest that both the location and the geometry of the features were controlled by sedimentary properties rather than joints and small faults the size and abundance of these features suggest that they were formed by great events rather than localized mechanisms field evidence also indicates that these features are the product of fluidization and elutriation and may have been induced by liquefaction processes associated with seismic shaking a nonseismic origin related to elutriation processes however cannot be ruled out for some of the features

concurrent deformation processes in the matese massif area central southern apennines italy abstract we investigated the interseismic gps velocity field across the transition zone between central and southern apennine comprising the meta mainarde venafro and alto molise sannio matese mounts the kinematic field obtained by combining gps network solutions is based on data collected by the unpublished episodic campaigns carried out on southern apennine geodetic network sagnet from 2000 to 2013 igm95 network giuliani et al 2009 from 1994 to 2007 and continuous gps stations the data collected after the 29 december 2013 earthquake mw 5 0 until early 2014 allowed estimating displacements at 15 sagnet stations the extension rate computed across the matese massif along an anti apennine profile is 2 0 0 2 mm yr the interseismic velocities projected along the profile show that the maximum extension does not follow the topographic high of the apennines but is shifted toward the eastern outer belt no significant gps deformation corresponding to inner faults systems of the matese massif is detected taking into account our results and other geophysical data we propose a conceptual model which identifies the 2013 2014 seismic sequence as not due to an extensional deformation style usual along the apennine chain in fact we have measured too large coseismic displacements that could be explained as the result of tectonic regional stress co2 rich fluid migration and elastic loading of water in the karst matese massif we recognized a tensile source as model of dislocation of 2013 2014 earthquakes it represents a simplification of a main fault system and fracture zone affecting the matese massif the dislocation along ne dipping north matese fault system nmfs could be the driving mechanism of the recent seismic sequences moreover to the first time the sagnet gps data collected from 1994 to 2014 are share and available to the scientific community in the open access data archive

seismites an attempt at critical analysis and classification abstract the main types of seismites are reviewed following the proposed classification and are illustrated by our own case studies the large variety of seismites depends on the sedimentologic hydrodynamic and diagenetic characters of the deposits subject to seismic shocks on a given site generally different types of seismites cane be related to the same seismic event these peculiar but widespread sedimentary structures are not always univocal and may often be related to different causes therefore the structures discussed must necessarily be placed in a detailed geological context

seismically induced soft sediment deformation structures seismites around sumdo in the lower spiti valley tethys himalaya abstract soft sediment deformation structures were observed in 120 m thick fluvio lacustrine sediments exposed in the sumdo area in the lower spiti valley tethys himalaya himachal pradesh india these structures vary in their morphology and pattern and occur at eight stratigraphic levels s1 s8 spaced at irregular intervals the deformation structures include over steepened stratification diapiric flame like intrusions of clayey material or complex type recumbent folding of flame like nature pseudonodules large scale soft sediment folding faulting small scale associated with folding and sand dykes these structures are restricted to single stratigraphic layers separated by undeformed beds and can be correlated over a large distance the deformation of the soft sediments is attributed to the combined effects of fluidization liquefaction and shear stress and can be related to past seismic activity in the area recently on 19 january 1975 a major earthquake kinnaur earthquake of magnitude 6 8 caused extensive damage including ground rupturing in the sumdo kaurik area this earthquake has been related to the activation of the kaurik chango fault the deformed layers seismites reported here lie adjacent to this fault zone and can be related with episodic seismicity along this fault it is evident from this study that the kaurik chango fault has been re activated a number of times and that the area suffered at least nine major earthquakes with a magnitude of more than 6 during late pleistocene holocene time including the 1975 kinnaur earthquake

long aftershock sequences within continents and implications for earthquake hazard assessment one of the most powerful features of plate tectonics is that the known plate motions give insight into both the locations and average recurrence interval of future large earthquakes on plate boundaries plate tectonics gives no insight however into where and when earthquakes will occur within plates because the interiors of ideal plates should not deform as a result within plate interiors assessments of earthquake hazards rely heavily on the assumption that the locations of small earthquakes shown by the short historical record reflect continuing deformation that will cause future large earthquakes here however we show that many of these recent earthquakes are probably aftershocks of large earthquakes that occurred hundreds of years ago we present a simple model predicting that the length of aftershock sequences varies inversely with the rate at which faults are loaded aftershock sequences within the slowly deforming continents are predicted to be significantly longer than the decade typically observed at rapidly loaded plate boundaries these predictions are in accord with observations so the common practice of treating continental earthquakes as steady state seismicity overestimates the hazard in presently active areas and underestimates it elsewhere

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

low gradient permeability measurements in a triaxial system permeability measurements were conducted with the flow pump method on sand sandy silt and silty clay specimens in a conventional triaxial system by introducing and withdrawing water at known constant flow rates into the base of a specimen with a flow pump and by monitoring the head difference induced across the length of the specimen with a sensitive differential pressure transducer the results show that the previously reported advantages of the flow pump method compared with conventional constant head and falling head methods were realized for permeability measurements in conventional triaxial equipment these advantages are that direct flow rate measurements are avoided together with the associated errors that arise from the effects of contaminants on capillary menisci and the long periods of time involved in flow rate measurements permeability measurements can be obtained much more rapidly and at substantially smaller gradients errors from the small intercept in the otherwise linear flow rate ve

a new phenomenon in ancient liquefaction the draw in process its final stage abstract the authors propose a draw in phenomenon which occurs at the final stage of liquefaction three case studies of ancient liquefaction accompanied with draw in phenomena are examined from the karasu river district gunmna prefecture and the sanbusho and motoyashiki archeological sites niigata prefecture central japan the intrusion spout phenomenon is the primary or the main process of liquefaction caused by the increase in pressure of the liquefied layer during the earthquake the draw in phenomenon is the secondary or final process of liquefaction which occurs just after the earthquake the draw in structure is important to recognize in the field because only the final form of ancient liquefaction is preserved during the draw in stage the ancient surface soils are mixed and drawn in therefore the draw in structure is useful in order to estimate the age of ancient liquefaction events

alluvial deposits liquefied by the flims rock slide abstract the origin of the bonaduz gravel switzerland in the vicinity of the large holocene flims rock slide deposits has been discussed for a century the internal structure shows many features that imply transport as an over sized mud debris stream this flow of gravel sand and fines must have been triggered by the mobilisation of the valley alluvium by the impact of the rock slide the mobilised mud with a volume of several 100 million m 3 must have had enormous transport capacities as large units of loose material were transported over kilometres without breaking apart accordingly the shear forces in the flow must have been negligible similar features have been found at several other sites in the alps all in the vicinity of large rock slides our interpretation of these sediments as catastrophic mass movement deposits suggests that such events could happen again also in other parts of the world