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Remobilization and deformation of surficial subaqueous slope sediments create turbidites and soft sediment deformation structures, which are common features in many depositional records. Palaeoseismic studies have used seismically‐induced turbidites and soft sediment deformation structures preserved in sedimentary sequences to reconstruct recurrence patterns and – in some cases – allow quantifying rupture location and magnitude of past earthquakes. However, current understanding of earthquake‐triggered remobilization and deformation lacks studies targeting where these processes take place, the subaqueous slope and involving direct comparison of sedimentary fingerprint with well‐documented historical earthquakes. This study investigates the sedimentary imprint of six megathrust earthquakes with varying rupture characteristics in 17 slope sediment cores from two Chilean lakes, Riñihue and Calafquén, and evaluates how it links to seismic intensity, peak ground acceleration, bracketed duration and slope angle. Centimetre‐scale stratigraphic gaps ranging from ca 1 to 20 cm – caused by remobilization of surficial slope sediment – were identified using high‐resolution multi‐proxy core correlation of slope to basin cores, and six types of soft sediment deformation structures ranging from ca 1 to 25 cm thickness using high‐resolution three‐dimensional X‐ray computed tomography data. Stratigraphic gaps occur on slope angles of ≥2.3°, whereas deformation already occurs from slope angle 0.2°. The thickness of both stratigraphic gaps and soft sediment deformation structures increases with slope angle, suggesting that increased gravitational shear stress promotes both surficial remobilization and deformation. Seismic shaking is the dominant trigger for surficial remobilization and deformation at the studied lakes. Total remobilization depth correlates best with bracketed duration and is highest in both lakes for the strongest earthquakes (M w ca 9.5). In lake Riñihue, soft sediment deformation structure thickness and type correlate best with peak ground acceleration providing the first field‐based evidence of progressive soft sediment deformation structure development with increasing peak ground acceleration for soft sediment deformation structures caused by Kelvin‐Helmholtz instability. The authors propose that long duration and low frequency content of seismic shaking favours surficial remobilization, whereas ground motion amplitude controls Kelvin‐Helmholtz instability‐related soft sediment deformation structure development.

Soft-sediment deformation structures were identified along Nandakini River valley near Chamoli village of Garhwal Lesser Himalaya. The deformation, in each outcrop, is restricted to a single stratigraphic layer bounded by undeformed flat-lying layers, eliminating the influence of slope failure. The structures are multiple liquefaction features like sand dikes, flame structures, pear-drop disturbance and downward warping of beds. The preferred interpretation is that the deformations resulted from earthquake-induced liquefaction and their existence adjacent to the Nandaprayag Fault can be related to episodic seismicity that occurred along this fault. However, more data and dating technique is needed to constrain the timing and distance to the causative seismic source. It is possible that more than one earthquake has effected the deformations.

During the last years many studies focused on soft-sediment deformation structures (SSDS) to identify past seismic events. However, in regions that were affected by glaciations and periglacial processes like northern and central Europe, the use of SSDS as paleo-earthquake indicator is challenging. Interpretations require great care. Earthquakes are only one possible trigger mechanism of many that can cause liquefaction and/or fluidization of sediments, which leads to the formation of e.g. sand volcanoes, clastic dykes, flame structures, or ball-and-pillow structures.SSDS triggered by seismic shaking are so-called seismites. Originally the term ‘seismites’ was used by Sailacher (1969) and only referred to sediment beds that were deformed by earthquake-related shaking. Pleistocene seismites are described from former glaciated areas in Germany, Denmark, Sweden, Poland, Latvia, and Lithuania.However, ice-sheet loading, glaciotectonism as well as freeze and thaw processes in periglacial environments are also potential trigger mechanisms causing the formation of similar looking types of SSDS, which can be easily mistaken for seismites. Therefore, it is important to use a set of clear criteria to recognize seismites in the field.Extensive studies of Pleistocene sediments in northern Germany have shown that deformation bands are a suitable indicator for paleo-fault activity. Deformation bands that are developed close to the tip line of a fault in combination with e.g. sand volcanoes, clastic dykes, flame structures, or ball-and-pillow structures is the most robust indicator for paleo-earthquakes. References Seilacher, A. (1969). Fault-graded beds interpreted as seismites. Sedimentology, 13, 155-159.

Turbidites of the Early Cretaceous Lingshandao Formation on Lingshan Island, eastern China, show numerous soft-sediment deformation structures. The turbidites accumulated in a rift basin plain on the distal part of a low-energy fan, together with autochthonous fine-grained sediments that settled from suspension. Occasionally, sets of both types of sediments slumped down the basin slope. The turbidites were studied in two sections. Paleocurrent directions, measured from sole marks at the base of the sandy turbidites, indicate a slope from SE to NW; this is consistent with the dip direction of the axial planes of the major slump folds. Among the numerous types of soft-sediment deformation structures that are present, two types are of special interest because of their specific genesis, viz. rip-up clasts and dome structures. It appears that rapid sedimentation must be considered as the main trigger behind these deformations: the rapid accumulation of particularly the sandy turbidites resulted in overloading of the underlying beds and then consequently in an increase in their pore-water pressure that induced liquefaction and fluidization, which triggered the formation of the rip-up clasts and dome structures. The downslope movement of freshly deposited turbidites after slope failure over the inclined sedimentary surface induced shear stresses, which resulted in the complication of the rip-up clasts and the preferred orientation of some dome structures. Both the dip directions of the axial planes of some of the dome structures and microfolds within the rip-up clasts are consistent with the paleocurrent direction indicated by the sole marks and the slump folds.

Fine-grained sediments from the Late Triassic Yanchang Fm. in the Ordos Basin (central China) were studied by core analysis and geophysical logging. Part of the mudstones in this formation are stratified, part of them are unstratified; the various mudstones can be subdivided into eight types on the basis of their structures and textures. They represent a variety of environments, ranging from delta fronts and subaqueous fans to deep-water environments. Part of the sediments were reworked and became eventually deposited from subaqueous gravity flows, such as mud flows, turbidity currents and hyperpycnal flows that easily developed on the clay-rich deltaic slopes. The sediments deposited by such gravity flows show abundant soft-sediment deformation structures. Understanding of such structures and recognition of fine-grained sediments as gravity-flow deposits is significant for the exploration of potential hydrocarbon occurrences. Because fine-grained deposits become increasingly important for hydrocarbon exploration, and because the sediments in the lacustrine Yanchang Formation were deposited by exactly the same processes that play a role in the accumulation of deltaic and prodeltaic fine-grained sediments, the sedimentological analysis provided here is not only important for the understanding of deep lacustrine sediments like the Yanchang Formation, but also for a better insight into the accumulation of fine-grained prodeltaic deep-marine sediments and their potential as hydrocarbon source rocks and reservoir rocks.

Geomorphic, tectonic and sedimentary investigations have been carried out to understand the landscape evolution of the Palar River basin, Southern Peninsular India. For this purpose, satellite data interpretations coupled with field investigations, fluvial architecture and optically stimulated luminescence (OSL) dating methods were adopted to infer climatic variations and neotectonic deformation that took place during the mid to late Holocene period. Several paleochannels have been identified in the Northern part of the present day Palar River. The distribution pattern of the Palar paleochannels and its present course indicate its migration towards the south, leaving behind the old Palar River streams as paleochannels. Significant changes in the morphological characteristics, channel width and river pattern in the successive paleochannels reveal evidences of channel movement by avulsion largely controlled by reactivation of pre-existing lineaments and intensified NE monsoon. Based on OSL ages, two major phases of migration have been identified that occurred between 4.83 ka to 1.88 ka. First phase occurred between 3.59 ka to 3.26 ka due to intensified monsoon accompanied with small scale neotectonic activity. The second phase took place between 2.42 ka to 1.88 ka which occurred probably due to the rapid upstream avulsion. This rapid avulsion is due to the close proximity of MPA and the reactivation of the pre-existing lineaments. Moreover, the present Palar River basin exhibits evidences of neotectonic activity such as soft sediment deformation structures, anomalous drainage deflections and reactivation of lineaments and faults further indicating that the Palar River is still draining a tectonically active region. Thus, neotctonics and fluctuations in the intensity of monsoon are largely responsible for sculpting the present landscape.

Cretaceous sedimentary rocks corresponding to the Las Plumas Member of the Cerro Barcino Formation were deposited in the eastern margin of the Somuncurá - Cañadón Asfalto Basin. The analyzed succession records alluvial settings in a fault-proximal scenario and contains a 7 m thick stratigraphic interval bearing soft-sediment deformation structures which include: pebble load casts, pseudonodules, flame structures and contorted bedding. Deformed beds are bounded by undisturbed strata and these features can be traced along the 800 m of exposures. The sedimentological features such as size and shape of SSDS, clast fabric of gravels and depositional paleoenvironment added to the proximity to a fault zone support the interpretation of the described deformation features as formed by liquefaction and/or fluidization triggered by seismic shocks during syn-tectonic deposition. Fil: Villegas, Pablo Martin. Universidad Nacional de La Pampa; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Confluencia. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas | Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas.; Argentina Fil: Umazano, Aldo Martin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Confluencia. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas | Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas.; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Melchor, Ricardo Nestor. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Confluencia. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas | Universidad Nacional de la Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de la Pampa. Grupo Vinculado Fundacion Centro de Salud E Investigaciones Medicas.; Argentina. Universidad Nacional de La Pampa; Argentina Fil: Kataoka, Kyoko. Niigata University; Japón

Some sections on Lingshan Island, in the Yellow Sea, close to the city of Qingdao, show the Early Cretaceous Lingshandao Formation. The exposed succession consists mainly of turbidites, some of which show uncommon soft-sediment deformation structures, and contains well-developed, large-scale slumps that consist of sets of turbidites. The sediments were deposited as part of lobes of turbidites and hyperpycnites (deposits of flood-generated sediment-laden bottom currents derived from an estuary) in a deep-sea environment that formed part of an inter-arc basin with a tensional tectonic regime. Some of the slumps have dimensions of the order of metres to tens of metres; they consist of the turbidites that build most of the succession. The soft-sediment deformation structures in the turbidites represent a wide variety of types, most of which are common in subaqueous environments with a high accumulation rate. The most interesting are, however, structures that indicate active tectonic tension. These structures are boudins, which are present with two subtypes. The most common are pinch-and-swell structures, sometimes leading to isolated parts of the affected sandy layer, enveloped by shales of the under- and overlying shale layers. The second type consists of domino boudins, which have, as far as we are aware of, not earlier been described from sediments that were still unlithified during their formation. The presence of the boudins and associated structures, which indicate synsedimentary stretching related to an extensional tectonic setting, form an additional argument in the long-lasting debate about the question of whether a compressional or an extensional tectonic regime dominated in the area during the Early Cretaceous.

Valley-fill terraces and fluvio-lacustrine sediment successions were investigated for the nature and type of soft-sediment deformation structures (SSDS) in the Alaknanda Valley of the Garhwal Himalaya. Based on their morphologies, sediment characteristics and comparison with existing data on SSDS, these features are classified into seismic and aseismic categories. The study indicates that, despite the terrain being in the seismically active domain of the Central Himalaya, the majority of the deformation structures seem to have been generated aseismically. We attribute their genesis to uneven loading, slope failure and, most importantly, turbulent flow and sudden loading by flash floods. The study suggests that a cautious approach is needed before assigning a seismic origin to deformation structures in sediments deposited in high-energy fluvial systems.

The eastern margin of the Tibetan Plateau is characterized by frequent earthquakes, which are closely associated with tectonic activity. To assess tectonic activity during the Late Pleistocene, we studied a well-exposed, 23-m-thick lacustrine sequence on the eastern margin of the plateau and found a variety of soft-sediment deformation (SSD) structures. Distributed in 24 stratigraphic levels, they comprise clastic dykes, ball-and-pillow structures, flame structures, clastic gravels, micro-faults, and slump folds. Most of the SSD structures indicate deformation mechanisms related to liquefaction and/or fluidization processes, most probably triggered by paleoseismic events. Given at least 4 historical earthquakes of M > 7 in the study area, most SSD structures in the Lixian lacustrine sequence indicate seismic events with M > 6 while simple flame structures point to some lower-magnitude earthquakes. OSL dating indicates that the sequence accumulated between 15.8 and 6.0 ka, giving a mean recurrence interval of 480 years for the 24 events, and demonstrating that lacustrine sediments in eastern Tibet have the potential to record a continuous seismic history on the centennial scale.

A well-exposed section in an esker near Ryssjon (S Sweden), strongly affected by several phases of glacitectonism, showed two phenomena that are uncommon and that seem to have a causal relationship. The first phenomenon is the occurrence of a load cast consisting predominantly of gravel in deposits formed just inside or outside a tunnel mouth. The load cast is over 3 m high and 8 m wide, a size that has previously not been described from unconsolidated sediments. Two nearby, somewhat smaller load casts consisting mainly of sand also have dimensions of over 2 m, indicating that the formation of huge load casts was apparently a feature related to the special conditions under which loading could develop at this site. The second remarkable feature is that not only is a till present in the succession above the load cast, thus indicating re-advance of the ice, but deposits overlying this till are also deformed by glacitectonism, proving that at least a second phase of ice re-advance must have occurred. This situation has not previously been documented. It is concluded that the varying differential overburden of sediment and particularly the retreating and re-advancing ice in this area were responsible for the formation of the extremely large load casts, possibly triggered by seismic shocks related to isostatic adjustment caused by oscillations of the ice front.

This paper discusses the composition and distribution of soft-sediment deformation structures induced by liquefaction in Late Pleistocene lacustrine terrace deposits on the southern shore of Issyk-Kul Lake in the northern Tien Shan mountains of Kyrgyzstan. The section contains seven deformed beds grouped in two intervals. Five deformed beds in the upper interval contain load structures (load casts and flame structures), convolute lamination, ball-and-pillow structures, folds and slumps. Deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope. The dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the Late Pleistocene.

Data gathered by electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to produce a three-dimensional image of subsurface soft-sediment deformation structures developed on the modern Lake Powell delta at Hite, Utah. ERT and GPR lines were run orthogonal across the crater. ERT resolved a low-resistivity layer up to 2 m thick in the area near the vents within the crater. This low-resistivity layer thins toward the margins representing clays ejected from the vents. Below and adjacent to this layer is a high-resistivity layer that reflects delta top and pro-delta sands. The deepest zone recognized in the ERT profiles consists of a low-resistivity layer, clay deposits that accumulated during the maximum lake high stand. This clay zone is connected to the vent within the crater by a conduit that changes diameter vertically. GPR profiles recognized the presence of collapse features restricted to the proximity of the vent. The geometry of the model is consistent with those proposed for marine pockmarks that can be generated seismically or aseismically with the exception of subaerial exposure after the dome stage development.

The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China). The flows and the resulting SSDS were probably triggered by earthquakes, volcanic eruptions, shear stress of gravity flows, and/or the sudden release of overburden-induced excess pore-fluid pressure. The tectonically active setting, the depositional slope and the high sedimentation rate facilitated the development of soft-sediment deformations, which consist mainly of load casts and associated structures such as pseudonodules and flame structures. Sediments with such deformations were occasionally eroded by slurries and became embedded in their deposits.

Soft-sediment deformation structures (SSDS) have been identified from well cores in the Palaeogene deposits of the Liaodong Bay Depression in the Bohai Bay basin, China. These deposits formed as interbedded sand and mud at a delta front or on the slope toe of the prodelta. According to criteria proposed by previous research, we established that these SSDS were induced by earthquakes and that they can be divided into two groups: ductile deformation structures (plastic intrusions, ball-and-pillow structures, flame structures, boudinage structures, irregular convolute stratifications, and synsedimentary faults and folds) and brittle deformation structures (sand dykes and autoclastic breccias). Based on their level of deformation, size, and complexity, the SSDS were divided into three Groups, from weak to strong, to reflect the intensity of palaeo-earthquakes. With consideration of the palaeo-sedimentary environment, we proposed a model to account for the production and preservation of these SSDS. According to the classification adopted in this study and the spatial stratigraphic distribution of the SSDS, the tectonic activities of the Tan–Lu faults in the Bohai Bay basin were investigated. The A and B oilfields (assumed names) are located in the tectonically active zones of the west and east branches of these faults, respectively. The extension tectonic activities in the A oilfield region exhibit a sharply decreasing trend from E2s3 to E2s1, and increase again in E3d2; whereas the strike–slip tectonic activities in the B oilfield region exhibit an increasing trend from E2s3 to E2s1, and finally, reach a maximum to E3d3. The results of this study show that the method of analysis of the spatial stratigraphic distribution of SSDS is suitable for determining the evolution of tectonic activity and thus, it can provide a new perspective for basin analysis.

Soft sediment deformation structures such as slump folds, clastic dyke, syn-sedimentary faults and convolute bedding are present in the coarse–fine grained yellowish buff coloured sandstone, and interbedded reddish brown fine grained sandstone and yellowish–white siltstone at the Khari River section belonging to Rudramata member of Jhuran Formation (Upper Jurassic), Kutch. These soft sediment deformation structures are confined to lower and middle parts of the section and are invariably underlain as well as overlain by undeformed beds that have restricted lateral and vertical extent and occur in close proximity of Kutch Mainland Fault, thereby suggesting that these structures were formed by seismic activity and therefore represents seismites.

This paper describes the Neogene lava–sediment mingling from the Abu Treifiya Basin, Cairo–Suez district, Egypt. The lava–sediment interactions as peperites have been identified for the first time at the study area and can be used as paleoenvironmental indicators. The identification of peperite reflects contemporaneous time relationship between volcanism and sedimentation and this finding is of primary importance to address the evolutional reconstruction of the Abu Treifiya Basin. Characterization of the facies architecture and textural framework of peperites was carried out through detailed description and interpretation of their outcrops. The peperites and sedimentary rocks are up to 350 m thick and form a distinct stratigraphic framework of diverse lithology that is widespread over several kilometers at the study area. Lateral and vertical facies of the peperites vary from sediment intercalated with the extrusive/intrusive basaltic rocks forming peperitic breccias to lava–sediment contacts at a large to small scales, respectively. Peperites encompass five main facies types ascribed to: (i) carbonate sediments-hosted fluidal and blocky peperites, (ii) lava flow-hosted blocky peperites, (iii) volcaniclastics-hosted fluidal and blocky peperites, (iv) sandstone/siltstone rocks-hosted blocky peperites, and (iv) debris-flows-hosted blocky peperites. Soft sediment deformation structures, vesiculated sediments, sediments filled-vesicles, and fractures in lava flows indicate that lava flows mingled with unconsolidated wet sediments. All the peperites in this study could be described as blocky or fluidal, but mixtures of different clast shapes occur regardless of the host sediment. The presence of fluidal and blocky juvenile clasts elucidates different eruptive styles, reflecting a ductile and brittle fragmentation. The gradual variation from fluidal to blocky peperite texture, producing the vertical grading is affected by influencing factors, e.g., the viscosity, magma temperature, confining pressure, sediment fluidization, and vapor film at the magma–sediment interactions. Peperites in the study area record deposition within a shallow marine and fluvio-lacustrine environment accumulated in a rift-related basin developed during pre- to syn-rift phase, respectively. The facies transitions (peperites) in this area resulted from the explosive and sediment depositional processes, which were mingled separately by volcanism under contrast geological conditions. The development of such contrast in the depositional sequences reflects variation in the accommodation to sediment supply in the same accumulation space inside the depocenters during the rifting of the Abu Treifiya Basin. Hydrothermal mineralizations comprising quartz and carbonate are restricted to peperites and lava flows.

The Mio-Pliocene Middle Siwalik Subgroup, in the Lish River Section in the Darjiling District of the Eastern Himalaya, consists of sandstone, mudrocks, heterolithic units and conglomerates preserving six distinct associations of soft-sediment deformation structures at different stratigraphic levels. The foreland basin sediments of the Himalayan orogen were deposited in alluvial fan settings. Deformation structures present are: folds of variable geometry, pseudonodules, water escape features, flame structures and chaotic laminae. Liquefaction and/or fluidization of sediments in the soft state are inferred to have been responsible for the origin of these structures. Both the depositional palaeoenvironment and seismic tremors generated due to thrusting activities in the hinterland situated to the north of the then Middle Siwalik basin contributed to triggering the liquefaction/fluidization and creation of the softsediment deformation structures within the Middle Siwalik sediments.

Soft-sediment deformation structures identified in lacustrine sediments of the San Pedro el Alto area, within the Acambay graben, Mexico, can be attributed to Pleistocene-Holocene seismic events. The analysis of these deformation structures, seismites, is a key tool for the characterization of parameters such as the intensity and magnitude of the events, and the measurement of the affected area. Analysis of the shape, distribution, abundance and genesis of these secondary structures in lacustrine basins, also provide guidelines for assessing seismic hazard. The analysis of seismites enabled the identification of three M ≥ 5 earthquakes, minimum magnitude required for the formation of such structures, these on ESI 2007 scale (Environmental Seismic Intensity Scale) correspond to VII-X intensities. The structures were identified with coseismic stratigraphy analysis in three trenches and three sediment cores from the dam within the locality. The basin infill consists of lacustrine sediments with intercalation of volcanic material. The soft-sediment deformation structures appear in different sectors of the study area and consist of surficial ruptures, vertical displacements, slumps, pseudonodules, clastic dikes, cracks filled with recent material, and diapir-like and load-flame structures.

This study analyzed multi-channel seismic reflection data from Lake Van, Eastern Anatolia, to provide key information on the structural elements, deformational patterns and overall tectonic structure of the Lake Van basin. The seismic data reveal three subbasins (the Tatvan, northern and Ahlat subbasins) separated by structural ridges (the northern and Ahlat ridges). The Tatvan basin is a tilted wedge-block in the west, it is a relatively undeformed and flat-lying deep basin, forming a typical example of strike-slip sedimentation. Seismic sections reveal that the deeper sedimentary sections of the Tatvan basin are locally folded, gently in the south and more intensely further north, suggesting a probable gravitational “wedge-block” instability, oblique to the northern margin. The northern subbasin, bounded by normal oblique faults, forms a basin-margin graben structure that is elongated in a northeast-southwest direction. The east-west trending Ahlat ridge forms a fault-wedged sedimentary ridge and appears to offset by reverse oblique faults forming as a push-up rhomb horst structure. The Ahlat subbasin is a fault-wedged trough fill that is elongated in the west-east direction and appears as a horst-foot graben formed by the normal oblique faults. The northeast-southwest directed northern ridge is a faulted crestal terrace of a sublacustrine basement block. Its step-like morphology, in response to the downfaulting of the Tatvan basin, as well as its backthrusted appearance, indicates the normal oblique nature of the bounding faults. The lacustrine shelf and slope show distinctive stratigraphic features; progradational deltas, submerged fluvial channels, distorted and collapsed beddings and soft sediment deformation structures, characterizing a highly unstable nature of shelf caused by strong oblique faulting and related earthquakes. The faulting caused uplift of the Carpanak spur zone, together with the northeastern Erek delta, deformation of deltaic structures and subsequently exposing the shelf and slope areas. The exposed areas are evident in the angular unconformity surface of the Carpanak basement block with the northeastern Erek delta and thinned sediments. The uplift resulted in the asymmetric depositional emplacement of the southeastern delta that is controlled by a series of ramp anticlines/low angle reverse faults. The Deveboynu subbasin and Varis spur zone form wide fault-controlled depressions with thick sediments that are elongated in the north-south direction. These subbasins appear as a small pull-apart boundary formed by normal oblique faults at the western end of the southeastern delta.

A pit located near Ballyhorsey, 28 km south of Dublin (eastern Ireland), displays subglacially deposited glaciofluvial sediments passing upwards into proglacial subaqueous ice-contact fan deposits. The coexistence of these two different depositional environments at the same location will help with differentiation between two very similar and easily confused glacial lithofacies. The lowermost sediments show aggrading subglacial deposits indicating a constrained accommodation space, mainly controlled by the position of an overlying ice roof during ice-bed decoupling. These sediments are characterized by vertically stacked tills with large lenses of tabular to channelized sorted sediments. The sorted sediments consist of fine-grained laminated facies, cross-laminated sand and channelized gravels, and are interpreted as subglaciofluvial sediments deposited within a subglacial de-coupled space. The subglaciofluvial sequence is characterized by glaciotectonic deformation structures within discrete beds, triggered by fluid overpressure and shear stress during episodes of ice/bed recoupling (clastic dykes and folds). The upper deposits correspond to the deposition of successive hyperpycnal flows in a proximal proglacial lake, forming a thick sedimentary wedge erosively overlying the subglacial deposits. Gravel facies and large-scale trough bedding sand are observed within this proximal wedge, while normally graded sand beds with developed bedforms are observed further downflow. The building of the prograding ice-contact subaqueous fan implies an unrestricted accommodation space and is associated with deformation structures related to gravity destabilization during fan spreading (normal faults). This study facilitates the recognition of subglacial/submarginal depositional environments formed, in part, during localized ice/bed coupling episodes in the sedimentary record. The sedimentary sequence exposed in Ballyhorsey permits characterization of the temporal framework of meltwater production during deglaciation, the impact on the subglacial drainage system and the consequences on the Irish Sea Ice Stream flow mechanisms.

Soft-sediment deformation structures (SSDS) are examined in the late Pleistocene marine terrace deposits of the southeastern coast of the Korean Peninsula. The marine terrace deposits are exposed in thicknesses of more than 10 m, and consist of lagoon, foreshore to backshore, coastal dune, and foreshore to backshore deposits in ascending order. The SSDS are restricted to the coastal dune deposits and the upper part of the underlying foreshore to backshore deposits, and are grouped into ductile and brittle deformation structures. The ductile deformation structures include irregular laminations, compacted laminations in the hinge zone of folds, asymmetric folds of foreset laminae, and water escape structures. The brittle deformation structures include syndepositional faults or deformation bands. The most probable triggering mechanism for the SSDS is liquefaction by moderate-magnitude earthquakes (M = 5–5.5). Likely, the SSDS were generated over time in various stress fields, including those of main shocks, aftershocks, and later seismic events. The evolution of the SSDS-bearing deposits in the study area can be summarised as follows: 1) rising of the groundwater table in the coastal dune deposits as a result of seismic shock, 2) formation of SSDS by liquefaction in the lower part of the dune deposits and upper part of the underlying foreshore to backshore deposits, 3) descending of the groundwater table, and 4) deposition of foreshore to backshore deposits on the SSDS-bearing dune deposits with erosion of the top of the dune deposits.

Soft sediment deformation structures were recognized in the Maastrichtian shallow marine wave to tide influenced regressive sediments of Ajali Formation in the western flank of Anambra basin, southern Nigerian. The soft sediment deformation structures were in association with cross bedded sands, clay and silt and show different morphological types. Two main types recognised are plastic deformations represented by different types of recumbent folds and injection structure represented by clastic dykes. Other structures in association with the plastic deformation structures include distorted convolute lamination, subsidence lobes, pillars, cusps and sand balls. These structures are interpreted to have been formed by liquefaction and fluidization mechanisms. The driving forces inferred include gravitational instabilities and hydraulic processes. Facies analysis, detailed morphologic study of the soft sediment deformation structures and previous tectonic history of the basin indicate that the main trigger agent for deformation is earthquake shock. The soft sediment deformation structures recognised in the western part of Anambra basin provide a continuous record of the tectonic processes that acted on the regressive Ajali Formation during the Maastrichtian.

The South Tibetan Detachment System (STDS) defines the lithological and tectonic boundary between the Higher Himalayan crystallines and the Tethyan sedimentaries. Earlier studies have suggested that the STDS has been dormant since its inception during the Miocene along with the Main Central Thrust (MCT). However, recent studies indicate that the STDS was active during the Pleistocene–Holocene period. We provide additional support for this more recent activity based on the occurrence of seismically induced Soft Sediment Deformation Structures (SSDS) preserved in relict lake sediments in the Dhauli Ganga, Gori Ganga and Kali Ganga river basins of the Central Himalaya. The relict lakes are located on the hanging wall of the STDS. An optical chronology of the lake sediments brackets the seismically induced SSDS between 20 ka and 11 ka with a major seismic event of magnitude > 6.5 occurring between 17 ka and 13.5 ka. Since MCT and STDS are considered to be the coupled structures, our observation supports the hypothesis that the STDS is providing accommodation space to the strain gradient arising due to the north–south compression in the Himalaya during the late Quaternary.

This paper focuses on soft-sediment deformation structures (SSDS) in both siliciclastic and carbonate storm deposits of the Cambrian Mantou and Chaomidian formations (Shandong Province, China) in order to understand their deformation mechanisms and possible triggers. Siliciclastic SSDS (e.g., sand volcanoes and pillows) and carbonate SSDS (e.g., sedimentary dykes, grainstone-matrix breccias, deformed cross-beddings, and marlstone-matrix breccias) occur exclusively in hummocky cross-stratified fine sandstone and peloidal grainstone, respectively. The siliciclastic SSDS formed in porous and permeable surface sediment, whereas the carbonate SSDS formed under shallow burial conditions when early marine cementation prevailed. The various deformation structures resulted mainly from differences between siliciclastic and carbonate sediment conditions and resulting deformation mechanisms. Sand volcanoes formed by upward extrusion of over-pressured fluidized sandy sediment, whereas sand pillows resulted from upward injection of lower density muddy sediment into overlying liquefied sandy sediment. Sedimentary dykes and grainstone-matrix limestone breccias formed as a result of differential liquefaction and fluidization of heterogeneously cemented carbonate sediment, whereas deformed cross-beddings and marlstone-matrix limestone breccias developed by the thixotropic liquidization and injection of clayey sediment, and further disruption of thin peloidal layers. Sedimentary facies analysis and analysis of the physical processes indicate that the SSDS were most likely caused by cyclic loading of storm waves.

Burdur city is located on lacustrine sedimentary deposits at the northeastern end of the Fethiye-Burdur Fault Zone (FBFZ) in SW Turkey. Fault steps were formed in response to vertical displacement along normal fault zones in these deposits. Soft sediment deformation structures were identified at five sites in lacustrine sediments located on both sides of the FBFZ. The deformed sediments are composed of unconsolidated alternations of sands, silts and clay layers and show different morphological types. The soft sediment deformation structures include load structures, flame structures, slumps, dykes, neptunian dykes, drops and pseudonodules, intercalated layers, ball and pillow structures, minor faults and water escape structures of varying geometry and dimension. These structures are a direct response to fluid escape during liquefaction and fluidization mechanism. The driving forces inferred include gravitational instabilities and hydraulic processes. Geological, tectonic, mineralogical investigations and age analysis were carried out to identify the cause for these soft sediment deformations. OSL dating indicated an age ranging from 15161 +/- 744 to 17434 +/- 896 years for the soft sediment deformation structures. Geological investigations of the soft sediment deformation structures and tectonic history of the basin indicate that the main factor for deformation is past seismic activity.

The development of soft-sediment deformation structures in clastic sediments is now reasonably well-understood but their development in various deltaic subenvironments is not. A sedimentological analysis of a Pleistocene (ca 13·1 to 15 10Be ka) Gilbert-type glaciolacustine delta with gravity-induced slides and slumps in the Mosty-Danowo tunnel valley (north-western Poland) provides more insight, because the various soft-sediment deformation structures in these deposits were considered in the context of their specific deltaic subenvironment. The sediments show three main groups of soft-sediment deformation structures in layers between undeformed sediments. The first group consists of deformed cross-bedding (inclined, overturned, recumbent, complex and sheath folds), large-scale folds (recumbent and sheath folds) and pillows forming plastic deformations. The second group comprises pillar structures (isolated and stress), clastic dykes with sand volcanoes and clastic megadykes as examples of water-escape structures. The third group consists of faults (normal and reverse) and extensional fissures (small fissures and neptunian dykes). Some of the deformations developed shortly after deposition of the deformed sediment, other structures developed later. This development must be ascribed to hydroplastic movement in a quasi-solid state, and due to fluidization and liquefaction of the rapidly deposited, water-saturated deltaic sediments. The various types of deformations were triggered by: (i) a high sedimentation rate; (ii) erosion (by wave action or meltwater currents); and (iii) ice-sheet loading and seasonal changes in the ablation rate. Analysis of these triggers, in combination with the deformational mechanisms, have resulted – on the basis of the spatial distribution of the various types of soft-sediment deformation structures in the delta under study – in a model for the development of soft-sediment deformation structures in the topsets, foresets and bottomsets of deltas. This analysis not only increases the understanding of the deformation processes in both modern and ancient deltaic settings but also helps to distinguish between the various subenvironments in ancient deltaic deposits.

Soft-sediment deformation (SSD) structures are observed in the Paleoproterozoic Damtha Group in the Garhwal Lesser Himalaya for a lateral extent of over 110 km in comparable litho-sections. The SSD structures are primarily observed in medium- to fine-grained sandstones, siltstones and shale at sand–mud interfaces that were deposited in an inter-tidal to supra-tidal setting of the shallow marine platform. The SSD structures are conspicuously absent in horizons within facies dominated by a single grain size. The SSD structures include load structures, namely drops, pseudonodules and ball-and-pillow structures, along with contorted beds, slumps, cusps and water-escape structures of varying geometry and dimensions. The SSD structures are invariably bounded by undeformed beds and their dimensions depend on the thickness of bed affected by liquefaction. The observed SSD structures show distinct similarities with liquefaction-induced deformation structures in geological records and those produced in the laboratory under reverse and normal density gradient conditions. The recurring nature of SSD structures in the stratigraphic column over large spatial distances points toward a trigger mechanism with recurrent activity that affected the basin on a regional scale such as prolonged rifting of the Damtha basin during the Paleoproterozoic. This would have caused frequent earthquakes and shakes of the basin floor, producing recurrent SSD structures. In view of the similarity with seismites and absence of a viable alternative, rift-related seismicity is preferred as the trigger mechanism for the observed SSD structures in the Damtha Group.

The Himalayan fold-and-thrust belt has propagated from its Tibetan hinterland to the southern foreland since ∼55 Ma. The Siwalik sediments (∼20 - 2 Ma) were deposited in the frontal Himalayan foreland basin and subsequently became part of the thrust belt since ∼ 12 Ma. Restoration of the deformed section of the Middle Siwalik sequence reveals that the sequence is ∼325 m thick. Sedimentary facies analysis of the Middle Siwalik rocks points to the deposition of the Middle Siwalik sediments in an alluvial fan setup that was affected by uplift and foreland-ward propagation of Greater and Lesser Himalayan thrusts. Soft-sediment deformation structures preserved in the Middle Siwalik sequence in the Darjiling Himalaya are interpreted to have formed by sediment liquefaction resulting from increased pore-water pressure probably due to strong seismic shaking. Soft-sediment structures such as convolute lamination, flame structures, and various kinds of deformed cross-stratification are thus recognized as palaeoseismic in origin. This is the first report of seismites from the Siwalik succession of Darjiling Himalaya which indicates just like other sectors of Siwalik foreland basin and the present-day Gangetic foreland basin that the Siwalik sediments of this sector responded to seismicity.

Well-exposed soft-sediment deformation (SSD) structures occur in Tecopa paleolake beds largely composed of ash from the Bishop (760 kyr) and the Lava Creek (640 kyr) ultra-plinian eruptions. In both cases the SSD structures affected volcaniclastic deposits concentrated by overland flow from the surrounding topography into the lower slope and lake environments. Re-sedimentation of ash produced alternations of volcaniclastic layers with different grain sizes and ash content that allowed for reverse density gradients, which favoured liquefaction and deformation. In the Tecopa Basin, extensive outcrops show these deformed strata continuing laterally for hundreds of metres, along with three-dimensional exposures. This study illustrates the 3-D complexity of soft-sediment deformation including some novel morphologic features. Of particular interest were examples of superposed deformed beds that laterally change into one single deformed horizon. Heterogeneities in ash concentration, grain-size, and water content produced contrasting permeabilities that were barriers to liquefaction and soft-sediment deformation. The probable causes for liquefaction were Middle Pleistocene paleo-earthquakes. There are several active faults in the region with enough seismic potential to produce moderate to large earthquakes. The fact that a single deformed deposit laterally merges into multiple superposed deformed beds indicates that multilayer liquefaction could be produced by a single shaking event. In these cases, SSD layers are insufficient and unreliable indicators of paleo-seismic recurrence intervals.

The Selmo Formation was deposited in the basins associated with the Southeastern Anatolian Thrust Belt and East Anatolian Fault Zone in SE Turkey. These structures developed as a result of compressional stresses created by the movement of the Arabian plate to the north and the Eurasian plate to the west from early Miocene to late Pliocene. The outcrops of the Selmo Formation in the Adýyaman area (SE Turkey) comprise braided river deposits (lower alluvial unit) at the base, lacustrine and deltaic deposits in the middle (lacustrine unit) and low sinuousity river and alluvial deposits at the top (upper alluvial unit). Soft-sediment deformation structures were developed in sandstone, siltstone and marl of the deltaic and lacustrine unit of the Selmo Formation. These are slumps, recumbent folds, load casts, ball-and-pillow structures, flame structures, neptunian dykes, chaotically associated structures and synsedimentary faults. The tectonic setting of the basin, the lateral extent of the soft-sediment deformation structures over tens of kilometers, their similarities to deformation structures interpreted as being induced seismically in other regions worldwide or in a laboratory setting, and being confined by undeformed layers suggest that the main trigger system was related to seismic activity in the area.

The Lower Permian succession of the Central Southern Alps (Lombardy, Northern Italy) was deposited in fault-controlled continental basins, probably related to transtensional tectonics. We focussed our study on the stratigraphic record of the Lower Permian Orobic Basin, which consists of a 1000 m thick succession of prevailing continental clastics with intercalations of ignimbritic flows and tuffs (Pizzo del Diavolo Formation, PDV) resting on the underlying prevailing pyroclastic flows of the Cabianca Volcanite. The PDV consists of a lower part (composed of conglomerates passing laterally to sandstones and distally to silt and shales), a middle part (pelitic, with carbonates) and an upper part (alternating sandstone, silt and volcanic flows). Syndepositional tectonics during the deposition of the PDV is recorded by facies distribution, thickness changes and by the presence of deformation and liquefaction structures interpreted as seismites. Deformation is recorded by both ductile structures (ball-and-pillow, plastic intrusion, disturbed lamination, convolute stratification and slumps) and brittle structures (sand dykes and autoclastic breccias). Both the sedimentological features and the geodynamic setting of the depositional basin confidently support the interpretation of the described deformation features as related to seismic shocks. The most significant seismically-induced deformation is represented by a slumped horizon (about 4 m thick on average) which can be followed laterally for more than 5 km. The slumped bed consists of playa-lake deposits (alternating pelites and microbial carbonates, associated with mud cracks and vertebrate tracks). The lateral continuity and the evidence of deposition on a very low-angle surface along with the deformation/liquefaction of the sediments suggest that the slump was triggered by a high-magnitude earthquake. The stratigraphic distribution of the seismites allows us to identify time intervals of intense seismic activity, which correspond to rapid and basin-wide changes in the stratigraphical architecture of the depositional basin and/or to the reprise of the volcanic activity. The nature of the structures and their distribution suggest that the magnitude of the earthquakes responsible for the observed structures was likely higher than 5 (in order to produce sediment liquefaction) and probably reached intensity as high as 7 or more. The basin architecture suggests that the foci of these earthquakes were located close to the fault-controlled borders of the basin or within the basin itself.

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.

The north–south-trending upper reaches of the Minjiang River run along the Longmen Shan–Min Shan fault zone, a zone of abrupt topographic change along the eastern margin of the Tibetan Plateau. Multiple levels of well-preserved soft-sediment deformation structures (seismites) occur in sediments deposited in paleo-dammed lakes in the upper part of the Minjiang River Valley. These deformation structures include liquefied convolute deformation, water-escape structures, flame structures, pseudonodules, ball-and-pillow structures, sedimentary dykes, mud lenses, and large-scale folds. Several kilometers from the barrier bar of the Diexi paleo-dammed lakes, seven deformed structural layers were identified at different heights in late Quaternary stratigraphic sequences near Shawan Village, Maoxian County. Analyses of the deformation structures, landforms, and the structural environment indicate that these deformation structures were caused by earthquakes, slumps, and landslides. OSL (optical stimulated luminescence) and 14C dating of soft-sediment layers from the Shawan site indicate that intense earthquakes occurred during the period 25–20 ka B.P. Therefore, accurate geological dating of deformed features in dammed lake deposits in high mountains and canyons enables the record of moderate- to large-magnitude earthquakes to be extended to the late Pleistocene–Holocene upon the eastern Tibetan Plateau.

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.

Permo-Carboniferous Talchir Formation, Talchir Coalbasin, India, records sedimentation during a phase of climatic amelioration in an ice-marginal storm-affected shelf. Evidences of subtidal processes are preserved only under thick mud drapes deposited during waning storm phases. Various soft-sediment deformation structures in some sandstone/siltstone–mudstone interbeds, like syn-sedimentary faults, deformed laminations, sand–silt flows, convolute laminations and various flame structures, suggest liquefaction and fluidization of the beds due to passage of syn-depositional seismic shocks. In the Late Paleozoic ice-marginal shelf, such earthquake tremors could be generated by crustal movements in response to glacioisostatic adjustments of the basin floor.

Intervals of soft-sediment deformation features, including vertical fluid escape and load structures, are common and well-exposed in Permian lower slope deposits of the Tanqua Depocentre, Karoo Basin. The structures mainly comprise elongated flames and load structures associated with ruptured sandstones and structureless siltstones, observed over a range of scales. The presence of an upper structureless siltstone layer linked to the flames, interpreted as a product of the debouching of fine-grained material transported through the flame onto the palaeo-seabed, together with the drag and upward folding of lower sandstone layers is evidence that the flames were formed in situ by upward movement of sediment-rich fluids. Flames are oriented parallel to the deep-water palaeoslope in lateral splay deposits between two major slope channel complexes. Statistical correlation and regression analyses of 180 flame structures from seven stratigraphic intervals suggest a common mechanism for the deformation and indicate the importance of fluidization as a deformation mechanism. Importantly, deformation occurred in an instantaneous and synchronous manner. Liquefaction and fluidization were triggered by incremental movement of sediment over steeper local gradients that were generated by deposition of a lateral splay on an inherited local north-west-facing slope. Seismic activity is not invoked as a trigger mechanism because of the restricted spatial occurrence of these features and the lack of indications of earthquakes during the time of deposition of the deep-water succession. The driving mechanisms that resulted in the final configuration of the soft-sediment deformation structures involved a combination of vertical shear stress caused by fluidization, development of an inverse density gradient and a downslope component of force associated with the local slope. Ground-penetrating radar profiles confirm the overall north-east orientation of the flame structures and provide a basis for recognition of potential larger-scale examples of flames in seismic reflection data sets.

During the Neogene, both strike-slip and extensional regimes coexisted in eastern Turkey and, a number of fault-bounded basins associated with the East Anatolian Fault System developed. The Caybagi Formation (Late Miocene–Early Pliocene) deposited in one of these basins consists of fluvio-lacustrine deposits. Numerous soft-sediment deformation structures are encountered in this formation, particularly in conglomerates, medium- to coarse-grained tuffaceous sandstones and claystones: folded structures (slumps, convolute laminations, and simple recumbent folds), water-escape structures (intruded sands, internal cusps, interpenetrative cusps and sand volcanoes), and load structures (load casts, pseudonodules, flame structures, and pillow structures). These structures are produced by liquefaction and/or fluidization of the unconsolidated sediments during a seismic shock. Consequently, the existence of seismically-induced deformation structures in the Caybagi Formation and the association with a Neogene intraformational unconformity, growth faults, and reverse faults in the Caybagi basin attest to the tectonic activity in this area during the Late Miocene and Early Pliocene. The East Anatolian Fault System, in particular the Uluova fault zone, is the most probable seismogenic source. Earthquakes with a magnitude of over 5 in the Richter scale can be postulated.

Recent studies on Neoproterozoic climate change has prompted renewed interests in Neoproterozoic glacial deposits and renewed debates over the criteria used to identify the nature of glacial influence on sedimentation. Analysis of soft sediment deformation structures have provided important clues to distinguish between competing paleoenvironmental interpretations of Quaternary glacial deposits. A similar approach is presented here in the analysis of Neoproterozoic glacial deposits of the Smalfjord Formation, northern Norway. Detailed sedimentological and structural analysis at several sites in the Varangerfjorden area reveals complex soft sediment deformation at various scales in conglomerate, sandstone and diamictite. Deformation is predominantly ductile and includes anticlinal and synclinal folding, flow noses, flame structures, recumbent folding and shear structures. The deformed sediments are predominantly associated with conglomerate and sandstone, which record glaciofluvial and deltaic depositional conditions. Some deformation can be attributed to rapid deposition and slumping, whereas others appear to record shear stress associated with overriding ice. The scale,style and range of deformation together with the coarse-grained nature of the deformed sediments and facies associations suggests these were unfrozen outwash sediments that were overridden by ice and resedimented in a dynamic ice proximal setting. Whereas recent previous studies of diamictite-bearing strata of the Smalfjord Formation had revealed no clear evidence of glacial influence on deposition, deformation structures documented here suggest that glacial conditions prevailed on the basin margin during deposition of Smalfjord Formation sediments, with sedimentary facies and deformation structures typical of temperate ice proximal settings.

Lateral extent and continuity of deformation has been used as criterion for the recognition of a seismic origin of soft-sediment deformations. Particular problems are posed by ancient seismites developed in deposits that show lateral variability of sedimentary facies. In such a context, the lateral continuity of deformation will depend on the lateral variability of physical properties of sediments that ultimately results in the lateral variability of seismites in a single deformation event. A variety of decimetre-scale soft-sediment deformation structures occurs in the synrift Escucha Formation (late Aptian–middle Albian) in Teruel, Spain. These structures, which include pseudonodules, ball-and-pillow structures, slumps, water-escape structures, multi-phase deformed structures, folds, sagging-like structures and synsedimentary faults, were developed contemporaneous to the formation of dark grey silty mudstones and grey clayey siltstones in a shallow-marine environment. The soft-sediment deformation is constrained to a 1.2-m thick horizon exposed in four outcrops consisting of quiet water mudstones and heterolithic storm deposits. The deformed horizon can be sub-divided into two parts, each reflecting a deformation event that affected both cohesive and granular (non-cohesive) sediments. The deformed structures occur in the vicinity of the Gargallo normal growth-fault, which is several kilometres long. Activity along this fault controlled the facies distribution of the unit bearing soft-sediment deformations. High-energy facies were located in the fault tip while low-energy facies developed in both the down-tilted hanging-wall and footwall blocks. In addition, fault-induced shocks released enough kinetic energy to trigger soft-sediment deformation. The soft-sediment deformation in the Escucha Formation represents different responses of deformation-susceptible sediments to earthquakes, which reflect the lateral variability of sedimentary facies.

The Middle Permian Wandrawandian Siltstone of the southern Sydney Basin is well exposed along the coastline from Lagoon Head in the south to North Head in the north near Ulladulla in southern New South Wales. The unit is dominated by fossiliferous siltstone and mudstone, with abundant dropstones and minor pebbly sandstone interbeds, and contains an interval of well-preserved and extensive soft-sediment deformation structures. These deformation structures occur mainly in the middle part of the cliff sections and are bounded above and below by undeformed sedimentary units of similar lithology. A wide range of soft-sediment deformation structures have been observed, including cracks, sandstone and sandy mudstone dykes, a possible sand volcano, networks of relatively small and closely connected fissure-like structures, metre-scale complex-type slump folds, flexural stratification, concave-up depressional structures, small-scale normal faults (with displacements usually

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.

The upper member of the Bima Sandstone (B3), a Cretaceous sedimentary unit in the Yola Arm of the Upper Benue Trough, has abundant soft-sediment deformation structures that include cusps, droplets, convolute bedding, deformed cross-bedding and sand volcanoes. The structures in most outcrops are sandwiched between undeformed cross-bedded strata that have no major textural differences with the sediments hosting them. The cusps are both simple internal cusps and interpenetrative cusps and are formed by post-depositional fluidization triggered by seismic shocks, where the interpenetrative cusps serve as conduits through which sands rose to the surface to form sand volcanoes. The droplets are the discrete type associated mostly with complex deformed cross-beddings, while the convolute bedding forms concentric antiforms and synforms without any evidence of faulting and gradually die out vertically upward. The deformed cross-bedding is represented by both simple and complex recumbent folds of flood and seismically induced origin respectively. The source of the seismic shocks may be episodic syndepositional Mesozoic volcanism of the Jurassic to Albian times within the Upper Benue Trough.

In the upper Ordovician glaciogenic rocks of West Gondwana, many soft-sediment deformation structures are attributed to glaciotectonic processes. However, little is known about the subglacial and ice-marginal processes associated with this ice sheet. A systematic description and interpretation of these soft-sediment deformation structures is supplemented by a comparison with Late Quaternary and Modern glacial settings to provide qualitative constraints on the character of ancient subglacial thermal regimes. Soft-sediment striations were formed by discontinuous, shear-induced deformation beneath an ice sheet that oscillated between warm and cold-based thermal regimes. Beneath warm-based ice, coupling across the ice–bed interface was poor with sliding and loading occurring at this surface. Loading of soft, waterlogged sediments allowed the development of fluted surfaces, which are also associated with the formation of truncated folded zones. During times of cold thermal regimes, coupling across the ice–bed interface was enhanced by freezing, which caused changes in the position of the freezing front. These discontinuous changes, coupled with sustained subglacial shearing, resulted in the development of stacked, soft-sediment striated surfaces. In areas where the subglacial substrate had an irregular topography, complex shear zones formed that comprised stacked duplex systems interlayered with highly strained units preserving pervasive, folded lineations. At the ice front, large glaciotectonic deformation structures (comparable with push moraines) developed during sustained periods of (re)advance that created composite thrust and fold systems. Deformation was transmitted for up to 1 km from the ice front and reduced in intensity with distance. Other deformation structures include dome-like folds that consist of central anticlines (30 to 70 m in width) with tight rim synclines that formed by the load-induced, diapiric intrusion of muds. An ice-sheet surging mechanism is inferred for the development of composite thrust and fold systems and the coeval sediment diapirs. These surges potentially caused the widespread reorganisation of a glacial load resulting in the pro- to subglacial extrusion of soft sediments.

The Kuscular Formation (Lower Paleocene), located in Eastern Turkey, is an alluvial and playa foreland basin succession deposited in a semi-arid climate. The playa deposits of the Kuscular Formation, composed of interbedded green sandstone–siltstone–mudrock, gypsiferous sandstone, red-green gypsiferous mudrock, and banded nodular secondary gypsum, are found among the distal alluvial fan deposits. Interbedded green sandstone–siltstone–mudrock with desiccation cracks are interpreted as dry mudflat–sandflat deposits. The banded nodular secondary gypsum and gypsiferous mudrocks, which contain desiccation cracks, are interpreted as a saline playa and saline mudflat. Distal alluvial fan deposits are represented by stratified conglomerate and stratified pebbly sandstone. The sulfur in the evaporites was very likely derived from the oxidation of sulfides in Upper Cretaceous magmatic rocks comprising the basement of the basin. Soft sediment deformation structures (slump folds), which indicate seismically active areas, were formed within the playa and dry mudflad–sandflat complex. The facies aspects of playa deposits would suggest that the climate in Turkey was semi-arid during the Early Paleocene.