Small-scale Faults Research Articles

Ordovician sediments sandwiched between Proterozoic basement slivers: tectonic structures in the Stumsnäs 1 drill core from the Siljan Ring, central Sweden

The Stumsnäs 1 core, drilled in 2011 in the southern part of the Siljan Ring, represents a structurally complex section and provides new insights into the impact-induced local structure in central Sweden. The Siljan Ring was formed around the central uplift of a Late Devonian meteorite crater, the largest known impact structure in Europe. The Stumsnäs 1 core section reveals that about 90 m of Palaeozoic (Lower to Upper Ordovician) sedimentary rocks are sandwiched between Proterozoic igneous basement rocks. The sedimentary contact to the underlying ∼260 m of Proterozoic basement is a prominent unconformity. The contact to the overlying ∼190-m-thick slab of Proterozoic basement is a few metres wide complex fault zone, comprising alternating thin slices of sedimentary and granitic rocks together with fault breccia and gouge. The tectonic emplacement of basement rocks over the Palaeozoic sedimentary succession is apparently impact-related and caused folding and faulting of the underlying sediments, some of which were overturned and cut out. Minor fault zones occur throughout the Stumsnäs 1 core section and have large damage zones with intense fracture networks along which alteration and mineralisation took place, likely also impact-related. Small-scale faults and fractures are common and are critical for fluid migration and hence for ongoing exploration for natural gas and geothermal energy reservoirs in the Siljan impact structure.

Quantified spatial relationships between gold mineralisation and key ore genesis controlling factors, and predictive mineralisation mapping, St Ives Goldfield, Western Australia

Determining the spatial relationships between various geological features and mineralisation is not only important for understanding the ore genesis of mineral deposits, but can also help to guide mineral exploration by providing predictive mineral maps. In this GIS-based study, we quantify the spatial relationships between gold mineralisation and plausible controlling factors in the central part of the St Ives area, Western Australia. We weigh plausible control factors including rock types, lithological boundaries and faults, using gold occurrences in drill-cores, and then apply the weights to the geological data to generate a predictive map for the entire St Ives area. The three major findings of this study are: (1) all major gold deposits are controlled by faults, and small-scale fault systems have a stronger correlation with gold mineralisation than large faults; (2) felsic to intermediate intrusive rocks show strong correlations with gold mineralisation, whereas metamorphic mafic rocks (greenstones) possibly acted as part of the broad regional environment for the mineral province rather than as a factor controlling the exact locations of the deposits; and (3) our predictive mapping indicates that the southeast part of the St Ives goldfield has a high potential for discovering new gold mineralisation.

Geological control and magnitude of methane ebullition from a high-flux seep area in the Black Sea—the Kerch seep area

We investigated gas bubble emissions at the Don–Kuban paleo-fan in the northeastern Black Sea regarding their geological setting, quantities as well as spatial and temporal variabilities during three ship expeditions between 2007 and 2011. About 600 bubble-induced hydroacoustic anomalies in the water column (flares) originating from the seafloor above the gas hydrate stability zone (GHSZ) at ~700m water depth were found. At about 890m water depth a hydrocarbon seep area named “Kerch seep area” was newly discovered within the GHSZ. We propose locally domed sediments (“mounds”) discovered during ultra-high resolution bathymetric mapping with an autonomous underwater vehicle (AUV) to result from gas hydrate accumulation at shallow depths. In situ measurements indicated spatially limited temperature elevations in the shallow sediment likely induced by upward fluid flow which may confine the local GHSZ to a few meters below the seafloor. As a result, gas bubbles are suspected to migrate into near-surface sediments and to escape the seafloor through small-scale faults. Hydroacoustic surveys revealed that several flares originated from a seafloor area of about 1km2 in size. The highest flare disappeared in about 350m water depth, suggesting that the released methane remains in the water column. A methane flux estimate, combining data from visual quantifications during dives with a remotely operated vehicle (ROV) with results from ship-based hydroacoustic surveys and gas analysis revealed that between 2 and 87×106mol CH4 yr−1 escaped into the water column above the Kerch seep area. Our results show that the finding of the Kerch seep area represents a so far underestimated type of hydrocarbon seep, which has to be considered in methane budget calculations.

Diffraction imaging as an interpretation tool

In naturally fractured reservoirs, detailed mapping and understanding of the subsurface fracture network is necessary to optimize field development. There are a variety of seismically driven technologies for mapping and detecting fracture zones. For example, by investigating seismic anisotropy one can hope to obtain preferential fracture orientation. Moreover, by generating and extracting volume and/or horizon-based attributes, potential fracture corridors can be identified and mapped. In this work we present an imaging technology that focuses diffraction energy produced by sharp discontinuities and at the same time suppresses specular reflection arrivals. The diffraction-enhanced seismic sections assist and contribute significantly in the interpretation and identification of small-scale faults and fractures, and they are used in addition to other derived post-stack attributes such as coherency and curvature cubes. We describe the diffraction imaging methodology and illustrate its application using synthetic and real data examples. We also show the ability of the technique to map fracture swarms by focusing the associated diffracted energy in the pre-stack time domain.

Effective friction law for small-scale fault heterogeneity in 3D dynamic rupture

[1] We address the problem of modeling dynamic rupture on multiscale heterogeneous faults in 3D. Under the assumption of slip-weakening friction, we numerically construct effective friction laws that integrate the effects of small-scale heterogeneity during the rupture. This homogenization process is based on the description of the initial phase of the rupture by the dominant unstable spectral mode. Its dynamics is influenced by the geometry of the fault, the static friction heterogeneities and the friction law. We first define a periodic small-scale heterogeneous model, introducing heterogeneity in the distribution of the static friction coefficient. We then describe a method for constructing this effective friction law. Applying this new law homogeneously on the fault permits to reproduce the dynamic evolution of the heterogeneous fault. Furthermore, we show that the effective friction law can be used to replace small-scale heterogeneities in two-scale heterogeneous models, while preserving their effects. We study three kinds of two-scale models, with growing complexity: first periodic at both scales, then periodic only at small scale, and finally irregular at both scales. This homogenization method can be adapted to the case where the heterogeneity is introduced in the initial stress rather than in the static friction value. Finally, we show in a simple example that the effective friction law permits to reproduce the transition between subshear and supershear rupture propagation, originally produced by heterogeneities on the fault.

Single- and two-phase fluid flow properties of cataclastic fault rocks in porous sandstone

Understanding the impact of faults on fluid flow in the subsurface is important for the extraction of oil, gas and groundwater as well as the geological storage of waste products. We address two problems present in current industry-standard workflows for fault seal analysis that may lead to fault rocks not being represented adequately in computational fluid flow models. Firstly, fluid flow properties of fault rocks are often measured only for small-scale faults with throws not exceeding a few centimetres. Large seismic-scale faults (throws >20 m) are likely to act as baffles or conduits to flow but they are seldom recovered from subsurface cores and consequently fault rock data for them is sparse. Secondly, experimental two-phase fluid flow data is lacking for fault rocks and, consequently, uncertainties exist when modelling flow across faults in the presence of two or more immiscible phases. We present a data set encompassing both single- and two-phase fluid flow properties of fault and host rocks from the 90-Fathom fault and its damage zone at Cullercoats Bay, NE England. Measurements were made on low-throw single and zones of deformation bands as well as on slip-surface cataclasites present along the ∼120 m throw main fault. Samples were analysed using SEM and X-ray tomography prior to petrophysical measurements. We show that single deformation bands, deformation band zones and slip-surface cataclasites exhibit dissimilar single- and two-phase fluid flow properties. This is due to grain-size reduction being more pronounced in slip-surface cataclasites and changes in microstructure being fault-parallel for deformation bands but mostly fault-perpendicular for slip-surface cataclasites. A trend of fault rocks with low absolute permeabilities exhibiting lower relative permeabilities than more permeable rocks at the same capillary pressure is evident.

Crustal structure beneath Beijing and its surrounding regions derived from gravity data

In this paper we use gravity data to study fine crustal structure and seismogenic environment beneath Beijing and its surrounding regions. Multi-scale wavelet analysis method is applied to separating gravity fields. Logarithmic power spectrum method is also used to calculate depth of gravity field source. The results show that the crustal structure is very complicated beneath Beijing and its surrounding areas. The crustal density exhibits laterally inhomogeneous. There are three large scale tectonic zones in North China, i.e., WNW-striking Zhangjiakou-Bohai tectonic zone (ZBTZ), NE-striking Taihang piedmont tectonic zone (TPTZ) and Cangxian tectonic zone (CTZ). ZBTZ and TPTZ intersect with each other beneath Beijing area and both of them cut through the lithosphere. The upper and middle crusts consist of many small-scale faults, uplifts and depressions. In the lower crust, these small-scale tectonic units disappear gradually, and they are replaced by large-scale tectonic units. In surrounding regions of Beijing, ZBTZ intersects with several other NE-striking tectonic units, such as Cangxian uplift, Jizhong depression and Shanxi Graben System (SGS). In west of Taihangshan uplift, gravity anomalies in upper and middle crusts are correlated with geological and topographic features on the surface. Compared with the crust, the structure is comparatively simple in uppermost mantle. Earthquakes mainly occurred in upper and middle crusts, especially in transitional regions between high gravity anomaly and low gravity anomaly. Occurrence of large earthquakes may be related to the upwelling of upper mantle and asthenosphere heat flow materials, such as Sanhe earthquake (MS8.0) and Tangshan earthquake (MS7.8).

Tectonic and sedimentary inheritance on the structural framework of Provence (SE France): Importance of the Salon-Cavaillon fault

Using field data, balanced cross-sections, gravity and reprocessed seismic reflection data, a detailed structural study has been realized on the Salon-Cavaillon fault (SCF) area, in Provence region (SE France). This fault separates two main ridges (the Alpilles to the west and the Luberon to the east). Field data and balanced cross-sections allow us to characterize the present-day structures and the post-Oligocene deformation that significantly differ on either sides of the SCF. Our structural study shows a post-Oligocene southward displacement of the structures on the two sides of the SCF. The Luberon ridge is a fault propagation-fold developed on a S-verging ramp. The anticline is bent as a drag fold in the vicinity of the dextral strike-slip SCF. The Alpilles ridge is a less developed fault propagation fold. Its eastern termination was affected by a counter-clockwise rigid block rotation around a vertical axis. The differences between the two ridges in terms of structural architecture are explained by the deep geometry of their ramp, inherited from the Late Cretaceous to Middle Eocene Pyrenean tectonic phase. The décollement level is shallow to the western side of the SCF (2–3 km), probably in the Lower Cretaceous or Upper Jurassic marls, than in the eastern side, the fault is rooted in Triassic layers at a depth > 5 km. The deep rooting favoured a large-scale fault propagation type of folding, whereas shallow-seated rooting favoured a small-scale fault propagation type of folding and block rotations. To image the sub-surface structures to the west of the SCF, we also included gravity data and reprocessed seismic reflection. It allows us to refine the regional tectonic framework and to detect several hidden E-trending S-verging folds. The main shortening episode in Provence occurred during the Pyrenean phase, with 65% of the total shortening to the east of the SCF and 95% to the west. From the Miocene to the present, Alpine shortening decreases strongly to the West of the SCF (less than 400 m against 2 km to the East), providing evidence for the major role of the SCF in the transfer of the south-directed Alpine deformation.

Discovery of massive seafloor gas seepage along the Wagner Fault, northern Gulf of California

Large-scale gas seepage and fluid ejection features are described from the edges of the active pull-apart Wagner and Consag basins (northern Gulf of California, Mexico), at water depths between ∼ 65 and 150 m. Gas vents, pockmarks, possible mud volcanoes, pyrite- and barite-rich sediments, slabs of lithified shell debris, and chemosynthetic fauna were found. Gas venting occurs mainly through N–S synsedimentary small-scale faults and fault-propagation folds that are believed to derive from the Wagner Fault. The presumed mud volcanoes are sub-rounded, domed bathymetric features, several hundreds of metres across, underlain by gas-charged sediments and surrounded by gas vents. Upward gas migration throughout the thick sedimentary sequence produces the fluid expulsion features on the sea floor.

Evidence for Late Ordovician glaciation of Al Kufrah Basin, Libya

Fieldwork at the flanks of Al Kufrah Basin, Libya, reveals that Late Ordovician ice sheets were present in the eastern Sahara and that they extended northeastward toward Egypt. Evidence for grounded ice sheets is preserved at the both the southeastern (Jabal Azbah) and northern (Jabal az-Zalmah) basin margins. Characteristic soft-sediment deformation structures, including soft-sediment folds, small-scale faults and striated pavements indicate subglacial shearing and the formation of glacial erosion surfaces. These findings support the presence of a Late Ordovician ice margin in the eastern Sahara and add vital new constraints to reconstructions of the morphology of North African grounded ice sheets. Prior to our study, there existed two plausible models on ice sheet geometry. The first was that separate ice sheets – namely a north and west African ice sheet and an Arabian ice sheet – extended over this part of western North Gondwana. The second was that ice cover was continuous. The presence of a suite of subglacially-generated deformation structures adds considerable credence to the latter interpretation.

Nature of serpentinization of ultramafic rocks from Hero Fracture Zone, Antarctic: Constraints from stable isotopes

Serpentinites from the Hero Fracture Zone, Drake Passage, Antarctica, contain serpentine, amphibole, talc, chlorite, and magnetite as well as relict olivine, pyroxene, and spinel from a spinel peridotite precursor. Two episodes of serpentinization are recognized. The first event produced lizardite and antigorite, whereas the second produced only lizardite. The initial and subsequent serpentinization events occurred at about 178–283 °C and 170–298 °C, respectively. Calculated water/rock ratios of the serpentinization events are less than 5 for the initial event and greater than 5 for the subsequent event. A model involving deep seawater infiltration in the fracture zone, followed by serpentinization of mantle peridotite and buoyancy-driven uplift controlled by relatively small-scale faults and not by a large-scale detachment fault, is invoked to explain the emplacement of serpentinite on the surface.

Timer-based composition of fault-containing self-stabilizing protocols

One of the desired properties of distributed systems is self-adaptability against faults. Self-stabilizing protocols provide autonomous recovery from any finite number of transient faults. However, in practice, catastrophic faults rarely occur, while small-scale faults are more likely to occur. Fault-containing self-stabilizing protocols promise not only self-stabilization but also containment of the effect of small-scale faults, i.e., they promise quick recovery and small effect for small-scale faults. Hierarchical composition of self-stabilizing protocols is expected to ease the design of new self-stabilizing protocols. However, existing composition techniques for self-stabilizing protocols cannot preserve the fault-containment property of source protocols. In this paper, we propose a novel timer-based hierarchical composition of fault-containing self-stabilizing protocols that preserves the fault-containment property of source protocols. To implement timers, we propose a local neighborhood synchronizer that synchronizes limited number of processes during a short time after a fault without involving the entire network into the synchronization. The proposed composition technique facilitates the design of new fault-containing self-stabilizing protocols and enhances the reusability of existing fault-containing self-stabilizing protocols.

Magnetotelluric and aeromagnetic investigations for assessment of groundwater resources in Parnaiba basin in Piaui State of North-East Brazil

In an attempt to locate the presence of possible groundwater resource regions in the semi-arid North-East Brazil, an integrated survey including aeromagnetic and magnetotelluric (MT) studies have been undertaken in the Guaribas region and only MT survey in the Caracol region. In the Guaribas region the aeromagnetic data, its analytic signal and Euler solutions reveal several subsurface small-scale faults and intrusives that are conducive to be potential groundwater resource regions. A total of about 22 broad-band magnetotelluric (MT) soundings in the period range of 0.006–300 s along two profiles on the marginal arcs of the intra-cratonic sedimentary Parnaíba basin in North-East Brazil have been made across the regional geological strike, the Senador Pompeu Lineament (SPL). SPL trends N40°E and marks a basement high reflecting an irregularity in the original basin geometry. While one of the MT profiles traverses across the SPL, the other lies only in the aeromagnetically surveyed sedimentary region. Two-dimensional inversion of MT data of both profiles shows that the sedimentary basin is conductive (100–150 Ω m) and shows as a thin graben with an average thickness of about 2–3 km beneath both profiles. The basin is located to be at shallow depths (from surface to about 500 m). Based on the facts that the study region falls on sedimentary region having low-to-very low permeability and also in accordance with the subsurface lithology around the study region, the mapped sedimentary basin largely manifests the zone of potential sedimentary aquifer having moderate resistivity of 50–250 Ω m and is located at relatively shallow depths. The identified aquifer zone is believed to have links with the Parnaiba River flowing at a distance of about 300 km NW from the study region. We discuss interpretation of our results of MT and aeromagnetic data sets in the light of hydrological features of the study region.

Diffraction imaging in depth

ABSTRACTHigh resolution imaging is of great value to an interpreter, for instance to enable identification of small scale faults, and to locate formation pinch‐out positions. Standard approaches to obtain high‐resolution information, such as coherency analysis and structure‐oriented filters, derive attributes from stacked, migrated images. Since they are image‐driven, these techniques are sensitive to artifacts due to an inadequate migration velocity; in fact the attribute derivation is not based on the physics of wave propagation. Diffracted waves on the other hand have been recognized as physically reliable carriers of high‐ or even super‐resolution structural information. However, high‐resolution information, encoded in diffractions, is generally lost during the conventional processing sequence, indeed migration kernels in current migration algorithms are biased against diffractions. We propose here methods for a diffraction‐based, data‐oriented approach to image resolution. We also demonstrate the different behaviour of diffractions compared to specular reflections and how this can be leveraged to assess characteristics of subsurface features. In this way a rough surface such as a fault plane or unconformity may be distinguishable on a diffraction image and not on a traditional reflection image.We outline some characteristic properties of diffractions and diffraction imaging, and present two novel approaches to diffraction imaging in the depth domain. The first technique is based on reflection focusing in the depth domain and subsequent filtering of reflections from prestack data. The second technique modifies the migration kernel and consists of a reverse application of stationary‐phase migration to suppress contributions from specular reflections to the diffraction image. Both techniques are proposed as a complement to conventional full‐wave pre‐stack depth migration, and both assume the existence of an accurate migration velocity.

Prediction of subseismic faults and fractures: Integration of three-dimensional seismic data, three-dimensional retrodeformation, and well data on an example of deformation around an inverted fault

In addition to seismically mapped fault structures, a large number of faults below the limit of seismic resolution contribute to subsurface deformation. However, a correlation between large- and small-scale faults is difficult because of their strong variation in orientation. A workflow to analyze deformation over different scales is described here. Based on the combination of seismic interpretation, coherency analysis, geostatistical analysis, kinematic modeling, and well data analysis, we constrained the density and orientation of subseismic faults and made predictions about reactivation and opening of fractures. We interpreted faults in seismic and coherency volumes at scales between several kilometers and a few tens of meters. Three-dimensional (3-D) retrodeformation was performed on a detailed interpreted 3-D structural model to simulate strain in the hanging wall at the time of faulting, at a scale below seismic resolution. The modeling results show that (1) considerable strain is observed more than 1 km (0.62 mi) away from the fault trace and (2) deformation around the fault causes strain variations, depending on the fault morphology. This strain variation is responsible for the heterogeneous subseismic fracture distribution observed in wells. We linked the fracture density from the well data with the modeled strain magnitude and used the strain magnitude as a proxy for fracture density. With this method, we can predict the relative density of small-scale fractures in areas without well data. Furthermore, knowing the orientation of the local strain axis, we predict a fault strike and opening or reactivation of fractures during a particular deformation event.

Chert in the Pacific: Biogenic silica and hydrothermal circulation

Data on sections drilled by DSDP and ODP in the Pacific have been compiled for 187 sites, 105 of which contain chert. The spatial pattern of siliceous deposits in the Pacific generally follows the pattern of biologic productivity. There is some evidence that enhanced vertical diffusivity in the ocean during the Eocene warm climate gave rise to siliceous deposits on and near bathymetric highs and basin margins. The most common occurrence of chert is in Eocene and older sections; however, cherts do occur in sections as young as 7 Ma in the sites investigated. Over half of the youngest chert occurrences in sedimentary sections are within 150 m of basement. Nearly all the chert occurrences on crust younger than 60 Ma are within 150 m of basement. The deficit in heat flow over ocean crust younger than 60 Ma is explained as the result of heat advection by hydrothermal waters circulating in the upper part of the ocean crust. These waters appear to dissolve biogenic silica and deposit it as chert in the lower parts of sedimentary sections. Diffusion of these waters into the lower sediment section is enhanced by small-scale faulting. This faulting may be associated with intra-plate stresses that develop during ridge jumps and reorientations of plate motion. The relatively warm bottom waters of the early Cenozoic may have also enhanced the dissolution of biogenic silica during hydrothermal circulation in the upper oceanic crust and basal sediment section.

Strain and vorticity analysis using small-scale faults and associated drag folds

Small-scale faults with associated drag folds in brittle-ductile rocks can retain detailed information on the kinematics and amount of deformation the host rock experienced. Measured fault orientation ( α), drag angle ( β) and the ratio of the thickness of deflected layers at the fault ( L) and further away ( T) can be compared with α, β and L/ T values that are calculated with a simple analytical model. Using graphs or a numerical best-fit routine, one can then determine the kinematic vorticity number and initial fault orientation that best fits the data. The proposed method was successfully tested on both analogue experiments and numerical simulations with BASIL. Using this method, a kinematic vorticity number of one (dextral simple shear) and a minimum finite strain of 2.5–3.8 was obtained for a population of antithetic faults with associated drag folds in a case study area at Mas Rabassers de Dalt on Cap de Creus in the Variscan of the easternmost Pyrenees, Spain.

Evidence for structurally controlled recharge in the Blue Ridge Province, Virginia, USA

Physical and geophysical data collected at a fractured-rock research site in the Blue Ridge Province of Virginia, USA indicate that recharge rates to a fractured-rock aquifer are controlled by a small-scale thrust fault associated with regional thrust faulting. Recharge rates appear to be correlated to spatial variation in the hydraulic conductivity of the regolith, which has been influenced by weathering rates and the metamorphic and structural history of the underlying parent material. The angle of dip of the thrust-fault shear zone and the fracturing within the crystalline rock adjacent to the fault plane appear to serve as geologic controls that preferentially direct infiltrated meteoric water to a deeper confined fractured-rock aquifer. In-situ analysis of electrical resistivity, matric potential and moisture content shows two distinctly different recharge processes which are spatially correlated with the structure of the shallow subsurface (regolith overlying the vertically oriented shear zone and regolith overlying the thrust-fault hanging wall), and which have strong temporal correlations with the dynamics of the underlying saturated conditions. Recharge flux within the regolith overlying the vertically oriented shear zone is strongly controlled by the orientation and areal extent of the thrust-fault shear zone, highlighting the importance of accurate delineation of recharge areas in crystalline rock aquifer systems.

Tracing the middle strand of the North Anatolian Fault Zone through the southern Sea of Marmara based on seismic reflection studies

We studied the active deformation zone of the middle strand of the North Anatolian Fault Zone through the southern part of the Sea of Marmara by means of high-resolution as well as deep seismic reflection data. Our main objective was to investigate the active deformation within the uppermost sedimentary layers at high resolution as well as deeper sedimentary layers, focusing on the tectonic and stratigraphic setting between Gemlik and Bandirma. The middle strand of the North Anatolian Fault reaching the Gulf of Gemlik is a main fault which has a lazy-S shape in the Gulf of Gemlik, and extends westwards to Bandirma as a main fault which is an E–W-trending single right-lateral fault controlling the zone along the Gemlik and Bandirma sub-basins. Small-scale faults, consistent with a dextral shear regime, are present in the vicinity of the main fault. Several oblique fault groups parallel to the main fault were detected. The deformation in the Gulf of Gemlik is characterized by a series of synthetic and antithetic faults emanating from the main fault. The boundary faults in the Gulf of Gemlik have a compressive component, which indicates the sill areas of the gulfs of Gemlik and Bandirma to be push-up structures. Four seismic stratigraphic units were identified in the sediments of the gulfs of Gemlik and Bandirma, providing evidence of tectonic influence. The present tectonic structure between Gemlik and Bandirma is not a pull-apart structure. The microseismic study in this area has shown that fault planes are either strike-slip or compressional, and that the stress tensor is compatible with pure strike-slip in the E–W fault system.

Elastic dislocation modelling for prediction of small-scale fault and fracture network characteristics

Abstract Predicting the effects of small-scale faults and fractures on reservoir behaviour requires a definition of their spatial distribution, orientation and mode. Elastic dislocation (ED) theory can predict the distribution of displacement, strain and stress in the rock volume surrounding major faults, from mapping of fault geometry and slip distribution in 3D seismic-reflection datasets. The intensity of small-scale faulting can be related to the predicted local strain, or the degree to which the shear stresses exceeded the rock failure envelope. We illustrate the methodology with three case studies: (i) a relatively-simple thrust anticline from Venezuela, where hydrocarbons are trapped in Pliocene sandstones within the faulted hanging wall anticline; (ii) the Gull-faks Field and of the North Sea; and (iii) the Miskar Field, offshore Tunisia, where large seismically mapped normal faults are forward-modelled to predict small-scale fault characteristics for comparison with detailed interpretation and seismic attribute analysis. Key requirements for the development of a robust predictive model of the small-scale fault and fracture network are a geometrically consistent framework model, judicious choice of mechanical properties, and a reasonable estimate of regional background strain.