LOW-ANGLE NORMAL FAULTING ALONG SOUTHERN COASTAL CALIFORNIA AS DISPLAYED BY THE HANGING-WALL ROLLOVER GEOMETRY OF THE SAN ONOFRE BRECCIA

In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (∼100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

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Loading transfer mechanism of a piled raft subjected to normal faulting in sand

Géotechnique Letters ◽

10.1680/jgele.21.00098 ◽

2022 ◽

Vol 12 (1) ◽

pp. 1-19

Author(s):

Q. Cai ◽

B. Xiang ◽

C. W. W. Ng ◽

K. S. Wong ◽

X. Chen ◽

...

Keyword(s):

Finite Difference ◽

Hanging Wall ◽

Three Dimensional ◽

Pile Group ◽

Transfer Mechanism ◽

Centrifuge Test ◽

Fault Rupture ◽

Normal Faulting ◽

Compression Failure ◽

Piled Raft

Although different kinds of foundations have been investigated against an earthquake faulting, the interaction between pile group and dip-slip fault has not yet been fully understood. This letter investigates the interaction between piled raft and normal faulting by means of centrifuge and numerical modelling. In centrifuge test, a piled raft was simulated with a half model for a better observation of fault rupture path under the raft. The loading transfer mechanism was further examined using a three-dimensional finite difference software (FLAC3D). The measured and computed results showed that the piled raft displaced and tilted linearly with the magnitude of faulting. The fault rupture bifurcated into two and diverted towards both edges of the raft. Two types of loading transfer mechanism were identified during faulting. Working load transferred from the raft to the underneath piles, and also from the piles on the side of the hanging wall to the piles on the footwall side, resulting in compression failure of the piles on the footwall side.

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Validation of Coupled FDM-DEM Approach on the Soil-Raft Foundation Interaction Subjected to Normal Faulting

10.5194/egusphere-egu21-9783 ◽

2021 ◽

Author(s):

Fang Ru-Ya ◽

Lin Cheng-Han ◽

Lin Ming-Lang

Keyword(s):

Active Fault ◽

Ground Deformation ◽

Numerical Models ◽

Hanging Wall ◽

Normal Fault ◽

Small Scale ◽

Foot Wall ◽

Normal Faulting ◽

Raft Foundation ◽

Overburden Soil

Recent earthquake events have shown that besides the strong ground motions, the coseismic faulting often caused substantial ground deformation and destructions of near-fault structures. In Taiwan, many high-rise buildings with raft foundation are close to the active fault due to the dense population. The Shanchiao Fault, which is a famous active fault, is the potentially dangerous normal fault to the capital of Taiwan (Taipei). This study aims to use coupled FDM-DEM approach for parametrically analyzing the soil-raft foundation interaction subjected to normal faulting. The coupled FDM-DEM approach includes two numerical frameworks: the DEM-based model to capture the deformation behavior of overburden soil, and the FDM-based model to investigate the responses of raft foundation. The analytical approach was first verified by three&#160; benchmark cases and theoretical solutions. After the verification, a series of small-scale sandbox model was used to validate the performance of the coupled FDM-DEM model in simulating deformation behaviors of overburden soil and structure elements. The full-scale numerical models were then built to understand the effects of relative location between the fault tip and foundation in the normal fault-soil-raft foundation behavior. Preliminary results show that the raft foundation located above the fault tip suffered to greater displacement, rotation, and inclination due to the intense deformation of the triangular shear zone in the overburden soil. The raft foundation also exhibited distortion during faulting. Based on the results, we suggest different adaptive strategies for the raft foundation located on foot wall and hanging wall if the buildings are necessary to be constructed within the active fault zone. It is the first time that the coupled FDM-DEM approach has been carefully validated and applied to study the normal fault-soil-raft foundation problems. The novel numerical framework is expected to contribute to design aids in future practical engineering.Keywords: Coupled FDM-DEM approach; normal faulting; ground deformation; soil-foundation interaction; raft foundation.

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Testing of Permian – Lower Triassic stratigraphic data in a half-graben/tilt-block system: evidence for the initial rifting phase in Antalya Nappes

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2018-0169 ◽

2019 ◽

Vol 56 (11) ◽

pp. 1262-1283 ◽

Cited By ~ 3

Author(s):

Nazif Şahin ◽

Demir Altiner

Keyword(s):

Hanging Wall ◽

Volcanic Rocks ◽

Lower Triassic ◽

Normal Faulting ◽

Triassic Boundary ◽

Block System ◽

Basement Rocks ◽

Half Graben ◽

Facies Change ◽

Permian Triassic Boundary

Testing of Middle Permian – Lower Triassic stratigraphic data from the Antalya Nappes in a half-graben/tilt-block system has revealed the presence of episodic rifting events separated by periods of tectonic quiescence. Following a period of uplift during the Permian (Late Artinskian to Roadian), the basement rocks have been activated by displacement faults and several depocenters in half-graben-like asymmetrical basins began to be filled with Roadian to Wordian continental clastic deposits intercalated with coal and marine rocks. The Early Capitanian time was a period of tectonic quiescence. The second event occurred in Middle to Late Capitanian times and produced basaltic volcanic rocks intercalated in the shallow marine fossiliferous carbonate successions. Following the Lopingian (Wuchiapingian and Changhsingian) and Permian–Triassic boundary interval representing a long tectonic quiescence, the last rifting episode started with an abrupt facies change in the late Griesbachian. Variegated shales, limestones, volcanics, talus breccia, and debris flow deposits were laid down in a half-graben/tilt-block system. As normal faulting has become active, the deposition continued on the subsiding hanging wall side. The stratigraphic gap increased in magnitude as the erosional truncation has incised deeply the footwall side. This initial rifting phase in the Antalya Nappes is prior to the onset of a stronger and more continuous rifting event that occurred in the Anisian–Carnian interval including a variety of deepwater clastic and carbonate deposits, radiolarites containing sometimes blocks and clasts derived from the basin margins, and volcanic rocks carrying intraoceanic setting character.

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Analytical approach for estimating ground deformation profile induced by normal faulting in undrained clay

Canadian Geotechnical Journal ◽

10.1139/cgj-2012-0145 ◽

2013 ◽

Vol 50 (4) ◽

pp. 413-422 ◽

Cited By ~ 11

Author(s):

Q.P. Cai ◽

Charles W.W. Ng

Keyword(s):

Ground Deformation ◽

Error Function ◽

Hanging Wall ◽

Numerical Data ◽

Theoretical Models ◽

Failure Surface ◽

Vertical Displacement ◽

Normal Faulting ◽

Soil Thickness ◽

Undrained Shear

Although theoretical models have been developed to predict the location of the failure surface in soil induced by bedrock faulting, no analytical tool is available to estimate subsurface ground deformation. In this paper, a newly developed semi-empirical approach is introduced and developed for calculating surface and subsurface deformations induced by normal faulting in undrained clay. Based on observations from centrifuge model tests, the ground deformation mechanisms are identified by three regions; namely, a stationary zone, a shearing zone, and a rigid body zone. By using an error function to represent vertical displacement continuously, the ground deformation profile can be described quantitatively. It is revealed that the ground deformation profile depends on vertical displacement of the bedrock hanging wall, soil thickness, dip angle of the bedrock fault plane, and a shape parameter that is a function of the undrained shear modulus normalized by the undrained shear strength. Validation and consistent agreement are obtained between calculated ground deformation profiles and other independent centrifuge test results and reported numerical data.

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Channel flow, tectonic overpressure, and exhumation of high-pressure rocks in the Greater Himalayas

10.5194/se-2018-37 ◽

2018 ◽

Author(s):

Fernando O. Marques ◽

Nibir Mandal ◽

Subhajit Ghosh ◽

Giorgio Ranalli ◽

Santanu Bose

Keyword(s):

Current Knowledge ◽

Dynamic Pressure ◽

Hanging Wall ◽

Metamorphic Grade ◽

Lithostatic Pressure ◽

Normal Faulting ◽

Single Model ◽

Subduction Channel ◽

Mouth Width ◽

Grade 3

Abstract. The Himalayas are the archetype of continental collision, where a number of long-standing fundamental problems persist in the Greater Himalayan Sequence (GHS): (1) contemporaneous reverse and normal faulting; (2) inversion of metamorphic grade; (3) origin of high- (HP) and ultra-high (UHP) pressure rocks; (4) mode of ductile extrusion and exhumation of HP and UHP rocks close to the GHS hanging wall; (5) flow kinematics in the subduction channel; and (6) tectonic overpressure, here defined as TOP = P/PL where P is total (dynamic) pressure and PL is lithostatic pressure. In this study we couple Himalayan geodynamics to numerical simulations to show how one single model, upward-tapering channel (UTC) flow, can be used to find a unified explanation for the evidence. The UTC simulates a flat-ramp geometry of the main underthrust faults, as proposed for many sections across the Himalayan continental subduction. Based on the current knowledge of the Himalayan subduction channel geometry and geological/geophysical data, the simulations predict that a UTC can be responsible for high TOP (> 2). TOP increases exponentially with decrease in UTC's mouth width, and with increase in underthrusting velocity and channel viscosity. The highest overpressure occurs at depths or

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Numerical Investigation of Factors Influencing Oil and Gas Lifelines Behavior due to Normal Faulting Geo-Hazard

Current World Environment ◽

10.12944/cwe.10.special-issue1.97 ◽

2015 ◽

Vol 10 (Special-Issue1) ◽

pp. 806-813

Author(s):

Reza Khaksar ◽

Majid Moradi

Keyword(s):

Oil And Gas ◽

Hanging Wall ◽

Small Scale ◽

Foot Wall ◽

Buried Pipeline ◽

Normal Faulting ◽

Geotechnical Centrifuge ◽

Centrifuge Model ◽

Factors Influencing ◽

Centrifuge Model Tests

In this study, some factors influencing the response of buried oil and gas lifelines subjected to normal faulting are investigated. Due to such phenomenon, the stress, strain and displacement are induced in pipeline. Finite element code of Abaqus has been employed to model pipe and its surrounding soil considering material nonlinearities, soil-pipe interaction and foot wall and hanging wall interface. The numerical model has been calibrated through some small scale geotechnical centrifuge model tests and based on such calibrated model, some factors influencing the response of buried pipeline has been investigated.

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Gamma-ray spectroscopy in structural correlations: an example from the Neoproterozoic Dalradian succession of Donegal (NW Ireland)

Geological Magazine ◽

10.1017/s0016756800003976 ◽

2000 ◽

Vol 137 (3) ◽

pp. 319-333 ◽

Cited By ~ 4

Author(s):

M. J. HADLEY ◽

A. RUFFELL ◽

A. G. LESLIE

Keyword(s):

Shear Zone ◽

Cross Sections ◽

Gamma Ray ◽

Hanging Wall ◽

Well Logs ◽

The Novel ◽

Ductile Shear Zone ◽

Normal Faulting ◽

Fold And Thrust Belt ◽

Geophysical Well Logs

The Caledonian Horn Head Slide is a spectacular ductile shear zone transecting Neoproterozoic Appin Group Dalradian metasediments in Donegal (NW Ireland). Two conflicting stratigraphic interpretations exist for the inverted succession exposed in the hanging wall of the structure. These are based on correlation with two quite separate exposed pelite formations elsewhere. The two formations are lithologically indistinct and unfossiliferous. Here we document the novel use of assayed and logged spectral gamma-ray measurements in comparing the contentious pelite in the hanging wall of the Horn Head Slide to the two possible correlative pelite formations from a wide area of their unequivocal outcrop. The data from the contentious pelite show a clear statistical and stratigraphical affinity with one candidate unit only, thus providing the stratigraphical definition necessary for refining previous cross-sections. A new model, based on our spectral gamma-ray correlation, is proposed to account for the northwestwards directed emplacement of the Lower Falcarragh Pelite Formation along the slide. This model requires pre-Caledonian normal faulting as a precursor to the ensuing compressional event in which stratigraphically younger rocks were thrust over older, a common instance in fold and thrust belt geometry. Our work suggests that spectral gamma-ray measurements may provide a rapid, field-based method for differentiating unfossiliferous pelite or mudstone units at outcrop and in geophysical well-logs, even in structurally complex areas.

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Faulting, doming and basin formation during orogenic arcuation – the case of the Shkoder-Peja Normal Fault System (northern Albania and Kosovo)

10.5194/egusphere-egu21-14816 ◽

2021 ◽

Author(s):

Marc U. Grund ◽

Mark R. Handy ◽

Jörg Giese ◽

Jan Pleuger ◽

Lorenzo Gemignani ◽

...

Keyword(s):

Hanging Wall ◽

Normal Fault ◽

Sedimentary Basins ◽

Vertical Displacement ◽

Ductile Deformation ◽

Fault System ◽

Normal Faulting ◽

Two Phase ◽

Brittle Faulting ◽

Topographic Constraints

The junction between the Dinarides and the Hellenides coincides with an orogenic bend characterized by a complex system of faults, domes and sedimentary basins. The major structure at this junction is the Shkoder-Peja Normal Fault (SPNF) system, which trends oblique to the orogen and is segmented along strike, with ductile-to-brittle branches in its southwestern and central parts that border two domes in its footwall: (1) the Cukali Dome (RSCM peak-T 190-280&#176;C), a doubly-plunging upright antiform deforming Dinaric nappes, including the Krasta-Cukali nappe with its Middle Triassic to Early Eocene sediments; (2) the newly discovered Decani Dome (RSCM peak-T 320-460&#176;C) delimited to the E by the ~1500 m wide Decani Shear Zone (DSZ) that exposes Paleozoic to Mesozoic strata of the East Bosnian Durmitor nappe (EBD). In the northeasternmost segment, the strike of the SPNF system changes from roughly orogen-perpendicular to orogen-parallel. There, the SPNF system has brittle branches- most notably the Dukagjini Fault (DF) that forms the northwestern limit of the Western Kosovo Basin (WKB).The westernmost ductile-brittle SPNF segment strikes along the southern limb of the Cukali Dome with an increasing vertical offset from 0 m near Shkoder eastwards to >1000 m at the eastern extent of the dome (near Fierza) where normal faulting cuts the nappe contact between the High Karst and Krasta-Cukali unit. The central segment north of the Tropoja Basin, with several smaller branches changing in strike, has a vertical throw of at least 1500 meters based on topographic constraints. Even further to the northeast, the SPNF system includes the moderately E-dipping DSZ juxtaposing the EBD in its footwall against m&#232;lange of the West Vardar unit in its hanging wall, where offset is difficult to determine. 3 km eastwards, in the hanging wall to the DSZ, the brittle DF accommodates another 1000 m of vertical displacement as constrained by maximum depth of sediments of the WKB.Ductile deformation along the Cukali and Decani Domes occurred sometime between the end of Dinaric thrusting and the formation of the WKB. Brittle faulting partly reactivates ductile segments, but also creates new branches (DF) within the hanging wall of the ductile DSZ. These were active during mid-Miocene to Pliocene times as constrained by syn-tectonic sediments in the WKB. We interpret the SPNF system as a two-phase composite extensional structure with normal faulting that migrated from its older trace along the ductile DSZ to the brittle DF as indicated by cross-cutting relations. The Decani Dome, with higher metamorphic temperature conditions than the Cukali Dome, may reflect the south-westernmost extent of late Paleogene extension in the Dinarides. It may be related to other core complexes and possibly to limited subduction rollback beneath the Dinarides (Matenco and Radivojevi, 2012). Extension from mid-Miocene time onwards was probably related to Hellenic CW rotation during Neogene orogenic arcuation, possibly triggered by enhanced rollback beneath the Hellenides (Handy et al., 2019).Handy, M.R.,et al. 2019: Tectonics, v. 38, p. 2803&#8211;2828, doi:10.1029/2019TC005524.Matenco, L.,& Radivojevi, D. 2012: Tectonics, v. 31, p. 1&#8211;31, doi:10.1029/2012TC003206.

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Pluton emplacement by wall-rock thrusting, hanging-wall translation and extensional collapse: latest Devonian plutons of the Cobequid fault zone, Nova Scotia, Canada

Geological Magazine ◽

10.1017/s001675680000902x ◽

1996 ◽

Vol 133 (3) ◽

pp. 285-298 ◽

Cited By ~ 18

Author(s):

I. Koukouvelas ◽

G. Pe-Piper ◽

D. J. W. Piper

Keyword(s):

Fault Zone ◽

Hanging Wall ◽

Wall Rock ◽

Normal Faulting ◽

Flower Structure ◽

Pluton Emplacement ◽

Second Stage ◽

Type Granite ◽

Two Phases ◽

Rapid Uplift

AbstractLatest Devonian A-type granite-gabbro plutons, in part ductilely deformed, are spatially associated with the strike-slip Cobequid fault zone. The youngest intrusions are close to the Cobequid fault zone, which was the main conduit for magma. Two phases of deformation accompanying magma emplacement are recognized. Early magmas intruded ductile rocks during left-lateral oblique thrust movements. A second stage of right-lateral oblique slip normal faulting accommodated uplift of the plutons when coarse granite was emplaced in the crestal regions. Cross-cutting late stage porphyries, granitic clasts in marginal basins cut by granitic dykes, and superposition of brittle on ductile structures all indicate rapid uplift of the plutons. The geometry of the Cobequid fault zone shows that pluton emplacement was not the result of extension in releasing bends during transcurrent shear. Rather, flower-structure high-angle faults acted as magma conduits and space was created by two processes: translation of wall rocks along thrust faults at depth, developing space away from the master fault zone and backward collapse of the uplifted magma chamber creating space towards the fault zone.

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