Structural and stratigraphic development of the Whipple-Chemehuevi detachment fault system, southeastern California: Implications for the geometrical evolution of domal and basinal low-angle normal faults

1992 ◽  
Vol 104 (6) ◽  
pp. 659-674 ◽  
Author(s):  
AN YIN ◽  
JOHN F. DUNN
Keyword(s):  
Detachment Fault ◽  
Fault System ◽  
Normal Faults

scholarly journals Structural cross sections through the Corinth-Patras detachment fault-system in Northern Peloponnesus (Aegean Arc, Greece)

2001 ◽  
Vol 34 (1) ◽  
pp. 235 ◽  
Author(s):  
N. FLOTTÉ ◽  
D. SOREL
Keyword(s):  
Cross Sections ◽  
Detachment Fault ◽  
Fault System ◽  
Normal Faults ◽  
Field Observations ◽  
Structural Mapping ◽  
The North ◽  
Gulf Of Corinth ◽  
Aegean Arc

Structural mapping in northern Peloponnesus reveals the emergence of an E-W striking, more than 70km long, low angle detachment fault dipping to the north beneath the Gulf of Corinth. This paper describes four north-south structural cross-sections in northern Peloponnesus. Structural and sedimentological field observations show that in the studied area the normal faults of northern Peloponnesus branch at depth on this major low angle north-dipping brittle detachment. The southern part of the detachment and the related normal faults are now inactive. To the north, the active Helike and Aigion normal faults are connected at depth with the seismically active northern part of the detachment beneath the Gulf of Corinth.

scholarly journals Seismic characteristics of polygonal fault systems in the Great South Basin, New Zealand

2020 ◽  
Vol 12 (1) ◽  
pp. 851-865
Author(s):  
Sukonmeth Jitmahantakul ◽  
Piyaphong Chenrai ◽  
Pitsanupong Kanjanapayont ◽  
Waruntorn Kanitpanyacharoen
Keyword(s):  
Three Dimensional ◽  
Late Eocene ◽  
Seismic Survey ◽  
Fault System ◽  
Normal Faults ◽  
Tier 2 ◽  
South Basin ◽  
Fault Systems ◽  
Tier 1 ◽  
Polygonal Fault

AbstractA well-developed multi-tier polygonal fault system is located in the Great South Basin offshore New Zealand’s South Island. The system has been characterised using a high-quality three-dimensional seismic survey tied to available exploration boreholes using regional two-dimensional seismic data. In this study area, two polygonal fault intervals are identified and analysed, Tier 1 and Tier 2. Tier 1 coincides with the Tucker Cove Formation (Late Eocene) with small polygonal faults. Tier 2 is restricted to the Paleocene-to-Late Eocene interval with a great number of large faults. In map view, polygonal fault cells are outlined by a series of conjugate pairs of normal faults. The polygonal faults are demonstrated to be controlled by depositional facies, specifically offshore bathyal deposits characterised by fine-grained clays, marls and muds. Fault throw analysis is used to understand the propagation history of the polygonal faults in this area. Tier 1 and Tier 2 initiate at about Late Eocene and Early Eocene, respectively, based on their maximum fault throws. A set of three-dimensional fault throw images within Tier 2 shows that maximum fault throws of the inner polygonal fault cell occurs at the same age, while the outer polygonal fault cell exhibits maximum fault throws at shallower levels of different ages. The polygonal fault systems are believed to be related to the dewatering of sedimentary formation during the diagenesis process. Interpretation of the polygonal fault in this area is useful in assessing the migration pathway and seal ability of the Eocene mudstone sequence in the Great South Basin.

scholarly journals Influence of inherited structural domains and their particular strain distributions on the Roer Valley Graben evolution from inversion to extension

2020 ◽  
Author(s):  
Jef Deckers ◽  
Bernd Rombaut ◽  
Koen Van Noten ◽  
Kris Vanneste
Keyword(s):  
Late Cretaceous ◽  
Fault System ◽  
Normal Faults ◽  
Geological Model ◽  
Structural Domains ◽  
Stress Directions ◽  
Roer Valley Graben ◽  
Western Border ◽  
Border Fault ◽  
As Stress

Abstract. After their first development in the middle Mesozoic, the overall NW-SE striking border fault systems of the Roer Valley Graben were reactivated as reverse faults under Late Cretaceous compression (inversion) and reactivated again as normal faults under Cenozoic extension. In Flanders (northern Belgium), a new geological model was created for the western border fault system of the Roer Valley Graben. After carefully evaluating the new geological model, this study shows the presence of two structural domains in this fault system with distinctly different strain distributions during both Late Cretaceous compression and Cenozoic extension. A southern domain is characterized by narrow ( 10 km) distributed faulting. The total normal and reverse throw in the two domains was estimated to be similar during both tectonic phases. The repeated similarities in strain distribution during both compression and extension stresses the importance of inherited structural domains on the inversion/rifting kinematics besides more obvious factors such as stress directions. The faults in both domains strike NW-SE, but the change in geometry between them takes place across the oblique WNW-ESE striking Grote Brogel fault. Also in other parts of the Roer Valley Graben, WNW-ESE striking faults are associated with major geometrical changes (left-stepping patterns) in its border fault system. This study thereby demonstrates the presence of different long-lived structural domains in the Roer Valley Graben, each having their particular strain distributions that are related to the presence of non-colinear faults.

scholarly journals Methodology for Earthquake Rupture Rate estimates of fault networks: example for the Western Corinth Rift, Greece

2017 ◽  
Author(s):  
Thomas Chartier ◽  
Oona Scotti ◽  
Hélène Lyon-Caen ◽  
Aurélien Boiselet
Keyword(s):  
Active Faults ◽  
Slip Rate ◽  
Seismic Hazard Assessment ◽  
System Level ◽  
Fault System ◽  
Normal Faults ◽  
Accurate Estimation ◽  
Probabilistic Seismic Hazard Assessment ◽  
Earthquake Rupture ◽  
Multiple Faults

Abstract. Modelling the seismic potential of active faults is a fundamental step of probabilistic seismic hazard assessment (PSHA). An accurate estimation of the rate of earthquakes on the faults is necessary in order to obtain the probability of exceedance of a given ground motion. Most PSHA studies consider faults as independent structures and neglect the possibility of multiple faults or fault segments rupturing simultaneously (Fault to Fault -FtF- ruptures). The latest Californian model (UCERF-3) takes into account this possibility by considering a system level approach rather than an individual fault level approach using the geological , seismological and geodetical information to invert the earthquake rates. In many places of the world seismological and geodetical information long fault networks are often not well constrained. There is therefore a need to propose a methodology relying only on geological information to compute earthquake rate of the faults in the network. In this methodology, similarly to UCERF-3, a simple distance criteria is used to define FtF ruptures and consider single faults or FtF ruptures as an aleatory uncertainty. Rates of earthquakes on faults are then computed following two constraints: the magnitude frequency distribution (MFD) of earthquakes in the fault system as a whole must follow an imposed shape and the rate of earthquakes on each fault is determined by the specific slip-rate of each segment depending on the possible FtF ruptures. The modelled earthquake rates are then confronted to the available independent data (geodetical, seismological and paleoseismological data) in order to weigh different hypothesis explored in a logic tree. The methodology is tested on the Western Corinth Rift, Greece (WCR) where recent advancements have been made in the understanding of the geological slip rates of the complex network of normal faults which are accommodating the ~15 mm/yr North-South extension. Modelling results show that geological, seismological extension rates and paleoseismological rates of earthquakes cannot be reconciled with only single fault rupture scenarios and require hypothesising a large spectrum of possible FtF rupture sets. Furthermore, in order to fit the imposed regional Gutenberg-Richter MFD target, some of the slip along certain faults needs to be accommodated either with interseismic creep or as post-seismic processes. Furthermore, individual fault’s MFDs differ depending on the position of each fault in the system and the possible FtF ruptures associated with the fault. Finally, a comparison of modelled earthquake rupture rates with those deduced from the regional and local earthquake catalogue statistics and local paleosismological data indicates a better fit with the FtF rupture set constructed with a distance criteria based on a 5 km rather than 3 km, suggesting, a high connectivity of faults in the WCR fault system.

Quantifying fault reactivation risk in the western Gippsland Basin using geomechanical modelling

2013 ◽  
Vol 53 (1) ◽  
pp. 255 ◽  
Author(s):  
Ernest Swierczek ◽  
Cui Zhen-dong ◽  
Simon Holford ◽  
Guillaume Backe ◽  
Rosalind King ◽  
...  
Keyword(s):  
Structural Model ◽  
Strike Slip ◽  
Fault Reactivation ◽  
Fault System ◽  
Co2 Injection ◽  
Normal Faults ◽  
Surface Geometry ◽  
Northern Margin ◽  
Fault Surface ◽  
Gippsland Basin

The Rosedale Fault System (RFS) bounds the northern margin of the Gippsland Basin on the Southern Australian Margin. It comprises an anastomosing system of large, Cretaceous-age normal faults that have been variably reactivated during mid Eocene-Recent inversion. A number of large oil and gas fields are located in anticlinal traps associated with the RFS, and in the future these fields may be considered as potential storage sites for captured CO2. Given the evidence for geologically recent fault reactivation along the RFS, it is thus necessary to evaluate the potential impacts of CO2 injection on fault stability. The analysis and interpretation of 3D seismic data allowed the authors to create a detailed structural model of the western section of the RFS. Petroleum geomechanical data indicates that the in-situ stress in this region is characterised by hybrid strike-slip to reverse faulting conditions where SHmax (40.5 MPa/km) > SV (21 MPa/km) ~ Shmin (20 MPa/km). The authors performed geomechanical modelling to assess the likelihood of fault reactivation assuming that both strike-slip and reverse-stress faulting regimes exist in the study area. The authors’ results indicate that the northwest to southeast and east-northeast to west-southwest trending segments of the RFS are presently at moderate and high risks of reactivation. The authors’ results highlight the importance of fault surface geometry in influencing fault reactivation potential, and show that detailed structural models of potential storage sites must be developed to aid risk assessments before injection of CO2.

Neogene and active brittle deformation on Amorgos Island (Greece)

2020 ◽  
Author(s):  
Jan Behrmann ◽  
Jakob Schneider ◽  
Benjamin Zitzow
Keyword(s):  
Moment Tensor ◽  
Spatial Relationship ◽  
Shear Zones ◽  
Fault System ◽  
Normal Faults ◽  
Small Scale ◽  
Past Century ◽  
Fault Plane Solutions ◽  
Moment Tensor Solution ◽  
Late Neogene

<p>Amorgos is the south-eastern outpost of the Cyclades Islands in the Aegean Sea, which forms part of the Neogene-Quaternary zone of crustal and lithospheric N-S upper plate extension northward of the Hellenic subduction zone and deep sea trench. Apart from subduction-related earthquakes further south, the southern Aegean is affected by frequent earthquakes sourced in the upper plate. The twin earthquakes of 9 July 1956, followed by a strong tsunami, were the strongest events of this kind in the past Century. Hypocenters are related to a NE-SW oriented normal fault bounding the Amorgos-Santorini Graben System. There are questions in the literature regarding the seismic source and fault plane solutions, especially the contribution of a transcurrent faulting component.</p><p>We have analyzed the kinematics of brittle faults exposed on Amorgos Island itself that could be related to Neogene and active extensional and/or transcurrent deformation. Seismic slip often occurs on previously existing faults. Thus, their orientations and kinematics may help shed light on the structure of seismic sources at depth. We present evidence for a complex history of faulting. Early normal detachment faults and shear zones overprint older (rare) reverse faults, and are themselves overprinted by several sets of dominantly dextral NE and SE trending strike slip faults. Youngest is a conjugate set of NE trending high-angle normal faults. These are especially frequent along the SE coast of the island, suggesting a clear spatial relationship with the 1956 rupture. They can be fitted to a moment tensor solution similar to the published solutions for the 1956 Amorgos earthquake. The kinematic solution for the population of early normal faults suggests that the whole of Amorgos Island may have experienced a 15° NNW tilt during later extension, which lets us suspect that the island could be a tilted block of a much larger fault system. Regarding long-term late Neogene to Quaternary kinematics, dextrally transtensive fault slip is required to fit the regional pattern of extensional deformation in the Aegean, and this is reflected by small-scale brittle faulting on Amorgos.</p>

Geomorphic evidence for active, co-seismic slip along a low-angle normal fault: Panamint Valley, California

2020 ◽  
Author(s):  
Eric Kirby ◽  
Israporn (Grace) Sethanant ◽  
John Gosse ◽  
Eric McDonald ◽  
J Doug Walker
Keyword(s):  
Seismic Hazard ◽  
Normal Fault ◽  
Basin And Range ◽  
Detachment Fault ◽  
Airborne Lidar ◽  
Fault System ◽  
Seismic Slip ◽  
The Past ◽  
Detachment Faults ◽  
Fault Scarps

<p>The mechanical feasibility of co-seismic displacement along low-angle normal fault systems remains an outstanding problem in tectonics.  In the southwestern Basin and Range of North America, large magnitude extension during Miocene – Pliocene time was accommodated along a regionally extensive system of low-angle detachment faults.  Whether these faults remain active today and, if so, whether they rupture during large earthquakes are questions central to understanding the geodynamics of distributed lithospheric deformation and associated seismic hazard.  Here we evaluate the geometric and kinematic relationships of fault scarps developed in Pleistocene – Holocene alluvial and lacustrine deposits with low-angle detachment faults observed along the western flank of the Panamint Range, in eastern California.  We combine analysis of high-resolution topography generated from airborne LiDAR and photogrammetry with a detailed chronology of alluvial fan surfaces and a calibrated soil chronosequence to characterize the recent activity of the fault system.  The range-front fault system is coincident with a low-angle (15-20°), curviplanar detachment fault that is linked to strike-slip faults at its southern and northern ends.  Fanglomerate deposits in the hanging wall of the detachment are juxtaposed with brecciated bedrock in the footwall across a narrow fault surface marked by clay-rich gouge.  Isochron burial dating of the fanglomerate using the <sup>26</sup>Al and <sup>10</sup>Be requires displacement in the past ~800 ka.  The degree of soil development in younger alluvial deposits in direct fault contact with the footwall block suggest displacement along the main detachment in the past as ~80-100 ka.  The geometry of recent fault scarps in Holocene alluvium mimic range-scale variations in strike of the curviplanar detachment fault, suggesting that scarps merge with the detachment at depth.  Moreover, fault kinematics inferred from displaced debris-flow levees and from fault striae on the bedrock range front are consistent with slip on a low-angle detachment system beneath the valley.  Finally, paleoseismic results from a trench at the southern end of the fault system suggest 3-4 surface ruptures during past ~4-5 ka, the most recent of which (MRE) occurred ~330-485 cal yr BP.  Scarps related to the MRE can be traced for at least ~50 km northward along the range front and imply surface displacements of 2-4 meters during this event.  Thus, we conclude that ongoing dextral shear along the margin of the Basin and Range is, in part, accommodated by co-seismic slip along low-angle detachment faults in Panamint Valley.  Our results have important implications for the interaction of fault networks and seismic hazard in the region.</p>

From Corinth gulf extension to Ionian subduction/collision (W. Greece): micro-seismicity survey to constrain local tectonics and regional geodynamics

2020 ◽  
Author(s):  
Valentine Lefils ◽  
Alexis Rigo ◽  
Efthimios Sokos
Keyword(s):  
Seismic Velocity ◽  
Deformation Mode ◽  
Velocity Model ◽  
Fault System ◽  
Normal Faults ◽  
Corinth Gulf ◽  
National Network ◽  
The North ◽  
Gulf Of Corinth ◽  
Seismological Network

<p>The North-Eastern zone of the Gulf of Corinth in Greece is characterized by the rotation of a micro-plate in formation. The Island Akarnanian Block (IAB) have been progressively individualized since the Pleistocene (less than ~ 1.5 My ago). This micro-plate is the result of a larger-scale tectonic context with, on one side the N-S extension of the Gulf of Corinth to the East, and on the other side the Hellenic subduction to the South and the Apulian collision to the West. To the Northeast, the IAB micro-plate is bounded by a large North-South sinistral strike-slip fault system, the Katouna-Stamna Fault (KSF) and by several normal faults. To the North, normal faults reach the limit between Apulian and Eurasian plates and to the East, they form the East-West graben of Trichonis lake.</p><p>Although the structures and dynamics behind the Gulf of Corinth extension are today relatively known, nevertheless, the set of faults linking the Gulf of Corinth to the Western subduction structures remain poorly studied. The seismicity recorded by the Greek national network shows discrepancies regarding to the faults mapped on the surface.</p><p>At the end of 2015, a new micro-seismicity campaign started with the deployment of a temporary seismological network in an area ranging from the Gulf of Patras to the Amvrakikos Gulf toward the North. This network includes 17 seismic stations, recording continuously, added to the permanent stations of the Corinth Rift Laboratory (CRL) and of the Hellenic Unified Seismic Network (HUSN).</p><p>The analysis of the seismological records is still in process for the 2016 and 2017 years. Our study consists first in picking the <em>P</em>- and <em>S</em>- waves, and then to precisely localize the seismic events recorded by our temporary seismological network combined with the permanent ones. We will present here the event location map obtained for the 2016-2017 period, a new seismic velocity model, and focal mechanisms. The seismic activity including thousands of events, is characterized by the presence of numerous clusters of few days to few weeks duration. The clusters are analysed in detail by relative relocations in order to appraise their physical processes and their implications in the fault activity. We will discuss the deformation mode of the region and build a seismotectonic model consistent with the regional geodynamics and observations.</p>

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