Steep Plane Research Articles

Fluid-Induced Metamorphism and Deformation at the Eastern Boundary of the Sveconorwegian Province

Abstract The Sveconorwegian orogen in Scandinavia and the Grenville orogen in Canada are both remnants of large and hot orogens that formed part of the supercontinent Rodinia around 1 billion years ago. Formerly deeply buried portions of crust in these orogens are exposed and offer insights into the tectonic dynamics of the basement within large orogens. The Eastern Segment of the Sveconorwegian Province hosts a ~ 30 000 km2 crustal portion that was buried to c. 40 km depth at a late stage of the orogeny, 980–960 Ma ago, and is bound towards the foreland in the east by a ~ 25 km wide zone of step anastomosing deformation, the Frontal wedge. This zone represents the outermost ductile deformation that developed within the crystalline basement in the orogen. We investigated a heterogeneously deformed and recrystallised syenodiorite with the aim to understand the character of the deformation-related metamorphism within the Frontal wedge. Field relations, microtextures, and mineral reactions show that the metamorphic recrystallisation was governed by hydrous fluid infiltration along the ductile deformation zones. Equilibrium was attained on a millimetre scale only and metamorphic recrystallisation was dependent on the introduction of hydrous fluid. The metamorphism reached high-pressure epidote-amphibolite-facies; geothermobarometric estimates suggest 540°C to 600°C and 9 to 12 kbar. Metamorphic zircon formed during the breakdown of Zr-bearing igneous phases, primarily baddeleyite. SIMS U–Pb analyses of igneous zircon and baddeleyite date the igneous crystallisation of the syenodiorite at 1230 ± 6 Ma. Metamorphic zircon grains are <20 μm and too small for precise dating, but yielded ages around 1 Ga. Collectively, the metamorphic data indicate that subvertical movements along steep planes within the Frontal wedge allowed for the regional-scale tectonic burial to ~40 km depth of the Eastern Segment to the west. Some of the same steep deformation structures were re-utilised as discrete movement planes during later exhumation.

Earthquakes Induced by Rapid Loading of Faults During Pulichintala Reservoir Impoundment in the Stable Continental Region of India

AbstractThe first stage impoundment of the Pulichintala reservoir in the Proterozoic Cuddapah basin in the southeastern Indian shield began in August 2014. The second stage of impoundment started in 2019 when the height of the dam was increased and the filling of the reservoir was rapid. Soon after earthquakes started occurring which continued for a few months with a maximum magnitude of ML 4.6 on 25 January 2020. Two distinct clusters within the shallow crust were identified, which follow the faults/shear zones in the region. The estimated focal mechanisms with predominant strike slip motion on steep planes and the derived stress state are consistent with the regional stress and plate motion of the Indian plate. We simulated the influence of reservoir impoundment on the inferred seismogenic faults and found that the stress and pore pressure due to reservoir load indeed promoted failure, thus inducing earthquakes. We ascribe the induced earthquakes to rapid filling, longer and higher retention of high‐water levels during 2019–2020, which caused a stress change of 4–8 kPa. This stress change was at least two orders of magnitude higher than the typical tectonic loading rate in the stable continental region of the Indian Shield.

Two-Staged Rupture of the 19 October 2020 Mw 7.6 Strike-Slip Earthquake Illuminated the Boundary of Coupling Variation in the Shumagin Islands, Alaska

Abstract On 19 October 2020, an Mw 7.6 earthquake occurred within the Shumagin Islands, Alaska, which is the largest strike-slip earthquake occurred in the shallow subducted plates with abundant seismic observations. Here, we relocated the earthquake sequence, implemented back-projection analyses, and finite-fault inversion to investigate the source processes of the mainshock, and calculated mainshock focal mechanisms using the polarities of P waves and W-phase inversion, respectively. Our results show that the faulting of the mainshock can be divided into two segments with the initial rupture along a steep plane (strike = 15°, dip = 81°) and propagation southeastward along a more shallowly dipping plane (strike = 344°, dip = 48°). The inferred strikes of the mainshock faults are similar to the orientations of preexisting structures in the source region, likely indicating that the 2020 Mw 7.6 earthquake ruptured along the preexisting plate fabric in the downgoing plate. The fabrics are located at the boundary with significant variations of the plate coupling, indicating that these structures within the subducting plate may affect the interplate coupling or as a result of the varying interplate coupling in subduction zones.

Linear Relationships Among the Hand and Clubhead Motion Characteristics in Golf Driving in Skilled Male Golfers.

The purpose of this study was to investigate the linear relationships among the hand/clubhead motion characteristics in golf driving in skilled male golfers (n = 66; handicap ≤ 3). The hand motion plane (HMP) and functional swing plane (FSP) angles, the HMP-FSP angle gaps, the planarity characteristics of the off-plane motion of the clubhead, and the attack angles were computed from the drives captured by an optical motion capture system. The HMP angles were identified as the key variables, as the HMP and FSP angles were intercorrelated, but the plane angle gaps, the planarity bias, and the attack angles showed correlations to the HMP angles primarily. Three main swing pattern clusters were identified. The parallel HMP-FSP alignment pattern with a small direction gap was associated with neutral planarity and planar swing pattern. The inward alignment pattern with a large inward direction gap was characterized by flat planes, follow-through-centric planarity, spiral swing pattern, and inward/downward impact. The outward alignment pattern with a large outward direction gap was associated with steep planes, downswing-centric planarity, reverse spiral swing, and outward/upward impact. The findings suggest that practical drills targeting the hand motion pattern can be effective in holistically reprogramming the swing pattern.

Anatomy of October 30, 2020, Samos (Sisam) –Kuşadası earthquake (MW 6.92) and its influence on Aegean earthquake hazard

We investigated rupture geometry, size, and slip distribution of October 30, 2020, Samos (Sisam)-Kuşadası earthquake combining seismographs, GPS measurements, and SAR analysis. Right after the earthquake, we measured 13 additional campaign-based GPS sites to intensify the available GPS network consisting of 10 continuous stations. We combined all available seismographs to have the best possible accuracy for mainshock and aftershock hypocenter locations. We compiled all available seismic profiles and integrated them using high-resolution bathymetry to map seismically active faults. The mainshock hypocenter is located at 37.913 ± 0.009 N° and 26.768 ± 0.017 E° and a depth of 12.3 ± 1.7 km. Our fault plane solution shows that the mainshock has almost a pure normal-type mechanism. Based on accurate aftershock locations as well as InSAR results, the mainshock rupture is subsegmented with two north-dipping rupture planes. The rupture probably starts on a low angle plane generating 1.1 m average slip between the depths of 9-14 km. It merges to a steep plane at 9 km depth where it generates 1.2 m average slip extending towards the surface near the shoreline of Samos (Sisam) Island. Total size of the two rupture planes and their average slips determine that the magnitude of the mainshock is (Mw) 6.92 ± 0.02. The mainshock has substantially increased Coulomb stress on several fault segments near the towns Kuşadası and Söke, which have the potentials to generate strong earthquakes. It also nonnegligibly increased Coulomb stress on several fault segments south of İzmir giving a warning for increased earthquake hazard in this highly inhabited area.

Excessive seismicity over a limited source: the August 2019 earthquake swarm near Mt. Salak in West Java (Indonesia)

The triggering mechanism of swarm-like seismicity in the Java Island of Indonesia is generally not well understood. Understanding earthquake swarm phenomena in various tectonic settings can be improved by the detection of micro-earthquakes; however, such a catalog is not available due to various reasons including the existing limited seismic network and using an outdated algorithm for event detection. In this study, we analyze the seismic waveforms and explore the detection capability of small earthquakes during the August 2019 earthquake sequence near Mt. Salak (West Java) by using the known matched filter technique (MFT) and relocated events as templates. We analyze continuous waveforms from seven broadband seismic stations in a 150 km radius around the source center and for a ~ 1 month of data. Our derived complete catalog enables us to analyze the frequency-magnitude distribution of the sequence as well as the spatiotemporal evolution of micro-seismicity. The six largest events were hybrid-like-type volcano-tectonic earthquakes with oblique-thrust mechanisms. The relocation procedure shows that all of the events are located within an area of ~ 2 × 2 km2, probably bounded at 9–12 km of depth. The pattern of seismicity distribution was not clear; however, focal mechanisms might indicate N/NW or E/SE-trending orientation with a steep plane. We detect 280 additional micro-earthquakes to the improved catalog. The b-value of the sequence is close to 1.1, typical for many volcano-tectonic events. We show that the swarm might be initiated by the fluid intrusion into the seismogenic zone while the stress changes from the largest event affected the evolution of swarm.

Analysis of the 15 December 2017 Mw 6.5 and the 23 January 2018 Mw 5.9 Java Earthquakes

ABSTRACT The west part of Java sits at the transition from oblique subduction of the Australian plate under the Sunda block of the Eurasian plate along Sumatra to orthogonal convergence along central and eastern Java. This region has experienced several destructive earthquakes, the 17 July 2006 Mw 7.7 earthquake and tsunami off the coast of Pangandaran and the 2 September 2009 Mw 7 earthquake, located off the coast of Tasikmalaya. More recently, on 15 December 2017, an Mw 6.5 earthquake occurred off the coast near Pangandaran, and, on 23 January 2018, an Mw 5.9 earthquake occurred offshore Lebak, between Pelabuhan Ratu and Ujung Kulon. Ground shaking and damage occurred locally and in Jakarta on the northern coast of Java. In this study, we use the double-difference technique to relocate both mainshocks and 10 months of seismicity (228 events) following the earthquakes. The relocation result improved the mainshock locations and depth distribution of earthquakes. Moment tensor of the December 2017 event located the hypocenter at ∼108 km depth within the subducting slab. The best-fit relocation places the depth at 61 km, close to the slab interface. Aftershocks occur between 68 and 86 km depth and align along a steeper plane than slab geometry models. The January 2018 event is located at ∼46 km depth. Aftershocks form a near-vertical, pipe-like structure from the plate interface to ∼10 km depth. A burst of aftershocks immediately following the mainshock shows a shallowing upward trend at a rate of ∼2 km/hr, suggesting that a fluid pressure wave released from the oceanic crust is causing brittle failure in the overriding plate, followed by upward migration of fluids. Five months later, shallow (<25 km) seismicity collocates with background seismicity, suggesting the January 2018 event activated the Pelabuhan Ratu fault system close to the coast.

Fault image enhancement using a forward and backward diffusion method

Fault interpretation is a key step for seismic structural interpretation and reservoir characterization. In conventional approach, faults are identified as reflection discontinuity or abruption in post-stack seismic data. In order to highlight fault, several fault attributes by measuring waveform similarity or diversity have been proposed. However, noise and stratigraphic features can also be highlighted in a fault attribute image. We propose a forward and backward diffusion method to enhance the fault image so that the noisy features which unrelated to faults are suppressed and the fault features are sharpened. We first estimate the planarity (linearity in 2D) and fault orientation (strike and dip) of every sample in fault image by using a PCA-based algorithm. Combining the planarity and fault orientation, we then construct fault probability map based on the assumption that faults can be seemed as relatively steep planes in a small spatial window. Thanks to the fault probability map, we can adaptively switch the diffusion process from a forward mode to a backward mode. Forward diffusion force is used to suppress the non-fault features within the low fault probability area and backward diffusion force is used to enhance the fault features within the high fault probability area. A real 3D example is included to demonstrate that this method can effectively suppress the noise and sharpen the faults. Furthermore, automatic fault tracking on an enhanced fault image can get more accurate result than on an original fault image.

Shallow Seismic Reflection Investigation of Unstable Sedimentary Deposits in the Dăneasa Area, Romania

Results of shallow seismic reflection measurements, performed over an area with unstable sedimentary formations in the near subsurface, are presented. The investigated area is located on the Olt Valley, in the vicinity of the Dăneasa village, Romania, crossed by a railway line and a national road on which the traffic is very intense. Data were collected along a linear profile, with a length of 94 m, perpendicular to the railway line and the national road using a fixed spread of 48 vertical-component geophones with the sources rolling along the acquisition line. The surface waves generated by the intense traffic on the national road interfered with the seismic arrivals seen on most of shot gathers, especially with those seen on the traces from receiver locations greater than 48 m. The interrupted continuity of two shallow reflectors, R1 and R2, seen on the depth-converted seismic section at depth values shallower than 30 m, could be interpreted as an effect of the presence of two steep failure planes deveIoped into the ground. A P-wave velocity-depth model down to a depth of 20 m after first-arrival traveltime tomography was then created, on which four sedimentary layers with variable thicknesses and constant velocities, separated by the interfaces L1, L2 and L3, were interpreted. By comparing the depth-converted seismic section with the P-wave velocity-depth model, the reflectors R1 and R2 on the seismic section correspond pretty well with the interfaces L2 and L3 from the velocity-depth model.

Modeling coastal tsunami hazard from submarine mass failures: effect of slide rheology, experimental validation, and case studies off the US East Coast

We perform numerical simulations to assess how coastal tsunami hazard from submarine mass failures (SMFs) is affected by slide kinematics and rheology. Two types of two-layer SMF tsunami generation models are used, in which the bottom (slide) layer is depth-integrated and represented by either a dense Newtonian fluid or a granular flow, in which inter-granular stresses are governed by Coulomb friction (Savage and Hutter model). In both cases, the upper (water) layer flow is simulated with the non-hydrostatic 3D σ-layer model NHWAVE. Both models are validated by simulating laboratory experiments for SMFs made of glass beads moving down a steep plane slope. In those, we assess the convergence of results (i.e., SMF motion and surface wave generation) with model parameters and their sensitivity to slide parameters (i.e., viscosity, bottom friction, and initial submergence). The historical Currituck SMF is simulated with the viscous slide model, to estimate relevant parameters for simulating tsunami generation from a possible SMF sited near the Hudson River Canyon. Compared to a rigid slump, we find that deforming SMFs of various rheology, despite having a slightly larger initial acceleration, generate a smaller tsunami due to their spreading and thinning out during motion, which gradually makes them less tsunamigenic; the latter behavior is controlled by slide rheology. Coastal tsunami hazard is finally assessed by performing tsunami simulations with the Boussinesq long wave model FUNWAVE-TVD, initialized by SMF tsunami sources, in nested grids of increasing resolution. While initial tsunami elevations are very large (up to 25 m for the rigid slump), nearshore tsunami elevations are significantly reduced in all cases (to a maximum of 6.5 m). However, at most nearshore locations, surface elevations obtained assuming a rigid slump are up to a factor of 2 larger than those obtained for deforming slides. We conclude that modeling SMFs as rigid slumps provides a conservative estimate of coastal tsunami hazard while using a more realistic rheology, in general, reduces coastal tsunami impact.

Relocation of Earthquakes in the New Madrid Seismic Zone: Estimation of 1D Velocity Structure and Geometry of a Seismogenic Fault

Abstract Determination of reliable hypocenters of earthquakes is crucial to earthquake seismology and to evaluate hazards associated with earthquakes. There are many associated computer codes for this purpose; however, most of the location algorithms are designed to determine hypocentral parameters based on previously determined velocity models. In contrast, we employed a location method that is independent of the initial velocity model, using a genetic algorithm (GA) to determine an optimal 1D velocity model and the locations of earthquakes. Using this GA, we relocated earthquakes that occurred in the New Madrid Seismic Zone (NMSZ) in the central United States between October 1989 and August 1992. The goal of this work was to delineate the possible fault planes by reliable relocation of those earthquakes and to determine a 1D velocity structure for the NMSZ. A total of 502 earthquakes recorded by 37 Portable Array for Numerical Data Acquisition (PANDA) stations were used in the relocation study. In the relocation process, the root mean square travel‐time residuals were reduced by ∼35%, corresponding to an average of 2.3 km deeper in depth, 0.7 km shift in latitude, and 0.8 km shift in longitude compared with those in the initial catalog locations. The hypocenters of the earthquakes can be subdivided into four groups based on their spatial distributions. The group that corresponds to the Cottonwood Grove fault (CGF) in the southwestern NMSZ represents a very steep plane, whereas the other three groups fall into Reelfoot fault (RF). We inverted P ‐ and S ‐wave travel times from the new hypocentral parameters to determine 1D velocity models. The resulting eight‐layered velocity models consist of a 2 km thick surface layer followed by seven 2 km thick layers, with V P ranges from 5.36 to 6.74 km/s and V S ranges from 2.83 to 3.90 km/s for both CGF and RF regions. Online Material: Interactive visualizations of hypocentral distributions.

Automated full moment tensor inversion of coal mining-induced seismicity

Seismicity induced by coal mining in the Ruhr region, Germany, has been monitored continuously over the last 25 yr. In 2006, a dense temporary network (HAMNET) was deployed to locally monitor seismicity induced by longwall mining close to the town of Hamm. Between 2006 July and 2007 July, more than 7000 events with magnitudes M-L from -1.7 to 2.0 were detected. The spatiotemporal distribution of seismicity shows high correlation with the mining activity. In order to monitor rupture processes, we set up an automated source inversion routine and successfully perform double couple and full moment tensor (MT) inversions for more than 1000 events with magnitudes above M-L -0.5. The source inversion is based on a full waveform approach, both in the frequency and in the time domain, providing information about the centroid location, focal mechanism, scalar moment and full MT. Inversion results indicate a strong dominance of normal faulting focal mechanisms, with a steeper plane and a subhorizontal one. Fault planes are oriented parallel to the mining stopes. We classify the focal mechanisms based on their orientation and observe different frequency-magnitude distributions for families of events with different focal mechanisms; the overall frequency-magnitude distribution is not fitting the Gutenberg-Richter relation. Full MTs indicate that non-negligible opening tensile components accompanied normal faulting source mechanisms. Finally, extended source models are investigated for largest events. Results suggest that the rupture processes mostly occurred along the subvertical planes.

Earthquake occurrence processes in the Indo-Burmese wedge and Sagaing fault region

Earthquakes in the Indo-Burmese wedge and Sagaing fault regions occur in response to the partitioning of the India–Sunda motion along these two distinct boundaries. Under the accretionary wedge of the Indo-Burmese arc, majority of the earthquakes occur in the depth range of 30–60km and define an eastward gently dipping seismicity trend surface that coincides with the Indian slab. The dip of the slab steepens in the east direction and earthquakes occur down to a depth of 150km, though the slab can be traced up to the 660km discontinuity. Although these features are similar to a subduction zone, the nature of the earthquakes and our analysis of their focal mechanisms suggest that these earthquakes are of intra-slab type which occur on steep plane within the Indian plate and the sense of motion implies a northward relative motion with respect to the Sunda plate. Thus these earthquakes and the stress state do not support active subduction across the Indo-Burmese arc which is also consistent with the relative motion of India–Sunda plates. The absence of inter-plate earthquakes, lack of evidence of the occurrence of great earthquakes in the historical records and non-seismogenic nature of the plate interface under the accretionary wedge suggest that seismic hazard due to earthquakes along the plate boundary may be relatively low. However, major intra-slab earthquakes at shallow and intermediate depths may still cause damage in the sediment filled valley regions of Manipur and Cachar in India and Chittagong and Sylhet regions of Bangladesh. In the Sagaing fault region, earthquakes occur through dextral strike slip motion along the north–south oriented plane and the stress state is consistent with the plate motion across the Sagaing fault.

The Mw 7.5 2009 Coco earthquake, north Andaman region

The recent 10 August 2009 Coco earthquake (Mw 7.5), the largest aftershock of the giant 2004 Sumatra Andaman earthquake, occurred within the subducting India plate under the Burma plate. The Coco earthquake nucleated near the northwestern edge of the 2004 Sumatra-Andaman earthquake rupture under the unruptured updip segment of the plate boundary interface. The earthquake with predominant normal motion on approximately north-south to northeast-southwest oriented plane is very similar to the 27 June 2008 Little Andaman earthquake which occurred in the South Andaman region near the trench. We provide the only available estimate of coseismic offset due to the 2009 Coco earthquake at a survey-mode GPS site in the north Andaman, located about 60 km south of the Coco earthquake epicentre. The not so large coseismic displacement of about 2 cm in the ESE direction is consistent with the earthquake focal mechanism and its magnitude. We suggest that, like the 2008 Little Andaman earthquake, this earthquake too occurred on one of the approximately north-south to northeast-southwest oriented steep planes of the obliquely subducting 90°E ridge which was reactivated in normal motion after subduction, under the favourable influence of coseismic and ongoing postseismic deformation due to the 2004 Sumatra-Andaman earthquake. Another notable feature of this earthquake is its relatively low aftershock productivity. We suggest that the earthquake occurred very close to the aseismic region of the Irrawaddy frontal arc of very low seismicity where pre-existing faults are not so critically stressed and because of which the earthquake could trigger only a few aftershocks in its immediate vicinity.

Plane-confined magnetic lineations in mingled mafic and felsic magmas, the Sázava pluton, Bohemian Massif

Multiple magnetic lineations were revealed using the anisotropy of magnetic susceptibility (AMS) and anisotropy of magnetic remanence (AMR) methods in a domain of mafic–felsic magma mingling at the northwestern margin of the Sázava pluton, Central Bohemian Plutonic Complex, Bohemian Massif. Gabbrodioritic enclave swarms and sheets are steeply oriented and exhibit magnetic lineations plunging at steep to moderate angles (mostly 40–70°) whereas in their tonalitic host lineations plunge from vertical to horizontal angles, but mostly less than 40°. The magnetic lineations in both rock types spread along a ~ NNE-SSW steep plane that could be simplified as representing an “average” margin-parallel magmatic foliation in the pluton concordant with an “average” regional cleavage in the wall-rock. The plane-confined lineations are interpreted as having recorded the heterogeneous superposition of two processes: (1) vertical stretching during emplacement and magma mingling which left behind the steep lineations; and (2) regional tectonic stretching, which progressively rotated the mineral grains in rheologically weaker domains (chiefly in the host tonalite) to form the sub-horizontal lineation. The average foliation bearing the multiple lineations is interpreted as a composite foliation that recorded both margin-perpendicular shortening during emplacement, overprinted by coaxial regional tectonic shortening. This example reaffirms that (1) magmatic fabrics in crystallizing magmas can record accumulated strain resulting from both emplacement and regional tectonic deformation; and that (2) separating magmatic (and also magnetic) fabrics related exclusively to the internal chamber processes from fabrics caused by regional tectonic deformation is problematic or even impossible in cases where composite fabrics are recognized.

Probing Fine Crustal Structure in the Beijing Region Using a Deep Seismic Reflection Profile

AbstractThe fine crustal structure and tectonics of the Beijing region are explored by using a 100 km long, NW‐trending deep seismic reflection profile. This profile passed through the Sanhe‐Pinggu earthquake (M8.0) area and main faults in the Beijing region. The results show that the crust beneath the investigated area is divided into upper and lower crust by a strong reflective zone at about 6~7 s TWT. The thickness of the upper and lower crust is about 18~21 km and 13~15 km, respectively. There are rich reflective layers and clear structural patterns above 3~4 s TWT as well as obviously different structural features along the profile. In the west of the Sanhe‐Pinggu earthquake area, the stacked deep seismic reflection section shows 2~3 groups of strong reflective layers and a series of basement faults. In the east of the Sanhe‐Pinggu earthquake area, there is a set of dense, west‐dipping, reflective strata with relatively strong energy, which have the typical characteristics of a sedimentary basin. The largest depth of the sedimentary basin is about 8~9 km. The deep fault in crust revealed by the deep seismic reflection profile has a steep plane, and it cuts and disturbs the lower crust and crust‐mantle transitional zone. This deep fault extends upwards into the upper crust, and joins the crustal deep structure to the shallow fault. The profile reveals that the deep‐shallow fault system represents the major deep‐shallow tectonic feature in the study region.

2008 Little Andaman aftershock: Genetic linkages with the subducting 90°E ridge and 2004 Sumatra–Andaman earthquake

We analyse the June 27, 2008 Little Andaman aftershock (Mw 6.6) of December 26, 2004 Sumatra–Andaman earthquake (Mw 9.2) that occurred near the trench in the subducting India plate beneath the Sunda Plate. Unlike majority of the other aftershocks in the frontal arc, the Little Andaman aftershock and its own aftershocks occurred through normal slip on the north–south oriented steep planes. We use the coseismic and ongoing postseismic deformation due to the 2004 Sumatra–Andaman earthquake at a GPS site nearest to the Little Andaman aftershock and compute changes in the Coulomb stresses due to the coseismic slip and postseismic afterslip. The Coulomb stress on the Little Andaman aftershock fault plane progressively increased since the 2004 Sumatra–Andaman earthquake which probably led to the occurrence of the Little Andaman aftershock on the pre-existing N–S oriented strike-slip steep planes of the subducting 90°E ridge that were reactivated through normal slip.

Caracterização estrutural de um segmento da rampa lateral de Capitólio, limite norte da nappe de Passos (MG)

The northern edge of Passos nappe, southwest of Minas Gerais state, is marked by a lateral ramp system called Capitólio Lateral Ramp. This ramp is the contact of the Internal and External domains of the Southern segment of the Brasilia Fold Belt. A detailed study of these domains permits to consider a model for the evolution of this ramp, explained as the vertical structures, which marks External Domain, changing to sub-horizontal structures verified in Internal Domain, both striking NW-SE. The contact between these domains is distinguished by a later thrust (D3) which obliterates the initial registers of the development of the lateral ramp, a steep plane (D2). The covered portion of this history involved complex deformation models, where by rotation of the vorticity axis is possible to see a transition of a vertical to horizontal Y-Monoclinic Shear Zone, respectively in the ramp and flat of the nappe.

Caracterização estrutural de um segmento da rampa lateral de Capitólio, limite norte da nappe de Passos (MG)

The northern edge of Passos nappe, southwest of Minas Gerais state, is marked by a lateral ramp system called Capitolio Lateral Ramp. This ramp is the contact of the Internal and External domains of the Southern segment of the Brasilia Fold Belt. A detailed study of these domains permits to consider a model for the evolution of this ramp, explained as the vertical structures, which marks External Domain, changing to sub-horizontal structures verified in Internal Domain, both striking NW-SE. The contact between these domains is distinguished by a later thrust (D 3 ) which obliterates the initial registers of the development of the lateral ramp, a steep plane (D 2 ). The covered portion of this history involved complex deformation models, where by rotation of the vorticity axis is possible to see a transition of a vertical to horizontal Y-Monoclinic Shear Zone, respectively in the ramp and flat of the nappe.

Craniofacial Profile Assessment in Patients with Obstructive Sleep Apnea

Craniofacial Profile Assessment in Patients with Obstructive Sleep Apnea