Low-angle normal faults and seismicity: A review

Although large, low-angle normal faults in the continental crust are widely recognized, doubts persist that they either initiate or slip at shallow dips (<30°), because (1) global compilations of normal fault focal mechanisms show only a small fraction of events with either nodal plane dipping less than 30° and (2) Andersonian fault mechanics predict that normal faults dipping less than 30° cannot slip. Geological reconstructions, thermochronology, paleomagnetic studies, and seismic reflection profiles, mainly published in the last 5 years, reinforce the view that active low-angle normal faulting in the brittle crust is widespread, underscoring the paradox of the seismicity data. For dip-slip faults large enough to break the entire brittle layer during earthquakes (M_w ∼ 6.5), consideration of their surface area and efficiency in accommodating extension as a function of dip θ suggests average recurrence intervals of earthquakes R' ∝ tan θ, assuming stress drop, rigidity modulus, and thickness of the seismogenic layer do not vary systematically with dip. If the global distribution of fault dip, normalized to total fault length, is uniform, the global recurrence of earthquakes as a function of dip is shown to be R ∝ tan θ sin θ. This relationship predicts that the frequency of earthquakes with nodal planes dipping between 30° and 60° will exceed those with planes shallower than 30° by a factor of 10, in good agreement with continental seismicity, assuming major normal faults dipping more than 60° are relatively uncommon. Revision of Andersonian fault mechanics to include rotation of the stress axes with depth, perhaps as a result of deep crustal shear against the brittle layer, would explain both the common occurrence of low-angle faults and the lack of large faults dipping more than 60°. If correct, this resolution of the paradox may indicate significant seismic hazard from large, low-angle normal faults

Cenozoic evolution of Neotethys and implications for the causes of plate motions

Africa-North America-Eurasia plate circuit rotations, combined with Red Sea rotations and new estimates of crustal shortening in Iran define the Cenozoic history of the Neotethyan ocean between Arabia and Eurasia. The new constraints indicate that Arabia-Eurasia convergence has been fairly constant at 2 to 3 cm/yr since 56 Ma with slowing of Africa-Eurasia motion to <1 cm/yr near 25 Ma, coeval with the opening of the Red Sea. Ocean closure occurred no later than 10 Ma, and could have occurred prior to this time only if a large amount of continental lithosphere was subducted, suggesting that slowing of Africa significantly predated the Arabia-Eurasia collision. These kinematics imply that Africa's disconnection with the negative buoyancy of the downgoing slab of lithosphere beneath southern Eurasia slowed its motion. The slow, steady rate of northward subduction since 56 Ma contrasts with strongly variable rates of magma production in the Urumieh-Dokhtar arc, implying magma production rate in continental arcs is not linked to subduction rate

A Comparison of Perceptual and Semantic Priming

Masked Priming is an established paradigm to investigate consciousness. The impact of prime visibility on specific priming effects determines whether associated processes can occur independently of consciousness or might rely on consciousness. A meta-analytic review of 84 studies was conducted to assess the impact of prime visibility on effect sizes in interaction with various moderators (Chapter 2). A psychological model concerning the emergence of priming effects was proposed. Two main confoundings between moderators were identified. Specific task levels were predominantly applied with specific masking methods. Furthermore, temporal parameters were chosen differently between effect types. Subsequent experiments (Chapter 3) revealed that priming effects increase with increasing prime visibility when pattern masks are applied. Priming effects were independent of prime visibility with metacontrast masks. Pattern masks are thought to reduce prime visibility on an early level whereas metacontrast masks disturb recurrent processing. Lamme and Roelfsema (2000) previously proposed that recurrent processing characterizes consciousness. Perceptual and semantic priming effects were equally affected by variations in prime visibility. However, perceptual priming effects were generally larger than semantic priming effects. Further experiments were conducted to determine the courses of perceptual and semantic priming effects with increasing prime-mask SOA and mask-target SOA (Chapter 4). Priming effects generally increase with increasing prime-mask SOA and decline at long mask-target SOA. This decline seems to be based on a simple decay and active mechanisms of inhibition (e.g. Klapp, 2005). However, courses of perceptual and semantic priming effects with increasing mask-target SOA differed. This seems to be due to an additional mechanism of object updating that acts only with relevant masks (Lleras & Enns, 2004). In the current design, masks only activated the incongruent category (i.e. relevant masks) with perceptual congruency. An electrophysiological study was conducted to compare perceptual and semantic priming with identical stimulation (Chapter 5). The applied design allowed the estimation of behavioral priming effects without response association as well as effects on event-related potentials without response execution. Perceptual priming effects without response association were larger than semantic priming effects without response association. Furthermore, the P2 component and the P3(b) component were modulated through perceptual congruency. Semantic congruency was reflected in an N400-like effect with a delayed latency. Perceptual ERP effects were observed earlier and with different distributions than semantic ERP effects. Perceptual and semantic priming effects seem to be based on different mechanisms that share several attributes. However, the current work supports the idea of approaching consciousness through the comparison of different masking methods (cf. Breitmeyer, 2014)

Results of the Basin and Range Geoscientific Experiment (BARGE): A marine-style seismic reflection survey across the eastern boundary of the central Basin and Range Province

Approximately 120 km of marine-style deep seismic reflection data were shot during a survey on the waters of Lake Mead in southeastern Nevada. The survey extends from near the abrupt eastern edge of the Basin and Range Province (BRP) to a point ~80 km into the extended domain. Data quality throughout the survey ranged from fair to poor; the recorded data include significant towing noise and occasionally problematic diffractions and sideswipe from canyon walls. The upper 2–4 s of the data shows well-defined reflections from sedimentary fill, but below that point, reflectivity is weak. Lower crustal reflectivity is generally absent under the eastern part of the survey, with a slight increase in reflectivity to the west. The reflection Moho appears as a series of weakly defined, discontinuous reflections, most of which occur at 10–11 s. A particularly interesting feature of the data set is the relative lack of reflectivity from the lower crust, which is a region of strong reflectivity on other seismic reflection data sets from the BRP

Gotthelf und Dickens : Armutsdarstellungen im "Bauernspiegel", in den "Leiden und Freuden eines Schulmeisters" und im "Oliver Twist"

Armut und Armenpflege ist eines der großen Themen in der öffentlichen Diskussion und der Literatur der ersten Hälfte des 19. Jahrhunderts. So erstaunt es nur wenig, dass nahezu gleichzeitig zwei äusserst populäre Romane mit ähnlichen Verläufen sich mit dem Thema beschäftigen, obwohl keine intertextuelle Beeinflussung erkennbar ist: der "Bauernspiegel" (1837) von Albert Bitzius (1797–1854), in dem Bitzius das Pseudonym Jeremias Gotthelf, mit dem er als Schriftsteller bekannt wurde, das erste Mal benutzte, und "Oliver Twist, or The Parish Boy’s Progress" (1837–1839), der zweite Roman von Charles Dickens (1812–1870), unter dessen Pseudonym Boz erschienen. Auch Gotthelfs zweiter Roman, die "Leiden und Freuden eines Schulmeisters" (1838/39), beschäftigen sich mit der Armut, hier mit Bezug auf eines der weiteren großen Themen des frühen 19. Jahrhunderts, dem (Primar-)Schulwesen. Oliver Twist war als Reaktion auf das "New Poor Law" von 1834 entstanden, die Leiden und Freuden eines Schulmeister nehmen direkt Bezug auf die Schullehrertaxation von 1836 und das 1835 verabschiedete Berner Primarschulgesetz

Dangerous Grounds: Territorial Disputes in the Asia Pacific

This study examines five countries with overlapping claims to territories in the Asia Pacific. Domestic, Regional, and National Security are based in a country’s ability to effectively occupy these territories. The occupation extends a country’s Exclusive Economic Zone and provides the country with territorial ownership, access to maritime resources, and fishing rights. Neoliberal trade theory suggests that as these countries become more interdependent the number of conflicts over disputed territory will decrease. The high level of economic interdependence will influence political and foreign policy decisions such as territorial disputes. Neorealist theory suggests that economic interdependence will not impact the number of conflicts over disputed territory. Using the Diaoyu/Senkaku, Paracel, and Spratly Island disputes as case studies, the data suggest that territorial disputes within the East and South China Sea do not impact trade/economic interdependence and that the two phenomena operate independently of one another. Thus, the data confirms the neorealist hypothesis

Geologic map of the east-central Meadow Valley Mountains, and implications for reconstruction of the Mormon Peak detachment, Nevada

The role of low-angle faults in accommodating extension within the upper crust remains controversial because the existence of these faults markedly defies extant continuum theories of how crustal faults form, and once initiated, how they continue to slip. Accordingly, for many proposed examples, basic kinematic problems like slip direction, dip angle while active, and magnitude of offset are keenly debated. A well-known example is the Miocene Mormon Peak detachment and overlying Mormon Peak allochthon of southern Nevada (USA), whose origin and evolution have been debated for several decades. Here, we use geologic mapping in the Meadow Valley Mountains to help define the geometry and kinematics of emplacement of the Mormon Peak allochthon, the hanging wall of the Mormon Peak detachment. Pre-exten­sion structural markers, inherited from the east-vergent Sevier thrust belt of Meso­zoic age, are well suited to constrain the geometry and kine­matics of the detachment. In this study, we add to these markers a newly mapped Sevier-­age monoclinal flexure preserved in the hanging wall of the detachment. The bounding axial surfaces of the flexure can be readily matched to the base and top of the frontal Sevier thrust ramp, which is exposed in the footwall of the detachment to the east in the Mormon Mountains and Tule Springs Hills. Multiple proxies for the slip direction of the detachment, including the mean tilt direction of hanging wall fault blocks, the trend of striations measured on the fault plane, and other structural features, indicate that it is approximately S77°W (257°). Given the observed structural separation lines between the hanging wall and footwall, this slip direction indicates 12–13 km of horizontal displacement on the detachment (14–15 km net slip), lower than a previous estimate of 20–22 km, which was based on erroneous assumptions in regard to the geometry of the thrust system. Based on a new detailed map compilation of the region and recently published low-temperature thermochronologic data, palinspastic constraints also preclude earlier suggestions that the Mormon Peak allochthon is a composite of diachronously emplaced, surficial landslide deposits. Although earlier suggestions that the initiation angle of the detachment in the central Mormon Mountains is ∼ 20°–25° remain valid, the geometry of the Sevier-age monocline in the Meadow Valley Mountains and other structural data suggest that the initial dip of the detachment steepens toward the north beneath the southernmost Clover Mountains, where the hanging wall includes kilometer-scale accumulations of volcanic and volcaniclastic strata