The timescale of the modification stage basin-sized impact structures is not well understood. Owing to ca. 10 km erosion since its formation, Vredefort structure, South Africa, an ideal testing ground for deciphering post-impact modification. Here, we present geophysical and geochemical evidence from Granophyre Dikes, which were derived - now eroded melt sheet. dikes have been studied mostly in...

Citation: Ogburn SE and Calder ES (2017) The Relative Effectiveness of Empirical and Physical Models for Simulating the Dense Undercurrent of Pyroclastic Flows under Different Emplacement Conditions. Front. Earth Sci. 5:83. doi: 10.3389/feart.2017.00083 The Relative Effectiveness of Empirical and Physical Models for Simulating the Dense Undercurrent of Pyroclastic Flows under Different Emplacem...

In this paper an example is elaborated of the design of a river dike, incorporating reliability-based models. The design is demonstrated with the help of this example, which is based on [1]. 1. PROBLEM DESCRIPTION A river dike has to be designed to protect a particular region of land. The goal is to minimize the construction cost and the expected loss, due to inundation. The total cost can be e...

This paper determines the optimal timing of dike heightenings as well as the corresponding optimal dike heightenings to protect against floods. To derive the optimal policy we design an algorithm based on the Impulse Control Maximum Principle. In this way the paper presents one of the first real life applications of the Impulse Control Maximum Principle developed by Blaquière. We show that the ...

Global Positioning System geodesy was used to measure surface deformation on Soufriere Hills volcano, Montserrat from October 6, 1995 to July 1, 1997 during initial dome growth and gravitational collapse. Our data from this period show non-axially symmetric horizontal displacements, and decreasing subsidence as a function of radial distance from the former topographic high of the volcanic edifi...

Introduction: The Yaxcopoil borehole (Yax-1) penetrates below the suevitic units through 600 m of sediments (894.9 m – 1510.9 m). These rocks are most likely of Cretaceous age and are regarded as a displaced “megablock”. The stratified sequence was intruded by suevitic dikes (910 m, 916 m), one impact melt dike (1347 m) and several clastic, polymict dikes. The latter are the focus of this study...

The analysis of Anisotropy of Magnetic Susceptibility (AMS) is a powerful and rapid technique to examine the preferred orientations of mineral (magnetic) fabrics and can indicate the nature of a magma transport (vertical or lateral). The relationship between magnetic fabric and geometry of a dyke swarm enables us to understand magma emplacement processes. Depending on the mutual relationship of...

Severe events around the globe have highlighted the threat to life, infrastructure and the environment posed by flooding. Flood forecasting systems are a vital component of broader flood risk management activities. These systems are becoming increasingly more sophisticated as their importance in reducing life loss and economic damages is realized. Part of this increase in complexity is focused ...

This paper is an extension of previous work which characterises soil behaviours using the grading entropy diagram. The present work looks at the piping process in granular soils, by considering some new data from flood-protection dikes. The piping process is divided into three parts here: particle movement at the micro scale to segregate free water; sand boil development (which is the initiatio...

a r t i c l e i n f o a b s t r a c t Keywords: basaltic shield InSAR data sill radial dike circumferential fissure Galápagos Islands Space-geodetic measurements of surface deformation produced by the most recent eruptions at Fernandina – the most frequently erupting volcano in the Galápagos Archipelago – reveal that all have initiated with the intrusion of subhorizontal sills from a shallow ma...