ALBERT

Description: Fabrication of roll diffusion bonding test packs of titanium panels

Description: Fabrication, welding, and quality control of titanium skin sections

Description: Titanium alloy skin section for Saturn S-IC FUEL tank

Description: Roll diffusion bonding technique is used for fabricating T-stiffened panel assemblies from titanium alloy. The single unit fabrication exhibits excellent strength characteristics under tensile and compressive loads. This program is applied to structures in which weight/strength ratio and integral construction are important considerations.

Description: Geophysical datasets sensitive to different physical parameters can be used to improve resolution of Earth's internal structure. Herein, we jointly invert long-period magnetotelluric (MT) data and surface-wave dispersion curves. Our approach is based on a joint inversion using a genetic algorithm for a one-dimensional (1-D) isotropic structure, which we extend to 1-D anisotropic media. We apply our new anisotropic joint inversion to datasets from Central Germany demonstrating the capacity of our joint inversion algorithm to establish a 1-D anisotropic model that fits MT and seismic datasets simultaneously and providing new information regarding the deep structure in Central Germany. The lithosphere/asthenosphere boundary is found at approx. 84 km depth and two main anisotropic layers with coincident most conductive/seismic fast-axis direction are resolved at lower crustal and asthenospheric depths. We also quantify the amount of seismic and electrical anisotropy in the asthenosphere showing an emerging agreement between the two anisotropic coefficients.

Description: Two‐dimensional inversions of lithospheric‐probing magnetotelluric (MT) data at a total of 20 sites acquired along an approximately east–west 300‐km‐long profile across the Wopmay orogen in the Northwest Territories, Canada, provide electrical resistivity models of the boundary between the Archean Slave craton and the adjacent Proterozoic Bear Province. An analysis of distortion effects and structural dimensionality indicates that the MT responses are primarily one‐dimensional or only weakly two‐dimensional with a depth‐independent geoelectric strike angle of N32°E, consistent with regional structural geology. The regional‐scale model, generated from the longer period responses from all of the sites along the profile, reveals significant lateral variations in the lithospheric mantle. Resistive cratonic roots are imaged to depths of ∼200 km beneath both the Slave craton and the Hottah terrane of the Bear Province. These are separated by a less resistive region beneath the Great Bear magmatic zone, which is speculatively interpreted as a consequence of a decrease in the grain size of olivine in the Wopmay mantle, caused by localized shearing, compared to its neighboring cratonic roots. Focused two‐dimensional models, from higher frequency responses at sites on specific sections of the profile, reveal the resistivity structure at crustal depths beneath the region. These suggest that the root of the Slave craton crosses beneath the Wopmay orogen, and that the Wopmay fault zone does not penetrate into the lower crust. A comparison of these results with those obtained during the Lithoprobe project farther south shows striking along strike variations in the conductivity structure associated with the Wopmay orogen.

Description: TOPO-EUROPE addresses the 4-D topographic evolution of the orogens and intra-plate regions of Europe through a multidisciplinary approach linking geology, geophysics, geodesy and geotechnology. TOPO-EUROPE integrates monitoring, imaging, reconstruction and modelling of the interplay between processes controlling continental topography and related natural hazards. Until now, research on neotectonics and related topography development of orogens and intra-plate regions has received little attention. TOPO-EUROPE initiates a number of novel studies on the quantification of rates of vertical motions, related tectonically controlled river evolution and land subsidence in carefully selected natural laboratories in Europe. From orogen through platform to continental margin, these natural laboratories include the Alps/Carpathians–Pannonian Basin System, the West and Central European Platform, the Apennines–Aegean–Anatolian region, the Iberian Peninsula, the Scandinavian Continental Margin, the East-European Platform, and the Caucasus–Levant area. TOPO-EUROPE integrates European research facilities and know-how essential to advance the understanding of the role of topography in Environmental Earth System Dynamics. The principal objective of the network is twofold. Namely, to integrate national research programs into a common European network and, furthermore, to integrate activities among TOPO-EUROPE institutes and participants. Key objectives are to provide an interdisciplinary forum to share knowledge and information in the field of the neotectonic and topographic evolution of Europe, to promote and encourage multidisciplinary research on a truly European scale, to increase mobility of scientists and to train young scientists. This paper provides an overview of the state-of-the-art of continental topography research, and of the challenges to TOPO-EUROPE researchers in the targeted natural laboratories

Description: We present joint inversion of magnetotelluric, receiver function, and Raleigh wave dispersion data for a one‐dimensional Earth using a multiobjective genetic algorithm (GA). The chosen GA produces not only a family of models that fit the data sets but also the trade‐off between fitting the different data sets. The analysis of this trade‐off gives insight into the compatibility between the seismic data sets and the magnetotelluric data and also the appropriate noise level to assume for the seismic data. This additional information helps to assess the validity of the joint model, and we demonstrate the use of our approach with synthetic data under realistic conditions. We apply our method to one site from the Slave Craton and one site from the Kaapvaal Craton. For the Slave Craton we obtain similar results to our previously published models from joint inversion of receiver functions and magnetotelluric data but with improved resolution and control on absolute velocities. We find a conductive layer at the bottom of the crust, just above the Moho; a low‐velocity, low‐resistivity zone in the lithospheric mantle, previously termed the Central Slave Mantle Conductor; and indications of the lithosphere‐asthenosphere boundary in terms of a decrease in seismic velocity and resistivity. For the Kaapvaal Craton both the seismic and the MT data are of lesser quality, which prevents as detailed and robust an interpretation; nevertheless, we find an indication of a low‐velocity low‐resistivity zone in the mantle lithosphere. These two examples demonstrate the potential of joint inversion, particularly in combination with nonlinear optimization methods.