The egiin davaa prehistoric rupture, central mongolia: A large magnitude normal faulting earthquake on a reactivated fault with little cumulative slip located in a slowly deforming intraplate setting

The prehistoric Egiin Davaa earthquake rupture is well-preserved in late Quaternary deposits within the Hangay Mountains of central Mongolia. The rupture is expressed by a semicontinuous 80 km-long topographic scarp. Geomorphological reconstructions reveal a relatively constant scarp height of 4-4.5 m and a NW-directed slip vector. Previous researchers have suggested that the scarp's exceptional geomorphological preservation indicates that it may correspond to an earthquake that occurred in the region c. 500 years ago. However, we constrain the last rupture to have been at least 4 ka ago from morphological dating and < 7.4 ka ago based on radiocarbon dating from one of two palaeoseismic trenches. Our study shows that discrete earthquake ruptures, along with details such as the locations of partially infilled fissures, can be preserved for periods well in excess of 1000 years in the interior of Asia, providing an archive of fault movements that can be directly read from the Earth's surface over a timescale appropriate for the study of slowly deforming continental interiors. The Egiin Davaa rupture involved c. 8 m of slip which, along with the observations that it is largely unsegmented along its length and that the ratio of cumulative slip (c. 250 m) to fault length (c. 80 km) is small, suggests relatively recent reactivation of a pre-existing geological structure

A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention

Late Pleistocene slip rate of the Hoh Serh-Tsagaan Salaa fault system, Mongolian Altai and intracontinental deformation in central Asia

The Mongolian Altai is an intracontinental oblique contractional orogen related to the far-field effects of the Indo-Asian collision. Global Positioning System (GPS) data suggest that ~10-15 per cent of total Indo-Asia convergence is accommodated across this orogen. The Höh Serh-Tsagaan Salaa fault system is one of several NNW-SSE-trending oblique contractional faults acting to partition strain and accommodate shortening and dextral shear in the Mongolian Altai. This fault zone displaces late Pleistocene alluvium along the southwest piedmont of the Höh Serh range in western Mongolia. Along the central third of the fault zone, strain is partitioned onto two separate strands, one that accommodates nearly pure dextral shear and one that accommodates thrust motion. We determined late Pleistocene rates of deformation along each of the Höh Serh-Tsagaan Salaa fault strands based on differential GPS surveys and cosmogenic nuclide 10Be geochronology. Combining the measured offsets and 10Be dates yields a minimum right-lateral slip rate of 0.9 +0.2/-0.1 mm a-1; the minimum shortening rate is 0.3 ± 0.1 mm a-1, with uplift of at least 0.1 ± 0.1 mm a-1. Resolving the shortening and dextral components of deformation yields a slip vector of 0.8 +0.2/-0.1 mm a-1 toward 336°. This long-term deformation vector is consistent with the short-term strain field determined by GPS in the region and indicates that ~20 per cent of Indo-Asian deformation in the Mongolian Altai (~2 per cent of the total Indo-Asia strain accumulation) occurs along the Höh Serh-Tsagaan Salaa fault zone. Although rate data for other active faults in the Mongolian Altai are sparse, our results suggest that strain may be accommodated almost exclusively on discrete structures in this intraplate tectonic setting. © 2010 The Authors Geophysical Journal International © 2010 RAS