Aspects of the tectonics of the Greater Caucasus and Western South Caspian Basin

The main objectives of this project are to (a) understand the relationship between climate, topography and the tectonics in the Greater Caucasus belt, (b) construct regional geological cross-sections showing major stratigraphic sequences and structures along the belt using the focal mechanisms of the earthquakes events, (c) evaluate the evolution and development of a single fold structure (Yasamal anticline) and (d) investigate strain accommodation mechanisms using 3D Move to unfold the Yasamal structure. Topographic variations were investigated to understand the interplay between topography, climate and the tectonics of the Greater Caucasus range and compare the findings with other active and inactive belts (Pyrenees, Northern Tibetan Plateau and Himalayas). There is a correlation between elevation changes and climate along the Greater Caucasus belt, where the gradual reduction of the mean altitude, has a close relationship with a wetter climate, and the sharper altitude decrease with a drier climate. And the elevation changes are strongly correlated with the Moho depths underneath the region. The relief along the belt is extremely high, with a strong correlation between the high relief and the large thrusts in the region. And the relief of the eastern part is slightly low compared with the western part of the belt, even though the eastern part is more active than the western part. The structural study undertaken at regional scale for the Caucasus belt and the western side of the South Caspian Basin gave insights on the style of deformation in the basin and the evolution of the Greater Caucasus belt and the preferred distribution, geometry and formation mechanism of the structural elements. The regional cross-sections along the Greater Caucasus were constructed and constrained by using focal mechanisms show that the belt is deformed by active thrust faults that dip inwards from the margins of the range where the northern thrusts are dipping south, and the southern thrusts are dipping to the north, these results have contrary to some previous models that emphasise only south-directed thrusting. The spatial arrangement, geometry and temporal evolution of spectacular kilometre-amplitude fold structures actively forming in Cenozoic sediments on the uplifted western margin of the South Caspian Basin are described and strain accommodation mechanisms established using 3D Move to unfold the Yasamal structure enabled a reconstruction of pre-folding templates and predictively model the fold-related deformation at small-scale. The 3D model of the Yasamal anticline shows that the anticline hinge has about 30° south-directed plunging. The area was characterized by a low rate of sedimentation and high rate of uplift in the Upper Pliocene. The minor structures (accommodating the overall strain in the anticline) are developed throughout the entire anticline. Compressional strain is present at the anticline hinge line, and the extensional strain dominates the anticline limbs. Suggesting potential extensional structures development in the anticline flanks, which correspond with the field observations in the Yasamal valley confirming that; the small normal faults are concentrated within the anticline flanks, and the contractional deformation bands along the hinge area of the anticline

NASA Geodynamics Program

Activities and achievements for the period of May 1983 to May 1984 for the NASA geodynamics program are summarized. Abstracts of papers presented at the Conference are inlcuded. Current publications associated with the NASA Geodynamics Program are listed

Finite Element Models of Elastic Earthquake Deformation

The Earth’s surface deforms in response to earthquake fault dislocations at depth. Deformation models are constructed to interpret the corresponding ground movements recorded by geodetic data such GPS and InSAR, and ultimately characterize the seismic ruptures. Conventional analytical and latest numerical solutions serve similar purpose but with different technical constraints. The former cannot simulate the heterogeneous rock properties and structural complexity, while the latter directly tackles these challenges but requires more computational resources. As demonstrated in the 2015 M7.8 Gorkha, Nepal earthquake and the 2016 M6.2 Amatrice, Italy earthquake, we develop state-of-art finite element models (FEMs) to efficiently accommodate both the material and tectonic complexity of a seismic deformational system in a seamless model environment. The FEM predictions are significantly more accurate than the analytical models embedded in a homogeneous half-space at the 95% confidence level. The primary goal of this chapter is describe a systematic approach to design, construct, execute and calibrate FEMs of elastic earthquake deformation. As constrained by coseismic displacements, FEM-based inverse analyses are employed to resolve linear and nonlinear fault-slip parameters. With such numerical techniques and modeling framework, researchers can explicitly investigate the spatial distribution of seismic fault slip and probe other in-depth rheological processes

Geophysics for Mineral Exploration

This Special Issue contains ten papers which focus on emerging geophysical techniques for mineral exploration, novel modeling, and interpretation methods, including joint inversions of multi physics data, and challenging case studies. The papers cover a wide range of mineral deposits, including banded iron formations, epithermal gold–silver–copper–iron–molybdenum deposits, iron-oxide–copper–gold deposits, and prospecting forgroundwater resources

CRS-stack-based seismic reflection imaging for land data in time and depth domains

Land data acquisition often suffers from rough top-surface topography and complicated near-surface conditions. The resulting poor data quality makes conventional data processing very difficult. Under such circumstances, where simple model assumptions may fail, it is of particular importance to extract as much information as possible directly from the measured data. Fortunately, the ongoing increase in available computing power makes advanced data-driven imaging approaches feasible; thus, these have increasingly gained in relevance during the past few years. The common-reflection-surface (CRS) stack, a generalized high-density velocity analysis and stacking process, is one of these promising methods. It is applied in a non-interactive manner and provides, besides an improved zero-offset simulation, an entire set of physically interpretable stacking parameters that include and complement the conventional stacking velocity. For every zero-offset sample, these so-called kinematic wavefield attributes are obtained as a by-product of the data-driven stacking process. As will be shown, they can be applied both to improve the stack itself and to support subsequent processing steps...thesi

Seismic Waves

The importance of seismic wave research lies not only in our ability to understand and predict earthquakes and tsunamis, it also reveals information on the Earth's composition and features in much the same way as it led to the discovery of Mohorovicic's discontinuity. As our theoretical understanding of the physics behind seismic waves has grown, physical and numerical modeling have greatly advanced and now augment applied seismology for better prediction and engineering practices. This has led to some novel applications such as using artificially-induced shocks for exploration of the Earth's subsurface and seismic stimulation for increasing the productivity of oil wells. This book demonstrates the latest techniques and advances in seismic wave analysis from theoretical approach, data acquisition and interpretation, to analyses and numerical simulations, as well as research applications. A review process was conducted in cooperation with sincere support by Drs. Hiroshi Takenaka, Yoshio Murai, Jun Matsushima, and Genti Toyokuni