Alik Ismail-Zadeh

Salt structures and hydrocarbons in the Pricaspian basin

Pricaspian basin geology is reviewed in the light of 500,000 km of seismic profiles and several thousand wells. We focus on how hydrocarbons from three sources accumulated in relation to the 1800 salt structures in a basin that changed little in planform from the Devonian to the Paleogene. Riphean to Carboniferous shelf sedimentary strata are still flat lying between a poorly known crystalline basement and a base of salt now 10 km deep. Slow and almost continuous sedimentation in the basin center downbuilt huge massifs in Permian salt initially 4.5 km thick. Basin sediments are flat lying or backtilted between down-to-basin growth faults along northern and western margins starved of sediments. By contrast, progradation of Permian sediments from the Urals, Triassic sediments from the South Emba shear zone, and Jurassic sediments from the Dombass-Tuarkyr fold belt downbuilt successive waves of salt structures basinward from margins in the east, southeast and then the south. A zone of salt overhangs records extrusion that starved basin-marginal salt structures, particularly during a basinwide hiatus in the Early Jurassic. Salt diapirs along polygonal normal faults rooting to the crests of still-potent salt structures through Cretaceous–Paleogene strata indicate that salt upbuilt back to the surface and resumed downbuilding. Coarse clastic fans infill deep canyons incised across the basin by rivers draining to the Caspian in Pliocene times.

Stress in the Descending Relic Slab beneath the Vrancea Region, Romania

Abstract—We examine the effects of viscous flow, phase transition, and dehydration on the stress field of a relic slab to explain the intermediate-depth seismic activity in the Vrancea region. A 2-D finite-element model of a slab gravitationally sinking in the mantle predicts (1) downward extension in the slab as inferred from the stress axes of earthquakes, (2) the maximum stress occurring in the depth range of 70 km to 160 km, and (3) a very narrow area of the maximum stress. The depth distribution of the annual average seismic energy released in earthquakes has a shape similar to that of the depth distribution of the stress in the slab. Estimations of the cumulative annual seismic moment observed and associated with the volume change due to the basalt-eclogite phase changes in the oceanic slab indicate that a pure phase-transition model cannot solely explain the intermediate-depth earthquakes in the region. We consider that one of the realistic mechanisms for triggering these events in the Vrancea slab can be the dehydration of rocks which makes fluid-assisted faulting possible.

Dynamic restoration of profiles across diapiric salt structures: numerical approach and its applications

Abstract The backstripping method that is widely used in basin analysis sometimes fails for salt-bearing basins because the highly mobile and buoyant salt deforms its sedimentary overburden. We present a numerical approach for 2-D dynamic restoration of cross-sections through successive earlier depositional stages. The approach is based on a solution of the inverse problem of the gravitational (Rayleigh–Taylor) instability and combines the Galerkin-spline finite-element method with interface tracking and a backstripping method. Our model interprets basin profiles as multiple layers of viscous fluids with various densities and viscosities. The evolution of salt structures is modelled backward in time by removing successively younger layers and restoring older layers and any diapirs to the stage they were likely to have been. We test the sensitivity of the restoration technique to small variations in density of the layers at different stages in the evolution of diapiric structures. The applicability of the technique was demonstrated by reconstructions of upbuilt and downbuilt diapirs. The technique is used to restore a depth-converted seismic cross-section through the south-eastern part of the Pricaspian salt basin. Mature salt diapirs in the section are shown to have been downbuilt from a salt layer with an initially uniform thickness as a result of differential sedimentary loading until the end of the Triassic before one of the diapirs was buried and actively upbuilt. The numerical approach is well suited for restoration of cross-sections with ductile overburdens, but despite limitations can be developed to 3-D restorations and other rheologies.

Non-linear dynamics of the lithosphere and intermediate-term earthquake prediction

Abstract The lithosphere of the Earth is structured as a hierarchical system of volumes of different sizes, from about 10 tectonic plates to about 10 25 grains of rock. Their relative movement against the forces of friction and cohesion is realized to a large extent through earthquakes. The movement is controlled by a wide variety of independent processes, concentrated in the thin boundary zones between the volumes. The boundary zone has a similar hierarchical structure, consisting of volumes, separated by boundary zones, etc. Altogether, this hierarchy of volumes and multitude of processes compose the lithosphere into a large non-linear complex system. Upon coarse graining the integral mesoscale empirical regularities emerge, indicating a wide range of similarity, collective behavior, and the possibility of earthquake prediction. This approach led to new paradigms in the dynamics of the lithosphere and, on the practical side, created a capacity to predict from 70 to 90% of large earthquakes, with alarms occupying 10–20% of the time–space considered. Such predictions may be used to undertake earthquake preparedness measures, which would prevent a considerable part of the damage (although far from the total damage). The methodology linking prediction with preparedness was developed; it may help a disaster management authority to choose the preparedness measures, allowing for the currently realistic accuracy of predictions. A large-scale experiment in advance prediction of large earthquakes worldwide has been launched to test the prediction algorithms. The test is unprecedented in rigor and coverage. The forecasts are communicated, with due discretion, to several dozen leading scientists and administrators in many countries. Among already predicted earthquakes are all the last eight great ones with magnitude 8 and more. The major drawback is the rate of false alarms. The possibility is outlined to develop a new generation of prediction methods, with fivefold increase in accuracy and the transition to short-term prediction. The links with prediction of geotechnical and engineering disasters are established: scenarios of transitions to a large earthquake happen to share some features with a broader class of catastrophes. This experience now opens as yet untapped possibilities for reduction of technological disasters.

Models of Dynamics of Block-and-Fault Systems

A model of block-and-fault dynamics (block model for short) of the lithosphere was developed to analyze how the basic features of seismicity depend on the lithosphere structure and dynamics and to study the specific features of this dependence. A seismic region is modeled by a system of perfectly rigid blocks divided by infinitely thin plane faults.

Linking mantle upwelling with the lithosphere descent and the Japan Sea evolution: a hypothesis

Recent seismic tomography studies image a low velocity zone (interpreted as a high temperature anomaly) in the mantle beneath the subducting Pacific plate near the Japanese islands at the depth of about 400 km. This thermal feature is rather peculiar in terms of the conventional view of mantle convection and subduction zones. Here we present a dynamic restoration of the thermal state of the mantle beneath this region assimilating geophysical, geodetic, and geological data up to 40 million years. We hypothesise that the hot mantle upwelling beneath the Pacific plate partly penetrated through the subducting plate into the mantle wedge and generated two smaller hot upwellings, which contributed to the rapid subsidence in the basins of the Japan Sea and to back-arc spreading. Another part of the hot mantle migrated upward beneath the Pacific lithosphere, and the presently observed hot anomaly is a remnant part of this mantle upwelling.

Three-dimensional forward and backward numerical modeling of mantle plume evolution : Effects of thermal diffusion

We investigate the effects of thermal diffusion on the evolution of mantle plumes by means of three-dimensional numerical modeling forward and backward in time. Mantle plumes are fed by a hot, low-viscous material from the thermal boundary layer. The material of the plumes is mainly advected toward the Earths surface with some effects of thermal diffusion. However, the feeding can become weaker with time, and then thermal diffusion can take over and control the evolution of the plumes. Numerical experiments forward in time show that a week feeding of mantle plumes by the hot material from the boundary layer results in the diffusive disappearance of plume tails first and plume heads later. This is the most likely explanation for the seismically detected low-velocity mantle structures (mantle plumes) with prominent heads and almost invisible tails at midmantle depths. We develop restoration models (backward in time) to recover strong features of mantle plumes in the geological past after they have dissipated due to thermal diffusion and analyze effects of thermal diffusion and temperature-dependent viscosity on the reconstruction of the mantle plumes. We investigate the impact of thermal diffusion on the performance of our restoration (variational data assimilation) algorithm. For a given range of Rayleigh number Ra and two values of the viscosity ratio r (between the upper and lower boundaries of the model domain) we show that (1) the residuals between the temperature predicted by the forward model and that reconstructed by the backward modeling become larger and (2) the restoration process becomes poorer as Ra decreases and r increases. We assimilate temperature obtained from high-resolution seismic tomography data for the southeastern Carpathians and show that present diffused mantle structures can be restored to their prominent state in the Miocene times. We discuss the problems of smoothness of model input and output data, errors associated with the modeling, and some other challenges in the data assimilation for thermoconvective flow in the mantle.

Risk science and sustainability : science for reduction of risk and sustainable development of society

Preface. Acknowledgements. Workshop Initiative, Programme and Organising Committees. Workshop Synopsis. Budapest Manifesto. Talks: The Globalisation of Risk in the XXIst Century J.-P. Connerade. Risk and Sustainability in Water Resources Management U. Shamir. Aids to Decision Making in Risk Management: Mobilisation of the Scientific Community to Improve Risk Management J.-P. Massue. Science and Risk: Scientific Authority at Risk G. Schmeder. Basic Science for Prediction and Reduction of Geological Disasters V. Keilis-Borok. Papers: Environmental Risk and Sustainability T. Beer. Science for Risk Reduction and Sustainable Development: The Role of Law J. Paterson. Sustainable Development and Risk Evaluation: Challenges and Possible New Methodologies A. Makarenko. On Predictability of Homicide Surges in Megacities V. Keilis-Borok, et al. Earthquakes and Megacities F. Wenzel, F. Bendimerad. Case Studies: Earth Sciences Contribution to the Sustainable Development of Ground Transportation Systems: Relevant Case Studies in Central Europe G. Panza, M. Kouteva. Modelling of Stress and Seismicity in the South-Eastern Carpathians: A Basis for Seismic Risk Estimation A. Ismail-Zadeh. Earthquake Loss Estimation for India Based on Macroeconomic Indicators P. Dunbar, et al. Monitors and Methods for Investigation of Submarine Landslides, Seawater Intrusion and Contaminated Groundwater Discharge as Coastal Hazards L. Lobkovsky, et al. Risk of Collective Youth Violence in French Suburbs: A Clinical Scale of Evaluation, an Alert System L. Bui Trong. Abstracts: Lessons from Macrophagic Myofasciitis: Towards Definition of a Vaccine Adjuvant-Related Syndrome R. Gherardi. Flood Risk Management in the Upper Tisza Basin in Hungary: A System Analytical Approach J. Linnerooth-Bayer, et al. Volcanoes and Cities G. Heiken. Geo-Risk Management Practices in the Asia Pacific Region A. Jayawardena. Values, Interests and Symbolic Politics in a Nuclear Waste Disposal Debate: About the Societal Dimensions of Risk Perception P. Tamas, A. Vari. Appendix: List of Contributors. List of Reviewers. Subject Index. GBP/LISTGBP

Forging a paradigm shift in disaster science

Despite major advancements in knowledge on disaster risks and disasters caused by natural hazards, the number and severity of disasters are increasing. Convolving natural, engineering, social and behavioral sciences and practices with policymaking should significantly reduce disaster risks caused by natural hazards. To this end, a fundamental change in scientific approaches to disaster risk reduction is needed by shifting the current emphasis on individual hazard and risk assessment dominant in the geoscientific community to a transdisciplinary system analysis with action-oriented research on disaster risk reduction co-produced with multiple stakeholders, including policymakers. This paradigm shift will allow for acquisition of policy-relevant knowledge and its immediate application to evidence-based policy and decision making for disaster risk reduction. The need for the paradigm shift is more critical now than ever before because of the increasing vulnerability and exposure of society to disaster risk and the need for cross-cutting actions in policy and practice related to climate change and sustainability.

Extreme Natural Hazards, Disaster Risks and Societal Implications

Great advances in understanding planet Earth and its environment allow its geophysical processes and phenomena including their extreme manifestations, which lead to floods, hurricanes, earthquakes, tsunamis, volcanoes, landslides, severe space weather, wildfires and other natural hazard events, to be studied. There is a deep belief in the community of natural scientists that with progress in science and the scientific ability to predict extreme events the problem of disaster risk reduction will be resolved. That is perhaps true to some extent.