Subduction Dynamics

Subduction dynamics has been actively studied through seismology, mineral physics, and laboratory and numerical experiments. Understanding the dynamics of the subducting slab is critical to a better understanding of the primary societally relevant natural hazards emerging from our planetary interior, the megathrust earthquakes and consequent tsunamis. Subduction Dynamics is the result of a meeting that was held between August 19 and 22, 2012 on Jeju island, South Korea, where about fifty researchers from East Asia, North America and Europe met. Chapters treat diverse topics ranging from the response of the ionosphere to earthquake and tsunamis, to the origin of mid-continental volcanism thousands kilometers distant from the subduction zone, from the mysterious deep earthquakes triggered in the interior of the descending slabs, to the detailed pattern of accretionary wedges in convergent zones, from the induced mantle flow in the deep mantle, to the nature of the paradigms of earthquake occurrence, showing that all of them ultimately are due to the subduction process. Volume highlights include: Multidisciplinary research involving geology, mineral physics, geophysics and geodynamics Extremely large-scale numerical models with sliate-of-the art high performance computing facilities Overview of exceptional three-dimensional dynamic representation of the evolution of the Earth interiors and of the earthquake and subsequent tsunami dynamics Global risk assessment strategies in predicting natural disasters This volume is a valuable contribution in earth and environmental sciences that will assist with understanding the mechanisms behind plate tectonics and predicting and mitigating future natural hazards like earthquakes, volcanoes and tsunamis.

Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.

The cosmogenic radionuclide (10)Be is a unique tracer of shallow sediment subduction in volcanic arcs. The range in (10)Be enrichment in the Central American Volcanic Arc between Guatemala and Costa Rica is not controlled by variations in (10)Be concentrations in subducting sediment seaward of the Middle America Trench. Grain size is the principal control on the sedimentary (10)Be concentrations. (10)Be in fine-grained, terrigenous sediments is diluted by larger grained volcanogenic material. The sharp decrease in (10)Be enrichment in the Central American Volcanic Arc between southeastern Nicaragua and northwestern Costa Rica correlates with fault structure in the subducting Cocos plate. Offshore of Nicaragua, extensional faults associated with plate bending have throw equal to or greater than the overlying subducting sediment thickness. These faults enable efficient subduction of the entire sediment package by preventing relocation of the decollement within the downgoing sediments. Offshore of Costa Rica, the reduction of fault relief results in basement faults that do not penetrate the overlying sediment. A conceptual model is proposed in which the absence of significant basement roughness allows the decollement to descend into the subducting sediment column, leading to subsequent underplating and therefore removal of the bulk of the sediment layer that contains (10)Be.

The Himalaya is well known as the largest and highest mountain belt on Earth. Advances in geoscience over the past few decades have revealed a complex picture of the dynamics of this giant, opening up questions about the initial stages of Himalayan building, lateral variations in its structures, variations in tectonic forcing, tectonic-climate coupling and assessments of the natural hazards affecting this area. In this three-volume book, we present the current knowledge on the building and present-day behavior of the Himalayan range. The objective is not to be exhaustive, but to provide some key elements used by researchers to unravel the many processes acting in the Himalayan dynamics. Mountain environments are at the forefront of climate change with glacier retreat, landslides, flash floods and water availability. Understanding the delicate balance that controls the dynamics of the Himalayan giant is now, more than ever, a major challenge for the scientific community.

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Reprint from Pure and Applied Geophysics (PAGEOPH), Volume 140 (1993), No. 2