New Frontiers in Integrated Solid Earth Sciences

Abstract

The book series is dedicated to the United Nations International Year of Planet Earth. The aim of the Year is to raise worldwide public and political awareness of the vast (but often under-used) potential of Earth sciences for improving the quality of life and safeguarding the planet. Geoscientific knowledge can save lives and protect property if threatened by natural disasters. Such knowledge is also needed to sustainably satisfy the growing need for Earth's resources by more people. Earths scientists are ready to contribute to a safer, healthier and more prosperous society. IYPE aims to develop a new generation of such experts to find new resources and to develop land more sustainably.

Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes

“…Central Chile, where the Maule earthquake occurred, is interesting because it lies to the north of the through-going Liquiñe-Ofqui Fault, and does not appear to exhibit a regional scale strike slip system. Tectonic settings controlled by a strong compressional component show a general diffuse distribution of volcanic centres (Nakamura et al, 1977), with a direct correlation between convergence and diffusion of the volcanic systems (Tibaldi et al, 2010). This is consistent with the diffuse distribution of volcanoes in Japan.…”

“…In compressive subduction systems, thrust faulting is favoured prior to mega-thrust earthquakes, with the maximum principal stress (σ 1 = σ H ) assumed to be horizontal in the direction of convergence, the minimum principal stress (σ 3 = σ v ) vertical (weight of the overburden), and the intermediate principal stress (σ 2 = σ h ) also horizontal and orthogonal to σ H . This stress state favours sill development and thrust faulting but hinders vertical dike formation and propagation (Tibaldi et al, 2010). The maximum shear stress developed during compression is τ max = (σ H − σ v )/2 and it is proportional to the angle of incidence of the ongoing subduction (Chemenda et al, 2000).…”

“…Instead, this favours sill development when the pressure of magma at depth exceeds the minimum principal stress. Reviews of the structural and petrological characteristics of volcanic systems associated with reverse and strike-slip faults (Tibaldi et al, 2010) show how evolutionary effects of the local stress field affect eruption rates and volcanic behaviours. Over non-geological time periods, the complexity of these systems is partially due to variations in the loading environment throughout mega-thrust earthquake cycles, from sub-horizontal compression during convergence, to short-lived viscoelastic relaxation during post-seismic periods.…”

Structure of volcano plumbing systems: A review of multi-parametric effects

“…6) (Davis et al, 1996), and ii) magma can enter ductile extensional jogs within shear zones as envisaged for example by Aydin et al (1990), D'Lemos et al (1992) and Chiarabba et al (2004a). Recently it has been suggested that even transpressional tectonics can be an efficient mechanism for moving magma through the lithosphere (Saint Blanquat et al, 1998), although magma upwelling under transpression might result in the movement of only a small volume of magma to the surface (Marcotte et al, 2005), and finally an in-depth review by Tibaldi et al (2010) shows several examples of volcanism along transpressional, transcurrent and transtensional fault zones. For felsic magmas it is also interesting to note a close temporal relation between peak anatexis and regional strike-slip displacements, suggesting that strike-slip motions may initiate along zones that were thermally softened by anatexis and that regional tectonics and granite formation may be inextricably linked processes (D'Lemos et al, 1992).…”

“…Volcanoes can also overlie zones of active compression with horizontal  1 and  2 (for a review see Tibaldi et al, 2010) and there are some field and experimental data that indicate which planes are the prime candidates to host magma paths in such contractional settings. Magma migration along pre-existing faults is consistent with several cases found in different geodynamic settings and spanning from evidence at deep crustal level (e.g.…”