The European Regional Technical Committee (ERTC7) of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) and the Organizing Committee welcome all participants of the 9th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2018), held at the Faculty of Engineering of University of Porto (FEUP), in Porto, Portugal, from 25th to 27th June 2018.

Exploration seismology is a complex technology that blends advanced physics, mathematics, and computation. Seismic imaging, an essential part of exploration seismology, has evolved over roughly 100 years of effort into a sophisticated imaging system capable  of forming detailed 3D images of the interior of the Earth’s crust. We have been involved in research, teaching, and practice in this field for many decades and this book is an outgrowth of our experience. With it we hope to bring a more detailed understanding of the methods of seismic imaging to a broad audience of scientists and engineers. <...>

Our understanding of the subsurface system of the earth is becoming increasingly more sophisticated both at the level of the behaviour of its components (solid, liquid and gas) as well as their variations in space and time. The implementation of coupled models (e.g. mechanical-hydraulic, mechanical-thermal and hydraulic-thermal) is essential for the understanding of an increasing number of natural phenomena and in predicting human impact on these.

Crystallography, an interdisciplinary subject, plays an important role in a wide range of subjects of science and technology. Its rudimentary knowledge is essential for beginners in physics, chemistry, mathematics, molecular biology, geology, metallurgy, and particularly to materials science and mineralogy. Its relationship with physics can be understood in terms of the following examples:
1. All conservation laws in physics are essentially interrelated with symmetry operations.
2. Symmetry considerations allow us to establish Pauli’s exclusion principle.
3. Periodic potential of the lattice is responsible for the creation of allowed and forbidden energy bands. Accordingly, materials can be classified as conductor, semi-conductor and insulator depending on the amount of band gap.
4. Relationships between the magnitudes of measurable parameters give rise to the tensor components of different physical properties in crystals. This list can be elaborated further. <...>