Chapter 1: Introduction to earthquake geotechnical engineering in relation to foundation design

Earthquakes cause damage to engineering structures and often result in loss of life. Forecasting the exact time of an earthquake can at best reduce casualties, and at present also appears to be an impossible task. Therefore, structures need to be designed to withstand the impact of an earthquake and prevent collapse, as it is buildings and soil structure (dams, embankments, retaining walls) that kill people, not earthquakes. This chapter provides a brief overview of the field of earthquake geotechnical engineering; that is, where the ground is the main contributor to the damage.

Earthquakes cause damage to the built environment and result in fatalities and financial loss. During earthquakes, structures may collapse or be severely damaged as a result of structural inadequacies, foundation collapse/damage, ground failure or, more frequently, a combination of these effects. In addition, earthquakes may trigger a series of cascading catastrophic events (e.g. tsunami, fire, landslide, debris flow, flooding and nuclear contamination) that may lead to shortage of food and water. Furthermore, recent seismic events have shown that secondary events such as tsunami or fire are responsible for the vast majority of casualties and substantial economic damage. The impact of earthquakes in terms of fatalities and monetary loss may exhibit significant disparities between different geographical regions of the world, as may be observed from Figure 1.1. This graph is based on the work of Goda and Tesfamariam (2015), who showed that the impact of earthquakes in developed countries results in relatively few fatalities but may have considerable monetary loss. In contrast, emerging economies (in South America, Asia and Africa) had higher fatalities but lower monetary loss. However, two exceptions can be noted from Figure 1.1: the 1995 Kobe and 2011 Tōhoku earthquakes, both in Japan, in which the post-earthquake fire and tsunami, respectively, were responsible for the high fatality rate – not the earthquake itself. It is therefore evident that a comprehensive assessment of the impact of earthquakes on infrastructure and people requires a multidisciplinary approach and professionals with different expertise.