Although a natural process, human actions and extreme climatic events can accentuate slope instability, leading to disastrous slope failures and loss of life, like the one that occurred in the Brazilian city of Petrópolis on February 17, 2022. Over 200 people died in the mudflows, caused by intense rainfall (258 mm in three hours) and the deforestation of upslope areas. Understanding how and why materials move downslope helps geomorphologists to predict where and when future mass movement events may occur.

Except for perhaps volcanic eruptions and earthquakes, the most impressive (and deadly) geomorphic “events” involve the downslope movement of rock, debris, and sediment – referred to as mass movements because the material moves en masse. In their simplest sense, mass movements represent the downslope transport of rock and soil materials. Examples range from massive, fast-moving landslides and debris flows, to the inexorably slow process of soil creep.

For many, public speaking is nothing less than terrifying. But the art is indispensable if you want to get on in life, and can be mastered by learning certain techniques. These include how to start and end a talk, effective structures and the use of slides and data, as well as incorporating your character to help make presentations come alive.