In June 1991, Mount Pinatubo erupted in the second largest eruption in the world, during the 20th century. The Philippine authorities managed to rescue 60 000 people from around the volcano, thanks to timely warnings. The information that prompted these warnings was provided by several teams of scientists.
 
There is one activity in this unit, in two parts – a starter discussion in which students are prompted to consider how they might have reacted to the alerts of imminent volcano eruption, followed by the main part of the activity involving the interpretation of information recorded by research scientists studying the activity of the volcano.
 
Students read about the evidence gathered by different scientists, and follow how this information lead to increasing levels of alert being raised. They are asked to summarise this information, and then to link each rise in alert level with the scientific evidence that prompted it. They consider the limitations of the scientific information, and of the precision of warnings based upon it.