1For sites at which nuclear installations of different types are collocated, particular consideration should be given to the use of a graded approach.

2Design also includes the design of site protection measures for some of the hazards.

3Ma: million years.

4In the following paragraphs, the term ‘geographical region’ refers to the region around the site(s) for which the volcanic hazard assessment is performed.

5As an example of the extension of the area affected by a volcanic eruption, a tephra fallout deposit of decimetric thickness off the Atlantic coast of South America from an unknown volcano located in the far Andean region, probably 1000 km distant, has been reported.

6Consistent with established volcanological terminology, a volcano of questionable Holocene age is indicated by Holocene(?).

7A cliff edge effect in a nuclear installation is an instance of severely abnormal system behaviour caused by an abrupt transition from one system status to another following a small deviation in a system parameter, and thus a sudden large variation in system conditions in response to a small variation in an input.

8http://www.geo.mtu.edu/volcanoes/hazards/primer/images/volc-images/basesurge.jpg