When a volcano that has been dormant for many centuries begins to show possible signs of reawakening, scientists and civil authorities rightly should be concerned about the possibility that the volcanic unrest might culminate in renewed eruptive activity. Such was the situation for Teide volcano, located on Tenerife in the Canary Islands, when a mild seismic swarm during April–July 2004 garnered much attention and caused public concern. However, that attention completely ignored the fact that the seismic recordings of the swarm were due to a much improved monitoring system rather than due to an actual event of alarming magnitude or extent.
It is important in any effective program of volcano-risk mitigation that the response to an apparent change in the status of a volcano should include the immediate implementation or augmentation of monitoring studies to better anticipate possible outcomes of the volcanic unrest. Equally important, emergency-management officials, using available scientific information and judgment, must take appropriate precautionary measures—including information of the populations at potential risk—while not creating unjust anxiety or alarm.