The current crisisA future eruption at Teide can be potentially hazardous due to the proximity of populated areas such as the Orotava and Icod Valleys, not protected by a sufficiently high caldera wall. According to recent studies led by CSIC (Madrid), the area with the maximum hazard for both lava and ash covers is the inside and surroundings of the Las Cañadas Caldera. The second zone in terms of hazard comprises both the northern flank of the Central Edifice and the northern and most of the southern slopes of the NW-SE ridge. The third zone includes the slopes of the southern part of the NE-SW ridge and the great valleys of Güimar and Orotava.
In 2000, the group of University of Granada showed the existence of only a moderate tectonic seismicity, with three families of source locations, i.e. below Teide-Pico Viejo, in the eastern border of the caldera, and offshore. At the same time a lack of any sign of volcanic tremor was noted.
However, after 2000, a significant increase of seismic activity was observed in the Archipelago, as observed by IGN (Istituto Geografico Nacional), CSIC (Consejo Superior de Investigaciones Cientificas) and educational local networks. Since 2003 several seismic events were felt by the population (El Hierro, Lanzarote, Gran Canaria and Tenerife). Since the first months of 2004 the seismic activity is concentrated more in the island of Tenerife, where variations of fumarolic activity and the presence of tremor are now also observed. All these signs can be related to a possible reactivation of the Teide volcanic complex, that, due to the presence of both basaltic (low explosivity potential) and phonolitic (high explosivity potential) magmas can lead to a wide spectrum of possible eruptions.
Image below: Example of seismic event recorded in the zone of Icod - Santiago del Teide on 7 October 2004, courtesy of CSIC: