Cascading Effects of Extreme Geohazards on Tenerife (Canary Islands)

Abstract

Extreme geohazards (volcanic eruptions, earthquakes, landslides, and tsunamis) have the potential to inflict cascading effects whose associated risks are difficult to predict and prepare for. Thus, these events are generally not taken into account in hazard assessment. Anticipating the occurrence of such extreme events is thus key if our life-styles are to remain safe and sustainable. Volcanic islands are often the source of complex successions of disastrous events, as is evident from any examination, for instance, of the geological record of regions such as Hawaii, the Canary Islands, Reunion and Indonesia. The island of Tenerife in the Canary Archipelago is an excellent example of where cascading extreme hazards have occurred several times in the past and could occur again in the future. A cascading sequence involving a caldera-forming eruption, high-magnitude seismicity, mega-landslides and tsunamis occurred at least twice during the construction of this island. In order to understand the possible consequences of such processes if they were to reoccur, we simulated the extent and potential impact of a multiple, extreme geohazard episode similar to the last recorded one that took place on the island of Tenerife around 180 ka. The implications of such a disastrous succession of events are analyzed at local, regional and global scales, and the results obtained are discussed within the framework of disaster risk-reduction policies.