A scientific assessment in 2006, published in the journal Eos, observed that in the past 30,000 years, eruptions have occurred at a rate of only four to six per millennium, with a predominance (70%) of very low hazard, basaltic eruptions. The authors further commented that the recent eruptive record, combined with the available petrological and radiometric data, provides a rather optimistic outlook on major volcanic hazards related to Teide and its rift zones, posing only very localized threats to the one million inhabitants of Tenerife and the 4.5 million annual visitors to Teide National Park. However, another study in 2009 concluded that Teide will probably erupt violently in the future, and that its structure is similar to that of Vesuvius and Etna. Thus the magnitude of the risk posed by Teide to the public remains a source of debate.