Scientists have discovered that La Palma will collapse at the time of some future volcanic eruption on the summit of the Cumbre Vieja volcano. Eruptions on the summit occur on average every 200 years or so. The last summit eruption was in 1949, so it may be many decades before the next summit eruption takes place.
Furthermore, the collapse will not necessarily happen during the next summit eruption. It may well take five, ten or more summit eruptions before the collapse occurs. But scientists simply do not know how many eruptions it will take.
http://www.bbc.co.uk/science/horizon/2000/mega_tsunami_qanda.shtml
No, I meant not much time to get people inland :')
In your article it says the wave would be 150 feet high.... much smaller than 2000 meters high.