Tsunami for the day

The BBC has an article by Melissa Hogenboom about a volcanic collapse and the resulting tsunami:

About seventy thousand years ago, a volcano collapsed into the sea.
Pico do Fogo is located on Fogo island, part of the Cape Verde archipelago off the north-west coast of Africa. As its rocks smashed into the ocean, the impact created a tsunami that engulfed Santiago island, thirty miles away.
The impact would have been catastrophic for anyone living on Santiago. Fortunately, the Cape Verde islands were uninhabited until the mid-1400s.
Pico do Fogo is still active today, with eruptions roughly every 20 years. Collapses like that one are extremely rare, but researchers can look to the past to understand the impact of any potential future volcanic collapses.
Geologist Ricardo Ramalho of Bristol University in the UK started working on the Cape Verde islands in 2005. He soon noticed a series of strange boulders on Santiago island.
The more he looked, the more he discovered. Eventually he found more than forty boulders, some weighing over seven hundred tons. Strangely, these large rocks were quite different from any other volcanic deposits on the island. Ramalho discovered they were made of the same stuff as the rocks on the island's shoreline, which had been generated by tsunamis. Since these deposits were situated at sea level, it had been assumed that the tsunami that created them was quite small.
Ramalho's latest study indicates that the tsunami was a big one. The boulders he analysed are two hundred meters above sea level. That could only mean one thing, he says: the tsunami generated by Pico do Fogo's collapse was powerful enough to push rock deposits all that way inland.
"Tsunamis are not waves that splash, they are like floods of immense water that can go uphill," says Ramalho. By dating the boulders, Ramalho and his colleagues have figured out when the tsunami occurred, a finding that is now published in the journal Science Advances.
The team was also able to estimate the size of the wave by calculating the energy needed to drag the boulders over six hundred meters inland, though Ramalho admits it is a "crude estimate".
More broadly, the work provides further evidence that large volcanic collapses can trigger mega-tsunamis. It was already clear that collapses could trigger smaller tsunamis, but nobody was sure if bigger waves could be generated. "Flank collapses can happen extremely fast and catastrophically, and therefore are capable of triggering giant tsunamis," says Ramalho. "These things are real and can potentially happen again," he says. "Because they have a high impact we should be vigilant. We need to start thinking about what we can do to improve resilience to such an event."
Mega-tsunamis like this might happen every ten thousand years, says Bill McGuire from University College London in the UK, who was not involved with the study. "The scale of such events, and their potentially devastating impact, makes them a clear and serious hazard in ocean basins that host active volcanoes," says McGuire.

Rico says this is old news in the oceanographic world, but ought to make people worry... (And let's remember that the use of tsunami, which is 'harbor wave' in Japanese, is wrong but there's no common replacement.)