Mt. Ontake

Until the weekend, it's likely that few people in the UK had heard of Mt. Ontake.

It is a volcano on the main island of Japan, close to the city of Nagoya. It's the second-highest mountain in the country.
The area is popular with hikers
At the weekend, over two hundred people were on their way up the slopes of the volcano when, on Saturday morning it erupted without warning. This resulted in a pyroclastic flow and ash falls, as well as other debris raining down on people.
The various news networks reacted quite quickly, as did the social media networks which were full of pictures, and also other tweets.
The Guardian has put up an impressive and dramatic series of images.
It also reported on Sunday that sadly there were about 30 people who had apparently succumbed to the eruption, after rescuers bravely reached the area close to the summit.

Several schools may well be mentioning this today as it's a topical story.

Throw in some video from the current and ongoing eruption of Holuhraun, and perhaps a mention of this story from the Franz Josef glacier and it's a reminder of the need to take care with many physical environments...