The terrible disaster in the Nepal and (probably) Tibet has happened, when a debris flow came down one of the river valleys. The toll is still unclear. The images show a wall of mud, tens of meters high, coming at extreme speed, giving no warning. The cause was 5 km up in the mountains, where…

What makes a volcano dangerous? Clearly, the severity of any eruption plays a role. So does the presence of people nearby. But it is not always the best known volcanoes that are the most dangerous. Tseax is hardly world-renowned, but it caused a major volcanic disaster in Canada. And sometimes a volcano can be dangerous…