In about 800 AD, the Mexican volcano Popocatépetl exploded, sending up several cubic kilometres of ash and pumice, and burying the surrounding area. Since then it has been relatively quiet, but every few decades it threatens to explode again — which could this time be catastrophic, as the area is now one of the most densely populated in Mexico. Seismic activity and eruptions are now increasing, with ash falls even 70 km away in Mexico City
- Servando De la Cruz-Reyna
- Claus Siebe
