Scientists keep watchful eye on volcano

Since it awoke in August from a 138-year slumber, Ecuador's Cotopaxi volcano has become one of the most-watched in the world, holding wary locals and fascinated scientists in thrall.

Cotopaxi, whose snowy peak rises majestically from the patchwork quilt of central Ecuador's high plains, rumbled to life on August 14, belching a column of ash in its first major eruption since 1877.

President Rafael Correa declared a state of emergency as authorities warned the volcano was one of the most dangerous on Earth because of its big snow cap and the relatively large population nearby.