Mt St Helens rebuilds the cone blasted out 26 years ago

The newly formed cone. Picture / Steve Schilling

One of the world's most famous volcanoes is growing by the day.

A hulking slab of rock in the crater of Mt St Helens is already 90m high, and rising by about 1.35m a day, although it occasionally loses height from rockfalls off its tip.

Mt St Helens, in Washington state on the US West Coast, has been bubbling away beneath the surface since a flurry of tiny earthquakes began in late September 2004.

The cause was initially thought to be rainwater seeping into the hot interior, but it soon became clear that magma was on the move.

Eventually, scientists expect the volcano to rebuild its conical peak, obliterated in the May 18, 1980, eruption that killed 57 people.