By Daniella Relph
BBC News, Washington
Scientists in the US fear a volcano in Washington state could be on the verge of erupting.
Small earthquakes in the north-west have stirred the volcano
The area around Mount St Helens has been sealed off after geologists noticed a surge in seismic activity earlier this week.
The volcano erupted almost 25 years ago killing 57 people and sending half a billion tons of ash into the air.
It left the nearest major city, Portland in Oregon - 50 miles (80km) away - covered in a layer of ash.
A number of small earthquakes in the region has stirred the volcano back to life.
Steam is rising from the crater and rocks are tumbling down its side.
Local communities and tourists have been told to stay away as scientists monitor the situation.
Scientists do not believe any eruption this time round will be as serious as that in 1980, but warn it is impossible to predict exactly what Mount St Helens has in store.