The eyes of geologists, disaster officials and sightseers are today focused on Mount St Helens, where a mix of volcanic gases and low-level earthquakes raised fears the mountain in Washington state might blow its top at any moment.

US government scientists raised the alert level for Mt St Helens in Washington state after its second steam eruption in two days was followed by a powerful tremor.

Mount St Helens, the volcano that blew its top with cataclysmic force in 1980, quietened down after spewing a plume of steam and ash – but only briefly.