Scientists have been left baffled by a record spike in earthquakes near Washington's Mount Adams that has been dormant for thousands of years.

The volcano is deemed a 'high threat' due to its ability to trigger landslides, debris avalanches and mudflow that can travel up to 50 miles per hour down the slope, which would put thousand of people at risk.

The region typically sees quakes once very three years, but the US Geological Survey (USGS) detected the six in September, which ranged from a 0.9 to 2.0 magnitude.

While very weak, previous studies have suggested that swarms of small earthquakes can precede a volcanic eruption.