Mount St Helens: Watch volcano dome SWELL and mountain rise by 500M

According to the USGS, there are historical records of the volcano erupting in the 19th century, which were witnessed by early American settlers.

The USGS said: “Since its 1980 eruption, the summit elevation has decreased.

“A survey in 1982 gave a measurement of 2,549.7m (8,365ft).

“However, a lidar survey done in 2009 found the maximum elevation to be 2,539m (8,330ft).

“The difference in elevation is likely due to erosion and loss of rimrock by crater-wall collapses.”