It's been four decades since Mt. St. Helens erupted.

40 years ago (on May 18) Mt. St. Helens literally blew its ... side; not so much its top.

Mount St. Helens is most notorious for its major eruption on May 18, 1980, the deadliest and most economically destructive volcanic event in US history. Fifty-seven people were killed; 250 homes, 47 bridges, 15 miles (24 km) of railways, and 185 miles (298 km) of highway were destroyed. A massive debris avalanche, triggered by an earthquake of magnitude 5.1, caused a lateral eruption that reduced the elevation of the mountain's summit from 9,677 ft (2,950 m) to 8,363 ft (2,549 m), leaving a 1 mile (1.6 km) wide horseshoe-shaped crater. The debris avalanche was up to 0.7 cubic miles (2.9 km3) in volume. The Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for the eruption's aftermath to be scientifically studied.

This video is instructive.

The pressure caused a landslide on the mountain's north side, which uncorked a horizontal explosion that killed every living thing within an expanse of 230 square miles -- roughly speaking, this:

After the huge blast, smaller eruptions continued over a period of six years.

As the poet once cooed, time heals all wounds. Nature rapidly is reclaiming the damaged areas around Mt. St. Helens.

Mount St. Helens Is Going Green Again

Forty years of satellite imagery chronicles a remarkable floral comeback.

Recently, the NASA Earth Observatory published satellite images of the mountain taken in the years after the eruption. Since Mount St. Helens’s collapse, life in the vicinity has bounced back. Though not yet visible from space, flowering plants like the prairie lupine have been seen on the Pumice Plain, a distinctive stretch of hostile volcanic sediment on the northern slope, the area that saw the worst devastation.

Mt. Etna in Sicily: "Amazingly the mountain grows and shrinks as the years roll by."

When I was a kid, volcanoes fascinated me. For about forty years, the interest was dormant, but during the past year, many things have come bubbling up from the subconscious -- as this link earlier in the year attests.

Lava lighting up the Sicilian sky as giant ash clouds spew, latest eruption of Mount Etna is caught on camera, by Francis Scott (Daily Mail)

... Mount Etna is located on the east coast of Sicily and prior eruptions have been elevated to at least seven kilometres above the summit, mainly due to prevailing winds.

The volcano is nearly two times the size of Mount Vesuvius, and remains in a state of almost constant activity.

Amazingly the mountain grows and shrinks as the years roll by.

Recently an animation from Nasa, which captures the volcano's activity using radio satellite imagery, went viral thanks to social media.

The natural wonder appears to 'breathe' over the course of a decade in the incredible video results.

Etna and the city of Catania, foreground.