;)

Magnificent capture!

Admired in:
www.ipernity.com/group/tolerance

Savage Beauty.

Admired in ~ I ♥ Nature

Can't help but compare this with photos of the Tunguska Event

Thanks, everyone! The scale of the destruction is remarkable--and this was a _small_ eruption. As I used to tell classes, no geologist can say "mother" Earth with a straight face!

Jeez! If that was a small eruption, I'd hate to think what you classify as a large one...

The May, 1980 eruption of Mt. St. Helens ejected a bit more than 1 km^3 of tephra (ash), and that ash was nowhere near hot enough to weld when it settled out (see below). The eruption of Mt. Mazama about 6800 years ago, which formed the spectacular caldera now filled by Crater Lake, ejected about 160 km^3 of ash. Mt. Mazama ash forms a distinctive marker layer in young sedimentary units across much of western North America. Crater Lake is also in the Cascade Range, about 250 miles south in Oregon. The eruption of Tambora in Indonesia in 1815, the largest documented historical eruption, was comparable in size to Mt. Mazama. It caused the "year without a summer", due to aerosols high in the stratosphere.

Far larger eruptions have occurred in the geologic past. Huge "welded tuffs" (a.k.a. "ignimbrites") occur across much of the US west. These are ash-flow units in which the ash was still hot enough to weld together when it settled out--and some of these units extend for _miles_. Originally the ash must have extended much farther, but was not hot enough to weld. J. Hoover Mackin, who first studied these rocks in detail, said that "Tertiary eruptions of the Great Basin would compare with those of modern times as the explosion of a hydrogen bomb to the bursting of a firecracker." (American J. of Science, 1960). You usually can't get phrasing like that past the referees! The youngest such units are the Bishop Tuff in California, about 600K years old, and the Yellowstone Tuff. Such eruptions are the source of the concern about "supervolcanoes", which have recently gotten popular attention.

Many thanks for the reply. Most interesting, and a little bit frightening... At least here in the UK we don't have to contend with volcanoes, though we're not immune to the after affects of an eruption, as witness the Icelandic eruption of a few years ago which brought air traffic to a halt over most of northern Europe.