There's nothing earth-shatteringly new in National Geographic Magazine's latest article on the slumbering supervolcano beneath Yellowstone National Park. But that doesn't mean it's not a good read.

Written by Joel Achenbach, who normally plies his trade at the Washington Post, the article in the August issue of the magazine has the requisite attention-grabbing headline, When Yellowstone Explodes, and the equally requisite dramatic artistic "depiction" of a red-molten-spewing behemoth towering over just about all of the continent west of the Continental Divide.

Sensationalism aside, the article mixes history, geology, and, of course, speculation on when -- not if, but when -- Yellowstone will next be obliterated by what lies sleeping beneath it

The odds of a full, caldera-forming eruption -- a cataclysm that could kill untold thousands of people and plunge the Earth into a volcanic winter -- are anyone's guess; it could happen in our lifetimes, or 100,000 years or more from now, or perhaps never. Bob Christiansen, now retired, suspects the supervolcano may be safely bottled up. For most of its history, the Yellowstone hot spot has formed calderas in the thin crust of the Basin and Range area of the American West. Now the hot spot is lodged beneath a much thicker crust at the crest of the Rockies. "I think that the system has more or less equilibrated itself," says Christiansen. Then he quickly adds, "But that's an interpretation that would not stand up in court."

The story is a quick read; 10 minutes at most to get through the text, longer if you linger over the maps, illustrations and charts, which you're likely to do. But pithiness does not equate with uninteresting. Mr. Achenbach nicely weaves Lt. Gustavus Doane's impression that he was staring out across a massive crater of "a now extinct volcano" when he looked south from the summit of Mount Washburn back on August 29, 1870, with the geology behind the volcano, and with passing mention of this past winter's swarm of some 900 earthquakes that caused more than a few geologists and volcanologists to cock their heads and wonder what was going on beneath Yellowstone Lake.

Of course, the article does not want for illustration. Along with the opening spread of that artistic rendering of what might be, there's a fold-out depiction of the magma pockets deep within the Earth that drive Yellowstone's geothermal wonders and fuel its volcano, and which is accompanied by three panels that reflect how scientists believe a cataclysmic eruption of this supervolcano would proceed; a map that tracks the movement of the North American tectonic plate over the "Yellowstone hot spot" and which includes a 350-mile-long connect-the-dots trail of volcanic activity associated with that hot spot, and; a page that tries to lend size to past eruptions of Yellowstone's volcano (with the usual comparison to the 1980 eruption of Mount St. Helens).

All in all, a nice summation of current thinking on Yellowstone's supervolcano.