There have been many versions, new and old, about how the world will end.
The version created by Indianapolis author Mike Mullin , based on what might happen if the "supervolcano" beneath Yellowstone National Park  were to erupt, has been given high praise by fellow authors and teen-lit reviewers as "way too real for comfort."
The novels, with the third part of the trilogy still to come, follow the story of a teen named Alex, who is home alone for the weekend when the natural disaster strikes. Left in a world covered by more than a foot of volcanic ash, he tries to survive the devastation that follows and reunite with his loved ones.
Scientists first predicted  in 1979 the Yellowstone Caldera, the largest volcano in North America - so large it can only been seen from satellite, could spell serious trouble for the region. In the event of a full explosion, as many as 87,000 people are expected to die instantly with the largest environmental impact to follow in the form of volcanic ashfall.
Scientists are not in agreement as to when it might erupt next. Some claim it could happen at any time , others that it is "overdue " and still others that the situation is not as dire  as all that.
Mullin has discussed the scientific research  that went into his novels, which included U.S. government publications as well as first-hand accounts of the eruption of Mount St. Helens and road trips.
Among the praise that has been heaped on Ashfall, which was named one of the Best Teen Books of 2011  by Kirkus Reviews, is the compelling characters and the realistic plot.
"The scariest apocalypse is one that could really happen," states Michael Grant, New York Times bestselling author of Gone, Lies, Hunger, and Plague,as quoted on the Ashfall website. "Mike Mullin's Ashfall is way too real for comfort: you'll live the panic and despair and know that all of this could really happen. It will be a long time before you get the taste of volcanic ash out of your mouth. This isn't fantasy, this is real."