John Engledew 
Tungus Event or The Great Siberian Meteorite [EPUB ebook] 

Something exploded above Siberia in 1908 and no one is quite sure what A- or why. What burned 830 square miles of forest and some 30 million trees on a fine summer’s morning? This book combines a hard popular science approach and lively description of the "Tungus event", giving the reader the stories of the early expeditions, the research that has gone on over a century, and a range of possible explanations.