National Geographic : 1924 Feb
213 THE HAWAIIAN ISLANDS 229, 230, 231, and 232) will convey some conception of its impressiveness. OBSERVATORY PERCHED ON VOLCANO'S RIM Perched on the edge of the volcano is the laboratory and home of Dr. Thomas A. Jaggar, who for 15 years has been the Director of the Hawaiian Volcano Ob servatory, maintained by public-spirited citizens of Honolulu. This observatory is the famous center of the important new science of vulcanology, the study of vol canoes and earthquakes, in which Dr. Jaggar is one of the pioneers. Forewarned of prospective eruptions by the earthquake tremors which his in struments record, Dr. Jaggar is ready, as soon as a new building operation is initi ated by a volcano, to proceed to the lo cality and record in photograph and note book every stage of construction. Thus he secured a complete photo graphic history of the Alika river erupt ing from the flank of Mauna Loa in 1919, one of the tremendous lava flows of the century (see pages 160, 216-224). He tells of his visit to the scene of greatest volcanic activity in a dramatic report :* "The horses were left at a high flow of brown block lava, and the walk to the source fountains was across some ten al ternations of AA and pahoehoe" (see picture, page 235). "Here could be seen the line of rift cones, some forty cones visible at one time, a true fissure eruption, along a crack" (see page 216). "Great fountains were spouting con tinuously along the fissure for a thousand feet, like a wall of red flames, and in de tail they were seen to be made of incan descent, light crumbly material, yellow when it shot up and red when it came down. "The noise was a roar like surf on the rocks, and was occasioned by gas rush ing through a lava pool filling the rift, churning it to a foam, and flinging up the foamy matter to solidify as it fell . . "We proceeded across much-faulted ground to the immediate base of the ram part built by the fountains and hemming in the eastern margin of the great lava lake . . * From Monthly Bulletin of the Hawaiian Volcano Observatory, Vol. VII, No. 1o. Photograph by lawaiian Volcano Ubservatory MIAUNA LOA SIGNALING THAT IT IS ABOUT TO RESUME BUILDING OPERATIONS Activity of this violence in the crater is usu ally a portent that a rift soon will open on the flanks of the mountain and a river of lava begin to flow. The column of lava fume and flame is Io,ooo feet high.