Littoral hydrovolcanic explosions: a case study of lava–seawater interaction at Kilauea Volcano

• Published in: Journal of volcanology and geothermal research 1997, Vol.75 (1), p.1-17
• Main Authors: Mattox, Tari N, Mangan, Margaret T
• Format: Article
• Language: English
• Subjects: basalt; explosion phenomenon; Kilauea; lava; littoral cone; Marine; pahoehoe; pyroclasts
• ISSN: 0377-0273; 1872-6097
• DOI: 10.1016/S0377-0273(96)00048-0

A variety of hydrovolcanic explosions may occur as basaltic lava flows into the ocean. Observations and measurements were made during a two-year span of unusually explosive littoral activity as tube-fed pahoehoe from Kilauea Volcano inundated the southeast coastline of the island of Hawai`i. Our observations suggest that explosive interactions require high entrance fluxes (≥4 m 3/s) and are most often initiated by collapse of a developing lava delta. Two types of interactions were observed. “Open mixing” of lava and seawater occurred when delta collapse exposed the mouth of a severed lava tube or incandescent fault scarp to wave action. The ensuing explosions produced unconsolidated deposits of glassy lava fragments or lithic debris. Interactions under “confined mixing” conditions occurred when a lava tube situated at or below sea level fractured. Explosions ruptured the roof of the tube and produced circular mounds of welded spatter. We estimate a water/rock mass ratio of 0.15 for the most common type of littoral explosion and a kinetic energy release of 0.07–1.3 kJ/kg for the range of events witnessed.