The character of long-term eruptions: Inferences from episodes 50-53 of the Pu'u 'Ō'ō-Kūpaianaha eruption of Kīlauea volcano - Heliker, C. C.; Mangan, M.; Mattox, T.; Kauahikaua, J.; Helz, Rosalind Tuthill (Bulletin of Volcanology, 1998)