Long, paired A'A/Pahoehoe flows of Mauna Loa: Volcanological significance and insights they provide into volcano plumbing systems

The long lava flows of Mauna Loa, Hawaii have been cited as Earth's closed analogs to the large Martian flows. It is therefore important to understand the flow mechanics and characteristics of the Mauna Loa flows and to make use of these in an attempt to gain insights into Martian eruptive processes. Two fundamentally different kinds of long lava flows can be distinguished on Hawaiian volcanoes as in Martian flows. The two kinds may have identical initial viscosities, chemical compositions, flow lengths, and flow volumes, but their flow mechanisms and thermal energy budgets are radically different. One travels a distance set by the discharge rate as envisaged by Walker and Wadge, and the other travels a distance set mainly by the eruption duration and ground slope. In the Mauna Loa lavas, yield strength becomes an important flow morphology control only in the distal part of a'a lavas. The occurrence of paired flows on Mauna Loa yields insights into the internal plumbing systems of the volcano, and it is significant that all of the volume of the a'a flow must be stored in a magma chamber before eruption, while none of the volume of the pahoehoe needs to be so stored. Differentiation between the two kinds of flows on images of Martian volcanoes is possible and hence an improved understanding of these huge structures is acquired.