VS02 Lava Flows

IAVCEI (Volcanology, Geochemistry)



01-Jul-2015, 13:30 - 15:00


 
Abstract content:

"Fill and spill" lava emplacement and its effects on local lava discharge rates and flow morphologies

Reconstructing magma effusion rates from lava flow dimensions and morphologies requires an understanding of how lava transport processes can affect local discharge rates and mask signatures of primary vent conditions. This study focuses on the December 1974 flow in the SW Rift Zone of Kilauea Volcano, Hawaii, USA, using observations of flow characteristics, airborne and tripod LiDAR, Differential GPS, and Multi-View Stereo Photogrammetry. The study area shows evidence of basin infilling with a prominent “bathtub ring” of lava standing 0.6–1.7 m above the current surface of the pond. The total area of the pond is 0.11 km2, implying 6.6–18.7 × 104 m3 of lava drainage. The pond has pahoehoe margins, and its interior is covered by meter- to tens of meters-wide plates, separated by spiny lava. The plates have pahoehoe-like surfaces that exhibit polygonal swales like those on the Kilauea Iki lava lake. We infer that lava from the source vent filled a basin between older flows and a prominent scarp in the Koae fault system. As the lava level rose, it embayed the surroundings and constructed a perched lava pond. Within a few hours (based on the cooling-limited thickness of the disrupted pahoehoe slabs), the pond breached its confinement and drained. This movement caused the pond's crust to separate into large plates, with spiny lava upwelling in the cracks. The surge of lava toward the SW also caused slabs of pahoehoe to pile up against the surrounding tumuli. In the channels, elevated discharge rates caused shear-induced disruption of the flow into aa clinker. The process of basin infilling and drainage, which we term “fill and spill” emplacement, was repeated several times along the length of the December 1974 flow, producing a series of ponds connected by spillway channels.

 
Author(s):
C. Hamilton1, S.P. Scheidt1, J.E. Bleacher2, R.P. Irwin III3, W.B. Garry2, L.P. Whelley2.
1University of Arizona, Lunar and Planetary Laboratory, Tucson, USA.
2NASA Goddard Space Flight Center, Planetary Geodynamics Laboratory Code 698, Greenbelt, USA.
3Smithsonian Institution, National Air and Space Museum / Center for Earth and Planetary Studies, Washington- DC, USA.

 

Keywords:
Lava     Pond     Drainage     Discharge     December 1974 flow     Kilauea Volcano     Pahoehoe     Aa