Details

Autor(en) / Beteiligte

• Chevrel, Magdalena Oryaëlle
• Harris, Andrew
• Ajas, Alexian
• Biren, Jonas
• Gurioli, Lucia
• Calabrò, Laura

Titel

Investigating physical and thermal interactions between lava and trees: the case of Kīlauea’s July 1974 flow

Ist Teil von

• Bulletin of volcanology, 2019-01, Vol.81 (6)

Ort / Verlag

Springer Verlag

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• To examine whether there was any physical or thermal interaction between trees and lava when a lava flow inundates a forest, we studied the Kīlauea’s July 1974 lava flow. We mapped the location of ∼ 600 lava-trees and the lava type (pāhoehoe versus ‘a‘ā), and sampled an additional ten lava-trees for chemical and textural analysis to infer flow viscosity and dynamics. The emplacement event lasted 3.5 h and markers on the outer surface of the lava-trees allowed us to define initial high effusion rate and velocity (∼ 400 m3/s and 5–10 m/s) that then declined to 9 m3/s and 4 m/s during a waning phase. We find that lava passing through the forest underwent an initial cooling rate of 4 °C/km which increased to 10 °C/km late in the eruption. This is no different to cooling rates recorded at Kīlauea for tree-free cases. There thus appears to be no effect on cooling for this case. The lava-trees did, though, form a network of vertical cylinder obstacles and evidence for local diversion of flow lines are noticed. However, this varies with lava type, as almost no lava-trees form in ‘a‘ā. We find a relation between the percentage of ‘a‘ā and the number of lava-trees per hectare. The pāhoehoe–‘a‘ā transition for this flow occurs at a viscosity of 103 Pa s and this appears to be a threshold below which lava-trees can form so as to behave as a network of obstacles, and above which they cannot.