Kīlauea summit lava fountain heights and chemistry over time

A) Maximum lava fountain heights during episodes 1-51 of the episodic eruption at the summit of Kīlauea in meters with three cycles of fountain height growth. B) Magnesium oxide (MgO) concentrations in the glass of tephra samples from episodes 1-51. 

Consistent positive-correlation of MgO and lava fountain height starts at episode 29 in growth period 3. Episode 44 shows abrupt drop in fountain height and decrease in MgO and coincides with the arrival of new differentiated olivine. Episode 46-48 shows early stages of new growth period with increase in MgO and fountain heights.