MAGMA ASCENT RATES DURING THE 1730-1736 CE TIMANFAYA ERUPTION ON LANZAROTE, CANARY ISLANDS

Magma ascent rates have been linked with eruption style and explosivity. Quantifying magma ascent rates is vital for assessing the timescales of processes prior to and during volcanic eruptions and therefore for volcanic hazards. This study focuses on the Timanfaya basaltic fissure eruption on Lanzarote in the Canary Islands, which occurred from 1730-1736, covering 146 km² and destroying 26 villages. The Timanfaya eruption underwent five eruptive phases, with the initial phase involving a significant amount of explosive activity, while the next four phases were mainly effusive. This eruption provides an excellent case study for understanding magma ascent and how it evolves through the course of large basaltic fissure eruptions. Scoriae from the first eruptive phase contain abundant fresh glass, Fo85-Fo91 olivine, as well as peridotite xenoliths. Previous work has identified two olivine populations: <Fo87 crystals interpreted to be autocrystic, and a population of olivines with high Fo cores likely derived from peridotite and overgrown by autocrystic rims. We will present preliminary estimates of decompression rates from Fourier transform infrared spectroscopy measurements of diffusion profiles of H in oriented olivine crystals. Independent perspectives on ascent rates from mantle xenoliths, melt embayments, and H-in-olivine can provide an integrated picture of the multiple timescales of magma ascent during the Timanfaya eruption.