Could volcanic crystals provide insight into future eruptions?
Do, 24. Dez 2020, 12:0412:04 PM | VON: ELEANOR WRIGHT
A key question in volcanology is when will the next eruption occur? and there is ongoing research into methods and techniques that could be developed to help answer this.
Lava fountain during 1959 Kīlauea Iki eruption producing the olivines used in this innovative study at Stanford University (Image: USGS).
Scientists working on this are hindered by the fact that many of the volcanic processes responsible for triggering an eruption take place deep underground and upon eruption, many subterranean markers that could have provided evidence of pre-eruptive processes are destroyed.
However, new research by scientists at Stanford University (DiBenedetto et al. 2020) suggests that volcanic crystals extracted from erupted scoria could reveal insights about past eruptions and possibly help predict future ones. The crystal in question is known as olivine – a green mineral typically found in mafic and ultramafic igneous rocks.
When a volcano erupts, the liquid magma – known as lava – cools and solidifies when it reaches the surface. This process quickly entraps the naturally occurring olivine crystals and bubbles, referred to as vesicles. Vesicles form when gases initially dissolved in the liquid magma escape during eruption, creating bubbles as the rock cools and solidifies. These vesicles can be empty, but occasionally they contain tiny, naturally occurring crystals. The process happens so rapidly that the crystals cannot grow, thus perfectly capturing what happened during the eruptive phase.
This new study of crystal analysis of scoria from the 1959 eruption of Kīlauea Iki in Hawaii suggests that crystal formations can tell scientists about magma flows underground and give hints about when they might next erupt. Kīlauea Iki is a pit crater that is next to the main summit caldera of Kīlauea. Analysis revealed crystals were oriented in an 'odd but surprisingly consistent'pattern – a large angle between intergrown crystals, signifying a large surface area for the crystal aggregate and therefore significant hydrodynamic drag.
Models helped demonstrate that the olivine aggregates contained several subtle but distinct clues allowing DiBenedetto et al. to infer specific quantitative attributes of the flow field at the time of formation. Additional detailed analysis by fluid dynamic specialists revealed the odd alignment of the crystals was caused by magma moving in two directions simultaneously, with one flow directly atop the other, rather than pouring through the conduit in one steady stream. Although this theory had been previously suggested, the lack of direct access to the molten conduit prevented conclusive evidence – crystal analysis, however, can now advance future work within understanding this aspect of volcanic hazard process, providing a unique opportunity for improving theoretical models of volcano dynamics.
Simulations and modelling of flow dynamics such as this provide a baseline for understanding the magma flow dynamics prior to it reaching the Earth's surface. It could offer a method of predicting future eruptions based on flow patterns and additionally, offer insight into volcanic activity from the past. The significance of volcanic crystal analysis is no better summarised than by Suckale in a recent university release 'we can actually infer quantitative attributes of the flow prior to eruption from this crystal data and learn about the processes that led to the eruption without drilling into the volcano. That to me is the Holy Grail in volcanology.'
Links / Quelle:
Links / Quelle:
- Science Advances: Crystal aggregates record the pre-eruptive flow field in the volcanic conduit at Kīlauea, Hawaii (DiBenedetto, Qin and Suckale, 2020)
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