Down to Earth Extra December 2024

The December 2024 edition of Down to Earth Extra has been published. You can download it HERE or you can read it below.

Crystals Hold Secret of When Volcanoes Erupt

I came across THIS ARTICLE in the New Scientist and found it very interesting for several reasons. Its about igneous petrology, Hawaii and volcanoes - what more do you need! It is based on THIS PAPER in Nature.

The researchers used several techniques of studying crystals - mainly olivine - from the 2022 eruption of Maunu Loa to determine the history of the crystals before the eruption. And they found that they had started moving into a higher magma chamber 70 days prior to the eruption. The eruption occurred when this chamber was full.

And seventy days prior to eruption a change in earthquake frequency and ground bulging (inflation) was noticed.

So if a similar change in inflation and earthquake frequency was noticed a warning of imminent eruption could be given.

Studies to see if similar things happened to Mauna Loa and other volcanoes prior to other eruptions are being carried out.

But the Hawaii volcanoes are among the most studied anywhere. Is there sufficient knowledge of other volcanoes to make predictions?

Looking at the Nature paper reminds me that igneous petrology has moved on considerably since I was a student!

A Map of Mauna Loa summit and upper Northeast Rift Zone (Island of Hawai‘i on inset map) with 2022 lava flow field78 (pink), lava flows since CE 184379,80 (dark gray), 1000 ft (~305 m) contours (brown lines), samples (black dots; green for large-volume tephra samples used for mineral chemistry), and monitoring network stations (various symbols; see Fig. S1 for wider view that includes all GPS stations in this study). Basemap generated from a 2005 NOAA digital terrain model81 and a 1983 USGS digital elevation model82. Caldera bounding faults are denoted as black lines with teeth pointing to the downthrown side and 2022 eruptive fissures are denoted with red lines. The 2022 flows crossed the NOAA Observatory access road (dashed black line) and came within ~3 km of Highway 200 (Daniel K. Inouye Highway, “Saddle Road”). B 3-D X-ray computed tomography scan (μCT scan) of an olivine from sample ML22-88 shows the rounded morphology typical of phenocrysts from this eruption and inclusions of melt (yellow), Cr-spinels (red), and fluids (blue). C Phosphorus and D magnesium X-ray element maps of an olivine crystal. Sharp truncations in phosphorus zoning record at least two dissolution events. Patchy zones of truncated high-phosphorus in the phenocryst interior represent older resorption histories, whereas truncation of secondary phosphorus branches by the crystal-melt boundary record the youngest resorption event that is also evident in the rounded morphology of the phenocryst. Diffusion gradients in magnesium show obvious differences along the a- vs. c-axes (shown in lower-hemisphere stereonet inset in C), a result of diffusion anisotropy. Part of the crystal rim in the a-axis direction also shows subtle skeletal rim texture, evidence of late-stage crystal growth.

 Down to Earth Extra November 2024

The November 2024 edition of Down to Earth Extra has been published. You can download it HERE or you can read it below.