Kristalinitas Abu Vulkanik Gunung Soputan dan Implikasinya Terhadap Perilaku Eksplosif pada Erupsi Tahun 2016 dan 2018
DOI:
https://doi.org/10.35799/jis.21.1.2021.31296Abstract
Gunung Soputan adalah gunung basaltik dengan tipe erupsi eksplosif. Tipikal eksplosif berkaitan dengan karakter magma. Penelitian ini bertujuan untuk mengkaji kristalinitas abu vulkanik Gunung Soputan tahun 2016 dan 2018 dan implikasinya terhadap perilaku eksplosifnya. Kristalinitas abu vulkanik dikarakterisasi menggunakan peralatan difraktometer sinar X. Indeks kristalinitas dikalkulasi menggunakan persamaan Soltys dan ukuran kristal dikomputasi dengan persamaan Debye-Scherrer. Morfologi partikel abu dikarakterisasi menggunakan SEM. Hasil karakterisasi menunjukkan bahwa abu Soputan tahun 2016 dan 2018 memiliki indeks kristalinitas yang tinggi dan mengandung sejumlah kristal berukuran kecil serta memiliki dua bentuk morfologi yaitu bentuk padat dan blok bervesikular untuk abu hasil erupsi 4 Januari 2016, dan bentuk padat dan blok untuk abu hasil erupsi 6 Februari 2016 dan 3 Oktober 2018. Kristalinitas yang tinggi menyebabkan magma Soputan memiliki viskositas yang memadai untuk terjadinya  erupsi yang eksplosif. Karakter eksplosif Gunung Soputan terekam dalam morfologi abu vulkaniknya.
Kata kunci: Abu vulkanik; erupsi eksplosif; fragmentasi getas; indeks kristalinitas
Cristallinity of Volcanic Ash of Mount Soputan and Its Implication to Explosive Behaviour on Eruption of 2016 and 2018
ABSTRACT
Mount Soputan is a basaltic mountain with an explosive eruption type. Typical explosives relate to the character of the magma. This study aims to examine the crystallinity of Mount Soputan's volcanic ash in 2016 and 2018 and its implications for its explosive behavior. The crystallinity of volcanic ash was characterized using an X-ray diffractometer. The crystallinity index was calculated using the Soltys equation and the crystal size computed using the Debye-Scherrer equation. The morphology of the ash particles was characterized using SEM. The characterization results show that the 2016 and 2018 Soputan ash has a high crystallinity index and contains a number of small crystals and has two morphological forms, namely solid form and vesicular block for ash from the eruption on January 4, 2016, and solid and block form for eruption ash 6 February 2016 and October 3 2018. High crystallinity causes the Soputan magma to have sufficient viscosity for explosive eruptions. The explosive character of Mount Soputan is recorded in the morphology of its volcanic ash.
Keywords: Brittle fragmentation; crystallinity index; explosive eruption; volcanic ashReferences
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