1887
ASEG2013 - 23rd Geophysical Conference
  • ISSN: 2202-0586
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Abstract

Potential field geophysical modelling techniques can be applied to better understand the subsurface morphology of volcanoes, and when linked with observations of surface geology can be used to develop a more complete understanding of the volcanic centres eruptive history.

High resolution ground gravity and magnetic data were acquired across several maar volcanoes located within the Newer Volcanics Province (NVP) of Western Victoria. The maar volcanoes surveyed represent a range of the different sizes and styles of eruptions observed within maar volcanoes of the NVP.

Gravity and magnetic data were subject to 2D forward and 3D inverse modelling in order to reveal details on the depth, geometry and petrophysical property distributions within subsurface volcanic structures. Gravity lows with corresponding magnetic highs are observed across the maar craters and were reproduced during modelling with the presence of a diatreme. Smaller wavelength gravity and magnetic anomalies detected in the centre of the more complex volcanic craters can be explained by the presence of intrusive dykes or vents filled with a higher proportion of denser volcanic debris.

Modelling suggests that multiple coalescing diatreme structures exist below the volcanic edifices, some containing intrusive dykes or a denser central vent filled in with volcanic debris. Multiple diatreme structures suggest a complex eruption history involving vent migration, while preserved dykes within the diatreme suggest short-lived fluctuations between phreatomagmatic and magmatic eruption styles.

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2013-12-01
2026-01-19

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  • Article Type: Research Article
Keyword(s): 3D inverse modelling; diatreme; forward modelling; gravity; Maar; magnetics

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