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Seismic Surveys

Samuel has been involved in several studies utilising 3D marine seismic surveying to map the external and internal structures of submarine volcanoes and lava flow fields.

 

While 3D seismic surveys have been a commonly used tool in the oil and gas industry, the application for understanding volcanism on our seafloor is relatively new, but growing rapidly with increasing seafloor exploration capabilities.

Morphology of deep submarine volcanoes

3D seismic surveying can be particularly useful in mapping the structure of submarine volcanic landforms that are buried beneath many (possibly hundreds of!) meters of marine sediment. In recent research, 3D seismic surveying of ancient volcanoes in the South China Sea was used to quantify the morphology of volcanic edifices and the extent of their associated lava flow fields.

The seismic profiles revealed the aggradation structures within the volcanoes themselves, as well as large basal structures representing the earliest stages of the eruption. Further research from this 3D mapping determined heights, volumes, flank dip, and growth mechanisms of understudied smaller volcanoes in a very deep paleo-marine setting. 

Application of physical volcanology theory (magma rheology, volatile contents, effects of hydrostatic pressure) was also used to assess lava flow runout distances, potential styles of volcanism 2-3km deep on the seafloor, and the possible growth/effusion rates of volcanic edifices and their lava flows.

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3D surveys of magma storage regions

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In the summer of 2019, the R/V Marcus G. Langseth set out to Axial Seamount (off the coast of Oregon, USA) with a team of onboard geologists and geophysicists seeking to understand the magma storage regions of the USA's most active submarine volcano.

The cruise successfully 3D-mapped the main magma reservoir underneath Axial's caldera and the secondary magma reservoir SE of the main caldera. Preliminary results from the cruise were presented at the AGU Fall Meeting in 2019. Deeper 2D seismic lines were also collected during the expedition.

Further research from this cruise over the next few years will seek to understand: i) how magma storage regions are connected within the volcano, ii) how magma storage reflects the locations of recent eruptive activity (1998, 2011 and 2015), iii) how much "active" melt is currently present within the magma storage region, and iv) how fractures within the volcano relate to external surface morphology.