I am an Associate Professor, Senior Research Fellow in tephrochronology in the Research Laboratory for Archaeology and the History of Art in the School for Archaeology. I obtained my PhD in Geology from the University of Auckland, New Zealand and I was a postdoctoral fellow in the Department of Earth Sciences, University of Bristol from 2006 until 2009.
My research focuses on large explosive eruptions and in particular their age, composition, and magnitude. I use this information to gain understanding on the tempo of explosive eruptions and establish their impact. The glass and mineral compositions of the volcanic deposits (tephra) serve as chemical fingerprints of specific eruptions that allow us to correlate and synchronise records that contain the volcanic ash even if it can only be identified with a microscope. These correlations allow us to map the full extent of the tephra dispersal, refine age models and constrain the eruption ages, and precisely link palaeoclimate and/or archaeological records. This allows us to identify temporal and spatial variations in eruptions, climate and/or culture.
The magnitude and impact of the 431 CE Tierra Blanca Joven eruption of Ilopango, El Salvador
Smith, VC, Costa, A, Aguirre-Díaz, G, Pedrazzi, D, Scifo, A, Plunkett, G, Poret, M, Tournigand, P-Y, Miles, D, Dee, MW, McConnell, JR, Sunyé-Puchol, I
Proceedings of the National Academy of Sciences
<jats:p>The Tierra Blanca Joven (TBJ) eruption from Ilopango volcano deposited thick ash over much of El Salvador when it was inhabited by the Maya, and rendered all areas within at least 80 km of the volcano uninhabitable for years to decades after the eruption. Nonetheless, the more widespread environmental and climatic impacts of this large eruption are not well known because the eruption magnitude and date are not well constrained. In this multifaceted study we have resolved the date of the eruption to 431 ± 2 CE by identifying the ash layer in a well-dated, high-resolution Greenland ice-core record that is &gt;7,000 km from Ilopango; and calculated that between 37 and 82 km<jats:sup>3</jats:sup> of magma was dispersed from an eruption coignimbrite column that rose to ∼45 km by modeling the deposit thickness using state-of-the-art tephra dispersal methods. Sulfate records from an array of ice cores suggest stratospheric injection of 14 ± 2 Tg S associated with the TBJ eruption, exceeding those of the historic eruption of Pinatubo in 1991. Based on these estimates it is likely that the TBJ eruption produced a cooling of around 0.5 °C for a few years after the eruption. The modeled dispersal and higher sulfate concentrations recorded in Antarctic ice cores imply that the cooling would have been more pronounced in the Southern Hemisphere. The new date confirms the eruption occurred within the Early Classic phase when Maya expanded across Central America.</jats:p>
Constraints on the timing of explosive volcanism at Aso and Aira calderas (Japan) between 50 and 30 ka: New insights from the Lake Suigetsu sedimentary record (SG14 core)
McLean, D, ALBERT, PG, SMITH JOHNSON, V
G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences
Chemical zoning and open system processes in the Laacher See magmatic system