Modeling Ash Dispersal From Future Eruptions of Taupo Supervolcano

Abstract

Hazard analysis at caldera volcanoes is challenging due to the wide range of eruptive and environmental conditions that can plausibly occur during renewed activity. Taupo volcano, New Zealand, is a frequently active and productive rhyolitic caldera volcano that has hosted the world's youngest known supereruption and numerous smaller explosive events. To assess ashfall hazard from future eruptions, we have simulated atmospheric ash dispersal using the Ash3d model. We consider five eruption scenarios spanning magma volumes of 0.1–500 km3 and investigate the main factors governing ash dispersal in modern atmospheric conditions. Our results are examined in the context of regional synoptic weather patterns (Kidson types) that provide a framework for assessing the variability of ashfall distribution in different wind fields. For the smallest eruptions (~0.1‐km3 magma), ashfall thicknesses >1 cm are largely confined to the central North Island, with dispersal controlled by day‐to‐day weather and the dominance of westerly winds. With increasing eruptive volume (1–5‐km3 magma), ashfall thicknesses >1 cm would likely reach major population centers throughout the North Island. Dispersal is less dependent on weather patterns as the formation of a radially expanding umbrella cloud forces ash upwind or crosswind, although strong stratospheric winds significantly restrict umbrella spreading. For large eruptions (50–500‐km3 magma), powerful expansion of the umbrella cloud results in widespread ashfall at damaging thicknesses (>10 cm) across most of the North Island and top of the South Island. Synoptic climatology may prove a useful additional technique for long‐term hazard planning at caldera volcanoes.

Volcanic Unrest at Taupō Volcano in 2019: Causes, Mechanisms and Implications

“…With the presence of Lake Taupō inhibiting detailed geophysical surveys, most of the insights into the Taupō's magmatic system have been provided by petrological studies of past eruptive products (Allan et al., 2017; Barker et al., 2014; 2015; 2016; Sutton et al., 2000). Taupō has been highly active since 12 ka, with at least 25 eruptions, mostly vented along the eastern side of the lake (Barker et al., 2019; Wilson, 1993). Petrological studies of the magmas erupted during this period provide insights into several key features of the Taupō's magmatic system. Repeated extraction of crystal‐poor rhyolites .…”

“…Interestingly, the surface projection of this aseismic region coincides with the vent locations for recent (<2.2 ka) eruptions from Taupō (Figure 1; Barker et al., 2016; Wilson, 1993), a large negative gravity anomaly interpreted to arise from caldera collapse following these previous eruptions (Davy & Caldwell, 1998), elevated heat flow (Whiteford, 1996), and active hydrothermal venting (de Ronde et al., 2002). This region is therefore considered to be the most likely location for the modern day focus of magmatism (Barker et al., 2019, 2021). It is possible that magmatic intrusion and/or deformation was occurring in this region, but in an aseismic fashion due to high crustal temperatures, as has been observed in Hawaii and Japan (Janiszewski et al., 2020; Uchide et al., 2016; Wright & Klein, 2006).…”

“…The southern section of the lake does not coincide with a negative gravity anomaly but is also thought to have partially collapsed during the Oruanui eruption (Wilson, 2001; Figure 1). The twenty-eight post-Oruanui eruptions (25 during the last 12 ka) range greatly in size and eruption style, with the latest and largest explosive event occurring at 232 ± 10 CE (Barker et al, 2015(Barker et al, , 2019Hogg et al, 2012Hogg et al, , 2019Wilson, 1993). This 232 CE "Taupō eruption" occurred in the northeast corner of the Oruanui caldera and caused further collapse (Davy & Caldwell, 1998, Figure 1).…”

TephraNZ: a major- and trace-element reference dataset for glass-shard analyses from prominent Quaternary rhyolitic tephras in New Zealand and implications for correlation

“…New Zealand's climatic setting strongly affects tephra dispersal. The landmass sits in the path of predominantly westerly to southern-westerly winds, and therefore the majority of tephra plumes are dispersed to the east of the volcanic zones (Barker et al, 2019). However, tephra deposits from these rhyolitic eruptions are found in a range of different environments, including 1. marine (e.g.…”

Novel statistical emulator construction for volcanic ash transport model Ash3d with physically motivated measures

“…Otherwise the vertical distribution of mass flux rate along the line source follows a uniform or Suzuki distribution [77]. Ash3d has been used by many scientists to model the transport and deposition of volcanic ash over a large area [70,[78][79][80][81].…”