Lateral migration of explosive hazards during maar eruptions constrained from crater shapes

Abstract

Maar volcanoes are produced by subsurface phreatomagmatic explosions that can move vertically and laterally during an eruption. Constraining the distances that maar-forming explosions move laterally, and the number of relocations common to these eruptions, is vital for informing hazard scenarios and numerical simulations. This study uses 241 intact Quaternary maar crater shapes to establish global trends in size and spacing of explosion position relocations. Maar craters are sorted into shape classes based on the presence of uniquely identifiable combinations of overlapping circular components in their geometry. These components are used to recognize the minimum number of explosion locations responsible for observed crater shapes. Craters with unique solutions are then used to measure the size and spacing of the explosion footprints, the circular area of the largest crater produced by a single explosion of a given energy, that produce the crater shape. Thus, even in the absence of abundant observations of maar-type eruptions, the typical range, size and spacing of explosion positions are derived from maar crater shapes. This analysis indicates that most Quaternary maar eruptions involved at least three different explosion locations spanning distances of 200–600 m that did not always follow the trend of the dike feeding the eruption. Additional evaluation of larger maars, consistent with stratigraphic studies, indicates that centers of explosive activity, and thus the origin of ballistic and density current hazards, can move as many as twenty times during a maar-forming eruption. These results provide the first quantitative constraints on the scale and frequency of lateral migration in maar eruptions and these values can directly contribute to hazard models and eruption event trees in advance of future maar-type eruptions.

Phreatic and Hydrothermal Eruptions: From Overlooked to Looking Over

“…The eruptive mechanisms and processes of phreatic and hydrothermal events are strongly influenced by the properties of fragmented lithologies (Fig. 3; Breard et al 2014;Graettinger et al 2015;Valentine et al 2015b;Pittari et al 2016;Geshi and Itoh 2018;Montanaro et al 2020Montanaro et al , 2021bGraettinger and Bearden 2021). In particular, rock permeability determines whether expanding fluids may fragment the host rocks or escape via efficient outgassing, while rock strength can modulate fragmentation initiation, craterisation processes, and eruptive dynamics (Haug et al 2013;Mayer et al 2015;Montanaro et al 2016aMontanaro et al , c, 2021a.…”

Small-volume monogenetic igneous landforms and edifices statistics (SMILES): A catalog of representative mafic volcanic landforms to enable quantitative remote identification

“…Unlike a lava collapse feature, simple maars have a narrow range of AR, IC, interior slope angle, and depth ratio. More complex maars with multiple overlapping depressions (Graettinger and Bearden, 2021) will require additional evaluation to determine the diagnostic parameter ranges and additional morphometric parameters. It is also worth noting that maars tend to be larger than lava collapse features; however, the emphasis of this study was to identify dimensionless parameters which translate to non-terrestrial landforms.…”

“…The process of multiple repeated explosions through a debris-filled crater contributes to the final shape of a maar by recycling crater fill and ejecta (Valentine and White, 2012;Graettinger et al, 2016;Macorps et al, 2016) allowing gravitational processes to dominate the interior slope. Further evidence of the influence of this backfill debris on morphology was explored in large-scale experiments where closely spaced laterally migrating explosions still produced circular craters Graettinger and Bearden, 2021). There have also been studies of how maar craters degrade after the eruption where observations of Ukinrek maar in Alaska documented continued to fill with material from the rim through gravitational processes and an infilling lake (Pirrung et al, 2008).…”

Stratigraphy and eruption history of maars in the Clear Lake Volcanic Field, California

“…However, because of the close proximity of many of the known maar craters to each other, and the typical characteristics of maar eruptions (multiple eruptions from a single crater, migrating craters, or even multiple crater formation) (Graettinger et al, 2014;Sonder et al, 2015;Valentine et al, 2017;Graettinger and Bearden, 2021), it is possible that individual stratigraphic sections record not only multiple explosive events from single or even multiple craters in the same eruption, but also interlayered deposits from multiple maars, if there were coeval eruptions in the CLVF. Additional radiocarbon dating, as well as systematic geochemical and textural analyses of tephra are the necessary next steps in unraveling these relationships.…”

“…Processes during maar eruptions can vary from largely steam-driven (lacking a juvenile component in deposits) (Barberi et al, 1992;Pardo et al, 2014;Houghton et al, 2015;Zimanowski et al, 2015), to phreatomagmatic (in which juvenile material makes up a significant component of deposits) (Pardo et al, 2014;Valentine et al, 2014Valentine et al, , 2017Houghton et al, 2015;White and Valentine, 2016), to Strombolian (magma-dominated) (Houghton and Hackett, 1984;Kokelaar, 1986;Gutmann, 2002), and even to Surtseyan (eruptions occurring through bodies of water, often displaying characteristic "rooster-tail" plumes) (Cole et al, 2001;Németh et al, 2006;Murtagh and White, 2013;Gjerløw et al, 2015;Verolino et al, 2019). Maar eruptions may not only produce locally significant tephra-fall deposits (Brand and Heiken, 2009;Valentine et al, 2015;Fierstein and Hildreth, 2017;Ort et al, 2018), ballistics (Self et al, 1980;Mastin and Witter, 2000;Taddeucci et al, 2010;Ort et al, 2018;Graettinger and Bearden, 2021), and ballistic curtains (Melosh, 1986;Graettinger et al, 2015aGraettinger et al, , 2015bValentine et al, 2017), but may also create a variety of dense and dilute pyroclastic density currents (PDCs) (Fisher and Schmincke, 1984;1998;Cas and Wright, 1988;Lirer and Vinci, 1991;Giaccio et al, 2007;…”