Abstract
This study addresses the characteristics, potential hazards, and both eruptive and non-eruptive role of water at selected volcanic crater lakes in Alaska. Crater lakes are an important feature of some stratovolcanoes in Alaska. Of the volcanoes in the state with known Holocene eruptive activity, about one third have summit crater lakes. Also included are two volcanoes with small caldera lakes (Katmai, Kaguyak). The lakes play an important but not well studied role in influencing eruptive behavior and pose some significant hydrologic hazards. Floods from crater lakes in Alaska are evaluated by estimating maximum potential crater lake water volumes and peak outflow discharge with a dam-break model. Some recent eruptions and hydrologic events that involved crater lakes also are reviewed. The large volumes of water potentially hosted by crater lakes in Alaska indicate that significant flowage hazards resulting from catastrophic breaching of crater rims are possible. Estimates of maximum peak flood discharge associated with breaching of lake-filled craters derived from dam-break modeling indicate that flood magnitudes could be as large as 103–106 m3/s if summit crater lakes drain rapidly when at maximum volume. Many of the Alaska crater lakes discussed are situated in hydrothermally altered craters characterized by complex assemblages of stratified unconsolidated volcaniclastic deposits, in a region known for large magnitude (>M7) earthquakes. Although there are only a few historical examples of eruptions involving crater lakes in Alaska, these provide noteworthy examples of the role of external water in cooling pyroclastic deposits, acidic crater-lake drainage, and water-related hazards such as lahars and base surge.
Highlights
Volcanic crater lakes are distinguishing features of many active stratovolcanoes in Alaska and elsewhere (Christenson et al, 2015)
Eruptions through crater lakes pose a special type of hazard because of the potential for explosivity associated with magma-water interaction and the possibility for voluminous water-rich mass flows that can develop if lake water is explosively expelled from its host crater or produced by catastrophic breaching of the crater wall (Mastin and Witter, 2000; Manville et al, 2007)
The hazards associated with volcanic crater lakes beyond Alaska have received some study especially in locations where people and infrastructure are at risk (Mastin and Witter, 2000; Manville, 2010; Manville, 2015, and references therein)
Summary
Volcanic crater lakes are distinguishing features of many active stratovolcanoes in Alaska and elsewhere (Christenson et al, 2015). Eruptions through crater lakes pose a special type of hazard because of the potential for explosivity associated with magma-water interaction and the possibility for voluminous water-rich mass flows that can develop if lake water is explosively expelled from its host crater or produced by catastrophic breaching of the crater wall (Mastin and Witter, 2000; Manville et al, 2007). Alaska Crater Lakes highlighting the importance of catastrophic crater lake drainage These works and others (Neall, 1996; Strehlow et al, 2017; Rouwet, 2021) have noted the hazard implications of large volumes of water within the craters of active volcanoes and this is in part the motivation to evaluate hydrologic hazards at crater lakes in Alaska
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