Waves Generated by Discrete and Sustained Gas Eruptions With Implications for Submarine Volcanic Tsunamis. Issue 21 (1st November 2021)

• Record Type: Journal Article
• Authors: Shen, Yaxiong; Whittaker, Colin N.; Lane, Emily M.; White, James D. L.; Power, William; Melville, Bruce W.
• Is Part Of: Geophysical research letters. Volume 48:Issue 21(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-01
• Subjects: subaqueous volcanic eruption -- submarine volcano -- laboratory experiment -- critical water depth -- saturation duration -- tsunami; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL094539
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Submarine volcanic eruptions can perturb the water surface and subsequently generate localized tsunamis. Herein waves are produced in analogous laboratory experiments by injections of non‐condensable expanding air into fresh water. By varying source pressures, jet durations and water depths, we obtain two key results. There exists a saturation duration above which the maximum wave height will not increase as the eruption continues. Apart from in extremely shallow or deep water depths, this saturation duration is positively correlated with the source intensity and negatively with the water depth. There also exists a critical water depth where an eruption with a given source intensity can generate the largest waves. When an eruption lasts less than the saturation duration, increasing the eruption duration will increase the critical water depth and the corresponding maximum wave height. The saturation duration and critical water depth are the primary controls on tsunami size and hazard. Plain Language Summary: When volcanoes erupt underwater, they can generate waves that are dangerous even at coastlines far away from the eruption itself. In this study, we investigated whether the wave heights changed when the underwater eruption lasted a different amount of time. Our experiments modeled an underwater eruption by releasing compressed air into a tank of water. We carefully controlled the duration of the eruption and measured the size of the waves generated in the tank. Although at first longer eruptions generated larger wave heights, eventually the height reached a maximum value. Further increases in the duration did not lead to larger wave heights. Changing the water depth also affected the wave heights; there is a water depth where a given eruption can generate the largest wave heights. Our experiments show how this "critical" water depth changes depending on the eruption duration. Because both the depth and duration of eruption are important in determining the wave height, they should be considered in future hazard assessments of tsunamis generated by underwater volcanic eruptions. Key Points: We investigate the effect of underwater volcanic eruption duration on the properties of generated waves, using analogous gas jet experiments There is a saturation duration above which the maximum wave amplitude does not increase with increasing eruption duration For durations shorter than the saturation duration, longer eruptions increase the critical water depths associated with the largest waves