What Produced the Giant Hunga Tonga-Hunga Ha’apai Eruption Cloud?
The January 15, 2022, Hunga Tonga Hunga-Ha’apai eruption produced the largest umbrella cloud since the 1991 eruption of Mt. Pinatubo. Infrared data from the Himawari–8 and GOES–17 geostationary satellites show that, starting around 0415 UTC, the umbrella cloud expanded at heights of 25–35 km above sea level (asl) with an overshooting top that may have reached 55 km asl. Over the first 50 minutes, the cloud radius R grew to ~200 km, following a growth relationship with time t approximated by R~ t2/3. This extreme growth rate suggests an average volume flux of particles, gas and entrained air of 300-500 km3/s. We used a one-dimensional model of plume rise in local atmospheric conditions to approximately reproduce the observed umbrella height and volume flux with a mass eruption rate of solids (MER) of about 3.3e09 kg/s. This rate is several times greater than the Pinatubo eruption and would imply ejection of several km3 dense-rock equivalent (DRE) of magma over just the first hour of eruption. Using these source parameters, we modeled tephra dispersal and found that an 8 km3 DRE eruption should produce tens of centimeters (cm) of tephra at Tongatapu, 65–75 km SE of the volcano. However, only a few cm were reported there. In addition, the SO2 emitted (~0.4 Tg) was 10-50x smaller than expected for an eruption of 8 km3 DRE (S. Carn, written commun.) Many volcanologists have speculated that entrained seawater enhanced the umbrella growth rate; however, our 1-D plume modeling indicates that addition of seawater would have the opposite effect. Addition of >50 wt% magmatic gas could produce the 300–500 km3/s volume flux with an MER<1e09 kg/s; however, that would require an implausibly large (>10 km3) gas reservoir at 2-4 km depth. Such inconsistencies could in part be due to our use of a 1-D plume model; it is likely that understanding the origin of this giant cloud will require more complex modeling, as well as more field study of the eruption deposits.
Session: The 15 January 2022 Tonga Eruption and Tsunami II
Type: Oral
Room: Grand E-K
Date: 4/21/2022
Presentation Time: 02:00 PM Pacific
Presenting Author: Larry G. Mastin
Student Presenter: No
Additional Authors
Larry Mastin Presenting Author Corresponding Author lgmastin@usgs.gov U.S. Geological Survey |
Alexa Van Eaton avaneaton@usgs.gov U.S. Geological Survey |
David Schneider djschneider@usgs.gov U.S. Geological Survey, Alaska Volcano Observatory |
Christoph Kern ckern@usgs.gov U.S. Geological Survey |
Hans Schwaiger hschwaiger@usgs.gov U.S. Geological Survey, Alaska Volcano Observatory |
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What Produced the Giant Hunga Tonga-Hunga Ha’apai Eruption Cloud?
Category
The 15 January 2022 Tonga Eruption and Tsunami
Description