A Terrestrial Gamma‐Ray Flash From the 2022 Hunga Tonga–Hunga Ha'apai Volcanic Eruption

Abstract

The Hunga Tonga–Hunga Ha'apai submarine volcano recently resumed activity. Violent eruptions on 14th and 15th January 2022 launched a tall ash plume that produced extremely high lightning rates. Here we report a terrestrial gamma‐ray flash (TGF) that was produced by the volcanic lightning and observed from space by the Fermi Gamma‐ray Burst Monitor (GBM). Observations by radio lightning networks and especially by the Geostationary Lightning Mapper show that the only lightning close enough to produce a TGF detectable by Fermi GBM was from the volcano's plume. With the observing duration of Fermi, observing a single TGF is consistent with the hypothesis that the volcanic lightning of this eruption produced TGFs at the average rate of thunderstorm lightning. The observation of a strong TGF from space also indicates that the electric field was oriented so as to accelerate electrons upward.

First field evidence of the electrical multipolar nature of volcanic aggregates

“…Vesuvius. The high electrical activity in the eruptive events implies a strong link between the physics of charge generation at the microscale and the final phenomena observed by the naked eye at the macroscopic scale, i.e., the lightning ( 18 , 19 , 46 ). Following the logical path from micro to macro, the electrical shielding due to ash aggregation may thus have visible consequences also at the macroscopic scale of the volcanic plume and cloud.…”

“…The presence of a bulk charge Q on the surface of volcanic ash is believed to influence both the binding mechanisms (8) and the collision rate between particles (14,15). At the macroscopic scale, a well-known consequence of the highly charged nature of ash particles can be found in the ubiquitous observation of volcanic lightning inside volcanic plumes (16)(17)(18)(19). At the microscopic scale, charge rearrangement among atoms or the production of free electrons involves several distinct processes (20,21), such as tribocharging due to particle collisions (22), fractoemission after multiple breakages (23), and release or absorption of ions contained in the surrounding gas and the induced charge due to background potentials (24).…”

Radiation Risk Assessment Associated With Terrestrial Gamma Ray Flashes for Commercial Flights

“…To calculate the radius r of Fermi-GBM field of view, we used Figure A1 of Briggs et al (2022), describing Fermi-GBM TGF detection rate R as a function of the radial distance r. FoV is calculated to have a radius r of 416 km, and this value is used in this work. The density map is expressed in TGF/km 2 /year.…”

Lightning Rings and Gravity Waves: Insights Into the Giant Eruption Plume From Tonga's Hunga Volcano on 15 January 2022

“…Additionally, Briggs et al. (2022) noted the high rates of volcanic lightning during this eruption, leading to key questions about the nature of electrification during such an extreme event. Here, we examine the evolution of the volcanic plume and its extraordinary lightning activity.…”