Massive eruption in Tonga

[bjdeming]

 

[bjdeming]

Someone credible finally "went there" in my media feeds. I don't know enough of any of the relevant scientific fields to say yes, no, or maybe, but do look forward to the AGU discussions and findings that will be published from this fall's meeting on the topic:



Meanwhile, the sky glow is still amazing. My room's windows face north, more or less, and sunset colors on these clear summer evenings extend there and well into the eastern sky, making it much harder to see the "belt of Venus" (backscatter) that usually is so dramatic and pretty.

Again, I'm not knowledgeable, but common sense suggests that all that diffuse light, etc., must affect climate and, to some extent perhaps, weather.

In Oppenheimer's Eruptions That Shook The World is an interesting discussion of the effects of Pinatubo's heavy sulfur load farther down in the stratosphere. He notes that it followed the general "summer cooling/winter warming" pattern but with surprising regional variations.

Heavy humidization of the upper stratosphere is something else, something brand new in the instrumental age.

 

[bjdeming]

I haven't kept documenting it but keep an eye on the sky for glow around sunset every now and then and noticed a few weeks ago that the whole sky seems to glow now, subtly perhaps but enough to make the typical backscattering "belt of Venus" effect much harder to see.

 

[bjdeming]

Another paper out.

“This eruption put us in uncharted territory,” said Ross Salawitch, professor at the University of Maryland’s Earth System Science Interdisciplinary Center and co-author of the study. “We’ve never seen, in the history of satellite records, this much water vapor injected into the atmosphere and our paper is the first that looks at the downstream consequences over broad regions of both hemispheres in the months following the eruption using satellite data and a global model.”

--Source

 

[bjdeming]

Just a couple of things encountered while working up a chapter on this for the Vella project:

1. Information on the December 2023 AGU event is here.

2. PBS released its NOVA video on the January 15th eruption. If you've already seen it, then you know it starts off with images taken by some people who were safely but not too far from the big event, and then has lots of video from that day on Tonga.

This was actually taken the day before by Tongan geologists, who thought such massive energy release was the max for the volcano (so little is known about submarine volcanoes):



The blast next day was 70x as intense.

I was just reading this description by Yuen et al. and got a kick over the contrast between those images in the NOVA video and the dry academic discussion of their model (which is different from the two described in the NOVA video and just as plausible -- AFAIK, research is still ongoing on the cause):

...
We surmise that breaching of the magma chamber occurred at depth at 0402±1UTC, after which a bubbly, gas-laden and fragmenting magma made its way towards the surface. The exponential increase in eruption intensity at 0408 UTC could reflect the transition from surtseyan to subplinian activity, with the change to phreatoplinian activity marked by intense explosions beginning at 0414 ± 2 UTC and peaking at 0429 ± 2 UTC—the likely source of the incredibly large Lamb waves, tsunami, ground-coupled airwaves, meteo-tsunami, and colossal amounts of volcanic lightning.

Based on these first-order observations, peak volumetric discharge and mass flow rates of the volcanic plume are ∼9 × 105 m3/s and 1.3 × 109 kg/s, respectively, given a mean column density of 1500 kg/m3 typical of phreatoplinian volcanic columns (e.g., Sparks et al., 1997). Integration of the plume height time series reconstructed from imagery gives a preliminary total eruptive volume of 1.9 km3, corresponding to an eruptive mass of ∼2 850 Tg. Explosive activity was aided by the relatively high concentration (∼5 wt.% H2O) of juvenile (magmatic) H2O dissolved in the pre-eruptive melt, assuming that pre-eruptive wt.% H2O is consistent with eruptive products from 2009 to 2014–2015 (Colombier et al., 2018; Brenna et al., 2022), which is a reasonable preliminary approximation. A high magmatic volatile content presumably increased the depth in the volcanic conduit at which magma fragmentation occurred, supercharging the later and shallower exchange of heat between already-fragmented magma and seawater, and affording the rapid flashing to steam with attendant enormous increase in volume. The conversion of pressure-volume work associated with the expansion to kinetic energy and vertically-directed momentum coupled to enhanced plume buoyancy enabled the vigorous plume to develop with associated atmospheric shock waves. As a crude estimate, if the mass fraction of seawater constituted 15% of the eruptive product, then the flashing of seawater from liquid to steam contributes ∼2 300 km3 of volume expansion (Haar et al., 1984) when heated to magmatic temperatures. Indeed, a unique aspect of the HTHH eruption was the ingress of seawater (external, not magmatic water) and its phase change to a supercritical fluid. The PV work done pushing the atmosphere away from the eruptive vent constitutes an approximate mechanical energy of ∼2 × 1017 J, which is in relatively good agreement with preliminary blast energies associated with atmospheric shock waves of 4–18 MT...

Just for reference, the highest output of Iceland's Sundhnuk eruptions thus far has been around 300 m/s.