1TT is equivalent of almost 20,000 Tsar bombs. It can't be an airburst because it's a laser. Depending on wavelength used some shit may be set on fire from the thermal bloom but that's an if.
As it's a laser, it doesn't direct energy in a spherical pattern, but in a linear one, so depending on how wide the beam is will change the affected area and crater depth a lot.
Overall will be very inefficient in destroying a large area of things compared to a nuke, however will glass large and deep amount of landmass, and start massive fires for some area. I'd guess hundreds of thousands dead, up to hundreds depending on weather, wavelength and how fire spreads, the worst case scenario being the laser using a wavelength that causes a lot of atmospheric bloom, and in turn causes massive fires across a large section of SEA, which may be as, if not worse than the laser itself in the scale of effect.
Also fallout? It's not a nuclear weapon, so at least it's not radioactive.
Yes, in some ways it would be similar to a volcano but laser's nature does not convert energy into it efficiently either. Neither will it release large sulfur amounts as volcanoes do for their climate cooling climate effect.
en.wikipedia.org
That was rated at 24 megaton equivalent.
The 1815 eruption at Tambora was the largest in recorded human history. So, what exactly does that mean?
www.wired.com
That was 33 gigaton equivalent, so it's getting close.
Speaking of efficiency, with those historically recent eruptions we are talking close to 200 cubic kilometers of rock ejected, only some of it ash as volcanoes "cheat" by throwing large chunks of solid rock too, while magma is liquid with only some vapor dissolved in it.. Assuming a cubic centimeter of rock needs on average 25 kJ to
vaporize, a cubic meter takes 25 GJ, which means 1 kiloton fully converted gets you 167 cubic meters of vaporized rocks, and scaling up to a teraton, you get... convenient 167 cubic kilometers, so about the same as the 1815 eruption.
At worst we are talking little ice age level of effect, that is if the thermal bloom caused fires get bad and contribute much more in ash of their own.
Thailand and Malaysia are gone as countries, depending on aforementioned variables few neighboring countries may be too, and in such case there may be significant global effects, but not apocalyptic ones.
