The words that are used in LXX for what becomes "brimstone and fire" in the English translation are θεῖον and πυρ. Interesting enough they both etymologically connect to the root/meaning of pure. Pure/fire being clearly phonetically connected to πυρ and θεῖον being a synonym (though may be having a distinct meaning like e.g. watch and clock).
So the full sentence 19:24 could be read as:
and the lord rained on Sodom and Gomorrah cleansing and purification for the lord from the heaven
Then 19:25 uses the verb κατέστρεψεν "turn upside down (so as to drain)".
And so it could be read as:
and overturned to drain these cities and all suburbs and everyone living in the city and everything growing from the earth
This water related (rain/draining) interpretation connects the two sentences 24-25 into a coherent story. In absent of factual knowledge about the events it is certainly a valid argument for choosing these meanings from many other options often found in the dictionary articles.
So does this passage suggest that the cities of Sodom and Gomorrah were struck by a natural disaster such as a volcanic eruption? - I think it may not be the a volcanic eruption in a sense that magma or ashes just completely flooded and covered the city and stayed there so it became inaccessible.
So let us note that in 19:28 Abraham sees some fire coming up from the earth like an evaporation/smoke of an oven and search a little further.
When Isaiah in 4:4 talks about cleansing the sons and daughters of Sion he refers to the spirit of judgement and the spirit of burning, so those left will be called clean ἅγιος. Some commentators point to the Isaiah 4:4 as the source for the Mt 3:11 (my rough translation):
I [John] am baptizing/drowning you in the water ... he will be baptizing/drowning (again compare "drain") you in the spirit of cleaning ἁγίῳ and [the spirit of] purification πυρί*
Then in Mt 3:12 John in another parabola talks about cleaning and then burning in πυρί ἀσβέστῳ that is translated as inextinguishable fire. Interesting enough ἀσβέστῳ is used in Russian (негашеная известь) to refer to the caustic unslaked lime aka quicklime aka Calcium Oxide CaO that comes from limestone СаCО3 when it's heated.
The unslaked lime caught fire easily ... and was used to make an
early, high-intensity lamp for the stage – the original limelight. ...
It also made a rather fearsome weapon, as it could sear the skin and
blind the eyes. ... unslaked lime was also shoveled into graves to
decompose bodies more quickly 
Now if we put all these facts together, we may have an explanation: It may be some event where the limestone got heated (maybe indeed because of a volcano eruption or some other geothermal source) and brought upon Sodom and Gomorrah following by a rain. It may have ignited first burning the city and the earth and what haven't burned then turned into the caustic unslaked lime because of the falling rain and so it corroded/cleansed the rest. The action of the unslaked lime on the corpses is said to be rather disinfecting and inhibiting putrification than the destruction of corpses.
Thus we have cleaning via rain, fire and corrosion (inextinguishable fire). The fire that Abraham saw in 19:28 was the limelight. What happened to the Lot's wife in 19:26? Maybe she was blinded to death or paralyzed from the same limelight.
To me this looks like an explanation worth considering due to the so many linguistic and chemical/physical connections that give it credibility.
P.S. As a less convincing hypothesis re: Lot's wife in 19:26 - the burning of limestone was done in kilns that may look like a column of salt. Some of those may have been found in that area. I don't think though it is what was meant in that sentence.
θεῖον looks like it shares the root with the word θεός - god (and compare ἅγιος - clean, pure, holy - also an epithet of god)
 https://lsj.gr/wiki/%CE%BA%CE%B1%CF%84%CE%B1%CF%83%CF%84%CF%81%CE%AD%CF%86%CF%89 (hence catastrophe)