Circle casting: Augment will increase the range of a spell. 

2024 Earth Tremor https://www.dndbeyond.com/spells/2378-earth-tremor seems to have Range/Area linked together, so some people argue that you should be able to augment the effective area (and damage) of earth tremor to a mile size with not many spellcasters needed. 

Is this True?

So, first off: there is no 2024 version of Earth Tremor. The only version that exists is from the 2015 adventure module Princes of the Apocalypse (the character options from which were also published as the free Elemental Evil Player's Companion).

Probably because it's so old, it is written in kind of an odd way that makes it hard to figure out how it's meant to work, but I think the general consensus is that it's meant to work the way 2024 Emanation AoEs do, affecting all the ground within a specified distance from the caster. If this spell were written in the 2024 style, it would have a range of Self and thus not be eligible for the "Augment" option of Circle Casting.

So, I think you could maybe make an argument that under RAW it can work, but that's pretty clearly unintended and I expect a lot of DMs would not allow it (I wouldn't).

Yeah, that's definitely meant to be an area. I wouldn't allow it either. I would, however, allow Expand.

Quote from wagnarokkr >>

So, first off: there is no 2024 version of Earth Tremor. The only version that exists is from the 2015 adventure module Princes of the Apocalypse (the character options from which were also published as the free Elemental Evil Player's Companion).

Probably because it's so old, it is written in kind of an odd way that makes it hard to figure out how it's meant to work, but I think the general consensus is that it's meant to work the way 2024 Emanation AoEs do, affecting all the ground within a specified distance from the caster. If this spell were written in the 2024 style, it would have a range of Self and thus not be eligible for the "Augment" option of Circle Casting.

So, I think you could maybe make an argument that under RAW it can work, but that's pretty clearly unintended and I expect a lot of DMs would not allow it (I wouldn't).

 The story behind the spell is interesting, since it was updated between EE and XGtE, which ended up causing some confusion. I shared my interpretation a while ago here:

Quote from TarodNet >>

I was reading some spells from Xanathar's Guide to Everything when I spotted Earth Tremor, and it has a strange combination of range and description.

RAW:

• Range: 10 feet
• Description: You cause a tremor in the ground within range. Each creature other than you in that area must make a Dexterity saving throw. [...]

It seems that previously the range and description was a little bit different according to this tweet and if you read this edition of the Elemental Evil Player's Companion:

• Range: Self (10-foot radius)
• Description: You cause a tremor in the ground in a 10-foot radius. Each creature other than you in that area must make a Dexterity saving throw [...]

Assuming then it's not a radius, even RAW, I see two interpretations if you're playing on a grid:

• You choose a point of origin and then the tremor is a 10 x 10 ft square (2x2 squares on a grid)
• Your character is the point of origin and then the tremor is a 25 x 25 ft square (5x5 squares on a grid). This could be sustained by the previous linked tweet:

and the next one:

If we draw the second interpretation, we'd have something like this where the caster is the green circle and the brown squares are the area of effect:

I need your opinion guys one more time!