Introduction[]
According to a statement, Abyss falling to Chaos destroyed 1% of the world
Basic values, information and the calculation[]
Chaos's radius = 6371 km (Chaos was stated to resemble Earth)

Surface area of Chaos = surface area of a sphere = 4*Pi*R
Surface area of Chaos = 510064471.91 km^2
Area of destruction = 1% (statement)
Area of destruction = 5100644.7191 km^2
Radius of the destroyed area = 1274.2 km = Air blast radius (near total fatalities)
Use the nuclear explosion calculator to find the yield
Abyss falling to the ground = 121.1 teratons (Country+)
Conclusion and important notes[]

Abyss falls = 121.1 teratons (Country+)
What's really worthy of note is that Serin and Nex were trying to hold the abyss from falling. Serin previously substituted as a battery to hold half of Abyss in the sky. That means that Nex and Serin stopped at least half of the damage from occuring.
Total energy of the Abyss fall = calculated energy*2 = 242.2 teratons (Country+)
Serin + Nex's power = energy of the Abyss falling = 121.1 teratons
Since Nex and Serin were pretty much stated as equals in power at that point with Nex having a slight edge due to Depore, each of them gets half the value.
Serin's love = 60.55 teratons (Country)
Nex's hatred = 60.55 teratons (Country)
What's more to note is that magical power = general physical characteristics in CoA's verse so that means that Both Nex and Serin get this to their durability as well.