
Izumi Curtis Feat (Fullmetal Alchemist 2003)
Island Size: 3.53 km
Radius: 1.76 km
I will go off and say this is a Magnitude 5 Earthquake
5+0.0238*1.76 = 5.041888
10^1.5*(5.041888)+4.8] = 2.305855e+12 Joules or 551.11 Tons of TNT
assuming its a 6 or 7 Magnitude Earthquake
10^1.5*(6.041888)+4.8] = 7.2917539e+13 Joules or 17.42 Kilotons of TNT
10^[1.5*(7.041888)+4.8] = 551.11 Kilotons of TNT
Assuming he only shook the part where they were
Using angular size calculator the distance between Envy and the Earthquake is 2.83 km
again using 5 Magnitude and a radius of 1.415 km
5+0.0238*1.415 = 5.033677
10^[1.5*(5.033677)+4.8] = 2.24138e+12 Joules or 535.70 Tons of TNT
again using higher Magnitude
7.087866e+13 Joules or 16.94 Kilotons of TNT
2.2414e+15 Joules or 535.70 Kilotons of TNT