In the Fate Series, it is said that Berserker (Heracles) physical strikes are strong enough to destroy a mountain, so I'll calc that.
The average volume of a mountain is 758590275.6 Meters^3.
758590275.6 Meters^3 = 7.585902756e+14 Cm^3
Fragmentation: (7.585902756e+14 Cm^3)*(8 Joules/cc) = 1.45 Megatons (Small City level) ACCEPTED
Violent Fragmentation: (7.585902756e+14 Cm^3)*(69 Joules/cc) = 12.5 Megatons (City level)
Pulverization: (7.585902756e+14 Cm^3)*(214.35 Joules/cc) = 38.9 Megatons (City level)
Personally I think Violent Fragmentation is the best end to use.