For nuclear explosive devices where the fallout is not attainable or would be misleading , neutron activation analysis is often employed as the second most accurate method , with it having been used to determine the yield of both Little Boy and thermonuclear Ivy Mike 's respective yields . Yields can also be inferred in a number of other remote sensing ways , including scaling law calculations based on blast size , infrasound , fireball brightness ( Bhangmeter ) , seismographic data ( CTBTO ) , and the strength of the shock wave
Ivy Mike
Ivy Mike
Nuclear weapon yield