144' The existing knowledge of the effects of the use of nucr-ear weapons is farfrom. complete. Although numerous tests have been carried out, formi.ng a basisfor the uncierstanding of the physical explosion phenomena, there &re onfy tffoinstances when ttlese veapons have been used in ,lr, on g arg""i -rql*i "g"io"t Iliroshina and on 9 August r-9\5 against Nagas'ki. The outcome of these explosionshas been. painstakingly investigated, in particular with regard. to the nr::mer otpeople ki1led or inJured.J_ and yet considerabl.y different aita are given bydifferent sources, as will be iLlustrated bellw. 145. Furthernore, a.iy assessnent of a hlT)othetical future situation based on theJapanese data *ould have to rest on interpretation and sometimes ertrapofation,as todayrs arsenals contain weapons that are a thoussrd tines nore pov-erful than lh: t*. used in Japan, but also smaJ-ler and, in sone cases, specialized weapons(cf' chap. rr). Thus there are 'ncertainties as to the effects of one sinsreexplosion. l'46. rt is a well-established fact that the explosion of a nucr-ear weapon causes d a:nage through several effects: a powerful bllst wave, intense heat r-adiationand nuclear radiation from the firebau- and from racrioactive farlout. There isalso a pul-se of electronag'etic rad.iation not directly harnfuL to living crearures.However, the size of the area affected. by these various phenomena, theii strength - in absolute terns and rerative to each oit u" - and the extent of the damage theycause wil-I depend strongly on the explosive yield but al-so on a nunber of otherfactors specific to each situation. Among tlese are the height above gxound ofAl35 /392 r,nl1'rt sn Annex I',afle > 4 the explosion, veather conditions and (parti cularly for explosions close to the grounal vind. velocity and' of course, the nature of target. The design of the weapon vi}1 also influence the outcome. 1\7. Should large mrmbers of nuclear weapons ever come to be used' the total effect vould be much more complex than the sul}: of indivi dual cases. This is in