percentage of capacity required; the rest of the manufacturing industries are distributed as follows:

In only 10 industries would 20 to 40 percent of capacity be required; the remaining 51 are below 20 percent.

The definition of capacity is not sufficiently unambiguous in agriculture and the service industries to make comparisons of this sort meaningful.

The requirements for the output of the various industries were computed by the technique of input-output analysis, and both the direct requirements for output delivered to consumers, and the indirect requirements generated by other industries are included.

Thus the 40 percent of petroleum capacity required includes not only the allowance for such things as gasoline for private automobiles, but also the requirements for tractor fuel needed to produce food. The general conclusion is that for almost all industries under 50 percent of capacity is needed to support the full population at about the 1929 level.

Another way of putting it is to say that as long as the ratio of surviving capacity in most industries to surviving population is not much less than half the prewar ratio, support of the population at the 1929 level of consumption or better should be possible.

This is the underlying reason why studies of particular industries generally reach optimistic conclusions destruction of capacity relative to population casualties has to be quite large before a situation is reached where the support of the survivors will constitute a serious problem. Relatively minor efforts at restoring damaged capacity or building new will generally suffice.

POSSIBLE SURVIVAL LEVELS OF INDUSTRY

Let me now turn to the problem of what sort of ratios between surviving economic capacity and population might be expected to result from a thermonuclear war. The answer depends on the relative geographic concentrations of population and various types of capacity, on the enemy's choice of a targeting strategy, and on the level of the attack.

The influence of all of these factors is summarized in the series of charts I will now present.

The curves in figures W-1 and W-2 (pp. 316 and 317) show the percentage of the particular resource that is contained in the indicated number of target areas, up to the point where the curve is getting quite flat. The basic data on which these curves are based were supplied by the National Resource Evaluation Center of OCDM.

If a 10-megaton weapon made a direct hit on a target area, a large fraction of the population of that target area would be killed, unless blast shelters were available. Also, the destruction of productive capacity would be essentially total. If fallout shelter were available for the entire population, and there were essentially no primary blast shelter available, the population curves may give a rough approximation to the casualties that would result if the indicated number of target areas were attacked.

These, of course, are urban and industrial areas, and the number given does not include any allowance for attacks on strategic forces per se.

Perhaps, in order to clarify the situation with respect to the degree of blast protection involved here, I should say that the peak overpressure at the edge of a target area would be in the range of 2 to 7 p.s.i. if a 10-megaton weapon were detonated at the center of the target area.

Mr. HOLIFIELD. At what distance?

Mr. WINTER. The target areas used in this calculation are actually square areas, 20 kilometers (12.4 miles) on a side. Thus the points on the perimeter of the area would be between 6.2 and 8.8 miles from the center of the square. For a surface burst, the peak overpressure at the shorter distance would be about 3 p.s.i. and at the longer about 5; the results would of course be different for airbursts at various altitudes. The physical damage produced at these overpressure levels would be severe. However, good fallout shelters would provide blast protection adequate for this range of overpressures, as you have pointed out, Mr. Chairman.

The "rough approximation" that these curves provide to the casualty levels when the indicated number of areas are hit is probably very rough indeed.

These curves cannot safely be used for the purpose of estimating casualties and damage from any particular attack, but they are very useful for getting a picture of the range of situations that may arise with respect to the balance between surviving resources and population.

EFFECTS OF DIFFERENT TARGET SYSTEMS ON INDUSTRY

The level of destruction of any particular resource when a given number of target areas are hit obviously depends on which target areas are on the list. Figures W-1 and W-2 illustrate the different situations that arise with respect to the balance between population and survival industry. Survival industry is a broad industrial category including the industries that are important in meeting the basic

needs of the population-for example-food processing industries, medicines and medical supplies, apparel, fuels, and various industries that produce goods needed in repair of basic utilities. In Figure W-1, the concentrations are shown for the case where the areas are ranked according to population. The population curve shows, for example, that the 120 largest target areas in terms of population contain 40 percent of the country's population. The survival industry curve shows that those same 120 areas contain about 55 percent of the survival industry, in spite of the fact that the 120 areas were chosen for their high population rather than the amount of survival industry they contained. This illustrates the general tendency for industrial activity to be more concentrated geographically than the population. Figure W-2 shows the situation when survival industry, rather than population, is singled out as the target system. As might be expected, the result is that the amount of survival industry included in any given number of areas substantially exceeds the amount shown on the previous chart, while the percentage of the population is smaller. I want to relate this second chart to the conclusion I developed earlier, that the problem of supporting the surviving population is unlikely to be serious if the proportion between surviving economic capacity and population does not fall below about half its prewar value. The case where survival industry is specifically targeted is the worst case from the point of view of reducing that ratiounless, of course, the enemy also attempts specifically to avoid causing population casualties, which would be welcome. Examining the ratio between the proportions of the two categories outside any given number of target areas, we find that the ratio is about 0.75 at 40 areas, and at the right-hand side of the chart the ratio seems to be stabilizing at around 0.40. Since, as was noted earlier, the percentage of most industries required to support 1929 consumption standards is well under 40, and since 1929 standards are a long way from threatening the survival of the population, it appears that enough capacity would survive to support the surviving population even in the worst possible case. It should be noted, however, that survival industry is an aggregate, and some industries would suffer destruction in greater proportion than the aggregate. However, surviving inventories of necessities should be more than sufficient to support the population until these severe bottlenecks can be alleviated.

CONCENTRATION OF MILITARY SUPPORT INDUSTRY

The next two curves show the relative concentrations of population and of a group of industries needed in recovery and support of military forces. (See figs. W-3 and W-4, pp. 320 and 321.)