EARTHQUAKES AND HUMAN LIFE

Evening Star, Issue 20612, 11 October 1930, Page 2

EARTHQUAKES AND HUMAN LIFE

ESTIMATES OF AHHUAI LOSS [By Chaiu.es Davison, Sc.D. iu ‘The Times. 5 ] s The recent earthquake in Italy has drawn attention to the_ heavy loss of life that may occur within a small area, and has shown how serious must be the total loss every year in all the earthquake countries of the world. In his recent work ‘ Our Mobile Earth 5 (pp. 1-4), Professor R. A. Daly quotes an estimate made by One of the early seismologists, Robert Mallet, that in nearly -4,000 years earthquakes have caused the loss of 13,000,000 _ lives. Pointing to “the newest pestilence, the automobile, 55 he adds that this rate is only one-sixth of that at which the automobile is destroying lives in the United States alone.

I have been led by this interesting comparison to attempt a new estimate of the average annual loss of life from earthquakes, for Mallet does not seem to have been acquainted with the figures for some of the most destructive earthquakes on record—with those, for instance, of the Indian earthquake: of 1737, when 300,000 persons were killed, and of the Chinese earthquake of 1556, in which more than 830,000 persons are said to have lost their lives. Even during the present century the three great earthquakes of Messina in 1908, Northwest China in 1920, and Japan in 1923. if spread over the whole century, would give an average of at least 3,800 deaths a year, a figure that is rather higher than Mallet’s rate for all the earthquakes of the century. In 1911 the late Professor Milne published his great catalogue of destructive earthquakes for the _ whole world. It begins with the Christian era and ends with the year 1899. During the last century covered by it the catalogue cannot be otherwise than very nearly complete. The total number of earthquakes recorded from 1800 to 1899. is 2,096, of which 1,222 were just strong enough to crack some walls or throw down a few chimneys, 510 unroofed or shattered buildings, while 364 were so powerful that whole towns were destroyed, and districts devastated, a class in which the recent Italian earthquake would, no doubt, have been: placed. For oiir present purpose the first class may be neglected, since few, if any, of them can have resulted in an appreciable loss of life. In his valuable catalogue of Italian earthquakes (‘ I Terremoti d s ltalia 5 ) Dr Mario Baratta gives the number of lives lost during nearly every destructive shock of the last three centuries. He describes thirty-five earthquakes of Milne 5 s third or highest degree of intensity and 125 of the second. In eight of the latter, however, the numbers of deaths were so high, ranging from 200 to 20,000, that I have transferred them to the higher grade, thus giving fortythree earthquakes of the third and 117 of the second degree. The total number of deaths caused by earthquakes of the third degree was 181,567, or 4,222 per earthquake., The number due to earthquakes of the second degree was 971, or 8.3 deaths per earthquake. Thus, if we may assume that the Italian rates prevail for the whole world during the ninteenth century, the average number of deaths every year would be 15,368 for earthquakes or the third degree and forty-two for those of the second, a total of 15,410. It may be urged with some force thak to apply the Italian rates to the whole world would magnify the total loss. Owing to .the faulty construction of.the older Italian ! houses and to the,: situation of many of the towns on the summits of steep hills the death rates in some cities are far above the average for other countries. To realise this we have only to recall that 41 per cent, of the inhabitants of Casamicciola were killed during the Ischian earthquake of 1883, 50 per cent, of those at Messina during the earthquake of 1908, 71 per cent, at Montemurro during the Neapolitari earthquake of 1857, 77 per cent, at Terranova during the Calabrian earthquakes of 1783, and Simper cent, at Avendita during the Norcian earthquake of 1703. On the other hand, the area of destruction, ,in Italian earthquakes is always unusually small—in tile Avezzano earthquake of 1915, for instance, about 100 square miles, and in some of the Etnean and Ischian earthquakes less than sis square miles—while in the great earthquakes of other lands the corresponding area may range from 1,000 to 6,000 square miles. In only three or four Italian earthquakes during the three centuries considered does tlie total loss exceed 10,000_ lives. The only other country for which we possess a similar series of figures is Japan, and we are indebted to Professor A/ Imamura for the number of persons killed during the more important earthquakes of that _ country. During the eighteenth and nineteenth centuries eight 'great earthquakes contributed . a total death roll of 31,140, an average of 3,892 per earthquake. At the same rate the total number of deaths every year for the whole world would be 14,169. , Thus, though we must remember that the centuries considered included no earthquake so destructive of human life as, say, the Japanese earthquake bf 1923, it would seem fair to conclude that the average number of persons killed by earthquakes every year is about 14,000 or 15.000, certainly less than the number of persons kdled by motors every year in the United States alone, and not much more than twice the number killed in this country.