The Earthquake at San Juan, January 15, 1944

Abstract

HORACIO J. HARRINGTON, professor of geology at the University of Buenos Aires, has described some of the effects of this earthquake ("El Sismo de San Juan del 15 de enero de 1944", Cienciae Investigación, Jan. 1945). The shock occurred at 19h. 46m. 29s. without any previous warning and attained a maximum intensity in a few seconds, ending suddenly about 15 seconds after the first shock. The first shock was from below upwards, and in a few seconds afterwards a new shock took place in a horizontal direction and of an undulatory nature, from west to east. When the tremors had ceased, some 90 per cent of the buildings in San Juan had been totally or partially destroyed. The depth of focus was 14 km., with a probable error of 3 km., and the epicentre included the zone extending north from San Juan to Chimbas and Albardón. The intensity of the San Juan earthquake was ix on Sieberg's scale, and so was not excessive; nevertheless the destruction was very much greater than would have been expected. Out of a total population of seventy to eighty thousand, about eight thousand were killed and twelve thousand injured; the disproportion between the intensity of the earthquake and the destruction effected is obvious. The loss of life in the San Juan earthquake was due to the buildings being made with unbaked bricks of clay; these should be avoided in reconstruction. In addition, many of the cities of the country are built at the foot of high mountain ranges, and zones of fracture render their existence more or less precarious.