EARTHQUAKES OF MAY 1960 IN CHILE — SAINT-AMAND 343 



INVESTIGATIONS 



As soon as it was possible to organize properly and equip field 

 parties, the Instituto de Investigaciones Geologicas (ILG), the 

 Chilean Geological Survey, under the direction of Don Carlos Ruiz, 

 and the Escuela de Geologia under the direction of Don Humberto 

 Fuenzalida, working in unison, divided the south into four parts and 

 sent four tracks, each with a group of geologists, into each of the areas. 

 They remained for about 3 weeks, making observations of earthquake 

 damage and recording all the geologic effects that could be observed. 

 Each group carried food, water, gasoline, and camping equipment. 



A fifth expedition was sent by private plane to make an aerial ex- 

 amination of the epicentral region and to study the needs of the people 

 in the region so that aid could be distributed more effectively. The 

 plane was placed at the disposal of the investigation by its owner, 

 Vernon Goakes, son of Harry Goakes, chief of the U.S. ICA Civil 

 Air Mission to Chile. 



Subsequently, personnel of the U.S. Geological Survey, the Inter- 

 national Cooperation Administration, the U.S. Department of State, 

 the University of California, and various other organizations joined 

 the Chilean groups in the field work. Scientific personnel from Mex- 

 ico, France, West Germany, and Japan came to do what they could 

 to help. The U.S. Coast and Geodetic Survey, the California Insti- 

 tute of Technology, and the University of California at Los Angeles 

 all contributed information. The results of the observations by these 

 people are summarized in this article. A detailed study of structural 

 damage was undertaken by members of the Earthquake Engineering 

 Research Institute and will be published elsewhere. 



DISTRIBUTION OF INTENSITY 



There were two zones of high intensity. One zone lay along the 

 coast from about Puerto Saavedra to the south of Isla Chiloe. The 

 intensity varied in this region from MMVIII to IX, with occasional 

 high points where landsliding and settling of overloaded ground de- 

 stroyed parts of some of the larger cities (pis. 2 and 3, and pi. 4, fig. 1) . 

 The intensity in the central valley was less — VI to VIII. There, 

 comparatively little damage was noted except near river banks where 

 landslides destroyed a number of buildings, and the railroad and high- 

 way were interrupted. A second zone of high intensity, coincident 

 with the Reloncavi Fault (fig. 3), was found to the east of the Lakes. 

 Here, a long narrow band some tens of kilometers wide and several 

 hundred kilometers long suffered from a rapid high- intensity shaking. 

 The two zones converged toward the south. 



In the Lakes Region landslides occurred in thousands of localities. 

 Waves were produced in the Lakes by the earthquake, and an oscilla- 



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